Imported Upstream version 2.27.0
[platform/upstream/git.git] / builtin / pack-objects.c
index c753e92..c5b433a 100644 (file)
@@ -1,5 +1,6 @@
 #include "builtin.h"
 #include "cache.h"
+#include "repository.h"
 #include "config.h"
 #include "attr.h"
 #include "object.h"
 #include "diff.h"
 #include "revision.h"
 #include "list-objects.h"
+#include "list-objects-filter.h"
+#include "list-objects-filter-options.h"
 #include "pack-objects.h"
 #include "progress.h"
 #include "refs.h"
 #include "streaming.h"
 #include "thread-utils.h"
 #include "pack-bitmap.h"
+#include "delta-islands.h"
 #include "reachable.h"
-#include "sha1-array.h"
+#include "oid-array.h"
 #include "argv-array.h"
-#include "mru.h"
+#include "list.h"
+#include "packfile.h"
+#include "object-store.h"
+#include "dir.h"
+#include "midx.h"
+#include "trace2.h"
+#include "shallow.h"
+
+#define IN_PACK(obj) oe_in_pack(&to_pack, obj)
+#define SIZE(obj) oe_size(&to_pack, obj)
+#define SET_SIZE(obj,size) oe_set_size(&to_pack, obj, size)
+#define DELTA_SIZE(obj) oe_delta_size(&to_pack, obj)
+#define DELTA(obj) oe_delta(&to_pack, obj)
+#define DELTA_CHILD(obj) oe_delta_child(&to_pack, obj)
+#define DELTA_SIBLING(obj) oe_delta_sibling(&to_pack, obj)
+#define SET_DELTA(obj, val) oe_set_delta(&to_pack, obj, val)
+#define SET_DELTA_EXT(obj, oid) oe_set_delta_ext(&to_pack, obj, oid)
+#define SET_DELTA_SIZE(obj, val) oe_set_delta_size(&to_pack, obj, val)
+#define SET_DELTA_CHILD(obj, val) oe_set_delta_child(&to_pack, obj, val)
+#define SET_DELTA_SIBLING(obj, val) oe_set_delta_sibling(&to_pack, obj, val)
 
 static const char *pack_usage[] = {
        N_("git pack-objects --stdout [<options>...] [< <ref-list> | < <object-list>]"),
@@ -40,7 +63,9 @@ static const char *pack_usage[] = {
 static struct packing_data to_pack;
 
 static struct pack_idx_entry **written_list;
-static uint32_t nr_result, nr_written;
+static uint32_t nr_result, nr_written, nr_seen;
+static struct bitmap_index *bitmap_git;
+static uint32_t write_layer;
 
 static int non_empty;
 static int reuse_delta = 1, reuse_object = 1;
@@ -50,7 +75,8 @@ static int pack_loose_unreachable;
 static int local;
 static int have_non_local_packs;
 static int incremental;
-static int ignore_packed_keep;
+static int ignore_packed_keep_on_disk;
+static int ignore_packed_keep_in_core;
 static int allow_ofs_delta;
 static struct pack_idx_option pack_idx_opts;
 static const char *base_name;
@@ -60,24 +86,45 @@ static unsigned long pack_size_limit;
 static int depth = 50;
 static int delta_search_threads;
 static int pack_to_stdout;
+static int sparse;
+static int thin;
 static int num_preferred_base;
 static struct progress *progress_state;
 
 static struct packed_git *reuse_packfile;
 static uint32_t reuse_packfile_objects;
-static off_t reuse_packfile_offset;
+static struct bitmap *reuse_packfile_bitmap;
 
 static int use_bitmap_index_default = 1;
 static int use_bitmap_index = -1;
-static int write_bitmap_index;
-static uint16_t write_bitmap_options;
+static int allow_pack_reuse = 1;
+static enum {
+       WRITE_BITMAP_FALSE = 0,
+       WRITE_BITMAP_QUIET,
+       WRITE_BITMAP_TRUE,
+} write_bitmap_index;
+static uint16_t write_bitmap_options = BITMAP_OPT_HASH_CACHE;
+
+static int exclude_promisor_objects;
+
+static int use_delta_islands;
 
 static unsigned long delta_cache_size = 0;
-static unsigned long max_delta_cache_size = 256 * 1024 * 1024;
+static unsigned long max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE;
 static unsigned long cache_max_small_delta_size = 1000;
 
 static unsigned long window_memory_limit = 0;
 
+static struct list_objects_filter_options filter_options;
+
+enum missing_action {
+       MA_ERROR = 0,      /* fail if any missing objects are encountered */
+       MA_ALLOW_ANY,      /* silently allow ALL missing objects */
+       MA_ALLOW_PROMISOR, /* silently allow all missing PROMISOR objects */
+};
+static enum missing_action arg_missing_action;
+static show_object_fn fn_show_object;
+
 /*
  * stats
  */
@@ -107,18 +154,23 @@ static void *get_delta(struct object_entry *entry)
        void *buf, *base_buf, *delta_buf;
        enum object_type type;
 
-       buf = read_sha1_file(entry->idx.oid.hash, &type, &size);
+       buf = read_object_file(&entry->idx.oid, &type, &size);
        if (!buf)
-               die("unable to read %s", oid_to_hex(&entry->idx.oid));
-       base_buf = read_sha1_file(entry->delta->idx.oid.hash, &type,
-                                 &base_size);
+               die(_("unable to read %s"), oid_to_hex(&entry->idx.oid));
+       base_buf = read_object_file(&DELTA(entry)->idx.oid, &type,
+                                   &base_size);
        if (!base_buf)
                die("unable to read %s",
-                   oid_to_hex(&entry->delta->idx.oid));
+                   oid_to_hex(&DELTA(entry)->idx.oid));
        delta_buf = diff_delta(base_buf, base_size,
                               buf, size, &delta_size, 0);
-       if (!delta_buf || delta_size != entry->delta_size)
-               die("delta size changed");
+       /*
+        * We successfully computed this delta once but dropped it for
+        * memory reasons. Something is very wrong if this time we
+        * recompute and create a different delta.
+        */
+       if (!delta_buf || delta_size != DELTA_SIZE(entry))
+               BUG("delta size changed");
        free(buf);
        free(base_buf);
        return delta_buf;
@@ -149,8 +201,8 @@ static unsigned long do_compress(void **pptr, unsigned long size)
        return stream.total_out;
 }
 
-static unsigned long write_large_blob_data(struct git_istream *st, struct sha1file *f,
-                                          const unsigned char *sha1)
+static unsigned long write_large_blob_data(struct git_istream *st, struct hashfile *f,
+                                          const struct object_id *oid)
 {
        git_zstream stream;
        unsigned char ibuf[1024 * 16];
@@ -164,7 +216,7 @@ static unsigned long write_large_blob_data(struct git_istream *st, struct sha1fi
                int zret = Z_OK;
                readlen = read_istream(st, ibuf, sizeof(ibuf));
                if (readlen == -1)
-                       die(_("unable to read %s"), sha1_to_hex(sha1));
+                       die(_("unable to read %s"), oid_to_hex(oid));
 
                stream.next_in = ibuf;
                stream.avail_in = readlen;
@@ -173,7 +225,7 @@ static unsigned long write_large_blob_data(struct git_istream *st, struct sha1fi
                        stream.next_out = obuf;
                        stream.avail_out = sizeof(obuf);
                        zret = git_deflate(&stream, readlen ? 0 : Z_FINISH);
-                       sha1write(f, obuf, stream.next_out - obuf);
+                       hashwrite(f, obuf, stream.next_out - obuf);
                        olen += stream.next_out - obuf;
                }
                if (stream.avail_in)
@@ -218,7 +270,7 @@ static int check_pack_inflate(struct packed_git *p,
                stream.total_in == len) ? 0 : -1;
 }
 
-static void copy_pack_data(struct sha1file *f,
+static void copy_pack_data(struct hashfile *f,
                struct packed_git *p,
                struct pack_window **w_curs,
                off_t offset,
@@ -231,14 +283,14 @@ static void copy_pack_data(struct sha1file *f,
                in = use_pack(p, w_curs, offset, &avail);
                if (avail > len)
                        avail = (unsigned long)len;
-               sha1write(f, in, avail);
+               hashwrite(f, in, avail);
                offset += avail;
                len -= avail;
        }
 }
 
 /* Return 0 if we will bust the pack-size limit */
-static unsigned long write_no_reuse_object(struct sha1file *f, struct object_entry *entry,
+static unsigned long write_no_reuse_object(struct hashfile *f, struct object_entry *entry,
                                           unsigned long limit, int usable_delta)
 {
        unsigned long size, datalen;
@@ -248,15 +300,16 @@ static unsigned long write_no_reuse_object(struct sha1file *f, struct object_ent
        enum object_type type;
        void *buf;
        struct git_istream *st = NULL;
+       const unsigned hashsz = the_hash_algo->rawsz;
 
        if (!usable_delta) {
-               if (entry->type == OBJ_BLOB &&
-                   entry->size > big_file_threshold &&
-                   (st = open_istream(entry->idx.oid.hash, &type, &size, NULL)) != NULL)
+               if (oe_type(entry) == OBJ_BLOB &&
+                   oe_size_greater_than(&to_pack, entry, big_file_threshold) &&
+                   (st = open_istream(the_repository, &entry->idx.oid, &type,
+                                      &size, NULL)) != NULL)
                        buf = NULL;
                else {
-                       buf = read_sha1_file(entry->idx.oid.hash, &type,
-                                            &size);
+                       buf = read_object_file(&entry->idx.oid, &type, &size);
                        if (!buf)
                                die(_("unable to read %s"),
                                    oid_to_hex(&entry->idx.oid));
@@ -268,15 +321,15 @@ static unsigned long write_no_reuse_object(struct sha1file *f, struct object_ent
                FREE_AND_NULL(entry->delta_data);
                entry->z_delta_size = 0;
        } else if (entry->delta_data) {
-               size = entry->delta_size;
+               size = DELTA_SIZE(entry);
                buf = entry->delta_data;
                entry->delta_data = NULL;
-               type = (allow_ofs_delta && entry->delta->idx.offset) ?
+               type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
                        OBJ_OFS_DELTA : OBJ_REF_DELTA;
        } else {
                buf = get_delta(entry);
-               size = entry->delta_size;
-               type = (allow_ofs_delta && entry->delta->idx.offset) ?
+               size = DELTA_SIZE(entry);
+               type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
                        OBJ_OFS_DELTA : OBJ_REF_DELTA;
        }
 
@@ -300,48 +353,48 @@ static unsigned long write_no_reuse_object(struct sha1file *f, struct object_ent
                 * encoding of the relative offset for the delta
                 * base from this object's position in the pack.
                 */
-               off_t ofs = entry->idx.offset - entry->delta->idx.offset;
+               off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
                unsigned pos = sizeof(dheader) - 1;
                dheader[pos] = ofs & 127;
                while (ofs >>= 7)
                        dheader[--pos] = 128 | (--ofs & 127);
-               if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
+               if (limit && hdrlen + sizeof(dheader) - pos + datalen + hashsz >= limit) {
                        if (st)
                                close_istream(st);
                        free(buf);
                        return 0;
                }
-               sha1write(f, header, hdrlen);
-               sha1write(f, dheader + pos, sizeof(dheader) - pos);
+               hashwrite(f, header, hdrlen);
+               hashwrite(f, dheader + pos, sizeof(dheader) - pos);
                hdrlen += sizeof(dheader) - pos;
        } else if (type == OBJ_REF_DELTA) {
                /*
                 * Deltas with a base reference contain
-                * an additional 20 bytes for the base sha1.
+                * additional bytes for the base object ID.
                 */
-               if (limit && hdrlen + 20 + datalen + 20 >= limit) {
+               if (limit && hdrlen + hashsz + datalen + hashsz >= limit) {
                        if (st)
                                close_istream(st);
                        free(buf);
                        return 0;
                }
-               sha1write(f, header, hdrlen);
-               sha1write(f, entry->delta->idx.oid.hash, 20);
-               hdrlen += 20;
+               hashwrite(f, header, hdrlen);
+               hashwrite(f, DELTA(entry)->idx.oid.hash, hashsz);
+               hdrlen += hashsz;
        } else {
-               if (limit && hdrlen + datalen + 20 >= limit) {
+               if (limit && hdrlen + datalen + hashsz >= limit) {
                        if (st)
                                close_istream(st);
                        free(buf);
                        return 0;
                }
-               sha1write(f, header, hdrlen);
+               hashwrite(f, header, hdrlen);
        }
        if (st) {
-               datalen = write_large_blob_data(st, f, entry->idx.oid.hash);
+               datalen = write_large_blob_data(st, f, &entry->idx.oid);
                close_istream(st);
        } else {
-               sha1write(f, buf, datalen);
+               hashwrite(f, buf, datalen);
                free(buf);
        }
 
@@ -349,31 +402,33 @@ static unsigned long write_no_reuse_object(struct sha1file *f, struct object_ent
 }
 
 /* Return 0 if we will bust the pack-size limit */
-static off_t write_reuse_object(struct sha1file *f, struct object_entry *entry,
+static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
                                unsigned long limit, int usable_delta)
 {
-       struct packed_git *p = entry->in_pack;
+       struct packed_git *p = IN_PACK(entry);
        struct pack_window *w_curs = NULL;
        struct revindex_entry *revidx;
        off_t offset;
-       enum object_type type = entry->type;
+       enum object_type type = oe_type(entry);
        off_t datalen;
        unsigned char header[MAX_PACK_OBJECT_HEADER],
                      dheader[MAX_PACK_OBJECT_HEADER];
        unsigned hdrlen;
+       const unsigned hashsz = the_hash_algo->rawsz;
+       unsigned long entry_size = SIZE(entry);
 
