BUG #14524

Patch that fixes crashing when partition uses blackole for 
underlying tables.


mysql-test/r/partition.result:
  BUG #14524 New test result
mysql-test/t/partition.test:
  BUG #14524
  
  New test
sql/ha_partition.cc:
  BUG# 14524
  
  Added new class var m_no_locks to keep track of the absense of locks. If 
  '0', then lock_count returns 0, which keeps thr_multi_lock from crashing
  in the case of the underlying table being ha_blackhole.
sql/ha_partition.h:
  BUG #14524
  
  Added new class var m_no_locks to keep track of lock count
sql/lock.cc:
  BUG #14524
  
  DBUG PRINTs and ENTERs to make tracking the bug easier. I think these are 
  useful regardless of this bug.
sql/sql_partition.cc:
  BUG #14524
  
  Changed umlaut o to allow fixing bug 14524 using DDD (file would not display
  in DDD)

mysql-test/r/partition.result

@@ -108,3 +108,11 @@ insert into t1 values (3);
 insert into t1 values (4);
 UNLOCK TABLES;
 drop table t1;
+DROP TABLE IF EXISTS `t1`;
+Warnings:
+Note	1051	Unknown table 't1'
+CREATE TABLE `t1` (
+`id` int(11) default NULL
+) ENGINE=BLACKHOLE DEFAULT CHARSET=latin1 PARTITION BY HASH (id) ;
+SELECT * FROM t1;
+id

mysql-test/t/partition.test

@@ -162,3 +162,13 @@ UNLOCK TABLES;
 
 drop table t1;
 
+#
+# BUG 14524
+#
+--disable-warnings
+DROP TABLE IF EXISTS `t1`;
+--enable-warnings
+CREATE TABLE `t1` (
+  `id` int(11) default NULL
+) ENGINE=BLACKHOLE DEFAULT CHARSET=latin1 PARTITION BY HASH (id) ;
+SELECT * FROM t1;

sql/ha_partition.cc

@@ -15,7 +15,7 @@
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 /*
-  This handler was developed by Mikael Ronström for version 5.1 of MySQL.
+  This handler was developed by Mikael Ronstrom for version 5.1 of MySQL.
   It is an abstraction layer on top of other handlers such as MyISAM,
   InnoDB, Federated, Berkeley DB and so forth. Partitioned tables can also
   be handled by a storage engine. The current example of this is NDB
@@ -167,6 +167,10 @@ void ha_partition::init_handler_variables()
   m_last_part= 0;
   m_rec0= 0;
   m_curr_key_info= 0;
+  /*
+    this allows blackhole to work properly
+  */
+  m_no_locks= 0;
 
 #ifdef DONT_HAVE_TO_BE_INITALIZED
   m_start_key.flag= 0;
@@ -912,6 +916,7 @@ int ha_partition::open(const char *name, int mode, uint test_if_locked)
     if ((error= (*file)->ha_open((const char*) name_buff, mode,
                                  test_if_locked)))
       goto err_handler;
+    m_no_locks+= (*file)->lock_count();
     name_buffer_ptr+= strlen(name_buffer_ptr) + 1;
     set_if_bigger(ref_length, ((*file)->ref_length));
   } while (*(++file));
@@ -1098,6 +1103,9 @@ int ha_partition::start_stmt(THD *thd, thr_lock_type lock_type)
 uint ha_partition::lock_count() const
 {
   DBUG_ENTER("ha_partition::lock_count");
+  if (m_no_locks == 0)
+    DBUG_RETURN(0);
+
   DBUG_RETURN(m_tot_parts);
 }
 
@@ -1143,7 +1151,7 @@ void ha_partition::unlock_row()
   ADDITIONAL INFO:
 
   Most handlers set timestamp when calling write row if any such fields
-  exists. Since we are calling an underlying handler we assume the´
+  exists. Since we are calling an underlying handler we assume the
   underlying handler will assume this responsibility.
 
   Underlying handlers will also call update_auto_increment to calculate

sql/ha_partition.h

@@ -67,6 +67,7 @@ class ha_partition :public handler
   u_long m_low_byte_first;
 
   uint m_tot_parts;                      // Total number of partitions;
+  uint m_no_locks;                        // For engines like ha_blackhole, which needs no locks
   uint m_last_part;                      // Last file that we update,write
   int m_lock_type;                       // Remembers type of last
                                          // external_lock

sql/lock.cc

@@ -146,6 +146,7 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
     }
 
     thd->proc_info="System lock";
+    DBUG_PRINT("info", ("thd->proc_info %s", thd->proc_info));
     if (lock_external(thd, tables, count))
     {
       my_free((gptr) sql_lock,MYF(0));
@@ -153,6 +154,7 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
       break;
     }
     thd->proc_info="Table lock";
+    DBUG_PRINT("info", ("thd->proc_info %s", thd->proc_info));
     thd->locked=1;
     rc= thr_lock_errno_to_mysql[(int) thr_multi_lock(sql_lock->locks,
                                                      sql_lock->lock_count,
@@ -218,6 +220,7 @@ static int lock_external(THD *thd, TABLE **tables, uint count)
   int lock_type,error;
   DBUG_ENTER("lock_external");
 
+  DBUG_PRINT("info", ("count %d", count));
   for (i=1 ; i <= count ; i++, tables++)
   {
     DBUG_ASSERT((*tables)->reginfo.lock_type >= TL_READ);
@@ -460,6 +463,8 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
   THR_LOCK_DATA **locks;
   TABLE **to;
 
+  DBUG_ENTER("get_lock_data");
+  DBUG_PRINT("info", ("count %d", count));
   *write_lock_used=0;
   for (i=tables=lock_count=0 ; i < count ; i++)
   {
@@ -479,7 +484,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
     {
       my_error(ER_WRONG_LOCK_OF_SYSTEM_TABLE, MYF(0), table_ptr[i]->s->db,
                table_ptr[i]->s->table_name);
-      return 0;
+      DBUG_RETURN(0);
     }
   }
 
@@ -487,11 +492,13 @@ 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;
   sql_lock->lock_count=tables;
+  DBUG_PRINT("info", ("sql_lock->table_count %d sql_lock->lock_count %d",
+                      sql_lock->table_count, sql_lock->lock_count));
 
   for (i=0 ; i < count ; i++)
   {
@@ -507,7 +514,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
       {
 	my_error(ER_OPEN_AS_READONLY, MYF(0), table->alias);
 	my_free((gptr) sql_lock,MYF(0));
-	return 0;
+	DBUG_RETURN(0);
       }
     }
     THR_LOCK_DATA **org_locks = locks;
@@ -517,7 +524,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
       for ( ; org_locks != locks ; org_locks++)
 	(*org_locks)->debug_print_param= (void *) table;
   }
-  return sql_lock;
+  DBUG_RETURN(sql_lock);
 }
 
 

sql/sql_partition.cc

@@ -20,7 +20,7 @@
   used by all handlers that support partitioning, which in the first version
   is the partitioning handler itself and the NDB handler.
 
-  The first version was written by Mikael Ronström.
+  The first version was written by Mikael Ronstrom.
 
   This version supports RANGE partitioning, LIST partitioning, HASH
   partitioning and composite partitioning (hereafter called subpartitioning)