From c97f4ed1aef858ba352a7bfcc67532c774fd434f Mon Sep 17 00:00:00 2001 From: Howard Chu Date: Wed, 11 Jan 2017 09:51:43 +0000 Subject: [PATCH] ITS#8557 fix mdb_cursor_last Optimize mdb_page_search_root(PS_LAST) when cursor is already near last position, ignoring C_EOF flag for now. --- libraries/liblmdb/mdb.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c index 23c1f009b0..1644953047 100644 --- a/libraries/liblmdb/mdb.c +++ b/libraries/liblmdb/mdb.c @@ -5459,8 +5459,17 @@ mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int flags) if (flags & (MDB_PS_FIRST|MDB_PS_LAST)) { i = 0; - if (flags & MDB_PS_LAST) + if (flags & MDB_PS_LAST) { i = NUMKEYS(mp) - 1; + /* if already init'd, see if we're already in right place */ + if (mc->mc_flags & C_INITIALIZED) { + if (mc->mc_ki[mc->mc_top] == i) { + mc->mc_top = mc->mc_snum++; + mp = mc->mc_pg[mc->mc_top]; + goto ready; + } + } + } } else { int exact; node = mdb_node_search(mc, key, &exact); @@ -5486,6 +5495,7 @@ mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int flags) if ((rc = mdb_cursor_push(mc, mp))) return rc; +ready: if (flags & MDB_PS_MODIFY) { if ((rc = mdb_page_touch(mc)) != 0) return rc; @@ -6224,16 +6234,13 @@ mdb_cursor_last(MDB_cursor *mc, MDB_val *key, MDB_val *data) if (mc->mc_xcursor) mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF); - if (!(mc->mc_flags & C_EOF)) { - - if (!(mc->mc_flags & C_INITIALIZED) || mc->mc_top) { - rc = mdb_page_search(mc, NULL, MDB_PS_LAST); - if (rc != MDB_SUCCESS) - return rc; - } - mdb_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top])); - + if (!(mc->mc_flags & C_INITIALIZED) || mc->mc_top) { + rc = mdb_page_search(mc, NULL, MDB_PS_LAST); + if (rc != MDB_SUCCESS) + return rc; } + mdb_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top])); + mc->mc_ki[mc->mc_top] = NUMKEYS(mc->mc_pg[mc->mc_top]) - 1; mc->mc_flags |= C_INITIALIZED|C_EOF; leaf = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]); -- 2.39.2