Remove the unnecessary method handlerton::release_temporary_latches()

The sole purpose of handlerton::release_temporary_latches and its wrapper
function was to release the InnoDB adaptive hash index latch
(btr_search_latch).

When the btr_search_latch was split into an array of latches
in MySQL 5.7.8 as part of the Oracle Bug#20985298 fix, the "caching"
of the latch across storage engine API calls was removed. As part of that,
the function trx_search_latch_release_if_reserved() was changed to an
assertion and the function trx_reserve_search_latch_if_not_reserved()
was removed, and handlerton::release_temporary_latches() practically
became a no-op.

Note: MDEV-12121 replaced the function
trx_search_latch_release_if_reserved()
with the more appropriately named macro trx_assert_no_search_latch().

sql/filesort.cc

@@ -182,12 +182,6 @@ SORT_INFO *filesort(THD *thd, TABLE *table, Filesort *filesort,
 
   outfile= &sort->io_cache;
 
-  /*
-   Release InnoDB's adaptive hash index latch (if holding) before
-   running a sort.
-  */
-  ha_release_temporary_latches(thd);
-
   my_b_clear(&tempfile);
   my_b_clear(&buffpek_pointers);
   buffpek=0;

sql/handler.cc

@@ -2015,44 +2015,6 @@ commit_checkpoint_notify_ha(handlerton *hton, void *cookie)
 }
 
 
-/**
-  @details
-  This function should be called when MySQL sends rows of a SELECT result set
-  or the EOF mark to the client. It releases a possible adaptive hash index
-  S-latch held by thd in InnoDB and also releases a possible InnoDB query
-  FIFO ticket to enter InnoDB. To save CPU time, InnoDB allows a thd to
-  keep them over several calls of the InnoDB handler interface when a join
-  is executed. But when we let the control to pass to the client they have
-  to be released because if the application program uses mysql_use_result(),
-  it may deadlock on the S-latch if the application on another connection
-  performs another SQL query. In MySQL-4.1 this is even more important because
-  there a connection can have several SELECT queries open at the same time.
-
-  @param thd           the thread handle of the current connection
-
-  @return
-    always 0
-*/
-
-int ha_release_temporary_latches(THD *thd)
-{
-  Ha_trx_info *info;
-
-  /*
-    Note that below we assume that only transactional storage engines
-    may need release_temporary_latches(). If this will ever become false,
-    we could iterate on thd->open_tables instead (and remove duplicates
-    as if (!seen[hton->slot]) { seen[hton->slot]=1; ... }).
-  */
-  for (info= thd->transaction.stmt.ha_list; info; info= info->next())
-  {
-    handlerton *hton= info->ht();
-    if (hton && hton->release_temporary_latches)
-        hton->release_temporary_latches(hton, thd);
-  }
-  return 0;
-}
-
 /**
   Check if all storage engines used in transaction agree that after
   rollback to savepoint it is safe to release MDL locks acquired after

sql/handler.h

@@ -1211,7 +1211,6 @@ struct handlerton
                             enum_binlog_command binlog_command,
                             const char *query, uint query_length,
                             const char *db, const char *table_name);
-   int (*release_temporary_latches)(handlerton *hton, THD *thd);
 
    /*
      Get log status.
@@ -4282,9 +4281,6 @@ int ha_change_key_cache_param(KEY_CACHE *key_cache);
 int ha_repartition_key_cache(KEY_CACHE *key_cache);
 int ha_change_key_cache(KEY_CACHE *old_key_cache, KEY_CACHE *new_key_cache);
 
-/* report to InnoDB that control passes to the client */
-int ha_release_temporary_latches(THD *thd);
-
 /* transactions: interface to handlerton functions */
 int ha_start_consistent_snapshot(THD *thd);
 int ha_commit_or_rollback_by_xid(XID *xid, bool commit);

sql/sql_cache.cc

@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2013, Oracle and/or its affiliates.
-   Copyright (c) 2010, 2013, Monty Program Ab
+   Copyright (c) 2010, 2017, MariaDB Corporation
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1465,12 +1465,6 @@ def_week_frmt: %lu, in_trans: %d, autocommit: %d",
                           (int)flags.in_trans,
                           (int)flags.autocommit));
 
-    /*
-     Make InnoDB to release the adaptive hash index latch before
-     acquiring the query cache mutex.
-    */
-    ha_release_temporary_latches(thd);
-
     /*
       A table- or a full flush operation can potentially take a long time to
       finish. We choose not to wait for them and skip caching statements

sql/sql_class.cc

@@ -2751,13 +2751,6 @@ int select_send::send_data(List<Item> &items)
   if (thd->killed == ABORT_QUERY)
     DBUG_RETURN(FALSE);
 