-       if (entry->delta)
-               type = (allow_ofs_delta && entry->delta->idx.offset) ?
+       if (DELTA(entry))
+               type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
                        OBJ_OFS_DELTA : OBJ_REF_DELTA;
        hdrlen = encode_in_pack_object_header(header, sizeof(header),
-                                             type, entry->size);
+                                             type, entry_size);
 
        offset = entry->in_pack_offset;
        revidx = find_pack_revindex(p, offset);
        datalen = revidx[1].offset - offset;
        if (!pack_to_stdout && p->index_version > 1 &&
            check_pack_crc(p, &w_curs, offset, datalen, revidx->nr)) {
-               error("bad packed object CRC for %s",
+               error(_("bad packed object CRC for %s"),
                      oid_to_hex(&entry->idx.oid));
                unuse_pack(&w_curs);
                return write_no_reuse_object(f, entry, limit, usable_delta);
@@ -383,42 +438,42 @@ static off_t write_reuse_object(struct sha1file *f, struct object_entry *entry,
        datalen -= entry->in_pack_header_size;
 
        if (!pack_to_stdout && p->index_version == 1 &&
-           check_pack_inflate(p, &w_curs, offset, datalen, entry->size)) {
-               error("corrupt packed object for %s",
+           check_pack_inflate(p, &w_curs, offset, datalen, entry_size)) {
+               error(_("corrupt packed object for %s"),
                      oid_to_hex(&entry->idx.oid));
                unuse_pack(&w_curs);
                return write_no_reuse_object(f, entry, limit, usable_delta);
        }
 
        if (type == OBJ_OFS_DELTA) {
-               off_t ofs = entry->idx.offset - entry->delta->idx.offset;
+               off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
                unsigned pos = sizeof(dheader) - 1;
                dheader[pos] = ofs & 127;
                while (ofs >>= 7)
                        dheader[--pos] = 128 | (--ofs & 127);
-               if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
+               if (limit && hdrlen + sizeof(dheader) - pos + datalen + hashsz >= limit) {
                        unuse_pack(&w_curs);
                        return 0;
                }
-               sha1write(f, header, hdrlen);
-               sha1write(f, dheader + pos, sizeof(dheader) - pos);
+               hashwrite(f, header, hdrlen);
+               hashwrite(f, dheader + pos, sizeof(dheader) - pos);
                hdrlen += sizeof(dheader) - pos;
                reused_delta++;
        } else if (type == OBJ_REF_DELTA) {
-               if (limit && hdrlen + 20 + datalen + 20 >= limit) {
+               if (limit && hdrlen + hashsz + datalen + hashsz >= limit) {
                        unuse_pack(&w_curs);
                        return 0;
                }
-               sha1write(f, header, hdrlen);
-               sha1write(f, entry->delta->idx.oid.hash, 20);
-               hdrlen += 20;
+               hashwrite(f, header, hdrlen);
+               hashwrite(f, DELTA(entry)->idx.oid.hash, hashsz);
+               hdrlen += hashsz;
                reused_delta++;
        } else {
-               if (limit && hdrlen + datalen + 20 >= limit) {
+               if (limit && hdrlen + datalen + hashsz >= limit) {
                        unuse_pack(&w_curs);
                        return 0;
                }
-               sha1write(f, header, hdrlen);
+               hashwrite(f, header, hdrlen);
        }
        copy_pack_data(f, p, &w_curs, offset, datalen);
        unuse_pack(&w_curs);
@@ -427,7 +482,7 @@ static off_t write_reuse_object(struct sha1file *f, struct object_entry *entry,
 }
 
 /* Return 0 if we will bust the pack-size limit */
-static off_t write_object(struct sha1file *f,
+static off_t write_object(struct hashfile *f,
                          struct object_entry *entry,
                          off_t write_offset)
 {
@@ -450,28 +505,29 @@ static off_t write_object(struct sha1file *f,
        else
                limit = pack_size_limit - write_offset;
 
-       if (!entry->delta)
+       if (!DELTA(entry))
                usable_delta = 0;       /* no delta */
        else if (!pack_size_limit)
               usable_delta = 1;        /* unlimited packfile */
-       else if (entry->delta->idx.offset == (off_t)-1)
+       else if (DELTA(entry)->idx.offset == (off_t)-1)
                usable_delta = 0;       /* base was written to another pack */
-       else if (entry->delta->idx.offset)
+       else if (DELTA(entry)->idx.offset)
                usable_delta = 1;       /* base already exists in this pack */
        else
                usable_delta = 0;       /* base could end up in another pack */
 
        if (!reuse_object)
                to_reuse = 0;   /* explicit */
-       else if (!entry->in_pack)
+       else if (!IN_PACK(entry))
                to_reuse = 0;   /* can't reuse what we don't have */
-       else if (entry->type == OBJ_REF_DELTA || entry->type == OBJ_OFS_DELTA)
+       else if (oe_type(entry) == OBJ_REF_DELTA ||
+                oe_type(entry) == OBJ_OFS_DELTA)
                                /* check_object() decided it for us ... */
                to_reuse = usable_delta;
                                /* ... but pack split may override that */
-       else if (entry->type != entry->in_pack_type)
+       else if (oe_type(entry) != entry->in_pack_type)
                to_reuse = 0;   /* pack has delta which is unusable */
-       else if (entry->delta)
+       else if (DELTA(entry))
                to_reuse = 0;   /* we want to pack afresh */
        else
                to_reuse = 1;   /* we have it in-pack undeltified,
@@ -500,7 +556,7 @@ enum write_one_status {
        WRITE_ONE_RECURSIVE = 2 /* already scheduled to be written */
 };
 
-static enum write_one_status write_one(struct sha1file *f,
+static enum write_one_status write_one(struct hashfile *f,
                                       struct object_entry *e,
                                       off_t *offset)
 {
@@ -514,7 +570,7 @@ static enum write_one_status write_one(struct sha1file *f,
         */
        recursing = (e->idx.offset == 1);
        if (recursing) {
-               warning("recursive delta detected for object %s",
+               warning(_("recursive delta detected for object %s"),
                        oid_to_hex(&e->idx.oid));
                return WRITE_ONE_RECURSIVE;
        } else if (e->idx.offset || e->preferred_base) {
@@ -523,12 +579,12 @@ static enum write_one_status write_one(struct sha1file *f,
        }
 
        /* if we are deltified, write out base object first. */
-       if (e->delta) {
+       if (DELTA(e)) {
                e->idx.offset = 1; /* now recurse */
-               switch (write_one(f, e->delta, offset)) {
+               switch (write_one(f, DELTA(e), offset)) {
                case WRITE_ONE_RECURSIVE:
                        /* we cannot depend on this one */
-                       e->delta = NULL;
+                       SET_DELTA(e, NULL);
                        break;
                default:
                        break;
@@ -548,7 +604,7 @@ static enum write_one_status write_one(struct sha1file *f,
 
        /* make sure off_t is sufficiently large not to wrap */
        if (signed_add_overflows(*offset, size))
-               die("pack too large for current definition of off_t");
+               die(_("pack too large for current definition of off_t"));
        *offset += size;
        return WRITE_ONE_WRITTEN;
 }
@@ -556,13 +612,13 @@ static enum write_one_status write_one(struct sha1file *f,
 static int mark_tagged(const char *path, const struct object_id *oid, int flag,
                       void *cb_data)
 {
-       unsigned char peeled[20];
-       struct object_entry *entry = packlist_find(&to_pack, oid->hash, NULL);
+       struct object_id peeled;
+       struct object_entry *entry = packlist_find(&to_pack, oid);
 
        if (entry)
                entry->tagged = 1;
-       if (!peel_ref(path, peeled)) {
-               entry = packlist_find(&to_pack, peeled, NULL);
+       if (!peel_ref(path, &peeled)) {
+               entry = packlist_find(&to_pack, &peeled);
                if (entry)
                        entry->tagged = 1;
        }
@@ -573,7 +629,7 @@ static inline void add_to_write_order(struct object_entry **wo,
                               unsigned int *endp,
                               struct object_entry *e)
 {
-       if (e->filled)
+       if (e->filled || oe_layer(&to_pack, e) != write_layer)
                return;
        wo[(*endp)++] = e;
        e->filled = 1;
@@ -590,34 +646,34 @@ static void add_descendants_to_write_order(struct object_entry **wo,
                        /* add this node... */
                        add_to_write_order(wo, endp, e);
                        /* all its siblings... */
-                       for (s = e->delta_sibling; s; s = s->delta_sibling) {
+                       for (s = DELTA_SIBLING(e); s; s = DELTA_SIBLING(s)) {
                                add_to_write_order(wo, endp, s);
                        }
                }
                /* drop down a level to add left subtree nodes if possible */
-               if (e->delta_child) {
+               if (DELTA_CHILD(e)) {
                        add_to_order = 1;
-                       e = e->delta_child;
+                       e = DELTA_CHILD(e);
                } else {
                        add_to_order = 0;
                        /* our sibling might have some children, it is next */
-                       if (e->delta_sibling) {
-                               e = e->delta_sibling;
+                       if (DELTA_SIBLING(e)) {
+                               e = DELTA_SIBLING(e);
                                continue;
                        }
                        /* go back to our parent node */
-                       e = e->delta;
-                       while (e && !e->delta_sibling) {
+                       e = DELTA(e);
+                       while (e && !DELTA_SIBLING(e)) {
                                /* we're on the right side of a subtree, keep
                                 * going up until we can go right again */
-                               e = e->delta;
+                               e = DELTA(e);
                        }
                        if (!e) {
                                /* done- we hit our original root node */
                                return;
                        }
                        /* pass it off to sibling at this level */
-                       e = e->delta_sibling;
+                       e = DELTA_SIBLING(e);
                }
        };
 }
@@ -628,53 +684,20 @@ static void add_family_to_write_order(struct object_entry **wo,
 {
        struct object_entry *root;
 
-       for (root = e; root->delta; root = root->delta)
+       for (root = e; DELTA(root); root = DELTA(root))
                ; /* nothing */
        add_descendants_to_write_order(wo, endp, root);
 }
 
-static struct object_entry **compute_write_order(void)
+static void compute_layer_order(struct object_entry **wo, unsigned int *wo_end)
 {
-       unsigned int i, wo_end, last_untagged;
-
-       struct object_entry **wo;
+       unsigned int i, last_untagged;
        struct object_entry *objects = to_pack.objects;
 
        for (i = 0; i < to_pack.nr_objects; i++) {
-               objects[i].tagged = 0;
-               objects[i].filled = 0;
-               objects[i].delta_child = NULL;
-               objects[i].delta_sibling = NULL;
-       }
-
-       /*
-        * Fully connect delta_child/delta_sibling network.
-        * Make sure delta_sibling is sorted in the original
-        * recency order.
-        */
-       for (i = to_pack.nr_objects; i > 0;) {
-               struct object_entry *e = &objects[--i];
-               if (!e->delta)
-                       continue;
-               /* Mark me as the first child */
-               e->delta_sibling = e->delta->delta_child;
-               e->delta->delta_child = e;
-       }
-
-       /*
-        * Mark objects that are at the tip of tags.
-        */
-       for_each_tag_ref(mark_tagged, NULL);
-
-       /*
-        * Give the objects in the original recency order until
-        * we see a tagged tip.
-        */
-       ALLOC_ARRAY(wo, to_pack.nr_objects);
-       for (i = wo_end = 0; i < to_pack.nr_objects; i++) {
                if (objects[i].tagged)
                        break;
-               add_to_write_order(wo, &wo_end, &objects[i]);
+               add_to_write_order(wo, wo_end, &objects[i]);
        }
        last_untagged = i;
 
@@ -683,93 +706,267 @@ static struct object_entry **compute_write_order(void)
         */
        for (; i < to_pack.nr_objects; i++) {
                if (objects[i].tagged)
-                       add_to_write_order(wo, &wo_end, &objects[i]);
+                       add_to_write_order(wo, wo_end, &objects[i]);
        }
 
        /*
         * And then all remaining commits and tags.
         */
        for (i = last_untagged; i < to_pack.nr_objects; i++) {
-               if (objects[i].type != OBJ_COMMIT &&
-                   objects[i].type != OBJ_TAG)
+               if (oe_type(&objects[i]) != OBJ_COMMIT &&
+                   oe_type(&objects[i]) != OBJ_TAG)
                        continue;
-               add_to_write_order(wo, &wo_end, &objects[i]);
+               add_to_write_order(wo, wo_end, &objects[i]);
        }
 
        /*
         * And then all the trees.
         */
        for (i = last_untagged; i < to_pack.nr_objects; i++) {
-               if (objects[i].type != OBJ_TREE)
+               if (oe_type(&objects[i]) != OBJ_TREE)
                        continue;
-               add_to_write_order(wo, &wo_end, &objects[i]);
+               add_to_write_order(wo, wo_end, &objects[i]);
        }
 
        /*
         * Finally all the rest in really tight order
         */
        for (i = last_untagged; i < to_pack.nr_objects; i++) {
-               if (!objects[i].filled)
-                       add_family_to_write_order(wo, &wo_end, &objects[i]);
+               if (!objects[i].filled && oe_layer(&to_pack, &objects[i]) == write_layer)
+                       add_family_to_write_order(wo, wo_end, &objects[i]);
        }
+}
+
+static struct object_entry **compute_write_order(void)
+{
+       uint32_t max_layers = 1;
+       unsigned int i, wo_end;
+
+       struct object_entry **wo;
+       struct object_entry *objects = to_pack.objects;
+
+       for (i = 0; i < to_pack.nr_objects; i++) {
+               objects[i].tagged = 0;
+               objects[i].filled = 0;
+               SET_DELTA_CHILD(&objects[i], NULL);
+               SET_DELTA_SIBLING(&objects[i], NULL);
+       }
+
+       /*
+        * Fully connect delta_child/delta_sibling network.
+        * Make sure delta_sibling is sorted in the original
+        * recency order.
+        */
+       for (i = to_pack.nr_objects; i > 0;) {
+               struct object_entry *e = &objects[--i];
+               if (!DELTA(e))
+                       continue;
+               /* Mark me as the first child */
+               e->delta_sibling_idx = DELTA(e)->delta_child_idx;
+               SET_DELTA_CHILD(DELTA(e), e);
+       }
+
+       /*
+        * Mark objects that are at the tip of tags.
+        */
+       for_each_tag_ref(mark_tagged, NULL);
+
+       if (use_delta_islands)
+               max_layers = compute_pack_layers(&to_pack);
+
+       ALLOC_ARRAY(wo, to_pack.nr_objects);
+       wo_end = 0;
+
+       for (; write_layer < max_layers; ++write_layer)
+               compute_layer_order(wo, &wo_end);
 
        if (wo_end != to_pack.nr_objects)
-               die("ordered %u objects, expected %"PRIu32, wo_end, to_pack.nr_objects);
+               die(_("ordered %u objects, expected %"PRIu32),
+                   wo_end, to_pack.nr_objects);
 
        return wo;
 }
 
-static off_t write_reused_pack(struct sha1file *f)
+
+/*
+ * A reused set of objects. All objects in a chunk have the same
+ * relative position in the original packfile and the generated
+ * packfile.
+ */
+
+static struct reused_chunk {
+       /* The offset of the first object of this chunk in the original
+        * packfile. */
+       off_t original;
+       /* The offset of the first object of this chunk in the generated
+        * packfile minus "original". */
+       off_t difference;
+} *reused_chunks;
+static int reused_chunks_nr;
+static int reused_chunks_alloc;
+
+static void record_reused_object(off_t where, off_t offset)
+{
+       if (reused_chunks_nr && reused_chunks[reused_chunks_nr-1].difference == offset)
+               return;
+
+       ALLOC_GROW(reused_chunks, reused_chunks_nr + 1,
+                  reused_chunks_alloc);
+       reused_chunks[reused_chunks_nr].original = where;
+       reused_chunks[reused_chunks_nr].difference = offset;
+       reused_chunks_nr++;
+}
+
+/*
+ * Binary search to find the chunk that "where" is in. Note
+ * that we're not looking for an exact match, just the first
+ * chunk that contains it (which implicitly ends at the start
+ * of the next chunk.
+ */
+static off_t find_reused_offset(off_t where)
 {
-       unsigned char buffer[8192];
-       off_t to_write, total;
-       int fd;
+       int lo = 0, hi = reused_chunks_nr;
+       while (lo < hi) {
+               int mi = lo + ((hi - lo) / 2);
+               if (where == reused_chunks[mi].original)
+                       return reused_chunks[mi].difference;
+               if (where < reused_chunks[mi].original)
+                       hi = mi;
+               else
+                       lo = mi + 1;
+       }
 
