Fix mdb_split, tweak split_indx if space is tight

libraries/libmdb/mdb.c

@@ -2502,10 +2502,10 @@ mdb_add_node(MDB_txn *txn, MDB_dbi dbi, MDB_page *mp, indx_t indx,
 
 	assert(mp->mp_upper >= mp->mp_lower);
 
-	DPRINTF("add node [%s] to %s page %lu at index %i, key size %zu",
-	    key ? DKEY(key) : NULL,
+	DPRINTF("add to %s page %lu index %i, data size %zu key size %zu [%s]",
 	    IS_LEAF(mp) ? "leaf" : "branch",
-	    mp->mp_pgno, indx, key ? key->mv_size : 0);
+	    mp->mp_pgno, indx, data ? data->mv_size : 0,
+		key ? key->mv_size : 0, key ? DKEY(key) : NULL);
 
 	if (IS_LEAF2(mp)) {
 		/* Move higher keys up one slot. */
@@ -3213,7 +3213,7 @@ mdb_split(MDB_txn *txn, MDB_dbi dbi, MDB_page **mpp, unsigned int *newindxp,
 	int		 rc = MDB_SUCCESS, ins_new = 0;
 	indx_t		 newindx;
 	pgno_t		 pgno = 0;
-	unsigned int	 i, j, split_indx;
+	unsigned int	 i, j, split_indx, nkeys, pmax;
 	MDB_node	*node;
 	MDB_val	 sepkey, rkey, rdata;
 	MDB_page	*copy;
@@ -3255,12 +3255,13 @@ mdb_split(MDB_txn *txn, MDB_dbi dbi, MDB_page **mpp, unsigned int *newindxp,
 	rdp->h.md_pi = mdp->h.md_pi + 1;
 	DPRINTF("new right sibling: page %lu", rdp->p.mp_pgno);
 
-	split_indx = NUMKEYS(&mdp->p) / 2 + 1;
+	nkeys = NUMKEYS(&mdp->p);
+	split_indx = nkeys / 2 + 1;
 
 	if (IS_LEAF2(&rdp->p)) {
 		char *split, *ins;
 		int x;
-		unsigned int nkeys = NUMKEYS(&mdp->p), lsize, rsize, ksize;
+		unsigned int lsize, rsize, ksize;
 		/* Move half of the keys to the right sibling */
 		copy = NULL;
 		x = *newindxp - split_indx;
@@ -3307,6 +3308,46 @@ mdb_split(MDB_txn *txn, MDB_dbi dbi, MDB_page **mpp, unsigned int *newindxp,
 	memset(&mdp->p.mp_ptrs, 0, txn->mt_env->me_psize - PAGEHDRSZ);
 	mdp->p.mp_lower = PAGEHDRSZ;
 	mdp->p.mp_upper = txn->mt_env->me_psize;
+	/* For leaf pages, check the split point based on what
+	 * fits where, since otherwise add_node can fail.
+	 */
+	if (IS_LEAF(&mdp->p)) {
+		unsigned int psize, nsize;
+		/* Maximum free space in an empty page */
+		pmax = txn->mt_env->me_psize - PAGEHDRSZ;
+		nsize = mdb_leaf_size(txn->mt_env, newkey, newdata);
+		if (newindx <= split_indx) {
+split1:
+			psize = nsize;
+			for (i=0; i<split_indx; i++) {
+				node = NODEPTR(&mdp->p, i);
+				psize += NODESIZE + NODEKSZ(node);
+				if (F_ISSET(node->mn_flags, F_BIGDATA))
+					psize += sizeof(pgno_t);
+				else
+					psize += NODEDSZ(node);
+				if (psize > pmax) {
+					split_indx--;
+					goto split1;
+				}
+			}
+		} else {
+split2:
+			psize = nsize;
+			for (i=split_indx; i<nkeys; i++) {
+				node = NODEPTR(&mdp->p, i);
+				psize += NODESIZE + NODEKSZ(node);
+				if (F_ISSET(node->mn_flags, F_BIGDATA))
+					psize += sizeof(pgno_t);
+				else
+					psize += NODEDSZ(node);
+				if (psize > pmax) {
+					split_indx++;
+					goto split2;
+				}
+			}
+		}
+	}
 
 	/* First find the separating key between the split pages.
 	 */