Only read the logs that could have changed

This uses the new support for change bitmaps that is implemented in the
zlogger kernel module.

Change-Id: I6d4c9301003c7e436d9bddf7085fb1704f812674

diff --git a/src/libdlogutil/fdi_zero_copy.c b/src/libdlogutil/fdi_zero_copy.c
index 374a202..b8f7dc5 100644 (file)
--- a/src/libdlogutil/fdi_zero_copy.c
+++ b/src/libdlogutil/fdi_zero_copy.c
@@ -133,6 +133,7 @@ static int zero_copy_prepare_print(struct fd_info *fdi, int dump, bool monitor,
        zpd->monitor = monitor;
        zpd->prev_read_ts = monitor ? get_zlog_clock() : 0;
        zpd->this_read_ts = zpd->prev_read_ts;
+       zpd->read_everything = !monitor;
 
        return 0;
 }
@@ -218,13 +219,17 @@ static void append_dlogutil_entry_to_item_list(dlogutil_entry_s *de, struct zlog
        *items = item;
 }
 
-static void load_single_device(volatile struct zlogger_block *zb, struct zlog_entry_list **items, uint64_t min_timestamp, uint64_t max_timestamp)
+static void load_single_device(volatile struct zlogger_block *zb, struct zlog_entry_list **items, uint64_t min_timestamp, uint64_t max_timestamp, char *bitmap)
 {
        /* TODO: document this mumbo jumbo.
         * Requires expert earth magic to understand, probably. */
 
        static size_t const BLOCK_COUNT = ZLOGGER_MAP_SIZE / sizeof *zb;
        for (size_t i = 0; i < BLOCK_COUNT; i++, zb++) {
+               bool enabled = bitmap[i / CHAR_BIT] & (1 << (i % CHAR_BIT));
+               if (!enabled)
+                       continue;
+
                if (zb->head.offset > ZLOGGER_DATA_MAX)
                        continue;
 
@@ -331,11 +336,27 @@ static int zero_copy_read(struct fd_info *fdi)
        zpd->prev_read_ts = zpd->this_read_ts;
        zpd->this_read_ts = now;
 
+       __attribute__((cleanup(free_ptr))) char *bitmap = malloc(ZLOGGER_BITMAP_SIZE);
+       if (!bitmap)
+               return -ENOMEM;
+
+       int ret = ioctl(fdi->fd, ZLOGGER_IOCTL_COMMAND_GET_BITMAP, bitmap);
+       if (ret < 0)
+               return -errno;
+
+       if (zpd->read_everything) {
+               /* We want to read everything to see all the logs since the startup
+                * and not only all logs since opening. We still call the ioctl so that
+                * the next ioctl will know that we have read the existing logs. */
+               memset(bitmap, ~(char)0, ZLOGGER_BITMAP_SIZE);
+               zpd->read_everything = false;
+       }
+
        for (size_t i = 0; i < ZLOGGER_DEVICE_COUNT; ++i) {
                volatile void *const addr = mmap(NULL, ZLOGGER_MAP_SIZE, PROT_READ, MAP_SHARED, fdi->fd, ZLOGGER_MAP_SIZE * i);
                if (addr == MAP_FAILED)
                        break;
-               load_single_device(addr, &zpd->items, zpd->prev_read_ts, now);
+               load_single_device(addr, &zpd->items, zpd->prev_read_ts, now, bitmap + (ZLOGGER_BLOCK_MAP_COUNT / CHAR_BIT) * i);
                munmap((void *) addr, ZLOGGER_MAP_SIZE);
        }
 

diff --git a/src/libdlogutil/fdi_zero_copy.h b/src/libdlogutil/fdi_zero_copy.h
index 849696c..275ff22 100644 (file)
--- a/src/libdlogutil/fdi_zero_copy.h
+++ b/src/libdlogutil/fdi_zero_copy.h
@@ -40,5 +40,6 @@ struct zero_copy_priv_data {
        bool dump;
        bool monitor;
        bool eof;
+       bool read_everything;
 };