-       if (!is_pack_valid(reuse_packfile))
-               die("packfile is invalid: %s", reuse_packfile->pack_name);
+       /*
+        * The first chunk starts at zero, so we can't have gone below
+        * there.
+        */
+       assert(lo);
+       return reused_chunks[lo-1].difference;
+}
 
-       fd = git_open(reuse_packfile->pack_name);
-       if (fd < 0)
-               die_errno("unable to open packfile for reuse: %s",
-                         reuse_packfile->pack_name);
+static void write_reused_pack_one(size_t pos, struct hashfile *out,
+                                 struct pack_window **w_curs)
+{
+       off_t offset, next, cur;
+       enum object_type type;
+       unsigned long size;
 
-       if (lseek(fd, sizeof(struct pack_header), SEEK_SET) == -1)
-               die_errno("unable to seek in reused packfile");
+       offset = reuse_packfile->revindex[pos].offset;
+       next = reuse_packfile->revindex[pos + 1].offset;
 
-       if (reuse_packfile_offset < 0)
-               reuse_packfile_offset = reuse_packfile->pack_size - 20;
+       record_reused_object(offset, offset - hashfile_total(out));
 
-       total = to_write = reuse_packfile_offset - sizeof(struct pack_header);
+       cur = offset;
+       type = unpack_object_header(reuse_packfile, w_curs, &cur, &size);
+       assert(type >= 0);
 
-       while (to_write) {
-               int read_pack = xread(fd, buffer, sizeof(buffer));
+       if (type == OBJ_OFS_DELTA) {
+               off_t base_offset;
+               off_t fixup;
 
-               if (read_pack <= 0)
-                       die_errno("unable to read from reused packfile");
+               unsigned char header[MAX_PACK_OBJECT_HEADER];
+               unsigned len;
 
-               if (read_pack > to_write)
-                       read_pack = to_write;
+               base_offset = get_delta_base(reuse_packfile, w_curs, &cur, type, offset);
+               assert(base_offset != 0);
 
-               sha1write(f, buffer, read_pack);
-               to_write -= read_pack;
+               /* Convert to REF_DELTA if we must... */
+               if (!allow_ofs_delta) {
+                       int base_pos = find_revindex_position(reuse_packfile, base_offset);
+                       struct object_id base_oid;
+
+                       nth_packed_object_id(&base_oid, reuse_packfile,
+                                            reuse_packfile->revindex[base_pos].nr);
+
+                       len = encode_in_pack_object_header(header, sizeof(header),
+                                                          OBJ_REF_DELTA, size);
+                       hashwrite(out, header, len);
+                       hashwrite(out, base_oid.hash, the_hash_algo->rawsz);
+                       copy_pack_data(out, reuse_packfile, w_curs, cur, next - cur);
+                       return;
+               }
+
+               /* Otherwise see if we need to rewrite the offset... */
+               fixup = find_reused_offset(offset) -
+                       find_reused_offset(base_offset);
+               if (fixup) {
+                       unsigned char ofs_header[10];
+                       unsigned i, ofs_len;
+                       off_t ofs = offset - base_offset - fixup;
+
+                       len = encode_in_pack_object_header(header, sizeof(header),
+                                                          OBJ_OFS_DELTA, size);
+
+                       i = sizeof(ofs_header) - 1;
+                       ofs_header[i] = ofs & 127;
+                       while (ofs >>= 7)
+                               ofs_header[--i] = 128 | (--ofs & 127);
+
+                       ofs_len = sizeof(ofs_header) - i;
+
+                       hashwrite(out, header, len);
+                       hashwrite(out, ofs_header + sizeof(ofs_header) - ofs_len, ofs_len);
+                       copy_pack_data(out, reuse_packfile, w_curs, cur, next - cur);
+                       return;
+               }
+
+               /* ...otherwise we have no fixup, and can write it verbatim */
+       }
+
+       copy_pack_data(out, reuse_packfile, w_curs, offset, next - offset);
+}
+
+static size_t write_reused_pack_verbatim(struct hashfile *out,
+                                        struct pack_window **w_curs)
+{
+       size_t pos = 0;
+
+       while (pos < reuse_packfile_bitmap->word_alloc &&
+                       reuse_packfile_bitmap->words[pos] == (eword_t)~0)
+               pos++;
+
+       if (pos) {
+               off_t to_write;
+
+               written = (pos * BITS_IN_EWORD);
+               to_write = reuse_packfile->revindex[written].offset
+                       - sizeof(struct pack_header);
+
+               /* We're recording one chunk, not one object. */
+               record_reused_object(sizeof(struct pack_header), 0);
+               hashflush(out);
+               copy_pack_data(out, reuse_packfile, w_curs,
+                       sizeof(struct pack_header), to_write);
 
-               /*
-                * We don't know the actual number of objects written,
-                * only how many bytes written, how many bytes total, and
-                * how many objects total. So we can fake it by pretending all
-                * objects we are writing are the same size. This gives us a
-                * smooth progress meter, and at the end it matches the true
-                * answer.
-                */
-               written = reuse_packfile_objects *
-                               (((double)(total - to_write)) / total);
                display_progress(progress_state, written);
        }
+       return pos;
+}
+
+static void write_reused_pack(struct hashfile *f)
+{
+       size_t i = 0;
+       uint32_t offset;
+       struct pack_window *w_curs = NULL;
+
+       if (allow_ofs_delta)
+               i = write_reused_pack_verbatim(f, &w_curs);
 
-       close(fd);
-       written = reuse_packfile_objects;
-       display_progress(progress_state, written);
-       return reuse_packfile_offset - sizeof(struct pack_header);
+       for (; i < reuse_packfile_bitmap->word_alloc; ++i) {
+               eword_t word = reuse_packfile_bitmap->words[i];
+               size_t pos = (i * BITS_IN_EWORD);
+
+               for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
+                       if ((word >> offset) == 0)
+                               break;
+
+                       offset += ewah_bit_ctz64(word >> offset);
+                       write_reused_pack_one(pos + offset, f, &w_curs);
+                       display_progress(progress_state, ++written);
+               }
+       }
+
+       unuse_pack(&w_curs);
 }
 
 static const char no_split_warning[] = N_(
@@ -779,7 +976,7 @@ static const char no_split_warning[] = N_(
 static void write_pack_file(void)
 {
        uint32_t i = 0, j;
-       struct sha1file *f;
+       struct hashfile *f;
        off_t offset;
        uint32_t nr_remaining = nr_result;
        time_t last_mtime = 0;
@@ -791,22 +988,20 @@ static void write_pack_file(void)
        write_order = compute_write_order();
 
        do {
-               unsigned char sha1[20];
+               struct object_id oid;
                char *pack_tmp_name = NULL;
 
                if (pack_to_stdout)
-                       f = sha1fd_throughput(1, "<stdout>", progress_state);
+                       f = hashfd_throughput(1, "<stdout>", progress_state);
                else
                        f = create_tmp_packfile(&pack_tmp_name);
 
                offset = write_pack_header(f, nr_remaining);
 
                if (reuse_packfile) {
-                       off_t packfile_size;
                        assert(pack_to_stdout);
-
-                       packfile_size = write_reused_pack(f);
-                       offset += packfile_size;
+                       write_reused_pack(f);
+                       offset = hashfile_total(f);
                }
 
                nr_written = 0;
@@ -822,16 +1017,17 @@ static void write_pack_file(void)
                 * If so, rewrite it like in fast-import
                 */
                if (pack_to_stdout) {
-                       sha1close(f, sha1, CSUM_CLOSE);
+                       finalize_hashfile(f, oid.hash, CSUM_HASH_IN_STREAM | CSUM_CLOSE);
                } else if (nr_written == nr_remaining) {
-                       sha1close(f, sha1, CSUM_FSYNC);
+                       finalize_hashfile(f, oid.hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
                } else {
-                       int fd = sha1close(f, sha1, 0);
-                       fixup_pack_header_footer(fd, sha1, pack_tmp_name,
-                                                nr_written, sha1, offset);
+                       int fd = finalize_hashfile(f, oid.hash, 0);
+                       fixup_pack_header_footer(fd, oid.hash, pack_tmp_name,
+                                                nr_written, oid.hash, offset);
                        close(fd);
                        if (write_bitmap_index) {
-                               warning(_(no_split_warning));
+                               if (write_bitmap_index != WRITE_BITMAP_QUIET)
+                                       warning(_(no_split_warning));
                                write_bitmap_index = 0;
                        }
                }
@@ -848,7 +1044,7 @@ static void write_pack_file(void)
                         * to preserve this property.
                         */
                        if (stat(pack_tmp_name, &st) < 0) {
-                               warning_errno("failed to stat %s", pack_tmp_name);
+                               warning_errno(_("failed to stat %s"), pack_tmp_name);
                        } else if (!last_mtime) {
                                last_mtime = st.st_mtime;
                        } else {
@@ -856,22 +1052,23 @@ static void write_pack_file(void)
                                utb.actime = st.st_atime;
                                utb.modtime = --last_mtime;
                                if (utime(pack_tmp_name, &utb) < 0)
-                                       warning_errno("failed utime() on %s", pack_tmp_name);
+                                       warning_errno(_("failed utime() on %s"), pack_tmp_name);
                        }
 
                        strbuf_addf(&tmpname, "%s-", base_name);
 
                        if (write_bitmap_index) {
-                               bitmap_writer_set_checksum(sha1);
-                               bitmap_writer_build_type_index(written_list, nr_written);
+                               bitmap_writer_set_checksum(oid.hash);
+                               bitmap_writer_build_type_index(
+                                       &to_pack, written_list, nr_written);
                        }
 
                        finish_tmp_packfile(&tmpname, pack_tmp_name,
                                            written_list, nr_written,
-                                           &pack_idx_opts, sha1);
+                                           &pack_idx_opts, oid.hash);
 
                        if (write_bitmap_index) {
-                               strbuf_addf(&tmpname, "%s.bitmap", sha1_to_hex(sha1));
+                               strbuf_addf(&tmpname, "%s.bitmap", oid_to_hex(&oid));
 
                                stop_progress(&progress_state);
 
@@ -886,7 +1083,7 @@ static void write_pack_file(void)
 
                        strbuf_release(&tmpname);
                        free(pack_tmp_name);
-                       puts(sha1_to_hex(sha1));
+                       puts(oid_to_hex(&oid));
                }
 
                /* mark written objects as written to previous pack */
@@ -900,8 +1097,10 @@ static void write_pack_file(void)
        free(write_order);
        stop_progress(&progress_state);
        if (written != nr_result)
-               die("wrote %"PRIu32" objects while expecting %"PRIu32,
-                       written, nr_result);
+               die(_("wrote %"PRIu32" objects while expecting %"PRIu32),
+                   written, nr_result);
+       trace2_data_intmax("pack-objects", the_repository,
+                          "write_pack_file/wrote", nr_result);
 }
 
 static int no_try_delta(const char *path)
@@ -910,8 +1109,7 @@ static int no_try_delta(const char *path)
 
        if (!check)
                check = attr_check_initl("delta", NULL);
-       if (git_check_attr(path, check))
-               return 0;
+       git_check_attr(the_repository->index, path, check);
        if (ATTR_FALSE(check->items[0].value))
                return 1;
        return 0;
@@ -927,13 +1125,16 @@ static int no_try_delta(const char *path)
  * found the item, since that saves us from having to look it up again a
  * few lines later when we want to add the new entry.
  */
-static int have_duplicate_entry(const unsigned char *sha1,
-                               int exclude,
-                               uint32_t *index_pos)
+static int have_duplicate_entry(const struct object_id *oid,
+                               int exclude)
 {
        struct object_entry *entry;
 
-       entry = packlist_find(&to_pack, sha1, index_pos);
+       if (reuse_packfile_bitmap &&
+           bitmap_walk_contains(bitmap_git, reuse_packfile_bitmap, oid))
+               return 1;
+
+       entry = packlist_find(&to_pack, oid);
        if (!entry)
                return 0;
 
@@ -967,13 +1168,16 @@ static int want_found_object(int exclude, struct packed_git *p)
         * Otherwise, we signal "-1" at the end to tell the caller that we do
         * not know either way, and it needs to check more packs.
         */
-       if (!ignore_packed_keep &&
+       if (!ignore_packed_keep_on_disk &&
+           !ignore_packed_keep_in_core &&
            (!local || !have_non_local_packs))
                return 1;
 
        if (local && !p->pack_local)
                return 0;
-       if (ignore_packed_keep && p->pack_local && p->pack_keep)
+       if (p->pack_local &&
+           ((ignore_packed_keep_on_disk && p->pack_keep) ||
+            (ignore_packed_keep_in_core && p->pack_keep_in_core)))
                return 0;
 
        /* we don't know yet; keep looking for more packs */
@@ -989,15 +1193,16 @@ static int want_found_object(int exclude, struct packed_git *p)
  * function finds if there is any pack that has the object and returns the pack
  * and its offset in these variables.
  */
-static int want_object_in_pack(const unsigned char *sha1,
+static int want_object_in_pack(const struct object_id *oid,
                               int exclude,
                               struct packed_git **found_pack,
                               off_t *found_offset)
 {
-       struct mru_entry *entry;
        int want;
+       struct list_head *pos;
+       struct multi_pack_index *m;
 
-       if (!exclude && local && has_loose_object_nonlocal(sha1))
+       if (!exclude && local && has_loose_object_nonlocal(oid))
                return 0;
 
        /*
@@ -1011,14 +1216,39 @@ static int want_object_in_pack(const unsigned char *sha1,
                        return want;
        }
 