-  /*
-    We may be passing the control from mysqld to the client: release the
-    InnoDB adaptive hash S-latch to avoid thread deadlocks if it was reserved
-    by thd
-  */
-  ha_release_temporary_latches(thd);
-
   protocol->prepare_for_resend();
   if (protocol->send_result_set_row(&items))
   {
@@ -2776,13 +2769,6 @@ int select_send::send_data(List<Item> &items)
 
 bool select_send::send_eof()
 {
-  /* 
-    We may be passing the control from mysqld to the client: release the
-    InnoDB adaptive hash S-latch to avoid thread deadlocks if it was reserved
-    by thd 
-  */
-  ha_release_temporary_latches(thd);
-
   /* 
     Don't send EOF if we're in error condition (which implies we've already
     sent or are sending an error)

sql/sql_insert.cc

@@ -1,6 +1,6 @@
 /*
    Copyright (c) 2000, 2016, Oracle and/or its affiliates.
-   Copyright (c) 2010, 2016, MariaDB
+   Copyright (c) 2010, 2017, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -3751,9 +3751,6 @@ int select_insert::send_data(List<Item> &values)
     }
   }
 
-  // Release latches in case bulk insert takes a long time
-  ha_release_temporary_latches(thd);
-
   error= write_record(thd, table, &info);
   table->auto_increment_field_not_null= FALSE;
   

storage/innobase/handler/ha_innodb.cc

@@ -2035,28 +2035,6 @@ thd_to_trx_id(
 }
 #endif /* WITH_WSREP */
 
-/********************************************************************//**
-Call this function when mysqld passes control to the client. That is to
-avoid deadlocks on the adaptive hash S-latch possibly held by thd. For more
-documentation, see handler.cc.
-@return 0 */
-inline
-int
-innobase_release_temporary_latches(
-/*===============================*/
-	handlerton*	hton,	/*!< in: handlerton */
-	THD*		thd)	/*!< in: MySQL thread */
-{
-	DBUG_ASSERT(hton == innodb_hton_ptr);
-
-	if (!srv_was_started) {
-	} else if (trx_t* trx = thd_to_trx(thd)) {
-		trx_assert_no_search_latch(trx);
-	}
-
-	return(0);
-}
-
 /********************************************************************//**
 Increments innobase_active_counter and every INNOBASE_WAKE_INTERVALth
 time calls srv_active_wake_master_thread. This function should be used
@@ -3911,9 +3889,6 @@ innobase_init(
 	innobase_hton->flags =
 		HTON_SUPPORTS_EXTENDED_KEYS | HTON_SUPPORTS_FOREIGN_KEYS;
 
-	innobase_hton->release_temporary_latches =
-		innobase_release_temporary_latches;
-
 #ifdef MYSQL_REPLACE_TRX_IN_THD
         innobase_hton->replace_native_transaction_in_thd =
                 innodb_replace_trx_in_thd;
@@ -6538,37 +6513,19 @@ initialize_auto_increment(dict_table_t* table, const Field* field)
 	dict_table_autoinc_unlock(table);
 }
 
-/*****************************************************************//**
-Creates and opens a handle to a table which already exists in an InnoDB
-database.
-@return 1 if error, 0 if success */
-
+/** Open an InnoDB table
+@param[in]	name	table name
+@return	error code
+@retval	0	on success */
 int
-ha_innobase::open(
-/*==============*/
-	const char*		name,		/*!< in: table name */
-	int			mode,		/*!< in: not used */
-	uint			test_if_locked)	/*!< in: not used */
+ha_innobase::open(const char* name, int, uint)
 {
 	dict_table_t*		ib_table;
 	char			norm_name[FN_REFLEN];
-	THD*			thd;
 	dict_err_ignore_t	ignore_err = DICT_ERR_IGNORE_NONE;
 
 	DBUG_ENTER("ha_innobase::open");
 
-	UT_NOT_USED(mode);
-	UT_NOT_USED(test_if_locked);
-
-	thd = ha_thd();
-
-	/* Under some cases MySQL seems to call this function while
-	holding search latch(es). This breaks the latching order as
-	we acquire dict_sys->mutex below and leads to a deadlock. */
-	if (thd != NULL) {
-		innobase_release_temporary_latches(ht, thd);
-	}
-
 	normalize_table_name(norm_name, name);
 
 	m_user_thd = NULL;
@@ -6583,6 +6540,7 @@ ha_innobase::open(
 	m_upd_buf_size = 0;
 
 	char*	is_part = is_partition(norm_name);
+	THD*	thd = ha_thd();
 
 	/* Check whether FOREIGN_KEY_CHECKS is set to 0. If so, the table
 	can be opened even if some FK indexes are missing. If not, the table
@@ -7053,12 +7011,6 @@ ha_innobase::close()
 {
 	DBUG_ENTER("ha_innobase::close");
 
-	THD*	thd = ha_thd();
-
-	if (thd != NULL) {
-		innobase_release_temporary_latches(ht, thd);
-	}
-
 	row_prebuilt_free(m_prebuilt, FALSE);
 
 	if (m_upd_buf != NULL) {

storage/innobase/handler/ha_innodb.h

@@ -906,18 +906,6 @@ innodb_base_col_setup_for_stored(
 /** whether this is a computed virtual column */
 #define innobase_is_v_fld(field) ((field)->vcol_info && !(field)->stored_in_db())
 
