ITS#7772 Reduce spurious sub-page growth.

mdb_cursor_put(): Use free sub-page space added by a
previous put(existing DUPSORT item), if any.
Tweak NUMKEYS code to avoid a new signedness warning.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 78604712af9b4b13bdcb9f374f0469fd826a3d66..cd3805a880fcbffebd4c66277f13b33a55cf0394 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -5845,7 +5845,7 @@ more:
                         * it.  mp: new (sub-)page.  offset: growth in page
                         * size.  xdata: node data with new page or DB.
                         */
-                       unsigned        i, offset = 0;
+                       ssize_t         i, offset = 0;
                        mp = fp = xdata.mv_data = env->me_pbuf;
                        mp->mp_pgno = mc->mc_pg[mc->mc_top]->mp_pgno;
 
@@ -5901,17 +5901,17 @@ more:
                                fp = olddata.mv_data;
                                switch (flags) {
                                default:
+                                       i = -(ssize_t)SIZELEFT(fp);
                                        if (!(mc->mc_db->md_flags & MDB_DUPFIXED)) {
-                                               offset = EVEN(NODESIZE + sizeof(indx_t) +
-                                                       data->mv_size);
-                                               break;
-                                       }
-                                       offset = fp->mp_pad;
-                                       if (SIZELEFT(fp) < offset) {
+                                               offset = i += (ssize_t) EVEN(
+                                                       sizeof(indx_t) + NODESIZE + data->mv_size);
+                                       } else {
+                                               i += offset = fp->mp_pad;
                                                offset *= 4; /* space for 4 more */
-                                               break;
                                        }
-                                       /* FALLTHRU: Big enough MDB_DUPFIXED sub-page */
+                                       if (i > 0)
+                                               break;
+                                       /* FALLTHRU: Sub-page is big enough */
                                case MDB_CURRENT:
                                        fp->mp_flags |= P_DIRTY;
                                        COPY_PGNO(fp->mp_pgno, mp->mp_pgno);
@@ -5960,7 +5960,7 @@ prep_subDB:
                                } else {
                                        memcpy((char *)mp + mp->mp_upper, (char *)fp + fp->mp_upper,
                                                olddata.mv_size - fp->mp_upper);
-                                       for (i=0; i<NUMKEYS(fp); i++)
+                                       for (i = NUMKEYS(fp); --i >= 0; )
                                                mp->mp_ptrs[i] = fp->mp_ptrs[i] + offset;
                                }
                        }