-       for (entry = packed_git_mru->head; entry; entry = entry->next) {
-               struct packed_git *p = entry->item;
+       for (m = get_multi_pack_index(the_repository); m; m = m->next) {
+               struct pack_entry e;
+               if (fill_midx_entry(the_repository, oid, &e, m)) {
+                       struct packed_git *p = e.p;
+                       off_t offset;
+
+                       if (p == *found_pack)
+                               offset = *found_offset;
+                       else
+                               offset = find_pack_entry_one(oid->hash, p);
+
+                       if (offset) {
+                               if (!*found_pack) {
+                                       if (!is_pack_valid(p))
+                                               continue;
+                                       *found_offset = offset;
+                                       *found_pack = p;
+                               }
+                               want = want_found_object(exclude, p);
+                               if (want != -1)
+                                       return want;
+                       }
+               }
+       }
+
+       list_for_each(pos, get_packed_git_mru(the_repository)) {
+               struct packed_git *p = list_entry(pos, struct packed_git, mru);
                off_t offset;
 
                if (p == *found_pack)
                        offset = *found_offset;
                else
-                       offset = find_pack_entry_one(sha1, p);
+                       offset = find_pack_entry_one(oid->hash, p);
 
                if (offset) {
                        if (!*found_pack) {
@@ -1029,7 +1259,8 @@ static int want_object_in_pack(const unsigned char *sha1,
                        }
                        want = want_found_object(exclude, p);
                        if (!exclude && want > 0)
-                               mru_mark(packed_git_mru, entry);
+                               list_move(&p->mru,
+                                         get_packed_git_mru(the_repository));
                        if (want != -1)
                                return want;
                }
@@ -1038,27 +1269,25 @@ static int want_object_in_pack(const unsigned char *sha1,
        return 1;
 }
 
-static void create_object_entry(const unsigned char *sha1,
+static void create_object_entry(const struct object_id *oid,
                                enum object_type type,
                                uint32_t hash,
                                int exclude,
                                int no_try_delta,
-                               uint32_t index_pos,
                                struct packed_git *found_pack,
                                off_t found_offset)
 {
        struct object_entry *entry;
 
-       entry = packlist_alloc(&to_pack, sha1, index_pos);
+       entry = packlist_alloc(&to_pack, oid);
        entry->hash = hash;
-       if (type)
-               entry->type = type;
+       oe_set_type(entry, type);
        if (exclude)
                entry->preferred_base = 1;
        else
                nr_result++;
        if (found_pack) {
-               entry->in_pack = found_pack;
+               oe_set_in_pack(&to_pack, entry, found_pack);
                entry->in_pack_offset = found_offset;
        }
 
@@ -1069,54 +1298,52 @@ static const char no_closure_warning[] = N_(
 "disabling bitmap writing, as some objects are not being packed"
 );
 
-static int add_object_entry(const unsigned char *sha1, enum object_type type,
+static int add_object_entry(const struct object_id *oid, enum object_type type,
                            const char *name, int exclude)
 {
        struct packed_git *found_pack = NULL;
        off_t found_offset = 0;
-       uint32_t index_pos;
 
-       if (have_duplicate_entry(sha1, exclude, &index_pos))
+       display_progress(progress_state, ++nr_seen);
+
+       if (have_duplicate_entry(oid, exclude))
                return 0;
 
-       if (!want_object_in_pack(sha1, exclude, &found_pack, &found_offset)) {
+       if (!want_object_in_pack(oid, exclude, &found_pack, &found_offset)) {
                /* The pack is missing an object, so it will not have closure */
                if (write_bitmap_index) {
-                       warning(_(no_closure_warning));
+                       if (write_bitmap_index != WRITE_BITMAP_QUIET)
+                               warning(_(no_closure_warning));
                        write_bitmap_index = 0;
                }
                return 0;
        }
 
-       create_object_entry(sha1, type, pack_name_hash(name),
+       create_object_entry(oid, type, pack_name_hash(name),
                            exclude, name && no_try_delta(name),
-                           index_pos, found_pack, found_offset);
-
-       display_progress(progress_state, nr_result);
+                           found_pack, found_offset);
        return 1;
 }
 
-static int add_object_entry_from_bitmap(const unsigned char *sha1,
+static int add_object_entry_from_bitmap(const struct object_id *oid,
                                        enum object_type type,
                                        int flags, uint32_t name_hash,
                                        struct packed_git *pack, off_t offset)
 {
-       uint32_t index_pos;
+       display_progress(progress_state, ++nr_seen);
 
-       if (have_duplicate_entry(sha1, 0, &index_pos))
+       if (have_duplicate_entry(oid, 0))
                return 0;
 
-       if (!want_object_in_pack(sha1, 0, &pack, &offset))
+       if (!want_object_in_pack(oid, 0, &pack, &offset))
                return 0;
 
-       create_object_entry(sha1, type, name_hash, 0, 0, index_pos, pack, offset);
-
-       display_progress(progress_state, nr_result);
+       create_object_entry(oid, type, name_hash, 0, 0, pack, offset);
        return 1;
 }
 
 struct pbase_tree_cache {
-       unsigned char sha1[20];
+       struct object_id oid;
        int ref;
        int temporary;
        void *tree_data;
@@ -1124,9 +1351,9 @@ struct pbase_tree_cache {
 };
 
 static struct pbase_tree_cache *(pbase_tree_cache[256]);
-static int pbase_tree_cache_ix(const unsigned char *sha1)
+static int pbase_tree_cache_ix(const struct object_id *oid)
 {
-       return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
+       return oid->hash[0] % ARRAY_SIZE(pbase_tree_cache);
 }
 static int pbase_tree_cache_ix_incr(int ix)
 {
@@ -1143,14 +1370,14 @@ static struct pbase_tree {
        struct pbase_tree_cache pcache;
 } *pbase_tree;
 
-static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
+static struct pbase_tree_cache *pbase_tree_get(const struct object_id *oid)
 {
        struct pbase_tree_cache *ent, *nent;
        void *data;
        unsigned long size;
        enum object_type type;
        int neigh;
-       int my_ix = pbase_tree_cache_ix(sha1);
+       int my_ix = pbase_tree_cache_ix(oid);
        int available_ix = -1;
 
        /* pbase-tree-cache acts as a limited hashtable.
@@ -1159,7 +1386,7 @@ static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
         */
        for (neigh = 0; neigh < 8; neigh++) {
                ent = pbase_tree_cache[my_ix];
-               if (ent && !hashcmp(ent->sha1, sha1)) {
+               if (ent && oideq(&ent->oid, oid)) {
                        ent->ref++;
                        return ent;
                }
@@ -1175,7 +1402,7 @@ static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
        /* Did not find one.  Either we got a bogus request or
         * we need to read and perhaps cache.
         */
-       data = read_sha1_file(sha1, &type, &size);
+       data = read_object_file(oid, &type, &size);
        if (!data)
                return NULL;
        if (type != OBJ_TREE) {
@@ -1201,7 +1428,7 @@ static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
                free(ent->tree_data);
                nent = ent;
        }
-       hashcpy(nent->sha1, sha1);
+       oidcpy(&nent->oid, oid);
        nent->tree_data = data;
        nent->tree_size = size;
        nent->ref = 1;
@@ -1246,7 +1473,7 @@ static void add_pbase_object(struct tree_desc *tree,
                if (cmp < 0)
                        return;
                if (name[cmplen] != '/') {
-                       add_object_entry(entry.oid->hash,
+                       add_object_entry(&entry.oid,
                                         object_type(entry.mode),
                                         fullname, 1);
                        return;
@@ -1257,7 +1484,7 @@ static void add_pbase_object(struct tree_desc *tree,
                        const char *down = name+cmplen+1;
                        int downlen = name_cmp_len(down);
 
-                       tree = pbase_tree_get(entry.oid->hash);
+                       tree = pbase_tree_get(&entry.oid);
                        if (!tree)
                                return;
                        init_tree_desc(&sub, tree->tree_data, tree->tree_size);
@@ -1276,7 +1503,7 @@ static int done_pbase_path_pos(unsigned hash)
        int lo = 0;
        int hi = done_pbase_paths_num;
        while (lo < hi) {
-               int mi = (hi + lo) / 2;
+               int mi = lo + (hi - lo) / 2;
                if (done_pbase_paths[mi] == hash)
                        return mi;
                if (done_pbase_paths[mi] < hash)
@@ -1316,7 +1543,7 @@ static void add_preferred_base_object(const char *name)
        cmplen = name_cmp_len(name);
        for (it = pbase_tree; it; it = it->next) {
                if (cmplen == 0) {
-                       add_object_entry(it->pcache.sha1, OBJ_TREE, NULL, 1);
+                       add_object_entry(&it->pcache.oid, OBJ_TREE, NULL, 1);
                }
                else {
                        struct tree_desc tree;
@@ -1326,22 +1553,23 @@ static void add_preferred_base_object(const char *name)
        }
 }
 
-static void add_preferred_base(unsigned char *sha1)
+static void add_preferred_base(struct object_id *oid)
 {
        struct pbase_tree *it;
        void *data;
        unsigned long size;
-       unsigned char tree_sha1[20];
+       struct object_id tree_oid;
 
        if (window <= num_preferred_base++)
                return;
 
-       data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
+       data = read_object_with_reference(the_repository, oid,
+                                         tree_type, &size, &tree_oid);
        if (!data)
                return;
 
        for (it = pbase_tree; it; it = it->next) {
-               if (!hashcmp(it->pcache.sha1, tree_sha1)) {
+               if (oideq(&it->pcache.oid, &tree_oid)) {
                        free(data);
                        return;
                }
@@ -1351,7 +1579,7 @@ static void add_preferred_base(unsigned char *sha1)
        it->next = pbase_tree;
        pbase_tree = it;
 
-       hashcpy(it->pcache.sha1, tree_sha1);
+       oidcpy(&it->pcache.oid, &tree_oid);
        it->pcache.tree_data = data;
        it->pcache.tree_size = size;
 }
@@ -1364,10 +1592,10 @@ static void cleanup_preferred_base(void)
        it = pbase_tree;
        pbase_tree = NULL;
        while (it) {
-               struct pbase_tree *this = it;
-               it = this->next;
-               free(this->pcache.tree_data);
-               free(this);
+               struct pbase_tree *tmp = it;
+               it = tmp->next;
+               free(tmp->pcache.tree_data);
+               free(tmp);
        }
 
        for (i = 0; i < ARRAY_SIZE(pbase_tree_cache); i++) {
@@ -1381,17 +1609,68 @@ static void cleanup_preferred_base(void)
        done_pbase_paths_num = done_pbase_paths_alloc = 0;
 }
 
+/*
+ * Return 1 iff the object specified by "delta" can be sent
+ * literally as a delta against the base in "base_sha1". If
+ * so, then *base_out will point to the entry in our packing
+ * list, or NULL if we must use the external-base list.
+ *
+ * Depth value does not matter - find_deltas() will
+ * never consider reused delta as the base object to
+ * deltify other objects against, in order to avoid
+ * circular deltas.
+ */
+static int can_reuse_delta(const struct object_id *base_oid,
+                          struct object_entry *delta,
+                          struct object_entry **base_out)
+{
+       struct object_entry *base;
+
+       /*
+        * First see if we're already sending the base (or it's explicitly in
+        * our "excluded" list).
+        */
+       base = packlist_find(&to_pack, base_oid);
+       if (base) {
+               if (!in_same_island(&delta->idx.oid, &base->idx.oid))
+                       return 0;
+               *base_out = base;
+               return 1;
+       }
+
+       /*
+        * Otherwise, reachability bitmaps may tell us if the receiver has it,
+        * even if it was buried too deep in history to make it into the
+        * packing list.
+        */
+       if (thin && bitmap_has_oid_in_uninteresting(bitmap_git, base_oid)) {
+               if (use_delta_islands) {
+                       if (!in_same_island(&delta->idx.oid, base_oid))
+                               return 0;
+               }
+               *base_out = NULL;
+               return 1;
+       }
+
+       return 0;
+}
+
 static void check_object(struct object_entry *entry)
 {
-       if (entry->in_pack) {
-               struct packed_git *p = entry->in_pack;
+       unsigned long canonical_size;
+
+       if (IN_PACK(entry)) {
+               struct packed_git *p = IN_PACK(entry);
                struct pack_window *w_curs = NULL;
-               const unsigned char *base_ref = NULL;
+               int have_base = 0;
+               struct object_id base_ref;
                struct object_entry *base_entry;
                unsigned long used, used_0;
                unsigned long avail;
                off_t ofs;
                unsigned char *buf, c;
+               enum object_type type;
+               unsigned long in_pack_size;
 
                buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);
 
@@ -1400,11 +1679,15 @@ static void check_object(struct object_entry *entry)
                 * since non-delta representations could still be reused.
                 */
                used = unpack_object_header_buffer(buf, avail,
-                                                  &entry->in_pack_type,
-                                                  &entry->size);
+                                                  &type,
+                                                  &in_pack_size);
                if (used == 0)
                        goto give_up;
 
+               if (type < 0)
+                       BUG("invalid type %d", type);
+               entry->in_pack_type = type;
+
                /*
                 * Determine if this is a delta and if so whether we can
                 * reuse it or not.  Otherwise let's find out as cheaply as
@@ -1413,17 +1696,22 @@ static void check_object(struct object_entry *entry)
                switch (entry->in_pack_type) {
                default:
                        /* Not a delta hence we've already got all we need. */
-                       entry->type = entry->in_pack_type;
+                       oe_set_type(entry, entry->in_pack_type);
+                       SET_SIZE(entry, in_pack_size);
                        entry->in_pack_header_size = used;
-                       if (entry->type < OBJ_COMMIT || entry->type > OBJ_BLOB)
+                       if (oe_type(entry) < OBJ_COMMIT || oe_type(entry) > OBJ_BLOB)
                                goto give_up;
                        unuse_pack(&w_curs);
                        return;
                case OBJ_REF_DELTA:
-                       if (reuse_delta && !entry->preferred_base)
-                               base_ref = use_pack(p, &w_curs,
-                                               entry->in_pack_offset + used, NULL);
-                       entry->in_pack_header_size = used + 20;
+                       if (reuse_delta && !entry->preferred_base) {
+                               oidread(&base_ref,
+                                       use_pack(p, &w_curs,
+                                                entry->in_pack_offset + used,
+                                                NULL));
+                               have_base = 1;
+                       }
+                       entry->in_pack_header_size = used + the_hash_algo->rawsz;
                        break;
                case OBJ_OFS_DELTA:
                        buf = use_pack(p, &w_curs,
@@ -1434,7 +1722,7 @@ static void check_object(struct object_entry *entry)
                        while (c & 128) {
                                ofs += 1;
                                if (!ofs || MSB(ofs, 7)) {
-                                       error("delta base offset overflow in pack for %s",
+                                       error(_("delta base offset overflow in pack for %s"),
                                              oid_to_hex(&entry->idx.oid));
                                        goto give_up;
                                }
@@ -1443,7 +1731,7 @@ static void check_object(struct object_entry *entry)
                        }
                        ofs = entry->in_pack_offset - ofs;
                        if (ofs <= 0 || ofs >= entry->in_pack_offset) {
-                               error("delta base offset out of bound for %s",
+                               error(_("delta base offset out of bound for %s"),
                                      oid_to_hex(&entry->idx.oid));
                                goto give_up;
                        }
@@ -1452,76 +1740,85 @@ static void check_object(struct object_entry *entry)
                                revidx = find_pack_revindex(p, ofs);
                                if (!revidx)
                                        goto give_up;
-                               base_ref = nth_packed_object_sha1(p, revidx->nr);
+                               if (!nth_packed_object_id(&base_ref, p, revidx->nr))
+                                       have_base = 1;
                        }
                        entry->in_pack_header_size = used + used_0;
                        break;
                }
 
