Merge lp:~akopytov/percona-server/tp-high-prio-mode-5.6 into lp:percona-server/5.6

[Alexey Kopytov]

Manual merge from 5.5.

http://jenkins.percona.com/view/PS%205.6/job/percona-server-5.6-param/447/

[George Ormond Lorch III (gl-az)]

review: Approve (g2)

[Alexey Kopytov (akopytov)]

Same comments as in the 5.5 MP.

review: Needs Fixing

[Alexey Kopytov (akopytov)]

review: Approve

=== added file 'Percona-Server/mysql-test/suite/sys_vars/r/thread_pool_high_prio_mode_basic.result'
--- Percona-Server/mysql-test/suite/sys_vars/r/thread_pool_high_prio_mode_basic.result	1970-01-01 00:00:00 +0000
+++ Percona-Server/mysql-test/suite/sys_vars/r/thread_pool_high_prio_mode_basic.result	2013-12-12 13:56:46 +0000
@@ -0,0 +1,34 @@
+SET @start_global_value = @@GLOBAL.thread_pool_high_prio_mode;
+SET @@GLOBAL.thread_pool_high_prio_mode=DEFAULT;
+SELECT @@GLOBAL.thread_pool_high_prio_mode;
+@@GLOBAL.thread_pool_high_prio_mode
+transactions
+SET @@SESSION.thread_pool_high_prio_mode=DEFAULT;
+SELECT @@SESSION.thread_pool_high_prio_mode;
+@@SESSION.thread_pool_high_prio_mode
+transactions
+SHOW GLOBAL VARIABLES LIKE 'thread_pool_high_prio_mode';
+Variable_name	Value
+thread_pool_high_prio_mode	transactions
+SHOW SESSION VARIABLES LIKE 'thread_pool_high_prio_mode';
+Variable_name	Value
+thread_pool_high_prio_mode	transactions
+SET @@thread_pool_high_prio_mode='transactions';
+SELECT @@thread_pool_high_prio_mode;
+@@thread_pool_high_prio_mode
+transactions
+SET @@thread_pool_high_prio_mode='statements';
+SELECT @@thread_pool_high_prio_mode;
+@@thread_pool_high_prio_mode
+statements
+SET @@thread_pool_high_prio_mode='none';
+SELECT @@thread_pool_high_prio_mode;
+@@thread_pool_high_prio_mode
+none
+SET @@thread_pool_high_prio_mode='foo';
+ERROR 42000: Variable 'thread_pool_high_prio_mode' can't be set to the value of 'foo'
+SET @@thread_pool_high_prio_mode=1.1;
+ERROR 42000: Incorrect argument type to variable 'thread_pool_high_prio_mode'
+SET @@thread_pool_high_prio_mode=1e1;
+ERROR 42000: Incorrect argument type to variable 'thread_pool_high_prio_mode'
+SET @@GLOBAL.thread_pool_high_prio_mode = @start_global_value;

=== added file 'Percona-Server/mysql-test/suite/sys_vars/t/thread_pool_high_prio_mode_basic.test'
--- Percona-Server/mysql-test/suite/sys_vars/t/thread_pool_high_prio_mode_basic.test	1970-01-01 00:00:00 +0000
+++ Percona-Server/mysql-test/suite/sys_vars/t/thread_pool_high_prio_mode_basic.test	2013-12-12 13:56:46 +0000
@@ -0,0 +1,35 @@
+--source include/not_windows.inc
+--source include/not_embedded.inc
+
+SET @start_global_value = @@GLOBAL.thread_pool_high_prio_mode;
+
+# Test the default value
+SET @@GLOBAL.thread_pool_high_prio_mode=DEFAULT;
+SELECT @@GLOBAL.thread_pool_high_prio_mode;
+
+# Test that the session value is accepted
+SET @@SESSION.thread_pool_high_prio_mode=DEFAULT;
+SELECT @@SESSION.thread_pool_high_prio_mode;
+
+SHOW GLOBAL VARIABLES LIKE 'thread_pool_high_prio_mode';
+SHOW SESSION VARIABLES LIKE 'thread_pool_high_prio_mode';
+
+SET @@thread_pool_high_prio_mode='transactions';
+SELECT @@thread_pool_high_prio_mode;
+
+SET @@thread_pool_high_prio_mode='statements';
+SELECT @@thread_pool_high_prio_mode;
+
+SET @@thread_pool_high_prio_mode='none';
+SELECT @@thread_pool_high_prio_mode;
+
+--error ER_WRONG_VALUE_FOR_VAR
+SET @@thread_pool_high_prio_mode='foo';
+
+--error ER_WRONG_TYPE_FOR_VAR
+SET @@thread_pool_high_prio_mode=1.1;
+
+--error ER_WRONG_TYPE_FOR_VAR
+SET @@thread_pool_high_prio_mode=1e1;
+
+SET @@GLOBAL.thread_pool_high_prio_mode = @start_global_value;

=== modified file 'Percona-Server/sql/sql_class.h'
--- Percona-Server/sql/sql_class.h	2013-12-02 12:25:50 +0000
+++ Percona-Server/sql/sql_class.h	2013-12-12 13:56:46 +0000
@@ -610,7 +610,8 @@
 
   my_bool expand_fast_index_creation;
 