-/** Release temporary latches.
-Call this function when mysqld passes control to the client. That is to
-avoid deadlocks on the adaptive hash S-latch possibly held by thd. For more
-documentation, see handler.cc.
-@param[in]	hton	Handlerton.
-@param[in]	thd	MySQL thread.
-@return 0 */
-int
-innobase_release_temporary_latches(
-	handlerton*	hton,
-	THD*		thd);
-
 /** Always normalize table name to lower case on Windows */
 #ifdef _WIN32
 #define normalize_table_name(norm_name, name)           \

storage/innobase/handler/ha_innopart.cc

@@ -932,7 +932,6 @@ ha_innopart::open(
 {
 	dict_table_t*	ib_table;
 	char		norm_name[FN_REFLEN];
-	THD*		thd;
 
 	DBUG_ENTER("ha_innopart::open");
 
@@ -942,16 +941,11 @@ ha_innopart::open(
 		ut_ad(table->part_info != NULL);
 		m_part_info = table->part_info;
 	}
-	thd = ha_thd();
 
 	/* Under some cases MySQL seems to call this function while
 	holding search latch(es). This breaks the latching order as
 	we acquire dict_sys->mutex below and leads to a deadlock. */
 
-	if (thd != NULL) {
-		innobase_release_temporary_latches(ht, thd);
-	}
-
 	normalize_table_name(norm_name, name);
 
 	m_user_thd = NULL;
@@ -1017,6 +1011,7 @@ share_error:
 	MONITOR_INC(MONITOR_TABLE_OPEN);
 
 	bool	no_tablespace;
+	THD*	thd = ha_thd();
 
 	/* TODO: Should we do this check for every partition during ::open()? */
 	/* TODO: refactor this in ha_innobase so it can increase code reuse. */
@@ -1372,15 +1367,8 @@ void ha_innopart::clear_ins_upd_nodes()
 int
 ha_innopart::close()
 {
-	THD*	thd;
-
 	DBUG_ENTER("ha_innopart::close");
 
-	thd = ha_thd();
-	if (thd != NULL) {
-		innobase_release_temporary_latches(ht, thd);
-	}
-
 	ut_ad(m_pcur_parts == NULL);
 	ut_ad(m_clust_pcur_parts == NULL);
 	close_partitioning();

storage/myisam/ha_myisam.cc

@@ -1182,9 +1182,6 @@ int ha_myisam::repair(THD *thd, HA_CHECK &param, bool do_optimize)
   share->state.dupp_key= MI_MAX_KEY;
   strmov(fixed_name,file->filename);
 
-  // Release latches since this can take a long time
-  ha_release_temporary_latches(thd);
-
   /*
     Don't lock tables if we have used LOCK TABLE or if we come from
     enable_index()

storage/xtradb/handler/ha_innodb.cc

@@ -2122,39 +2122,6 @@ ha_innobase::is_fake_change_enabled(THD* thd)
 	return(trx && UNIV_UNLIKELY(trx->fake_changes));
 }
 
-/********************************************************************//**
-In XtraDB it is impossible for a transaction to own a search latch outside of
-InnoDB code, so there is nothing to release on demand.  We keep this function to
-simplify maintenance.
-@return 0 */
-static
-int
-innobase_release_temporary_latches(
-/*===============================*/
-	handlerton*	hton MY_ATTRIBUTE((unused)),	/*!< in: handlerton */
-	THD*		thd MY_ATTRIBUTE((unused)))	/*!< in: MySQL thread */
-{
-#ifdef UNIV_DEBUG
-	DBUG_ASSERT(hton == innodb_hton_ptr);
-
-	if (!innodb_inited || thd == NULL) {
-
-		return(0);
-	}
-
-	trx_t*	trx = thd_to_trx(thd);
-
-	if (trx != NULL) {
-#ifdef UNIV_SYNC_DEBUG
-		ut_ad(!btr_search_own_any());
-#endif
-		trx_search_latch_release_if_reserved(trx);
-	}
-#endif
-
-	return(0);
-}
-
 /********************************************************************//**
 Increments innobase_active_counter and every INNOBASE_WAKE_INTERVALth
 time calls srv_active_wake_master_thread. This function should be used
@@ -3813,9 +3780,6 @@ innobase_init(
 	innobase_hton->flags = HTON_SUPPORTS_EXTENDED_KEYS |
 		HTON_SUPPORTS_FOREIGN_KEYS;
 
-	innobase_hton->release_temporary_latches =
-		innobase_release_temporary_latches;
-
 	innobase_hton->kill_query = innobase_kill_connection;
 
         if (srv_file_per_table)
@@ -6262,9 +6226,6 @@ ha_innobase::open(
 
 	thd = ha_thd();
 
-	/* No-op in XtraDB */
-	innobase_release_temporary_latches(ht, thd);
-
 	normalize_table_name(norm_name, name);
 
 	user_thd = NULL;
@@ -6724,9 +6685,6 @@ ha_innobase::close()
 
 	thd = ha_thd();
 
-	/* No-op in XtraDB */
-	innobase_release_temporary_latches(ht, thd);
-
 	row_prebuilt_free(prebuilt, FALSE);
 
 	if (upd_buf != NULL) {