From ac90c289ab5ce18395c5fa53c30b38bc5f50ae1d Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Tue, 6 Jul 2010 20:28:51 +0200 Subject: Fix ets:select hanging on ordered_set with empty list as key. erl_db_tree.c incorrectly used NIL (empty list) as "lastkey" to mark start of the iteration. A real NIL key could then cause a select or match iteration to be restarted over and over again if the last key before a trap happended to be NIL. Changed NIL to THE_NON_VALUE. Should be ok as the initial key value can never be put into any continuation tuple. --- erts/emulator/beam/erl_db_tree.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'erts/emulator') diff --git a/erts/emulator/beam/erl_db_tree.c b/erts/emulator/beam/erl_db_tree.c index b6b3cabafe..96e577ed90 100644 --- a/erts/emulator/beam/erl_db_tree.c +++ b/erts/emulator/beam/erl_db_tree.c @@ -1081,11 +1081,12 @@ static int db_select_continue_tree(Process *p, static int db_select_tree(Process *p, DbTable *tbl, Eterm pattern, int reverse, Eterm *ret) { + /* Strategy: Traverse backwards to build resulting list from tail to head */ DbTableTree *tb = &tbl->tree; DbTreeStack* stack; struct select_context sc; struct mp_info mpi; - Eterm lastkey = NIL; + Eterm lastkey = THE_NON_VALUE; Eterm key; Eterm continuation; unsigned sz; @@ -1293,7 +1294,7 @@ static int db_select_count_tree(Process *p, DbTable *tbl, DbTreeStack* stack; struct select_count_context sc; struct mp_info mpi; - Eterm lastkey = NIL; + Eterm lastkey = THE_NON_VALUE; Eterm key; Eterm continuation; unsigned sz; @@ -1395,7 +1396,7 @@ static int db_select_chunk_tree(Process *p, DbTable *tbl, DbTreeStack* stack; struct select_context sc; struct mp_info mpi; - Eterm lastkey = NIL; + Eterm lastkey = THE_NON_VALUE; Eterm key; Eterm continuation; unsigned sz; @@ -1636,7 +1637,7 @@ static int db_select_delete_tree(Process *p, DbTable *tbl, DbTableTree *tb = &tbl->tree; struct select_delete_context sc; struct mp_info mpi; - Eterm lastkey = NIL; + Eterm lastkey = THE_NON_VALUE; Eterm key; Eterm continuation; unsigned sz; @@ -2628,7 +2629,7 @@ static void traverse_backwards(DbTableTree *tb, { TreeDbTerm *this, *next; - if (lastkey == NIL) { + if (lastkey == THE_NON_VALUE) { stack->pos = stack->slot = 0; if (( this = tb->root ) == NULL) { return; @@ -2666,7 +2667,7 @@ static void traverse_forward(DbTableTree *tb, { TreeDbTerm *this, *next; - if (lastkey == NIL) { + if (lastkey == THE_NON_VALUE) { stack->pos = stack->slot = 0; if (( this = tb->root ) == NULL) { return; -- cgit v1.2.3