From c2fa8748c57df1d99775af682307e403d527bf6f Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@symas.com>
Date: Sat, 7 Apr 2012 01:27:38 -0700
Subject: [PATCH] ITS#7229 more mdb_page_split fixes
---
libraries/libmdb/mdb.c | 37 +++++++++++++++++++++++++------------
1 file changed, 25 insertions(+), 12 deletions(-)
diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index ffbfefc8dd..e70e46d572 100644
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -5638,7 +5638,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
unsigned int nflags)
{
unsigned int flags;
- int rc = MDB_SUCCESS, ins_new = 0, new_root = 0;
+ int rc = MDB_SUCCESS, ins_new = 0, new_root = 0, newpos = 1;
indx_t newindx;
pgno_t pgno = 0;
unsigned int i, j, split_indx, nkeys, pmax;
@@ -5751,15 +5751,22 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
}
/* For leaf pages, check the split point based on what
- * fits where, since otherwise add_node can fail.
+ * fits where, since otherwise mdb_node_add can fail.
+ *
+ * This check is only needed when the data items are
+ * relatively large, such that being off by one will
+ * make the difference between success or failure.
+ * When the size of the data items is much smaller than
+ * one-half of a page, this check is irrelevant.
*/
- if (IS_LEAF(mp)) {
+ if (IS_LEAF(mp) && nkeys < 4) {
unsigned int psize, nsize;
/* Maximum free space in an empty page */
pmax = mc->mc_txn->mt_env->me_psize - PAGEHDRSZ;
nsize = mdb_leaf_size(mc->mc_txn->mt_env, newkey, newdata);
- if (newindx < split_indx) {
+ if (newindx <= split_indx) {
psize = nsize;
+ newpos = 0;
for (i=0; i<split_indx; i++) {
node = NODEPTR(mp, i);
psize += NODESIZE + NODEKSZ(node) + sizeof(indx_t);
@@ -5769,7 +5776,10 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
psize += NODEDSZ(node);
psize += psize & 1;
if (psize > pmax) {
- split_indx = i;
+ if (i == split_indx - 1 && newindx == split_indx)
+ newpos = 1;
+ else
+ split_indx = i;
break;
}
}
@@ -5792,8 +5802,11 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
}
/* First find the separating key between the split pages.
+ * The case where newindx == split_indx is ambiguous; the
+ * new item could go to the new page or stay on the original
+ * page. If newpos == 1 it goes to the new page.
*/
- if (newindx == split_indx) {
+ if (newindx == split_indx && newpos) {
sepkey.mv_size = newkey->mv_size;
sepkey.mv_data = newkey->mv_data;
} else {
@@ -5856,8 +5869,10 @@ newsep:
if (i == split_indx) {
/* Insert in right sibling. */
/* Reset insert index for right sibling. */
- j = (i == newindx && ins_new);
- mc->mc_pg[mc->mc_top] = rp;
+ if (i != newindx || (newpos ^ ins_new)) {
+ j = 0;
+ mc->mc_pg[mc->mc_top] = rp;
+ }
}
if (i == newindx && !ins_new) {
@@ -5872,9 +5887,7 @@ newsep:
ins_new = 1;
- /* Update page and index for the new key. */
- if (!newindx)
- mc->mc_pg[mc->mc_top] = copy;
+ /* Update index for the new key. */
mc->mc_ki[mc->mc_top] = j;
} else if (i == nkeys) {
break;
@@ -5910,7 +5923,7 @@ newsep:
mc->mc_txn->mt_env->me_psize - copy->mp_upper);
/* reset back to original page */
- if (!newindx || (newindx < split_indx)) {
+ if (newindx < split_indx || (!newpos && newindx == split_indx)) {
mc->mc_pg[mc->mc_top] = mp;
if (nflags & MDB_RESERVE) {
node = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
--
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