-               if (base_ref && (base_entry = packlist_find(&to_pack, base_ref, NULL))) {
-                       /*
-                        * If base_ref was set above that means we wish to
-                        * reuse delta data, and we even found that base
-                        * in the list of objects we want to pack. Goodie!
-                        *
-                        * Depth value does not matter - find_deltas() will
-                        * never consider reused delta as the base object to
-                        * deltify other objects against, in order to avoid
-                        * circular deltas.
-                        */
-                       entry->type = entry->in_pack_type;
-                       entry->delta = base_entry;
-                       entry->delta_size = entry->size;
-                       entry->delta_sibling = base_entry->delta_child;
-                       base_entry->delta_child = entry;
+               if (have_base &&
+                   can_reuse_delta(&base_ref, entry, &base_entry)) {
+                       oe_set_type(entry, entry->in_pack_type);
+                       SET_SIZE(entry, in_pack_size); /* delta size */
+                       SET_DELTA_SIZE(entry, in_pack_size);
+
+                       if (base_entry) {
+                               SET_DELTA(entry, base_entry);
+                               entry->delta_sibling_idx = base_entry->delta_child_idx;
+                               SET_DELTA_CHILD(base_entry, entry);
+                       } else {
+                               SET_DELTA_EXT(entry, &base_ref);
+                       }
+
                        unuse_pack(&w_curs);
                        return;
                }
 
-               if (entry->type) {
+               if (oe_type(entry)) {
+                       off_t delta_pos;
+
                        /*
                         * This must be a delta and we already know what the
                         * final object type is.  Let's extract the actual
                         * object size from the delta header.
                         */
-                       entry->size = get_size_from_delta(p, &w_curs,
-                                       entry->in_pack_offset + entry->in_pack_header_size);
-                       if (entry->size == 0)
+                       delta_pos = entry->in_pack_offset + entry->in_pack_header_size;
+                       canonical_size = get_size_from_delta(p, &w_curs, delta_pos);
+                       if (canonical_size == 0)
                                goto give_up;
+                       SET_SIZE(entry, canonical_size);
                        unuse_pack(&w_curs);
                        return;
                }
 
                /*
                 * No choice but to fall back to the recursive delta walk
-                * with sha1_object_info() to find about the object type
+                * with oid_object_info() to find about the object type
                 * at this point...
                 */
                give_up:
                unuse_pack(&w_curs);
        }
 
-       entry->type = sha1_object_info(entry->idx.oid.hash, &entry->size);
-       /*
-        * The error condition is checked in prepare_pack().  This is
-        * to permit a missing preferred base object to be ignored
-        * as a preferred base.  Doing so can result in a larger
-        * pack file, but the transfer will still take place.
-        */
+       oe_set_type(entry,
+                   oid_object_info(the_repository, &entry->idx.oid, &canonical_size));
+       if (entry->type_valid) {
+               SET_SIZE(entry, canonical_size);
+       } else {
+               /*
+                * Bad object type is checked in prepare_pack().  This is
+                * to permit a missing preferred base object to be ignored
+                * as a preferred base.  Doing so can result in a larger
+                * pack file, but the transfer will still take place.
+                */
+       }
 }
 
 static int pack_offset_sort(const void *_a, const void *_b)
 {
        const struct object_entry *a = *(struct object_entry **)_a;
        const struct object_entry *b = *(struct object_entry **)_b;
+       const struct packed_git *a_in_pack = IN_PACK(a);
+       const struct packed_git *b_in_pack = IN_PACK(b);
 
        /* avoid filesystem trashing with loose objects */
-       if (!a->in_pack && !b->in_pack)
+       if (!a_in_pack && !b_in_pack)
                return oidcmp(&a->idx.oid, &b->idx.oid);
 
-       if (a->in_pack < b->in_pack)
+       if (a_in_pack < b_in_pack)
                return -1;
-       if (a->in_pack > b->in_pack)
+       if (a_in_pack > b_in_pack)
                return 1;
        return a->in_pack_offset < b->in_pack_offset ? -1 :
                        (a->in_pack_offset > b->in_pack_offset);
@@ -1542,30 +1839,37 @@ static int pack_offset_sort(const void *_a, const void *_b)
  */
 static void drop_reused_delta(struct object_entry *entry)
 {
-       struct object_entry **p = &entry->delta->delta_child;
+       unsigned *idx = &to_pack.objects[entry->delta_idx - 1].delta_child_idx;
        struct object_info oi = OBJECT_INFO_INIT;
+       enum object_type type;
+       unsigned long size;
+
+       while (*idx) {
+               struct object_entry *oe = &to_pack.objects[*idx - 1];
 
-       while (*p) {
-               if (*p == entry)
-                       *p = (*p)->delta_sibling;
+               if (oe == entry)
+                       *idx = oe->delta_sibling_idx;
                else
-                       p = &(*p)->delta_sibling;
+                       idx = &oe->delta_sibling_idx;
        }
-       entry->delta = NULL;
+       SET_DELTA(entry, NULL);
        entry->depth = 0;
 
-       oi.sizep = &entry->size;
-       oi.typep = &entry->type;
-       if (packed_object_info(entry->in_pack, entry->in_pack_offset, &oi) < 0) {
+       oi.sizep = &size;
+       oi.typep = &type;
+       if (packed_object_info(the_repository, IN_PACK(entry), entry->in_pack_offset, &oi) < 0) {
                /*
                 * We failed to get the info from this pack for some reason;
-                * fall back to sha1_object_info, which may find another copy.
-                * And if that fails, the error will be recorded in entry->type
+                * fall back to oid_object_info, which may find another copy.
+                * And if that fails, the error will be recorded in oe_type(entry)
                 * and dealt with in prepare_pack().
                 */
-               entry->type = sha1_object_info(entry->idx.oid.hash,
-                                              &entry->size);
+               oe_set_type(entry,
+                           oid_object_info(the_repository, &entry->idx.oid, &size));
+       } else {
+               oe_set_type(entry, type);
        }
+       SET_SIZE(entry, size);
 }
 
 /*
@@ -1589,7 +1893,7 @@ static void break_delta_chains(struct object_entry *entry)
 
        for (cur = entry, total_depth = 0;
             cur;
-            cur = cur->delta, total_depth++) {
+            cur = DELTA(cur), total_depth++) {
                if (cur->dfs_state == DFS_DONE) {
                        /*
                         * We've already seen this object and know it isn't
@@ -1606,7 +1910,7 @@ static void break_delta_chains(struct object_entry *entry)
                 * is a bug.
                 */
                if (cur->dfs_state != DFS_NONE)
-                       die("BUG: confusing delta dfs state in first pass: %d",
+                       BUG("confusing delta dfs state in first pass: %d",
                            cur->dfs_state);
 
                /*
@@ -1614,7 +1918,7 @@ static void break_delta_chains(struct object_entry *entry)
                 * it's not a delta, we're done traversing, but we'll mark it
                 * done to save time on future traversals.
                 */
-               if (!cur->delta) {
+               if (!DELTA(cur)) {
                        cur->dfs_state = DFS_DONE;
                        break;
                }
@@ -1637,7 +1941,7 @@ static void break_delta_chains(struct object_entry *entry)
                 * We keep all commits in the chain that we examined.
                 */
                cur->dfs_state = DFS_ACTIVE;
-               if (cur->delta->dfs_state == DFS_ACTIVE) {
+               if (DELTA(cur)->dfs_state == DFS_ACTIVE) {
                        drop_reused_delta(cur);
                        cur->dfs_state = DFS_DONE;
                        break;
@@ -1652,7 +1956,7 @@ static void break_delta_chains(struct object_entry *entry)
         * an extra "next" pointer to keep going after we reset cur->delta.
         */
        for (cur = entry; cur; cur = next) {
-               next = cur->delta;
+               next = DELTA(cur);
 
                /*
                 * We should have a chain of zero or more ACTIVE states down to
@@ -1663,7 +1967,7 @@ static void break_delta_chains(struct object_entry *entry)
                if (cur->dfs_state == DFS_DONE)
                        break;
                else if (cur->dfs_state != DFS_ACTIVE)
-                       die("BUG: confusing delta dfs state in second pass: %d",
+                       BUG("confusing delta dfs state in second pass: %d",
                            cur->dfs_state);
 
                /*
@@ -1697,6 +2001,10 @@ static void get_object_details(void)
        uint32_t i;
        struct object_entry **sorted_by_offset;
 
+       if (progress)
+               progress_state = start_progress(_("Counting objects"),
+                                               to_pack.nr_objects);
+
        sorted_by_offset = xcalloc(to_pack.nr_objects, sizeof(struct object_entry *));
        for (i = 0; i < to_pack.nr_objects; i++)
                sorted_by_offset[i] = to_pack.objects + i;
@@ -1705,9 +2013,12 @@ static void get_object_details(void)
        for (i = 0; i < to_pack.nr_objects; i++) {
                struct object_entry *entry = sorted_by_offset[i];
                check_object(entry);
-               if (big_file_threshold < entry->size)
+               if (entry->type_valid &&
+                   oe_size_greater_than(&to_pack, entry, big_file_threshold))
                        entry->no_try_delta = 1;
+               display_progress(progress_state, i + 1);
        }
+       stop_progress(&progress_state);
 
        /*
         * This must happen in a second pass, since we rely on the delta
@@ -1732,10 +2043,14 @@ static int type_size_sort(const void *_a, const void *_b)
 {
        const struct object_entry *a = *(struct object_entry **)_a;
        const struct object_entry *b = *(struct object_entry **)_b;
+       const enum object_type a_type = oe_type(a);
+       const enum object_type b_type = oe_type(b);
+       const unsigned long a_size = SIZE(a);
+       const unsigned long b_size = SIZE(b);
 
-       if (a->type > b->type)
+       if (a_type > b_type)
                return -1;
-       if (a->type < b->type)
+       if (a_type < b_type)
                return 1;
        if (a->hash > b->hash)
                return -1;
@@ -1745,9 +2060,14 @@ static int type_size_sort(const void *_a, const void *_b)
                return -1;
        if (a->preferred_base < b->preferred_base)
                return 1;
-       if (a->size > b->size)
+       if (use_delta_islands) {
+               const int island_cmp = island_delta_cmp(&a->idx.oid, &b->idx.oid);
+               if (island_cmp)
+                       return island_cmp;
+       }
+       if (a_size > b_size)
                return -1;
-       if (a->size < b->size)
+       if (a_size < b_size)
                return 1;
        return a < b ? -1 : (a > b);  /* newest first */
 }
@@ -1775,30 +2095,65 @@ static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
        return 0;
 }
 
-#ifndef NO_PTHREADS
-
-static pthread_mutex_t read_mutex;
-#define read_lock()            pthread_mutex_lock(&read_mutex)
-#define read_unlock()          pthread_mutex_unlock(&read_mutex)
-
+/* Protect delta_cache_size */
 static pthread_mutex_t cache_mutex;
 #define cache_lock()           pthread_mutex_lock(&cache_mutex)
 #define cache_unlock()         pthread_mutex_unlock(&cache_mutex)
 
+/*
+ * Protect object list partitioning (e.g. struct thread_param) and
+ * progress_state
+ */
 static pthread_mutex_t progress_mutex;
 #define progress_lock()                pthread_mutex_lock(&progress_mutex)
 #define progress_unlock()      pthread_mutex_unlock(&progress_mutex)
 
-#else
+/*
+ * Access to struct object_entry is unprotected since each thread owns
+ * a portion of the main object list. Just don't access object entries
+ * ahead in the list because they can be stolen and would need
+ * progress_mutex for protection.
+ */
 
-#define read_lock()            (void)0
-#define read_unlock()          (void)0
-#define cache_lock()           (void)0
-#define cache_unlock()         (void)0
-#define progress_lock()                (void)0
-#define progress_unlock()      (void)0
+/*
+ * Return the size of the object without doing any delta
+ * reconstruction (so non-deltas are true object sizes, but deltas
+ * return the size of the delta data).
+ */
+unsigned long oe_get_size_slow(struct packing_data *pack,
+                              const struct object_entry *e)
+{
+       struct packed_git *p;
+       struct pack_window *w_curs;
+       unsigned char *buf;
+       enum object_type type;
+       unsigned long used, avail, size;
 
-#endif
+       if (e->type_ != OBJ_OFS_DELTA && e->type_ != OBJ_REF_DELTA) {
+               packing_data_lock(&to_pack);
+               if (oid_object_info(the_repository, &e->idx.oid, &size) < 0)
+                       die(_("unable to get size of %s"),
+                           oid_to_hex(&e->idx.oid));
+               packing_data_unlock(&to_pack);
+               return size;
+       }
+
+       p = oe_in_pack(pack, e);
+       if (!p)
+               BUG("when e->type is a delta, it must belong to a pack");
+
+       packing_data_lock(&to_pack);
+       w_curs = NULL;
+       buf = use_pack(p, &w_curs, e->in_pack_offset, &avail);
+       used = unpack_object_header_buffer(buf, avail, &type, &size);
+       if (used == 0)
+               die(_("unable to parse object header of %s"),
+                   oid_to_hex(&e->idx.oid));
+
+       unuse_pack(&w_curs);
+       packing_data_unlock(&to_pack);
+       return size;
+}
 
 static int try_delta(struct unpacked *trg, struct unpacked *src,
                     unsigned max_depth, unsigned long *mem_usage)
@@ -1811,7 +2166,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
        void *delta_buf;
 
        /* Don't bother doing diffs between different types */
-       if (trg_entry->type != src_entry->type)
+       if (oe_type(trg_entry) != oe_type(src_entry))
                return -1;
 
        /*
@@ -1822,8 +2177,8 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
         * it, we will still save the transfer cost, as we already know
         * the other side has it and we won't send src_entry at all.
         */
-       if (reuse_delta && trg_entry->in_pack &&
-           trg_entry->in_pack == src_entry->in_pack &&
+       if (reuse_delta && IN_PACK(trg_entry) &&
+           IN_PACK(trg_entry) == IN_PACK(src_entry) &&
            !src_entry->preferred_base &&
            trg_entry->in_pack_type != OBJ_REF_DELTA &&
            trg_entry->in_pack_type != OBJ_OFS_DELTA)
@@ -1834,50 +2189,51 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
                return 0;
 
        /* Now some size filtering heuristics. */
-       trg_size = trg_entry->size;
-       if (!trg_entry->delta) {
-               max_size = trg_size/2 - 20;
+       trg_size = SIZE(trg_entry);
+       if (!DELTA(trg_entry)) {
+               max_size = trg_size/2 - the_hash_algo->rawsz;
                ref_depth = 1;
        } else {
-               max_size = trg_entry->delta_size;
+               max_size = DELTA_SIZE(trg_entry);
                ref_depth = trg->depth;
        }
        max_size = (uint64_t)max_size * (max_depth - src->depth) /
                                                (max_depth - ref_depth + 1);
        if (max_size == 0)
                return 0;
-       src_size = src_entry->size;
+       src_size = SIZE(src_entry);
        sizediff = src_size < trg_size ? trg_size - src_size : 0;
        if (sizediff >= max_size)
                return 0;
        if (trg_size < src_size / 32)
                return 0;
 
