Allocate Transaction_state_tracker statically

One less new/delete per connection.

Part of MDEV-14984 - regression in connect performance

sql/lock.cc

@@ -252,16 +252,11 @@ static void track_table_access(THD *thd, TABLE **tables, size_t count)
 {
   if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
   {
-    Transaction_state_tracker *tst= (Transaction_state_tracker *)
-      thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER);
-
     while (count--)
     {
-      TABLE *t= tables[count];
-
-      if (t)
-        tst->add_trx_state(thd,  t->reginfo.lock_type,
-                           t->file->has_transaction_manager());
+      if (TABLE *t= tables[count])
+        thd->session_tracker.transaction_info.add_trx_state(thd,
+          t->reginfo.lock_type, t->file->has_transaction_manager());
     }
   }
 }

sql/session_tracker.cc

@@ -1345,7 +1345,7 @@ Session_tracker::Session_tracker()
   m_trackers[SESSION_SYSVARS_TRACKER]= 0;
   m_trackers[CURRENT_SCHEMA_TRACKER]= &current_schema;
   m_trackers[SESSION_STATE_CHANGE_TRACKER]= &state_change;
-  m_trackers[TRANSACTION_INFO_TRACKER]= 0;
+  m_trackers[TRANSACTION_INFO_TRACKER]= &transaction_info;
 }
 
 
@@ -1367,8 +1367,6 @@ void Session_tracker::enable(THD *thd)
   deinit();
   m_trackers[SESSION_SYSVARS_TRACKER]=
     new (std::nothrow) Session_sysvars_tracker();
-  m_trackers[TRANSACTION_INFO_TRACKER]=
-    new (std::nothrow) Transaction_state_tracker;
 
   for (int i= 0; i < SESSION_TRACKER_END; i++)
     m_trackers[i]->enable(thd);

sql/session_tracker.h

@@ -154,65 +154,6 @@ class Session_state_change_tracker: public State_tracker
 };
 
 
-/**
-  Session_tracker
-
-  This class holds an object each for all tracker classes and provides
-  methods necessary for systematic detection and generation of session
-  state change information.
-*/
-
-class Session_tracker
-{
-  State_tracker *m_trackers[SESSION_TRACKER_END];
-
-  /* The following two functions are private to disable copying. */
-  Session_tracker(Session_tracker const &other)
-  {
-    DBUG_ASSERT(FALSE);
-  }
-  Session_tracker& operator= (Session_tracker const &rhs)
-  {
-    DBUG_ASSERT(FALSE);
-    return *this;
-  }
-
-public:
-  Current_schema_tracker current_schema;
-  Session_state_change_tracker state_change;
-
-  Session_tracker();
-  ~Session_tracker() { deinit(); }
-
-  /* trick to make happy memory accounting system */
-  void deinit()
-  {
-    delete m_trackers[SESSION_SYSVARS_TRACKER];
-    m_trackers[SESSION_SYSVARS_TRACKER]= 0;
-    delete m_trackers[TRANSACTION_INFO_TRACKER];
-    m_trackers[TRANSACTION_INFO_TRACKER]= 0;
-  }
-
-  void enable(THD *thd);
-
-  /** Returns the pointer to the tracker object for the specified tracker. */
-  inline State_tracker *get_tracker(enum_session_tracker tracker) const
-  {
-    return m_trackers[tracker];
-  }
-
-  inline void mark_as_changed(THD *thd, enum enum_session_tracker tracker,
-                              LEX_CSTRING *data)
-  {
-    if (m_trackers[tracker]->is_enabled())
-      m_trackers[tracker]->mark_as_changed(thd, data);
-  }
-
-
-  void store(THD *thd, String *main_buf);
-};
-
-
 /*
   Transaction_state_tracker
 */
@@ -277,12 +218,17 @@ class Transaction_state_tracker : public State_tracker
   /** Helper function: turn table info into table access flag */
   enum_tx_state calc_trx_state(THD *thd, thr_lock_type l, bool has_trx);
 public:
-  /** Constructor */
-  Transaction_state_tracker(): tx_changed(TX_CHG_NONE),
-                               tx_curr_state(TX_EMPTY),
-                               tx_reported_state(TX_EMPTY),
-                               tx_read_flags(TX_READ_INHERIT),
-                               tx_isol_level(TX_ISOL_INHERIT) {}
+
+  bool enable(THD *thd)
+  {
+    m_enabled= false;
+    tx_changed= TX_CHG_NONE;
+    tx_curr_state= TX_EMPTY;
+    tx_reported_state= TX_EMPTY;
+    tx_read_flags= TX_READ_INHERIT;
+    tx_isol_level= TX_ISOL_INHERIT;
+    return State_tracker::enable(thd);
+  }
 
   bool update(THD *thd, set_var *var);
   bool store(THD *thd, String *buf);
@@ -332,12 +278,69 @@ class Transaction_state_tracker : public State_tracker
 
