bk commit into 5.0 tree (pem:1.2110) BUG#17260

[pem]

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ChangeSet
  1.2110 06/03/29 11:36:19 pem@stripped +2 -0
  Fixed BUG#17260: Triggers: crash while updating million-row table
    We must set a mem_root/arena for the function each time the trigger is
    fired, and free it afterwards, otherwise the allocated memory accumulates
    in the calling statement's mem_root.
    To test this, we must attempt to make the machine run out of memory (with
    a trigger on a miljon row table for instance) which is not practical to
    have in the test suite, so a test case is not included in the patch.
    (Also fixed minor memory hogging in st_lex:st_lex()).

  sql/sql_trigger.cc
    1.48 06/03/29 11:36:15 pem@stripped +14 -0
    Set a temporary arena and mem_root for the function call in a trigger,
    and free it after each call; otherwise memory accumulates in the calling
    statement's mem_root.

  sql/sql_lex.cc
    1.181 06/03/29 11:36:15 pem@stripped +1 -1
    Fixed memory hogging in st_lex::st_lex(): Allocate a smaller hash table than the
default.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	pem
# Host:	pem.mysql.com
# Root:	/extern/mysql/5.0/bug18300/mysql-5.0

--- 1.180/sql/sql_lex.cc	2006-03-10 01:44:01 +01:00
+++ 1.181/sql/sql_lex.cc	2006-03-29 11:36:15 +02:00
@@ -1628,7 +1628,7 @@
 st_lex::st_lex()
   :result(0), sql_command(SQLCOM_END), query_tables_own_last(0)
 {
-  hash_init(&sroutines, system_charset_info, 0, 0, 0, sp_sroutine_key, 0, 0);
+  hash_init(&sroutines, system_charset_info, 16, 0, 0, sp_sroutine_key, 0, 0);
   sroutines_list.empty();
   sroutines_list_own_last= sroutines_list.next;
   sroutines_list_own_elements= 0;

--- 1.47/sql/sql_trigger.cc	2006-03-10 01:44:01 +01:00
+++ 1.48/sql/sql_trigger.cc	2006-03-29 11:36:15 +02:00
@@ -1454,6 +1454,10 @@
 {
   bool err_status= FALSE;
   sp_head *sp_trigger= bodies[event][time_type];
+  /* Memory root/arena for the function call. */
+  MEM_ROOT execute_mem_root;
+  Query_arena execute_arena(&execute_mem_root, Query_arena::INITIALIZED_FOR_SP),
+    backup_arena;
 
   if (sp_trigger)
   {
@@ -1498,7 +1502,17 @@
 #endif // NO_EMBEDDED_ACCESS_CHECKS
 
     thd->reset_sub_statement_state(&statement_state, SUB_STMT_TRIGGER);
+    
+    /* Set execute arena for the function call. */
+    init_alloc_root(&execute_mem_root, MEM_ROOT_BLOCK_SIZE, 0);
+    thd->set_n_backup_active_arena(&execute_arena, &backup_arena);
+
     err_status= sp_trigger->execute_function(thd, 0, 0, 0);
+
+    /* Free the memory used by the function. */
+    free_root(&execute_mem_root, MYF(0));    
+    thd->restore_active_arena(&execute_arena, &backup_arena);
+
     thd->restore_sub_statement_state(&statement_state);
 
 #ifndef NO_EMBEDDED_ACCESS_CHECKS