+       if (!in_same_island(&trg->entry->idx.oid, &src->entry->idx.oid))
+               return 0;
+
        /* Load data if not already done */
        if (!trg->data) {
-               read_lock();
-               trg->data = read_sha1_file(trg_entry->idx.oid.hash, &type,
-                                          &sz);
-               read_unlock();
+               packing_data_lock(&to_pack);
+               trg->data = read_object_file(&trg_entry->idx.oid, &type, &sz);
+               packing_data_unlock(&to_pack);
                if (!trg->data)
-                       die("object %s cannot be read",
+                       die(_("object %s cannot be read"),
                            oid_to_hex(&trg_entry->idx.oid));
                if (sz != trg_size)
-                       die("object %s inconsistent object length (%lu vs %lu)",
-                           oid_to_hex(&trg_entry->idx.oid), sz,
-                           trg_size);
+                       die(_("object %s inconsistent object length (%"PRIuMAX" vs %"PRIuMAX")"),
+                           oid_to_hex(&trg_entry->idx.oid), (uintmax_t)sz,
+                           (uintmax_t)trg_size);
                *mem_usage += sz;
        }
        if (!src->data) {
-               read_lock();
-               src->data = read_sha1_file(src_entry->idx.oid.hash, &type,
-                                          &sz);
-               read_unlock();
+               packing_data_lock(&to_pack);
+               src->data = read_object_file(&src_entry->idx.oid, &type, &sz);
+               packing_data_unlock(&to_pack);
                if (!src->data) {
                        if (src_entry->preferred_base) {
                                static int warned = 0;
                                if (!warned++)
-                                       warning("object %s cannot be read",
+                                       warning(_("object %s cannot be read"),
                                                oid_to_hex(&src_entry->idx.oid));
                                /*
                                 * Those objects are not included in the
@@ -1887,13 +2243,13 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
                                 */
                                return 0;
                        }
-                       die("object %s cannot be read",
+                       die(_("object %s cannot be read"),
                            oid_to_hex(&src_entry->idx.oid));
                }
                if (sz != src_size)
-                       die("object %s inconsistent object length (%lu vs %lu)",
-                           oid_to_hex(&src_entry->idx.oid), sz,
-                           src_size);
+                       die(_("object %s inconsistent object length (%"PRIuMAX" vs %"PRIuMAX")"),
+                           oid_to_hex(&src_entry->idx.oid), (uintmax_t)sz,
+                           (uintmax_t)src_size);
                *mem_usage += sz;
        }
        if (!src->index) {
@@ -1901,7 +2257,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
                if (!src->index) {
                        static int warned = 0;
                        if (!warned++)
-                               warning("suboptimal pack - out of memory");
+                               warning(_("suboptimal pack - out of memory"));
                        return 0;
                }
                *mem_usage += sizeof_delta_index(src->index);
@@ -1911,9 +2267,9 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
        if (!delta_buf)
                return 0;
 
-       if (trg_entry->delta) {
+       if (DELTA(trg_entry)) {
                /* Prefer only shallower same-sized deltas. */
-               if (delta_size == trg_entry->delta_size &&
+               if (delta_size == DELTA_SIZE(trg_entry) &&
                    src->depth + 1 >= trg->depth) {
                        free(delta_buf);
                        return 0;
@@ -1928,7 +2284,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
        free(trg_entry->delta_data);
        cache_lock();
        if (trg_entry->delta_data) {
-               delta_cache_size -= trg_entry->delta_size;
+               delta_cache_size -= DELTA_SIZE(trg_entry);
                trg_entry->delta_data = NULL;
        }
        if (delta_cacheable(src_size, trg_size, delta_size)) {
@@ -1940,8 +2296,8 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
                free(delta_buf);
        }
 
-       trg_entry->delta = src_entry;
-       trg_entry->delta_size = delta_size;
+       SET_DELTA(trg_entry, src_entry);
+       SET_DELTA_SIZE(trg_entry, delta_size);
        trg->depth = src->depth + 1;
 
        return 1;
@@ -1949,13 +2305,13 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 
 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 {
-       struct object_entry *child = me->delta_child;
+       struct object_entry *child = DELTA_CHILD(me);
        unsigned int m = n;
        while (child) {
-               unsigned int c = check_delta_limit(child, n + 1);
+               const unsigned int c = check_delta_limit(child, n + 1);
                if (m < c)
                        m = c;
-               child = child->delta_sibling;
+               child = DELTA_SIBLING(child);
        }
        return m;
 }
@@ -1966,7 +2322,7 @@ static unsigned long free_unpacked(struct unpacked *n)
        free_delta_index(n->index);
        n->index = NULL;
        if (n->data) {
-               freed_mem += n->entry->size;
+               freed_mem += SIZE(n->entry);
                FREE_AND_NULL(n->data);
        }
        n->entry = NULL;
@@ -2007,7 +2363,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
                while (window_memory_limit &&
                       mem_usage > window_memory_limit &&
                       count > 1) {
-                       uint32_t tail = (idx + window - count) % window;
+                       const uint32_t tail = (idx + window - count) % window;
                        mem_usage -= free_unpacked(array + tail);
                        count--;
                }
@@ -2024,7 +2380,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
                 * otherwise they would become too deep.
                 */
                max_depth = depth;
-               if (entry->delta_child) {
+               if (DELTA_CHILD(entry)) {
                        max_depth -= check_delta_limit(entry, 0);
                        if (max_depth <= 0)
                                goto next;
@@ -2062,19 +2418,26 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
                 * between writes at that moment.
                 */
                if (entry->delta_data && !pack_to_stdout) {
-                       entry->z_delta_size = do_compress(&entry->delta_data,
-                                                         entry->delta_size);
-                       cache_lock();
-                       delta_cache_size -= entry->delta_size;
-                       delta_cache_size += entry->z_delta_size;
-                       cache_unlock();
+                       unsigned long size;
+
+                       size = do_compress(&entry->delta_data, DELTA_SIZE(entry));
+                       if (size < (1U << OE_Z_DELTA_BITS)) {
+                               entry->z_delta_size = size;
+                               cache_lock();
+                               delta_cache_size -= DELTA_SIZE(entry);
+                               delta_cache_size += entry->z_delta_size;
+                               cache_unlock();
+                       } else {
+                               FREE_AND_NULL(entry->delta_data);
+                               entry->z_delta_size = 0;
+                       }
                }
 
                /* if we made n a delta, and if n is already at max
                 * depth, leaving it in the window is pointless.  we
                 * should evict it first.
                 */
-               if (entry->delta && max_depth <= n->depth)
+               if (DELTA(entry) && max_depth <= n->depth)
                        continue;
 
                /*
@@ -2082,7 +2445,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
                 * currently deltified object, to keep it longer.  It will
                 * be the first base object to be attempted next.
                 */
-               if (entry->delta) {
+               if (DELTA(entry)) {
                        struct unpacked swap = array[best_base];
                        int dist = (window + idx - best_base) % window;
                        int dst = best_base;
@@ -2109,24 +2472,20 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
        free(array);
 }
 
-#ifndef NO_PTHREADS
-
-static void try_to_free_from_threads(size_t size)
-{
-       read_lock();
-       release_pack_memory(size);
-       read_unlock();
-}
-
-static try_to_free_t old_try_to_free_routine;
-
 /*
+ * The main object list is split into smaller lists, each is handed to
+ * one worker.
+ *
  * The main thread waits on the condition that (at least) one of the workers
  * has stopped working (which is indicated in the .working member of
  * struct thread_params).
+ *
  * When a work thread has completed its work, it sets .working to 0 and
  * signals the main thread and waits on the condition that .data_ready
  * becomes 1.
+ *
+ * The main thread steals half of the work from the worker that has
+ * most work left to hand it to the idle worker.
  */
 
 struct thread_params {
@@ -2150,18 +2509,14 @@ static pthread_cond_t progress_cond;
  */
 static void init_threaded_search(void)
 {
-       init_recursive_mutex(&read_mutex);
        pthread_mutex_init(&cache_mutex, NULL);
        pthread_mutex_init(&progress_mutex, NULL);
        pthread_cond_init(&progress_cond, NULL);
-       old_try_to_free_routine = set_try_to_free_routine(try_to_free_from_threads);
 }
 
 static void cleanup_threaded_search(void)
 {
-       set_try_to_free_routine(old_try_to_free_routine);
        pthread_cond_destroy(&progress_cond);
-       pthread_mutex_destroy(&read_mutex);
        pthread_mutex_destroy(&cache_mutex);
        pthread_mutex_destroy(&progress_mutex);
 }
@@ -2170,7 +2525,10 @@ static void *threaded_find_deltas(void *arg)
 {
        struct thread_params *me = arg;
 
+       progress_lock();
        while (me->remaining) {
+               progress_unlock();
+
                find_deltas(me->list, &me->remaining,
                            me->window, me->depth, me->processed);
 
@@ -2192,7 +2550,10 @@ static void *threaded_find_deltas(void *arg)
                        pthread_cond_wait(&me->cond, &me->mutex);
                me->data_ready = 0;
                pthread_mutex_unlock(&me->mutex);
+
+               progress_lock();
        }
+       progress_unlock();
        /* leave ->working 1 so that this doesn't get more work assigned */
        return NULL;
 }
@@ -2211,8 +2572,8 @@ static void ll_find_deltas(struct object_entry **list, unsigned list_size,
                return;
        }
        if (progress > pack_to_stdout)
-               fprintf(stderr, "Delta compression using up to %d threads.\n",
-                               delta_search_threads);
+               fprintf_ln(stderr, _("Delta compression using up to %d threads"),
+                          delta_search_threads);
        p = xcalloc(delta_search_threads, sizeof(*p));
 
        /* Partition the work amongst work threads. */
@@ -2252,7 +2613,7 @@ static void ll_find_deltas(struct object_entry **list, unsigned list_size,
                ret = pthread_create(&p[i].thread, NULL,
                                     threaded_find_deltas, &p[i]);
                if (ret)
-                       die("unable to create thread: %s", strerror(ret));
+                       die(_("unable to create thread: %s"), strerror(ret));
                active_threads++;
        }
 
@@ -2326,9 +2687,12 @@ static void ll_find_deltas(struct object_entry **list, unsigned list_size,
        free(p);
 }
 
-#else
-#define ll_find_deltas(l, s, w, d, p)  find_deltas(l, &s, w, d, p)
-#endif
+static int obj_is_packed(const struct object_id *oid)
+{
+       return packlist_find(&to_pack, oid) ||
+               (reuse_packfile_bitmap &&
+                bitmap_walk_contains(bitmap_git, reuse_packfile_bitmap, oid));
+}
 
 static void add_tag_chain(const struct object_id *oid)
 {
@@ -2341,16 +2705,16 @@ static void add_tag_chain(const struct object_id *oid)
         * it was included via bitmaps, we would not have parsed it
         * previously).
         */
-       if (packlist_find(&to_pack, oid->hash, NULL))
+       if (obj_is_packed(oid))
                return;
 
-       tag = lookup_tag(oid);
+       tag = lookup_tag(the_repository, oid);
        while (1) {
                if (!tag || parse_tag(tag) || !tag->tagged)
-                       die("unable to pack objects reachable from tag %s",
+                       die(_("unable to pack objects reachable from tag %s"),
                            oid_to_hex(oid));
 
-               add_object_entry(tag->object.oid.hash, OBJ_TAG, NULL, 0);
+               add_object_entry(&tag->object.oid, OBJ_TAG, NULL, 0);
 
                if (tag->tagged->type != OBJ_TAG)
                        return;
@@ -2364,8 +2728,8 @@ static int add_ref_tag(const char *path, const struct object_id *oid, int flag,
        struct object_id peeled;
 
        if (starts_with(path, "refs/tags/") && /* is a tag? */
-           !peel_ref(path, peeled.hash)    && /* peelable? */
-           packlist_find(&to_pack, peeled.hash, NULL))      /* object packed? */
+           !peel_ref(path, &peeled)    && /* peelable? */
+           obj_is_packed(&peeled)) /* object packed? */
                add_tag_chain(oid);
        return 0;
 }
@@ -2376,6 +2740,9 @@ static void prepare_pack(int window, int depth)
        uint32_t i, nr_deltas;
        unsigned n;
 
+       if (use_delta_islands)
+               resolve_tree_islands(the_repository, progress, &to_pack);
+
        get_object_details();
 
        /*
@@ -2397,13 +2764,14 @@ static void prepare_pack(int window, int depth)
        for (i = 0; i < to_pack.nr_objects; i++) {
                struct object_entry *entry = to_pack.objects + i;
 
-               if (entry->delta)
+               if (DELTA(entry))
                        /* This happens if we decided to reuse existing
                         * delta from a pack.  "reuse_delta &&" is implied.
                         */
                        continue;
 