 #define TRANSACT_TRACKER(X) \
  do { if (thd->variables.session_track_transaction_info > TX_TRACK_NONE) \
-   {((Transaction_state_tracker *) \
-         thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER)) \
-          ->X; } } while(0)
+        thd->session_tracker.transaction_info.X; } while(0)
 #define SESSION_TRACKER_CHANGED(A,B,C) \
   thd->session_tracker.mark_as_changed(A,B,C)
 
+
+/**
+  Session_tracker
+
+  This class holds an object each for all tracker classes and provides
+  methods necessary for systematic detection and generation of session
+  state change information.
+*/
+
+class Session_tracker
+{
+  State_tracker *m_trackers[SESSION_TRACKER_END];
+
+  /* The following two functions are private to disable copying. */
+  Session_tracker(Session_tracker const &other)
+  {
+    DBUG_ASSERT(FALSE);
+  }
+  Session_tracker& operator= (Session_tracker const &rhs)
+  {
+    DBUG_ASSERT(FALSE);
+    return *this;
+  }
+
+public:
+  Current_schema_tracker current_schema;
+  Session_state_change_tracker state_change;
+  Transaction_state_tracker transaction_info;
+
+  Session_tracker();
+  ~Session_tracker() { deinit(); }
+
+  /* trick to make happy memory accounting system */
+  void deinit()
+  {
+    delete m_trackers[SESSION_SYSVARS_TRACKER];
+    m_trackers[SESSION_SYSVARS_TRACKER]= 0;
+  }
+
+  void enable(THD *thd);
+
+  /** Returns the pointer to the tracker object for the specified tracker. */
+  inline State_tracker *get_tracker(enum_session_tracker tracker) const
+  {
+    return m_trackers[tracker];
+  }
+
+  inline void mark_as_changed(THD *thd, enum enum_session_tracker tracker,
+                              LEX_CSTRING *data)
+  {
+    if (m_trackers[tracker]->is_enabled())
+      m_trackers[tracker]->mark_as_changed(thd, data);
+  }
+
+
+  void store(THD *thd, String *main_buf);
+};
+
+
 int session_tracker_init();
 #else
 

sql/sys_vars.cc

@@ -3743,14 +3743,12 @@ bool Sys_var_tx_read_only::session_update(THD *thd, set_var *var)
 #ifndef EMBEDDED_LIBRARY
     if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
     {
-      Transaction_state_tracker *tst= (Transaction_state_tracker *)
-             thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER);
-
       if (var->type == OPT_DEFAULT)
-        tst->set_read_flags(thd,
+        thd->session_tracker.transaction_info.set_read_flags(thd,
                             thd->tx_read_only ? TX_READ_ONLY : TX_READ_WRITE);
       else
-        tst->set_read_flags(thd, TX_READ_INHERIT);
+        thd->session_tracker.transaction_info.set_read_flags(thd,
+                            TX_READ_INHERIT);
     }
 #endif //EMBEDDED_LIBRARY
   }
@@ -6145,8 +6143,7 @@ static bool update_session_track_tx_info(sys_var *self, THD *thd,
                                          enum_var_type type)
 {
   DBUG_ENTER("update_session_track_tx_info");
-  DBUG_RETURN(thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER)->
-              update(thd, NULL));
+  DBUG_RETURN(thd->session_tracker.transaction_info.update(thd, NULL));
 }
 
 static const char *session_track_transaction_info_names[]=

sql/sys_vars.ic

@@ -2219,14 +2219,6 @@ public:
       return TRUE;
     if (var->type == OPT_DEFAULT || !thd->in_active_multi_stmt_transaction())
     {
-#ifndef EMBEDDED_LIBRARY
-      Transaction_state_tracker *tst= NULL;
-
-      if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
-        tst= (Transaction_state_tracker *)
-          thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER);
-#endif //EMBEDDED_LIBRARY
-
       thd->tx_isolation= (enum_tx_isolation) var->save_result.ulonglong_value;
 