-  uint threadpool_high_prio_tickets;
+  uint  threadpool_high_prio_tickets;
+  ulong thread_pool_high_prio_mode;
 } SV;
 
 

=== modified file 'Percona-Server/sql/sys_vars.cc'
--- Percona-Server/sql/sys_vars.cc	2013-12-02 12:25:50 +0000
+++ Percona-Server/sql/sys_vars.cc	2013-12-12 13:56:46 +0000
@@ -3152,6 +3152,21 @@
   SESSION_VAR(threadpool_high_prio_tickets), CMD_LINE(REQUIRED_ARG),
   VALID_RANGE(0, UINT_MAX), DEFAULT(UINT_MAX), BLOCK_SIZE(1)
 );
+
+static Sys_var_enum Sys_threadpool_high_prio_mode(
+  "thread_pool_high_prio_mode",
+  "High priority queue mode: one of 'transactions', 'statements' or 'none'. "
+  "In the 'transactions' mode the thread pool uses both high- and low-priority "
+  "queues depending on whether an event is generated by an already started "
+  "transaction and whether it has any high priority tickets (see "
+  "thread_pool_high_prio_tickets). In the 'statements' mode all events (i.e. "
+  "individual statements) always go to the high priority queue, regardless of "
+  "the current transaction state and high priority tickets. "
+  "'none' is the opposite of 'statements', i.e. disables the high priority queue "
+  "completely.",
+  SESSION_VAR(thread_pool_high_prio_mode), CMD_LINE(REQUIRED_ARG),
+  thread_pool_high_prio_mode_names, DEFAULT(TP_HIGH_PRIO_MODE_TRANSACTIONS));
+
 #endif /* !WIN32 */
 static Sys_var_uint Sys_threadpool_max_threads(
   "thread_pool_max_threads",

=== modified file 'Percona-Server/sql/threadpool.h'
--- Percona-Server/sql/threadpool.h	2013-12-02 12:17:20 +0000
+++ Percona-Server/sql/threadpool.h	2013-12-12 13:56:46 +0000
@@ -15,6 +15,12 @@
 
 #define MAX_THREAD_GROUPS 128
 
+enum tp_high_prio_mode_t {
+  TP_HIGH_PRIO_MODE_TRANSACTIONS,
+  TP_HIGH_PRIO_MODE_STATEMENTS,
+  TP_HIGH_PRIO_MODE_NONE
+};
+
 /* Threadpool parameters */
 extern uint threadpool_min_threads;  /* Minimum threads in pool */
 extern uint threadpool_idle_timeout; /* Shutdown idle worker threads  after this timeout */
@@ -23,6 +29,9 @@
 extern uint threadpool_max_threads;  /* Maximum threads in pool */
 extern uint threadpool_oversubscribe;  /* Maximum active threads in group */
 
+/* Possible values for thread_pool_high_prio_mode */
+extern const char *thread_pool_high_prio_mode_names[];
+
 /* Common thread pool routines, suitable for different implementations */
 extern void threadpool_remove_connection(THD *thd);
 extern int  threadpool_process_request(THD *thd);

=== modified file 'Percona-Server/sql/threadpool_unix.cc'
--- Percona-Server/sql/threadpool_unix.cc	2013-12-12 13:56:46 +0000
+++ Percona-Server/sql/threadpool_unix.cc	2013-12-12 13:56:46 +0000
@@ -48,6 +48,10 @@
 for stall detection to kick in */
 #define THREADPOOL_CREATE_THREADS_ON_WAIT
 
+/* Possible values for thread_pool_high_prio_mode */
+const char *thread_pool_high_prio_mode_names[]= {"transactions", "statements",
+                                                 "none", NullS};
+
 /** Indicates that threadpool was initialized*/
 static bool threadpool_started= false; 
 
@@ -428,6 +432,21 @@
           > 1 + (int) threadpool_oversubscribe);
 }
 
+/*
+   Checks if a given connection is eligible to enter the high priority queue
+   based on its current thread_pool_high_prio_mode value, available high
+   priority tickets and transactional state.
+*/
+
+inline bool connection_is_high_prio(connection_t *c)
+{
+  const ulong mode= c->thd->variables.thread_pool_high_prio_mode;
+
+  return (mode == TP_HIGH_PRIO_MODE_STATEMENTS) ||
+    (mode == TP_HIGH_PRIO_MODE_TRANSACTIONS &&
+     c->tickets > 0 && thd_is_transaction_active(c->thd));
+}
+
 } // namespace
 
 /* Dequeue element from a workqueue */
@@ -761,7 +780,7 @@
     for(int i=(listener_picks_event)?1:0; i < cnt ; i++)
     {
       connection_t *c= (connection_t *)native_event_get_userdata(&ev[i]);
-      if (c->tickets > 0 && thd_is_transaction_active(c->thd))
+      if (connection_is_high_prio(c))
       {
         c->tickets--;
         thread_group->high_prio_queue.push_back(c);
@@ -1153,8 +1172,7 @@
           must either have a high priority ticket, or there must be not too many
           busy threads (as if it was coming from a low priority queue).
         */
-        if (connection->tickets > 0 &&
-            thd_is_transaction_active(connection->thd))
+        if (connection_is_high_prio(connection))
           connection->tickets--;
         else if (too_many_busy_threads(thread_group))
         {