MDEV-14756 - Remove trx_sys_t::rw_trx_list

Replaced UT_LIST_GET_LEN(trx_sys->rw_trx_list) with trx_sys->rw_trx_hash.size(). Moved freeing of trx objects at shutdown to rw_trx_hash destructor. Small clean-up in trx_rollback_recovered().

Author: svoj

storage/innobase/include/trx0sys.h

@@ -244,13 +244,6 @@ trx_sys_close(void);
 @return	whether the creation succeeded */
 bool
 trx_sys_create_rsegs();
-/*****************************************************************//**
-Get the number of transaction in the system, independent of their state.
-@return count of transactions in trx_sys_t::trx_list */
-UNIV_INLINE
-ulint
-trx_sys_get_n_rw_trx(void);
-/*======================*/
 
 /*********************************************************************
 Check if there are any active (non-prepared) transactions.
@@ -506,6 +499,35 @@ class rw_trx_hash_t
  }
 
 
+ /**
+ Destructor callback for lock-free allocator.
+
+ This destructor is used at shutdown. It frees remaining transaction
+ objects.
+
+ XA PREPARED transactions may remain if they haven't been committed or
+ rolled back. ACTIVE transactions may remain if startup was interrupted or
+ server is running in read-only mode or for certain srv_force_recovery
+ levels.
+ */
+
+ static void rw_trx_hash_shutdown_destructor(uchar *arg)
+ {
+ rw_trx_hash_element_t *element=
+ reinterpret_cast<rw_trx_hash_element_t*>(arg + LF_HASH_OVERHEAD);
+ if (trx_t *trx= element->trx)
+ {
+ ut_ad(trx_state_eq(trx, TRX_STATE_PREPARED) ||
+ (trx_state_eq(trx, TRX_STATE_ACTIVE) &&
+ (!srv_was_started ||
+ srv_read_only_mode ||
+ srv_force_recovery >= SRV_FORCE_NO_TRX_UNDO)));
+ trx_free_prepared(trx);
+ }
+ element->~rw_trx_hash_element_t();
+ }
+
+
  /**
  Initializer callback for lock-free hash.
 
@@ -522,6 +544,7 @@ class rw_trx_hash_t
  rw_trx_hash_element_t *element,
  trx_t *trx)
  {
+ ut_ad(element->trx == 0);
  element->trx= trx;
  element->id= trx->id;
  trx->rw_trx_hash_element= element;
@@ -562,6 +585,7 @@ class rw_trx_hash_t
 
  void destroy()
  {
+ hash.alloc.destructor= rw_trx_hash_shutdown_destructor;
  lf_hash_destroy(&hash);
  }
 

storage/innobase/include/trx0sys.ic

@@ -293,22 +293,3 @@ trx_sys_get_max_trx_id(void)
 return(trx_sys->max_trx_id);
 #endif /* UNIV_WORD_SIZE < DATA_TRX_ID_LEN */
 }
-
-/*****************************************************************//**
-Get the number of transaction in the system, independent of their state.
-@return count of transactions in trx_sys_t::rw_trx_list */
-UNIV_INLINE
-ulint
-trx_sys_get_n_rw_trx(void)
-/*======================*/
-{
-ulint	n_trx;
-
-trx_sys_mutex_enter();
-
-n_trx = UT_LIST_GET_LEN(trx_sys->rw_trx_list);
-
-trx_sys_mutex_exit();
-
-return(n_trx);
-}

storage/innobase/trx/trx0roll.cc

@@ -852,16 +852,6 @@ trx_rollback_recovered(bool all)
 
 ut_a(srv_force_recovery < SRV_FORCE_NO_TRX_UNDO);
 
-if (trx_sys_get_n_rw_trx() == 0) {
-
-return;
-}
-
-if (all) {
-ib::info() << "Starting in background the rollback"
-" of recovered transactions";
-}
-
 /* Note: For XA recovered transactions, we rely on MySQL to
 do rollback. They will be in TRX_STATE_PREPARED state. If the server
 is shutdown and they are still lingering in trx_sys_t::trx_list
@@ -894,11 +884,6 @@ trx_rollback_recovered(bool all)
 trx_sys_mutex_exit();
 
 } while (trx != NULL);
-
-if (all) {
-ib::info() << "Rollback of non-prepared transactions"
-" completed";
-}
 }
 
 /*******************************************************************//**
@@ -919,7 +904,13 @@ DECLARE_THREAD(trx_rollback_all_recovered)(void*)
 pfs_register_thread(trx_rollback_clean_thread_key);
 #endif /* UNIV_PFS_THREAD */
 
-trx_rollback_recovered(true);
+if (trx_sys->rw_trx_hash.size()) {
+ib::info() << "Starting in background the rollback of"
+" recovered transactions";
+trx_rollback_recovered(true);
+ib::info() << "Rollback of non-prepared transactions"
+" completed";
+}
 
 trx_rollback_is_active = false;
 

storage/innobase/trx/trx0sys.cc

@@ -591,20 +591,7 @@ trx_sys_close(void)
 trx_dummy_sess = NULL;
 }
 
-/* Only prepared transactions may be left in the system. Free them. */
-ut_a(UT_LIST_GET_LEN(trx_sys->rw_trx_list) == trx_sys->n_prepared_trx
- || !srv_was_started
- || srv_read_only_mode
- || srv_force_recovery >= SRV_FORCE_NO_TRX_UNDO);
-
-for (trx_t* trx = UT_LIST_GET_FIRST(trx_sys->rw_trx_list);
- trx != NULL;
- trx = UT_LIST_GET_FIRST(trx_sys->rw_trx_list)) {
-
-trx_free_prepared(trx);
-
-UT_LIST_REMOVE(trx_sys->rw_trx_list, trx);
-}
+trx_sys->rw_trx_hash.destroy();
 
 /* There can't be any active transactions. */
 
@@ -629,7 +616,6 @@ trx_sys_close(void)
 
 trx_sys->rw_trx_ids.~trx_ids_t();
 
-trx_sys->rw_trx_hash.destroy();
 ut_free(trx_sys);
 
 trx_sys = NULL;
@@ -643,12 +629,9 @@ ulint
 trx_sys_any_active_transactions(void)
 /*=================================*/
 {
-ulint	total_trx = 0;
+ulint	total_trx = trx_sys->rw_trx_hash.size();
 
 trx_sys_mutex_enter();
-
-total_trx = UT_LIST_GET_LEN(trx_sys->rw_trx_list);
-
 for (trx_t* trx = UT_LIST_GET_FIRST(trx_sys->mysql_trx_list);
  trx != NULL;
  trx = UT_LIST_GET_NEXT(mysql_trx_list, trx)) {

storage/innobase/trx/trx0trx.cc

@@ -645,6 +645,7 @@ trx_free_prepared(
 trx_undo_free_prepared(trx);
 
 assert_trx_in_rw_list(trx);
+UT_LIST_REMOVE(trx_sys->rw_trx_list, trx);
 
 ut_a(!trx->read_only);