 #ifndef EMBEDDED_LIBRARY
@@ -2250,13 +2242,11 @@ public:
           DBUG_ASSERT(0);
           return TRUE;
         }
-        if (tst)
-          tst->set_isol_level(thd, l);
-      }
-      else if (tst)
-      {
-        tst->set_isol_level(thd, TX_ISOL_INHERIT);
+        if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
+          thd->session_tracker.transaction_info.set_isol_level(thd, l);
       }
+      else if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
+        thd->session_tracker.transaction_info.set_isol_level(thd, TX_ISOL_INHERIT);
 #endif //EMBEDDED_LIBRARY
     }
     return FALSE;

sql/transaction.cc

@@ -32,10 +32,7 @@
 static void trans_track_end_trx(THD *thd)
 {
   if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
-  {
-    ((Transaction_state_tracker *)
-     thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER))->end_trx(thd);
-  }
+    thd->session_tracker.transaction_info.end_trx(thd);
 }
 #else
 #define trans_track_end_trx(A) do{}while(0)
@@ -51,11 +48,8 @@ void trans_reset_one_shot_chistics(THD *thd)
 #ifndef EMBEDDED_LIBRARY
   if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
   {
-    Transaction_state_tracker *tst= (Transaction_state_tracker *)
-      thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER);
-
-    tst->set_read_flags(thd, TX_READ_INHERIT);
-    tst->set_isol_level(thd, TX_ISOL_INHERIT);
+    thd->session_tracker.transaction_info.set_read_flags(thd, TX_READ_INHERIT);
+    thd->session_tracker.transaction_info.set_isol_level(thd, TX_ISOL_INHERIT);
   }
 #endif //EMBEDDED_LIBRARY
   thd->tx_isolation= (enum_tx_isolation) thd->variables.tx_isolation;
@@ -162,20 +156,11 @@ static bool xa_trans_force_rollback(THD *thd)
 bool trans_begin(THD *thd, uint flags)
 {
   int res= FALSE;
-#ifndef EMBEDDED_LIBRARY
-  Transaction_state_tracker *tst= NULL;
-#endif //EMBEDDED_LIBRARY
   DBUG_ENTER("trans_begin");
 
   if (trans_check(thd))
     DBUG_RETURN(TRUE);
 
-#ifndef EMBEDDED_LIBRARY
-  if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
-    tst= (Transaction_state_tracker *)
-      thd->session_tracker.get_tracker(TRANSACTION_INFO_TRACKER);
-#endif //EMBEDDED_LIBRARY
-
   thd->locked_tables_list.unlock_locked_tables(thd);
 
   DBUG_ASSERT(!thd->locked_tables_mode);
@@ -221,8 +206,8 @@ bool trans_begin(THD *thd, uint flags)
   {
     thd->tx_read_only= true;
 #ifndef EMBEDDED_LIBRARY
-    if (tst)
-      tst->set_read_flags(thd, TX_READ_ONLY);
+    if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
+      thd->session_tracker.transaction_info.set_read_flags(thd, TX_READ_ONLY);
 #endif //EMBEDDED_LIBRARY
   }
   else if (flags & MYSQL_START_TRANS_OPT_READ_WRITE)
@@ -246,8 +231,8 @@ bool trans_begin(THD *thd, uint flags)
       just from the session's default.
     */
 #ifndef EMBEDDED_LIBRARY
-    if (tst)
-      tst->set_read_flags(thd, TX_READ_WRITE);
+    if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
+      thd->session_tracker.transaction_info.set_read_flags(thd, TX_READ_WRITE);
 #endif //EMBEDDED_LIBRARY
   }
 
@@ -264,16 +249,16 @@ bool trans_begin(THD *thd, uint flags)
   DBUG_PRINT("info", ("setting SERVER_STATUS_IN_TRANS"));
 
 #ifndef EMBEDDED_LIBRARY
-  if (tst)
-    tst->add_trx_state(thd, TX_EXPLICIT);
+  if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
+    thd->session_tracker.transaction_info.add_trx_state(thd, TX_EXPLICIT);
 #endif //EMBEDDED_LIBRARY
 
   /* ha_start_consistent_snapshot() relies on OPTION_BEGIN flag set. */
   if (flags & MYSQL_START_TRANS_OPT_WITH_CONS_SNAPSHOT)
   {
 #ifndef EMBEDDED_LIBRARY
-    if (tst)
-      tst->add_trx_state(thd, TX_WITH_SNAPSHOT);
+    if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
+      thd->session_tracker.transaction_info.add_trx_state(thd, TX_WITH_SNAPSHOT);
 #endif //EMBEDDED_LIBRARY
     res= ha_start_consistent_snapshot(thd);
   }