ITS#7126 fix cursor tracking code

Don't compare cursors that aren't deep enough to match the
current cursor.

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index adf98be..cdd46c9 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -1234,6 +1234,7 @@ finish:
                        for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
                                if (m2 == mc) continue;
                                m3 = &m2->mc_xcursor->mx_cursor;
+                               if (m3->mc_snum < mc->mc_snum) continue;
                                if (m3->mc_pg[mc->mc_top] == mc->mc_pg[mc->mc_top]) {
                                        m3->mc_pg[mc->mc_top] = mp;
                                }
@@ -1242,7 +1243,7 @@ finish:
                        MDB_cursor *m2;
 
                        for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
-                               if (m2 == mc) continue;
+                               if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
                                if (m2->mc_pg[mc->mc_top] == mc->mc_pg[mc->mc_top]) {
                                        m2->mc_pg[mc->mc_top] = mp;
                                }
@@ -4167,7 +4168,7 @@ new_sub:
                                        m3 = &m2->mc_xcursor->mx_cursor;
                                else
                                        m3 = m2;
-                               if (m3 == mc) continue;
+                               if (m3 == mc || m3->mc_snum < mc->mc_snum) continue;
                                if (m3->mc_pg[i] == mp && m3->mc_ki[i] >= mc->mc_ki[i]) {
                                        m3->mc_ki[i]++;
                                }
@@ -4208,7 +4209,7 @@ put_sub:
                                        MDB_page *mp = mc->mc_pg[i];
 
                                        for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
-                                               if (m2 == mc) continue;
+                                               if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
                                                if (m2->mc_pg[i] == mp && m2->mc_ki[i] == mc->mc_ki[i]) {
                                                        mdb_xcursor_init1(m2, leaf);
                                                }
@@ -4713,6 +4714,7 @@ mdb_cursor_init(MDB_cursor *mc, MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx)
        mc->mc_dbx = &txn->mt_dbxs[dbi];
        mc->mc_dbflag = &txn->mt_dbflags[dbi];
        mc->mc_snum = 0;
+       mc->mc_top = 0;
        mc->mc_flags = 0;
        if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT) {
                assert(mx != NULL);
@@ -5076,6 +5078,7 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
                                m3 = &m2->mc_xcursor->mx_cursor;
                        else
                                m3 = m2;
+                       if (m3->mc_snum < csrc->mc_snum) continue;
                        if (m3->mc_pg[csrc->mc_top] == csrc->mc_pg[csrc->mc_top]) {
                                m3->mc_pg[csrc->mc_top] = mp;
                                m3->mc_ki[csrc->mc_top] += nkeys;
@@ -5167,6 +5170,7 @@ mdb_rebalance(MDB_cursor *mc)
                                                m3 = &m2->mc_xcursor->mx_cursor;
                                        else
                                                m3 = m2;
+                                       if (m3->mc_snum < mc->mc_snum) continue;
                                        if (m3->mc_pg[0] == mp) {
                                                m3->mc_snum = 0;
                                                m3->mc_top = 0;
@@ -5196,6 +5200,7 @@ mdb_rebalance(MDB_cursor *mc)
                                                m3 = &m2->mc_xcursor->mx_cursor;
                                        else
                                                m3 = m2;
+                                       if (m3->mc_snum < mc->mc_snum) continue;
                                        if (m3->mc_pg[0] == mp) {
                                                m3->mc_pg[0] = mc->mc_pg[0];
                                        }