SCRUM

two versions of KILL implementation


include/mysql_com.h:
  ONLY_KILL_QUERY flag definition
sql/lex.h:
  CONNECTION keyword added
sql/mysql_priv.h:
  kill_one_thread function extended
sql/sql_class.h:
  only_kill_query flag added to the THD structure
sql/sql_parse.cc:
  handling of KILL QUERY feature added
sql/sql_yacc.yy:
  KILL syntax extended with CONNECTION an QUERY options

include/mysql_com.h

@@ -118,6 +118,8 @@ enum enum_server_command
 #define NET_WRITE_TIMEOUT	60		/* Timeout on write */
 #define NET_WAIT_TIMEOUT	8*60*60		/* Wait for new query */
 
+#define ONLY_KILL_QUERY         1
+
 struct st_vio;					/* Only C */
 typedef struct st_vio Vio;
 

sql/lex.h

@@ -102,6 +102,7 @@ static SYMBOL symbols[] = {
   { "COMMITTED",	SYM(COMMITTED_SYM),0,0},
   { "COMPRESSED",	SYM(COMPRESSED_SYM),0,0},
   { "CONCURRENT",	SYM(CONCURRENT),0,0},
+  { "CONNECTION",	SYM(CONNECTION_SYM),0,0},
   { "CONSTRAINT",	SYM(CONSTRAINT),0,0},
   { "CREATE",		SYM(CREATE),0,0},
   { "CROSS",		SYM(CROSS),0,0},

sql/mysql_priv.h

@@ -45,7 +45,7 @@ char *sql_strdup(const char *str);
 char *sql_strmake(const char *str,uint len);
 gptr sql_memdup(const void * ptr,unsigned size);
 void sql_element_free(void *ptr);
-void kill_one_thread(THD *thd, ulong id);
+void kill_one_thread(THD *thd, ulong id, bool only_kill_query);
 bool net_request_file(NET* net, const char* fname);
 char* query_table_status(THD *thd,const char *db,const char *table_name);
 

sql/sql_class.h

@@ -550,6 +550,7 @@ class THD :public ilink
   bool	     system_thread,in_lock_tables,global_read_lock;
   bool       query_error, bootstrap, cleanup_done;
   bool	     volatile killed;
+  bool       volatile only_kill_query;
   bool       prepare_command;
   bool	     tmp_table_used;
   sp_rcontext *spcont;		// SP runtime context

sql/sql_parse.cc

@@ -848,7 +848,7 @@ pthread_handler_decl(handle_one_connection,arg)
     init_sql_alloc(&thd->mem_root, MEM_ROOT_BLOCK_SIZE, MEM_ROOT_PREALLOC);
     init_sql_alloc(&thd->transaction.mem_root,
 		   TRANS_MEM_ROOT_BLOCK_SIZE, TRANS_MEM_ROOT_PREALLOC);
-    while (!net->error && net->vio != 0 && !thd->killed)
+    while (!net->error && net->vio != 0 && !(thd->killed && !thd->only_kill_query))
     {
       if (do_command(thd))
 	break;
@@ -1054,6 +1054,12 @@ bool do_command(THD *thd)
   }
   else
   {
+    if (thd->only_kill_query)
+    {
+      thd->killed= FALSE;
+      thd->only_kill_query= FALSE;
+    }
+
     packet=(char*) net->read_pos;
     command = (enum enum_server_command) (uchar) packet[0];
     if (command >= COM_END)
@@ -1473,7 +1479,7 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
   {
     statistic_increment(com_stat[SQLCOM_KILL],&LOCK_status);
     ulong id=(ulong) uint4korr(packet);
-    kill_one_thread(thd,id);
+    kill_one_thread(thd,id,false);
     break;
   }
   case COM_DEBUG:
@@ -2890,7 +2896,7 @@ mysql_execute_command(THD *thd)
     reload_acl_and_cache(thd, lex->type, tables) ;
     break;
   case SQLCOM_KILL:
-    kill_one_thread(thd,lex->thread_id);
+    kill_one_thread(thd,lex->thread_id, lex->type & ONLY_KILL_QUERY);
     break;
   case SQLCOM_SHOW_GRANTS:
     res=0;
@@ -4179,7 +4185,7 @@ bool reload_acl_and_cache(THD *thd, ulong options, TABLE_LIST *tables)
     This is written such that we have a short lock on LOCK_thread_count
 */
 
-void kill_one_thread(THD *thd, ulong id)
+void kill_one_thread(THD *thd, ulong id, bool only_kill_query)
 {
   THD *tmp;
   uint error=ER_NO_SUCH_THREAD;
@@ -4199,6 +4205,12 @@ void kill_one_thread(THD *thd, ulong id)
     if ((thd->master_access & SUPER_ACL) ||
 	!strcmp(thd->user,tmp->user))
     {
+      if (only_kill_query)
+      {
+	tmp->killed= 1;
+	tmp->only_kill_query= 1;
+      }
+      else
 	tmp->awake(1 /*prepare to die*/);
       error=0;
     }

sql/sql_yacc.yy

@@ -201,6 +201,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token	COLUMNS
 %token	COLUMN_SYM
 %token	CONCURRENT
+%token	CONNECTION_SYM
 %token	CONSTRAINT
 %token	CONVERT_SYM
 %token	DATABASES
@@ -4231,18 +4232,23 @@ purge:
 /* kill threads */
 
 kill:
-	KILL_SYM expr
+	KILL_SYM kill_option expr
 	{
 	  LEX *lex=Lex;
-	  if ($2->fix_fields(lex->thd, 0, &$2) || $2->check_cols(1))
+	  if ($3->fix_fields(lex->thd, 0, &$3) || $3->check_cols(1))
 	  {
 	    send_error(lex->thd, ER_SET_CONSTANTS_ONLY);
 	    YYABORT;
 	  }
           lex->sql_command=SQLCOM_KILL;
-	  lex->thread_id= (ulong) $2->val_int();
+	  lex->thread_id= (ulong) $3->val_int();
 	};
 
+kill_option:
+	/* empty */	 { Lex->type= 0; }
+	| CONNECTION_SYM { Lex->type= 0; }
+	| QUERY_SYM      { Lex->type= ONLY_KILL_QUERY; };
+
 /* change database */
 
 use:	USE_SYM ident