Delay touching pages until cursor is positioned.

This avoids unnecessary rewrites of pages that do not change.
(Restructuring for upcoming mdb_page_spill work.)

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 336db31ca3763cbdc0e0e46ff12a41394466194e..a533ed4d8930772ec2a960e263998e4a5450428a 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -4968,6 +4968,7 @@ int
 mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
     unsigned int flags)
 {
+       enum { MDB_NO_ROOT = MDB_LAST_ERRCODE+10 }; /* internal code */
        MDB_node        *leaf = NULL;
        MDB_val xdata, *rdata, dkey;
        MDB_page        *fp;
@@ -5015,23 +5016,10 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
                        return EINVAL;
                rc = MDB_SUCCESS;
        } else if (mc->mc_db->md_root == P_INVALID) {
-               MDB_page *np;
-               /* new database, write a root leaf page */
-               DPUTS("allocating new root leaf page");
-               if ((rc = mdb_page_new(mc, P_LEAF, 1, &np))) {
-                       return rc;
-               }
+               /* new database, cursor has nothing to point to */
                mc->mc_snum = 0;
-               mdb_cursor_push(mc, np);
-               mc->mc_db->md_root = np->mp_pgno;
-               mc->mc_db->md_depth++;
-               *mc->mc_dbflag |= DB_DIRTY;
-               if ((mc->mc_db->md_flags & (MDB_DUPSORT|MDB_DUPFIXED))
-                       == MDB_DUPFIXED)
-                       np->mp_flags |= P_LEAF2;
-               mc->mc_flags |= C_INITIALIZED;
-               rc = MDB_NOTFOUND;
-               goto top;
+               mc->mc_flags &= ~C_INITIALIZED;
+               rc = MDB_NO_ROOT;
        } else {
                int exact = 0;
                MDB_val d2;
@@ -5049,7 +5037,7 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
                                }
                        }
                } else {
-               rc = mdb_cursor_set(mc, key, &d2, MDB_SET, &exact);
+                       rc = mdb_cursor_set(mc, key, &d2, MDB_SET, &exact);
                }
                if ((flags & MDB_NOOVERWRITE) && rc == 0) {
                        DPRINTF("duplicate key [%s]", DKEY(key));
@@ -5060,12 +5048,30 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
                        return rc;
        }
 
-       /* Cursor is positioned, now make sure all pages are writable */
-       rc2 = mdb_cursor_touch(mc);
-       if (rc2)
-               return rc2;
+       /* Cursor is positioned */
+
+       if (rc == MDB_NO_ROOT) {
+               MDB_page *np;
+               /* new database, write a root leaf page */
+               DPUTS("allocating new root leaf page");
+               if ((rc2 = mdb_page_new(mc, P_LEAF, 1, &np))) {
+                       return rc2;
+               }
+               mdb_cursor_push(mc, np);
+               mc->mc_db->md_root = np->mp_pgno;
+               mc->mc_db->md_depth++;
+               *mc->mc_dbflag |= DB_DIRTY;
+               if ((mc->mc_db->md_flags & (MDB_DUPSORT|MDB_DUPFIXED))
+                       == MDB_DUPFIXED)
+                       np->mp_flags |= P_LEAF2;
+               mc->mc_flags |= C_INITIALIZED;
+       } else {
+               /* make sure all cursor pages are writable */
+               rc2 = mdb_cursor_touch(mc);
+               if (rc2)
+                       return rc2;
+       }
 
-top:
        /* The key already exists */
        if (rc == MDB_SUCCESS) {
                /* there's only a key anyway, so this is a no-op */