-               if (entry->size < 50)
+               if (!entry->type_valid ||
+                   oe_size_less_than(&to_pack, entry, 50))
                        continue;
 
                if (entry->no_try_delta)
@@ -2411,11 +2779,11 @@ static void prepare_pack(int window, int depth)
 
                if (!entry->preferred_base) {
                        nr_deltas++;
-                       if (entry->type < 0)
-                               die("unable to get type of object %s",
+                       if (oe_type(entry) < 0)
+                               die(_("unable to get type of object %s"),
                                    oid_to_hex(&entry->idx.oid));
                } else {
-                       if (entry->type < 0) {
+                       if (oe_type(entry) < 0) {
                                /*
                                 * This object is not found, but we
                                 * don't have to include it anyway.
@@ -2429,6 +2797,7 @@ static void prepare_pack(int window, int depth)
 
        if (nr_deltas && n > 1) {
                unsigned nr_done = 0;
+
                if (progress)
                        progress_state = start_progress(_("Compressing objects"),
                                                        nr_deltas);
@@ -2436,7 +2805,7 @@ static void prepare_pack(int window, int depth)
                ll_find_deltas(delta_list, n, window+1, depth, &nr_done);
                stop_progress(&progress_state);
                if (nr_done != nr_deltas)
-                       die("inconsistency with delta count");
+                       die(_("inconsistency with delta count"));
        }
        free(delta_list);
 }
@@ -2473,23 +2842,25 @@ static int git_pack_config(const char *k, const char *v, void *cb)
                use_bitmap_index_default = git_config_bool(k, v);
                return 0;
        }
+       if (!strcmp(k, "pack.allowpackreuse")) {
+               allow_pack_reuse = git_config_bool(k, v);
+               return 0;
+       }
        if (!strcmp(k, "pack.threads")) {
                delta_search_threads = git_config_int(k, v);
                if (delta_search_threads < 0)
-                       die("invalid number of threads specified (%d)",
+                       die(_("invalid number of threads specified (%d)"),
                            delta_search_threads);
-#ifdef NO_PTHREADS
-               if (delta_search_threads != 1) {
-                       warning("no threads support, ignoring %s", k);
+               if (!HAVE_THREADS && delta_search_threads != 1) {
+                       warning(_("no threads support, ignoring %s"), k);
                        delta_search_threads = 0;
                }
-#endif
                return 0;
        }
        if (!strcmp(k, "pack.indexversion")) {
                pack_idx_opts.version = git_config_int(k, v);
                if (pack_idx_opts.version > 2)
-                       die("bad pack.indexversion=%"PRIu32,
+                       die(_("bad pack.indexversion=%"PRIu32),
                            pack_idx_opts.version);
                return 0;
        }
@@ -2498,56 +2869,134 @@ static int git_pack_config(const char *k, const char *v, void *cb)
 
 static void read_object_list_from_stdin(void)
 {
-       char line[40 + 1 + PATH_MAX + 2];
-       unsigned char sha1[20];
+       char line[GIT_MAX_HEXSZ + 1 + PATH_MAX + 2];
+       struct object_id oid;
+       const char *p;
 
        for (;;) {
                if (!fgets(line, sizeof(line), stdin)) {
                        if (feof(stdin))
                                break;
                        if (!ferror(stdin))
-                               die("fgets returned NULL, not EOF, not error!");
+                               die("BUG: fgets returned NULL, not EOF, not error!");
                        if (errno != EINTR)
                                die_errno("fgets");
                        clearerr(stdin);
                        continue;
                }
                if (line[0] == '-') {
-                       if (get_sha1_hex(line+1, sha1))
-                               die("expected edge sha1, got garbage:\n %s",
+                       if (get_oid_hex(line+1, &oid))
+                               die(_("expected edge object ID, got garbage:\n %s"),
                                    line);
-                       add_preferred_base(sha1);
+                       add_preferred_base(&oid);
                        continue;
                }
-               if (get_sha1_hex(line, sha1))
-                       die("expected sha1, got garbage:\n %s", line);
+               if (parse_oid_hex(line, &oid, &p))
+                       die(_("expected object ID, got garbage:\n %s"), line);
 
-               add_preferred_base_object(line+41);
-               add_object_entry(sha1, 0, line+41, 0);
+               add_preferred_base_object(p + 1);
+               add_object_entry(&oid, OBJ_NONE, p + 1, 0);
        }
 }
 
+/* Remember to update object flag allocation in object.h */
 #define OBJECT_ADDED (1u<<20)
 
 static void show_commit(struct commit *commit, void *data)
 {
-       add_object_entry(commit->object.oid.hash, OBJ_COMMIT, NULL, 0);
+       add_object_entry(&commit->object.oid, OBJ_COMMIT, NULL, 0);
        commit->object.flags |= OBJECT_ADDED;
 
        if (write_bitmap_index)
                index_commit_for_bitmap(commit);
+
+       if (use_delta_islands)
+               propagate_island_marks(commit);
 }
 
 static void show_object(struct object *obj, const char *name, void *data)
 {
        add_preferred_base_object(name);
-       add_object_entry(obj->oid.hash, obj->type, name, 0);
+       add_object_entry(&obj->oid, obj->type, name, 0);
        obj->flags |= OBJECT_ADDED;
+
+       if (use_delta_islands) {
+               const char *p;
+               unsigned depth;
+               struct object_entry *ent;
+
+               /* the empty string is a root tree, which is depth 0 */
+               depth = *name ? 1 : 0;
+               for (p = strchr(name, '/'); p; p = strchr(p + 1, '/'))
+                       depth++;
+
+               ent = packlist_find(&to_pack, &obj->oid);
+               if (ent && depth > oe_tree_depth(&to_pack, ent))
+                       oe_set_tree_depth(&to_pack, ent, depth);
+       }
+}
+
+static void show_object__ma_allow_any(struct object *obj, const char *name, void *data)
+{
+       assert(arg_missing_action == MA_ALLOW_ANY);
+
+       /*
+        * Quietly ignore ALL missing objects.  This avoids problems with
+        * staging them now and getting an odd error later.
+        */
+       if (!has_object_file(&obj->oid))
+               return;
+
+       show_object(obj, name, data);
+}
+
+static void show_object__ma_allow_promisor(struct object *obj, const char *name, void *data)
+{
+       assert(arg_missing_action == MA_ALLOW_PROMISOR);
+
+       /*
+        * Quietly ignore EXPECTED missing objects.  This avoids problems with
+        * staging them now and getting an odd error later.
+        */
+       if (!has_object_file(&obj->oid) && is_promisor_object(&obj->oid))
+               return;
+
+       show_object(obj, name, data);
+}
+
+static int option_parse_missing_action(const struct option *opt,
+                                      const char *arg, int unset)
+{
+       assert(arg);
+       assert(!unset);
+
+       if (!strcmp(arg, "error")) {
+               arg_missing_action = MA_ERROR;
+               fn_show_object = show_object;
+               return 0;
+       }
+
+       if (!strcmp(arg, "allow-any")) {
+               arg_missing_action = MA_ALLOW_ANY;
+               fetch_if_missing = 0;
+               fn_show_object = show_object__ma_allow_any;
+               return 0;
+       }
+
+       if (!strcmp(arg, "allow-promisor")) {
+               arg_missing_action = MA_ALLOW_PROMISOR;
+               fetch_if_missing = 0;
+               fn_show_object = show_object__ma_allow_promisor;
+               return 0;
+       }
+
+       die(_("invalid value for --missing"));
+       return 0;
 }
 
 static void show_edge(struct commit *commit)
 {
-       add_preferred_base(commit->object.oid.hash);
+       add_preferred_base(&commit->object.oid);
 }
 
 struct in_pack_object {
@@ -2556,8 +3005,8 @@ struct in_pack_object {
 };
 
 struct in_pack {
-       int alloc;
-       int nr;
+       unsigned int alloc;
+       unsigned int nr;
        struct in_pack_object *array;
 };
 
@@ -2585,7 +3034,7 @@ static int ofscmp(const void *a_, const void *b_)
                return oidcmp(&a->object->oid, &b->object->oid);
 }
 
-static void add_objects_in_unpacked_packs(struct rev_info *revs)
+static void add_objects_in_unpacked_packs(void)
 {
        struct packed_git *p;
        struct in_pack in_pack;
@@ -2593,22 +3042,22 @@ static void add_objects_in_unpacked_packs(struct rev_info *revs)
 
        memset(&in_pack, 0, sizeof(in_pack));
 
-       for (p = packed_git; p; p = p->next) {
-               const unsigned char *sha1;
+       for (p = get_all_packs(the_repository); p; p = p->next) {
+               struct object_id oid;
                struct object *o;
 
-               if (!p->pack_local || p->pack_keep)
+               if (!p->pack_local || p->pack_keep || p->pack_keep_in_core)
                        continue;
                if (open_pack_index(p))
-                       die("cannot open pack index");
+                       die(_("cannot open pack index"));
 
                ALLOC_GROW(in_pack.array,
                           in_pack.nr + p->num_objects,
                           in_pack.alloc);
 
                for (i = 0; i < p->num_objects; i++) {
-                       sha1 = nth_packed_object_sha1(p, i);
-                       o = lookup_unknown_object(sha1);
+                       nth_packed_object_id(&oid, p, i);
+                       o = lookup_unknown_object(&oid);
                        if (!(o->flags & OBJECT_ADDED))
                                mark_in_pack_object(o, p, &in_pack);
                        o->flags |= OBJECT_ADDED;
@@ -2619,7 +3068,7 @@ static void add_objects_in_unpacked_packs(struct rev_info *revs)
                QSORT(in_pack.array, in_pack.nr, ofscmp);
                for (i = 0; i < in_pack.nr; i++) {
                        struct object *o = in_pack.array[i].object;
-                       add_object_entry(o->oid.hash, o->type, "", 0);
+                       add_object_entry(&o->oid, o->type, "", 0);
                }
        }
        free(in_pack.array);
@@ -2628,14 +3077,14 @@ static void add_objects_in_unpacked_packs(struct rev_info *revs)
 static int add_loose_object(const struct object_id *oid, const char *path,
                            void *data)
 {
-       enum object_type type = sha1_object_info(oid->hash, NULL);
+       enum object_type type = oid_object_info(the_repository, oid, NULL);
 
        if (type < 0) {
-               warning("loose object at %s could not be examined", path);
+               warning(_("loose object at %s could not be examined"), path);
                return 0;
        }
 
-       add_object_entry(oid->hash, type, "", 0);
+       add_object_entry(oid, type, "", 0);
        return 0;
 }
 
@@ -2651,21 +3100,23 @@ static void add_unreachable_loose_objects(void)
                                      NULL, NULL, NULL);
 }
 
-static int has_sha1_pack_kept_or_nonlocal(const unsigned char *sha1)
+static int has_sha1_pack_kept_or_nonlocal(const struct object_id *oid)
 {
        static struct packed_git *last_found = (void *)1;
        struct packed_git *p;
 
-       p = (last_found != (void *)1) ? last_found : packed_git;
+       p = (last_found != (void *)1) ? last_found :
+                                       get_all_packs(the_repository);
 
        while (p) {
-               if ((!p->pack_local || p->pack_keep) &&
-                       find_pack_entry_one(sha1, p)) {
+               if ((!p->pack_local || p->pack_keep ||
+                               p->pack_keep_in_core) &&
+                       find_pack_entry_one(oid->hash, p)) {
                        last_found = p;
                        return 1;
                }
                if (p == last_found)
-                       p = packed_git;
+                       p = get_all_packs(the_repository);
                else
                        p = p->next;
                if (p == last_found)
@@ -2695,26 +3146,26 @@ static int loosened_object_can_be_discarded(const struct object_id *oid,
        return 1;
 }
 
-static void loosen_unused_packed_objects(struct rev_info *revs)
+static void loosen_unused_packed_objects(void)
 {
        struct packed_git *p;
        uint32_t i;
        struct object_id oid;
 
-       for (p = packed_git; p; p = p->next) {
-               if (!p->pack_local || p->pack_keep)
+       for (p = get_all_packs(the_repository); p; p = p->next) {
+               if (!p->pack_local || p->pack_keep || p->pack_keep_in_core)
                        continue;
 
                if (open_pack_index(p))
-                       die("cannot open pack index");
+                       die(_("cannot open pack index"));
 
                for (i = 0; i < p->num_objects; i++) {
-                       nth_packed_object_oid(&oid, p, i);
-                       if (!packlist_find(&to_pack, oid.hash, NULL) &&
-                           !has_sha1_pack_kept_or_nonlocal(oid.hash) &&
+                       nth_packed_object_id(&oid, p, i);
+                       if (!packlist_find(&to_pack, &oid) &&
+                           !has_sha1_pack_kept_or_nonlocal(&oid) &&
                            !loosened_object_can_be_discarded(&oid, p->mtime))
-                               if (force_object_loose(oid.hash, p->mtime))
-                                       die("unable to force loose object");
+                               if (force_object_loose(&oid, p->mtime))
+                                       die(_("unable to force loose object"));
                }
        }
 }
@@ -2726,29 +3177,32 @@ static void loosen_unused_packed_objects(struct rev_info *revs)
  */
 static int pack_options_allow_reuse(void)
 {
-       return pack_to_stdout &&
-              allow_ofs_delta &&
-              !ignore_packed_keep &&
+       return allow_pack_reuse &&
+              pack_to_stdout &&
+              !ignore_packed_keep_on_disk &&
+              !ignore_packed_keep_in_core &&
               (!local || !have_non_local_packs) &&
               !incremental;
 }
 
 static int get_object_list_from_bitmap(struct rev_info *revs)
 {
-       if (prepare_bitmap_walk(revs) < 0)
+       if (!(bitmap_git = prepare_bitmap_walk(revs, &filter_options)))
                return -1;
 
        if (pack_options_allow_reuse() &&
            !reuse_partial_packfile_from_bitmap(
+                       bitmap_git,
                        &reuse_packfile,
                        &reuse_packfile_objects,
-                       &reuse_packfile_offset)) {
+                       &reuse_packfile_bitmap)) {
                assert(reuse_packfile_objects);
                nr_result += reuse_packfile_objects;
                display_progress(progress_state, nr_result);
        }
 
-       traverse_bitmap_commit_list(&add_object_entry_from_bitmap);
+       traverse_bitmap_commit_list(bitmap_git, revs,
+                                   &add_object_entry_from_bitmap);
        return 0;
 }
 
@@ -2767,15 +3221,22 @@ static void record_recent_commit(struct commit *commit, void *data)
 static void get_object_list(int ac, const char **av)
 {
        struct rev_info revs;
+       struct setup_revision_opt s_r_opt = {
+               .allow_exclude_promisor_objects = 1,
+       };
        char line[1000];
        int flags = 0;
+       int save_warning;
 
-       init_revisions(&revs, NULL);
+       repo_init_revisions(the_repository, &revs, NULL);
        save_commit_buffer = 0;
-       setup_revisions(ac, av, &revs, NULL);
+       setup_revisions(ac, av, &revs, &s_r_opt);
 
        /* make sure shallows are read */
-       is_repository_shallow();
+       is_repository_shallow(the_repository);
+
+       save_warning = warn_on_object_refname_ambiguity;
+       warn_on_object_refname_ambiguity = 0;
 
        while (fgets(line, sizeof(line), stdin) != NULL) {
                int len = strlen(line);
@@ -2793,50 +3254,89 @@ static void get_object_list(int ac, const char **av)
                                struct object_id oid;
                                if (get_oid_hex(line + 10, &oid))
                                        die("not an SHA-1 '%s'", line + 10);
-                               register_shallow(&oid);
+                               register_shallow(the_repository, &oid);
                                use_bitmap_index = 0;
                                continue;
                        }
-                       die("not a rev '%s'", line);
+                       die(_("not a rev '%s'"), line);
                }
                if (handle_revision_arg(line, &revs, flags, REVARG_CANNOT_BE_FILENAME))
-                       die("bad revision '%s'", line);
+                       die(_("bad revision '%s'"), line);
        }
 
+       warn_on_object_refname_ambiguity = save_warning;
+
        if (use_bitmap_index && !get_object_list_from_bitmap(&revs))
                return;
 
