BUG#5390 - problems with merge tables

Problem #1: INSERT...SELECT
INSERT ... SELECT with the same table on both sides (hidden
below a MERGE table) does now work by buffering the select result.
The duplicate detection works now after open_and_lock_tables() 
on the locks.
I did not find a test case that failed without the change in
sql_update.cc. I made the change anyway as it should in theory
fix a possible MERGE table problem with multi-table update.


mysql-test/r/create.result:
  BUG#5390 - problems with merge tables
  Removed a duplicate test.
mysql-test/r/merge.result:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT
  Added test results.
mysql-test/t/create.test:
  BUG#5390 - problems with merge tables
  Removed a duplicate test.
mysql-test/t/merge.test:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT
  Added tests.
sql/lock.cc:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT
  Added a new function to find a duplicate lock in a list of tables.
sql/mysql_priv.h:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT
  Added a declaration for the new function.
sql/sql_parse.cc:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT
  Changed the duplicate tables detection for INSERT ... SELECT
  to use the new function, which does also work for MERGE tables.
sql/sql_update.cc:
  BUG#5390 - problems with merge tables
  Changed the duplicate tables detection for UPDATE
  to use the new function, which does also work for MERGE tables.

sql/lock.cc

@@ -390,6 +390,88 @@ MYSQL_LOCK *mysql_lock_merge(MYSQL_LOCK *a,MYSQL_LOCK *b)
 }
 
 
+/*
+  Find duplicate lock in tables.
+
+  SYNOPSIS
+    mysql_lock_have_duplicate()
+    thd                         The current thread.
+    table                       The table to check for duplicate lock.
+    tables                      The list of tables to search for the dup lock.
+
+  NOTE
+    This is mainly meant for MERGE tables in INSERT ... SELECT
+    situations. The 'real', underlying tables can be found only after
+    the table is opened. The easier way is to check this after the
+    tables are locked.
+
+  RETURN
+    1           A table from 'tables' matches a lock on 'table'.
+    0           No duplicate lock is present.
+    -1          Error.
+*/
+
+int mysql_lock_have_duplicate(THD *thd, TABLE *table, TABLE_LIST *tables)
+{
+  uint                  count;
+  MYSQL_LOCK            *sql_lock1;
+  MYSQL_LOCK            *sql_lock2;
+  TABLE                 **tables1= &table;
+  TABLE                 **tables2;
+  TABLE                 **table_ptr;
+  TABLE_LIST            *tablist2;
+  TABLE                 *write_lock_used;
+  THR_LOCK_DATA         **lock_data1;
+  THR_LOCK_DATA         **end_data1;
+  THR_LOCK_DATA         **lock_data2;
+  THR_LOCK_DATA         **end_data2;
+  THR_LOCK              *lock1;
+  DBUG_ENTER("mysql_lock_have_duplicate");
+
+  if (! (sql_lock1= get_lock_data(thd, tables1, 1, 1, &write_lock_used)))
+    goto err0;
+
+  count=0;
+  for (tablist2 = tables; tablist2; tablist2= tablist2->next)
+    count++;
+  if (! (tables2= (TABLE**) sql_alloc(sizeof(TABLE*) * count)))
+    goto err1;
+  table_ptr= tables2;
+  for (tablist2 = tables; tablist2; tablist2= tablist2->next)
+    *(table_ptr++)= tablist2->table;
+  if (! (sql_lock2= get_lock_data(thd, tables2, count, 1, &write_lock_used)))
+    goto err1;
+
+  count= 1;
+  for (lock_data1= sql_lock1->locks,
+         end_data1= lock_data1 + sql_lock1->lock_count;
+       lock_data1 < end_data1;
+       lock_data1++)
+  {
+    lock1= (*lock_data1)->lock;
+    for (lock_data2= sql_lock2->locks,
+           end_data2= lock_data2 + sql_lock2->lock_count;
+         lock_data2 < end_data2;
+         lock_data2++)
+    {
+      if ((*lock_data2)->lock == lock1)
+        goto end;
+    }
+  }
+  count= 0;
+
+ end:
+  my_free((gptr) sql_lock2, MYF(0));
+  my_free((gptr) sql_lock1, MYF(0));
+  DBUG_RETURN(count);
+
+ err1:
+  my_free((gptr) sql_lock1, MYF(0));
+ err0:
+  DBUG_RETURN(-1);
+}
+
+
 	/* unlock a set of external */
 
 static int unlock_external(THD *thd, TABLE **table,uint count)
@@ -426,6 +508,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
   MYSQL_LOCK *sql_lock;
   THR_LOCK_DATA **locks;
   TABLE **to;
+  DBUG_ENTER("get_lock_data");
 
   *write_lock_used=0;
   for (i=tables=lock_count=0 ; i < count ; i++)
@@ -441,7 +524,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
 	my_malloc(sizeof(*sql_lock)+
 		  sizeof(THR_LOCK_DATA*)*tables+sizeof(table_ptr)*lock_count,
 		  MYF(0))))
-    return 0;
+    DBUG_RETURN(0);
   locks=sql_lock->locks=(THR_LOCK_DATA**) (sql_lock+1);
   to=sql_lock->table=(TABLE**) (locks+tables);
   sql_lock->table_count=lock_count;
@@ -461,13 +544,13 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
       {
 	my_error(ER_OPEN_AS_READONLY,MYF(0),table->table_name);
 	my_free((gptr) sql_lock,MYF(0));
-	return 0;
+	DBUG_RETURN(0);
       }
     }
     locks=table->file->store_lock(thd, locks, get_old_locks ? TL_IGNORE :
 				  lock_type);
   }
-  return sql_lock;
+  DBUG_RETURN(sql_lock);
 }
 
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