ITS#7515 Fix mdb_txn_commit(nested txn with spills).

Catch malloc error.
Fix hunt for dirty vs spilled pages: Don't leave x at a deleted pageno.
Cleanup: Factor out variables, squash pages already marked for deletion.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index b49977df8c29735ff76e711375ce9de1156f9831..84429ee3d622d647ced1e11945fea3eef7072aa5 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -2779,14 +2779,18 @@ mdb_txn_commit(MDB_txn *txn)
 
        if (txn->mt_parent) {
                MDB_txn *parent = txn->mt_parent;
-               unsigned x, y, len;
                MDB_ID2L dst, src;
+               MDB_IDL pspill;
+               unsigned x, y, len, ps_len;
 
                /* Append our free list to parent's */
                rc = mdb_midl_append_list(&parent->mt_free_pgs, txn->mt_free_pgs);
                if (rc)
                        goto fail;
                mdb_midl_free(txn->mt_free_pgs);
+               /* Failures after this must either undo the changes
+                * to the parent or set MDB_TXN_ERROR in the parent.
+                */
 
                parent->mt_next_pgno = txn->mt_next_pgno;
                parent->mt_flags = txn->mt_flags;
@@ -2808,37 +2812,26 @@ mdb_txn_commit(MDB_txn *txn)
                dst = parent->mt_u.dirty_list;
                src = txn->mt_u.dirty_list;
                /* Remove anything in our dirty list from parent's spill list */
-               if (parent->mt_spill_pgs) {
-                       x = parent->mt_spill_pgs[0];
-                       len = x;
-                       /* zero out our dirty pages in parent spill list */
-                       for (i=1; i<=src[0].mid; i++) {
+               if ((pspill = parent->mt_spill_pgs) && (ps_len = pspill[0])) {
+                       x = y = ps_len;
+                       pspill[0] = (pgno_t)-1;
+                       /* Mark our dirty pages as deleted in parent spill list */
+                       for (i=0, len=src[0].mid; ++i <= len; ) {
                                MDB_ID pn = src[i].mid << 1;
-                               if (pn < parent->mt_spill_pgs[x])
-                                       continue;
-                               if (pn > parent->mt_spill_pgs[x]) {
-                                       if (x <= 1)
-                                               break;
+                               while (pn > pspill[x])
                                        x--;
-                                       continue;
-                               }
-                               parent->mt_spill_pgs[x] = 0;
-                               len--;
-                       }
-                       /* OK, we had a few hits, squash zeros from the spill list */
-                       if (len < parent->mt_spill_pgs[0]) {
-                               x=1;
-                               for (y=1; y<=parent->mt_spill_pgs[0]; y++) {
-                                       if (parent->mt_spill_pgs[y]) {
-                                               if (y != x) {
-                                                       parent->mt_spill_pgs[x] = parent->mt_spill_pgs[y];
-                                               }
-                                               x++;
-                                       }
+                               if (pn == pspill[x]) {
+                                       pspill[x] = 1;
+                                       y = --x;
                                }
-                               parent->mt_spill_pgs[0] = len;
                        }
+                       /* Squash deleted pagenums if we deleted any */
+                       for (x=y; ++x <= ps_len; )
+                               if (!(pspill[x] & 1))
+                                       pspill[++y] = pspill[x];
+                       pspill[0] = y;
                }
+
                /* Find len = length of merging our dirty list with parent's */
                x = dst[0].mid;
                dst[0].mid = 0;         /* simplify loops */
@@ -2872,7 +2865,10 @@ mdb_txn_commit(MDB_txn *txn)
                parent->mt_dirty_room = txn->mt_dirty_room;
                if (txn->mt_spill_pgs) {
                        if (parent->mt_spill_pgs) {
-                               mdb_midl_append_list(&parent->mt_spill_pgs, txn->mt_spill_pgs);
+                               /* TODO: Prevent failure here, so parent does not fail */
+                               rc = mdb_midl_append_list(&parent->mt_spill_pgs, txn->mt_spill_pgs);
+                               if (rc)
+                                       parent->mt_flags |= MDB_TXN_ERROR;
                                mdb_midl_free(txn->mt_spill_pgs);
                                mdb_midl_sort(parent->mt_spill_pgs);
                        } else {
@@ -2883,7 +2879,7 @@ mdb_txn_commit(MDB_txn *txn)
                parent->mt_child = NULL;
                mdb_midl_free(((MDB_ntxn *)txn)->mnt_pgstate.mf_pghead);
                free(txn);
-               return MDB_SUCCESS;
+               return rc;
        }
 
        if (txn != env->me_txn) {