+       if (use_delta_islands)
+               load_delta_islands(the_repository, progress);
+
        if (prepare_revision_walk(&revs))
-               die("revision walk setup failed");
-       mark_edges_uninteresting(&revs, show_edge);
-       traverse_commit_list(&revs, show_commit, show_object, NULL);
+               die(_("revision walk setup failed"));
+       mark_edges_uninteresting(&revs, show_edge, sparse);
+
+       if (!fn_show_object)
+               fn_show_object = show_object;
+       traverse_commit_list_filtered(&filter_options, &revs,
+                                     show_commit, fn_show_object, NULL,
+                                     NULL);
 
        if (unpack_unreachable_expiration) {
                revs.ignore_missing_links = 1;
                if (add_unseen_recent_objects_to_traversal(&revs,
                                unpack_unreachable_expiration))
-                       die("unable to add recent objects");
+                       die(_("unable to add recent objects"));
                if (prepare_revision_walk(&revs))
-                       die("revision walk setup failed");
+                       die(_("revision walk setup failed"));
                traverse_commit_list(&revs, record_recent_commit,
                                     record_recent_object, NULL);
        }
 
        if (keep_unreachable)
-               add_objects_in_unpacked_packs(&revs);
+               add_objects_in_unpacked_packs();
        if (pack_loose_unreachable)
                add_unreachable_loose_objects();
        if (unpack_unreachable)
-               loosen_unused_packed_objects(&revs);
+               loosen_unused_packed_objects();
 
        oid_array_clear(&recent_objects);
 }
 
+static void add_extra_kept_packs(const struct string_list *names)
+{
+       struct packed_git *p;
+
+       if (!names->nr)
+               return;
+
+       for (p = get_all_packs(the_repository); p; p = p->next) {
+               const char *name = basename(p->pack_name);
+               int i;
+
+               if (!p->pack_local)
+                       continue;
+
+               for (i = 0; i < names->nr; i++)
+                       if (!fspathcmp(name, names->items[i].string))
+                               break;
+
+               if (i < names->nr) {
+                       p->pack_keep_in_core = 1;
+                       ignore_packed_keep_in_core = 1;
+                       continue;
+               }
+       }
+}
+
 static int option_parse_index_version(const struct option *opt,
                                      const char *arg, int unset)
 {
        char *c;
        const char *val = arg;
+
+       BUG_ON_OPT_NEG(unset);
+
        pack_idx_opts.version = strtoul(val, &c, 10);
        if (pack_idx_opts.version > 2)
                die(_("unsupported index version %s"), val);
@@ -2865,12 +3365,12 @@ static int option_parse_unpack_unreachable(const struct option *opt,
 int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 {
        int use_internal_rev_list = 0;
-       int thin = 0;
        int shallow = 0;
        int all_progress_implied = 0;
        struct argv_array rp = ARGV_ARRAY_INIT;
        int rev_list_unpacked = 0, rev_list_all = 0, rev_list_reflog = 0;
        int rev_list_index = 0;
+       struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
        struct option pack_objects_options[] = {
                OPT_SET_INT('q', "quiet", &progress,
                            N_("do not show progress meter"), 0),
@@ -2881,9 +3381,9 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
                OPT_BOOL(0, "all-progress-implied",
                         &all_progress_implied,
                         N_("similar to --all-progress when progress meter is shown")),
-               { OPTION_CALLBACK, 0, "index-version", NULL, N_("version[,offset]"),
+               OPT_CALLBACK_F(0, "index-version", NULL, N_("<version>[,<offset>]"),
                  N_("write the pack index file in the specified idx format version"),
-                 0, option_parse_index_version },
+                 PARSE_OPT_NONEG, option_parse_index_version),
                OPT_MAGNITUDE(0, "max-pack-size", &pack_size_limit,
                              N_("maximum size of each output pack file")),
                OPT_BOOL(0, "local", &local,
@@ -2908,18 +3408,18 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
                         N_("do not create an empty pack output")),
                OPT_BOOL(0, "revs", &use_internal_rev_list,
                         N_("read revision arguments from standard input")),
-               { OPTION_SET_INT, 0, "unpacked", &rev_list_unpacked, NULL,
-                 N_("limit the objects to those that are not yet packed"),
-                 PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
-               { OPTION_SET_INT, 0, "all", &rev_list_all, NULL,
-                 N_("include objects reachable from any reference"),
-                 PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
-               { OPTION_SET_INT, 0, "reflog", &rev_list_reflog, NULL,
-                 N_("include objects referred by reflog entries"),
-                 PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
-               { OPTION_SET_INT, 0, "indexed-objects", &rev_list_index, NULL,
-                 N_("include objects referred to by the index"),
-                 PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
+               OPT_SET_INT_F(0, "unpacked", &rev_list_unpacked,
+                             N_("limit the objects to those that are not yet packed"),
+                             1, PARSE_OPT_NONEG),
+               OPT_SET_INT_F(0, "all", &rev_list_all,
+                             N_("include objects reachable from any reference"),
+                             1, PARSE_OPT_NONEG),
+               OPT_SET_INT_F(0, "reflog", &rev_list_reflog,
+                             N_("include objects referred by reflog entries"),
+                             1, PARSE_OPT_NONEG),
+               OPT_SET_INT_F(0, "indexed-objects", &rev_list_index,
+                             N_("include objects referred to by the index"),
+                             1, PARSE_OPT_NONEG),
                OPT_BOOL(0, "stdout", &pack_to_stdout,
                         N_("output pack to stdout")),
                OPT_BOOL(0, "include-tag", &include_tag,
@@ -2928,27 +3428,52 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
                         N_("keep unreachable objects")),
                OPT_BOOL(0, "pack-loose-unreachable", &pack_loose_unreachable,
                         N_("pack loose unreachable objects")),
-               { OPTION_CALLBACK, 0, "unpack-unreachable", NULL, N_("time"),
+               OPT_CALLBACK_F(0, "unpack-unreachable", NULL, N_("time"),
                  N_("unpack unreachable objects newer than <time>"),
-                 PARSE_OPT_OPTARG, option_parse_unpack_unreachable },
+                 PARSE_OPT_OPTARG, option_parse_unpack_unreachable),
+               OPT_BOOL(0, "sparse", &sparse,
+                        N_("use the sparse reachability algorithm")),
                OPT_BOOL(0, "thin", &thin,
                         N_("create thin packs")),
                OPT_BOOL(0, "shallow", &shallow,
                         N_("create packs suitable for shallow fetches")),
-               OPT_BOOL(0, "honor-pack-keep", &ignore_packed_keep,
+               OPT_BOOL(0, "honor-pack-keep", &ignore_packed_keep_on_disk,
                         N_("ignore packs that have companion .keep file")),
+               OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
+                               N_("ignore this pack")),
                OPT_INTEGER(0, "compression", &pack_compression_level,
                            N_("pack compression level")),
                OPT_SET_INT(0, "keep-true-parents", &grafts_replace_parents,
                            N_("do not hide commits by grafts"), 0),
                OPT_BOOL(0, "use-bitmap-index", &use_bitmap_index,
                         N_("use a bitmap index if available to speed up counting objects")),
-               OPT_BOOL(0, "write-bitmap-index", &write_bitmap_index,
-                        N_("write a bitmap index together with the pack index")),
+               OPT_SET_INT(0, "write-bitmap-index", &write_bitmap_index,
+                           N_("write a bitmap index together with the pack index"),
+                           WRITE_BITMAP_TRUE),
+               OPT_SET_INT_F(0, "write-bitmap-index-quiet",
+                             &write_bitmap_index,
+                             N_("write a bitmap index if possible"),
+                             WRITE_BITMAP_QUIET, PARSE_OPT_HIDDEN),
+               OPT_PARSE_LIST_OBJECTS_FILTER(&filter_options),
+               OPT_CALLBACK_F(0, "missing", NULL, N_("action"),
+                 N_("handling for missing objects"), PARSE_OPT_NONEG,
+                 option_parse_missing_action),
+               OPT_BOOL(0, "exclude-promisor-objects", &exclude_promisor_objects,
+                        N_("do not pack objects in promisor packfiles")),
+               OPT_BOOL(0, "delta-islands", &use_delta_islands,
+                        N_("respect islands during delta compression")),
                OPT_END(),
        };
 
-       check_replace_refs = 0;
+       if (DFS_NUM_STATES > (1 << OE_DFS_STATE_BITS))
+               BUG("too many dfs states, increase OE_DFS_STATE_BITS");
+
+       read_replace_refs = 0;
+
+       sparse = git_env_bool("GIT_TEST_PACK_SPARSE", -1);
+       prepare_repo_settings(the_repository);
+       if (sparse < 0)
+               sparse = the_repository->settings.pack_use_sparse;
 
        reset_pack_idx_option(&pack_idx_opts);
        git_config(git_pack_config, NULL);
@@ -2964,6 +3489,17 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
        if (pack_to_stdout != !base_name || argc)
                usage_with_options(pack_usage, pack_objects_options);
 
+       if (depth >= (1 << OE_DEPTH_BITS)) {
+               warning(_("delta chain depth %d is too deep, forcing %d"),
+                       depth, (1 << OE_DEPTH_BITS) - 1);
+               depth = (1 << OE_DEPTH_BITS) - 1;
+       }
+       if (cache_max_small_delta_size >= (1U << OE_Z_DELTA_BITS)) {
+               warning(_("pack.deltaCacheLimit is too high, forcing %d"),
+                       (1U << OE_Z_DELTA_BITS) - 1);
+               cache_max_small_delta_size = (1U << OE_Z_DELTA_BITS) - 1;
+       }
+
        argv_array_push(&rp, "pack-objects");
        if (thin) {
                use_internal_rev_list = 1;
@@ -2990,37 +3526,48 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
                argv_array_push(&rp, "--unpacked");
        }
 
+       if (exclude_promisor_objects) {
+               use_internal_rev_list = 1;
+               fetch_if_missing = 0;
+               argv_array_push(&rp, "--exclude-promisor-objects");
+       }
+       if (unpack_unreachable || keep_unreachable || pack_loose_unreachable)
+               use_internal_rev_list = 1;
+
        if (!reuse_object)
                reuse_delta = 0;
        if (pack_compression_level == -1)
                pack_compression_level = Z_DEFAULT_COMPRESSION;
        else if (pack_compression_level < 0 || pack_compression_level > Z_BEST_COMPRESSION)
-               die("bad pack compression level %d", pack_compression_level);
+               die(_("bad pack compression level %d"), pack_compression_level);
 
        if (!delta_search_threads)      /* --threads=0 means autodetect */
                delta_search_threads = online_cpus();
 
-#ifdef NO_PTHREADS
-       if (delta_search_threads != 1)
-               warning("no threads support, ignoring --threads");
-#endif
+       if (!HAVE_THREADS && delta_search_threads != 1)
+               warning(_("no threads support, ignoring --threads"));
        if (!pack_to_stdout && !pack_size_limit)
                pack_size_limit = pack_size_limit_cfg;
        if (pack_to_stdout && pack_size_limit)
-               die("--max-pack-size cannot be used to build a pack for transfer.");
+               die(_("--max-pack-size cannot be used to build a pack for transfer"));
        if (pack_size_limit && pack_size_limit < 1024*1024) {
-               warning("minimum pack size limit is 1 MiB");
+               warning(_("minimum pack size limit is 1 MiB"));
                pack_size_limit = 1024*1024;
        }
 
        if (!pack_to_stdout && thin)
-               die("--thin cannot be used to build an indexable pack.");
+               die(_("--thin cannot be used to build an indexable pack"));
 
        if (keep_unreachable && unpack_unreachable)
-               die("--keep-unreachable and --unpack-unreachable are incompatible.");
+               die(_("--keep-unreachable and --unpack-unreachable are incompatible"));
        if (!rev_list_all || !rev_list_reflog || !rev_list_index)
                unpack_unreachable_expiration = 0;
 
+       if (filter_options.choice) {
+               if (!pack_to_stdout)
+                       die(_("cannot use --filter without --stdout"));
+       }
+
        /*
         * "soft" reasons not to use bitmaps - for on-disk repack by default we want
         *
@@ -3037,32 +3584,35 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
                use_bitmap_index = use_bitmap_index_default;
 
        /* "hard" reasons not to use bitmaps; these just won't work at all */
-       if (!use_internal_rev_list || (!pack_to_stdout && write_bitmap_index) || is_repository_shallow())
+       if (!use_internal_rev_list || (!pack_to_stdout && write_bitmap_index) || is_repository_shallow(the_repository))
                use_bitmap_index = 0;
 
        if (pack_to_stdout || !rev_list_all)
                write_bitmap_index = 0;
 
+       if (use_delta_islands)
+               argv_array_push(&rp, "--topo-order");
+
        if (progress && all_progress_implied)
                progress = 2;
 
-       prepare_packed_git();
-       if (ignore_packed_keep) {
+       add_extra_kept_packs(&keep_pack_list);
+       if (ignore_packed_keep_on_disk) {
                struct packed_git *p;
-               for (p = packed_git; p; p = p->next)
+               for (p = get_all_packs(the_repository); p; p = p->next)
                        if (p->pack_local && p->pack_keep)
                                break;
                if (!p) /* no keep-able packs found */
-                       ignore_packed_keep = 0;
+                       ignore_packed_keep_on_disk = 0;
        }
        if (local) {
                /*
-                * unlike ignore_packed_keep above, we do not want to
-                * unset "local" based on looking at packs, as it
-                * also covers non-local objects
+                * unlike ignore_packed_keep_on_disk above, we do not
+                * want to unset "local" based on looking at packs, as
+                * it also covers non-local objects
                 */
                struct packed_git *p;
-               for (p = packed_git; p; p = p->next) {
+               for (p = get_all_packs(the_repository); p; p = p->next) {
                        if (!p->pack_local) {
                                have_non_local_packs = 1;
                                break;
@@ -3070,8 +3620,12 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
                }
        }
 
+       trace2_region_enter("pack-objects", "enumerate-objects",
+                           the_repository);
+       prepare_packing_data(the_repository, &to_pack);
+
        if (progress)
-               progress_state = start_progress(_("Counting objects"), 0);
+               progress_state = start_progress(_("Enumerating objects"), 0);
        if (!use_internal_rev_list)
                read_object_list_from_stdin();
        else {
@@ -3082,15 +3636,29 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
        if (include_tag && nr_result)
                for_each_ref(add_ref_tag, NULL);
        stop_progress(&progress_state);
+       trace2_region_leave("pack-objects", "enumerate-objects",
+                           the_repository);
 
        if (non_empty && !nr_result)
                return 0;
-       if (nr_result)
+       if (nr_result) {
+               trace2_region_enter("pack-objects", "prepare-pack",
+                                   the_repository);
                prepare_pack(window, depth);
+               trace2_region_leave("pack-objects", "prepare-pack",
+                                   the_repository);
+       }
+
+       trace2_region_enter("pack-objects", "write-pack-file", the_repository);
        write_pack_file();
+       trace2_region_leave("pack-objects", "write-pack-file", the_repository);
+
        if (progress)
-               fprintf(stderr, "Total %"PRIu32" (delta %"PRIu32"),"
-                       " reused %"PRIu32" (delta %"PRIu32")\n",
-                       written, written_delta, reused, reused_delta);
+               fprintf_ln(stderr,
+                          _("Total %"PRIu32" (delta %"PRIu32"),"
+                            " reused %"PRIu32" (delta %"PRIu32"),"
+                            " pack-reused %"PRIu32),
+                          written, written_delta, reused, reused_delta,
+                          reuse_packfile_objects);
        return 0;
 }