Remove trx_t::has_search_latch and simplify debug code

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, and
the field trx->has_search_latch would only be set during a short
time frame in the execution of row_search_mvcc(), which was
formerly called row_search_for_mysql().

This means that the column
INFORMATION_SCHEMA.INNODB_TRX.TRX_ADAPTIVE_HASH_LATCHED will always
report 0. That column cannot be removed in MariaDB 10.2, but it
can be removed in future releases.

trx_t::has_search_latch: Remove.

trx_assert_no_search_latch(): Remove.

row_sel_try_search_shortcut_for_mysql(): Remove a redundant condition
on trx->has_search_latch (it was always true).

sync_check_iterate(): Make the parameter const.

sync_check_functor_t: Make the operator() const, and remove result()
and the virtual destructor. There is no need to have mutable state
in the functors.

sync_checker<bool>: Replaces dict_sync_check and btrsea_sync_check.

sync_check: Replaces btrsea_sync_check.

dict_sync_check: Instantiated from sync_checker.

sync_allowed_latches: Use std::find() directly on the array.
Remove the std::vector.

TrxInInnoDB::enter(), TrxInInnoDB::exit(): Remove obviously redundant
debug assertions on trx->in_depth, and use equality comparison against 0
because it could be more efficient on some architectures.

storage/innobase/btr/btr0bulk.cc

@@ -1,6 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 2014, 2016, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 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 the Free Software
@@ -991,11 +992,7 @@ BtrBulk::finish(dberr_t	err)
 		ut_ad(err == DB_SUCCESS);
 	}
 
-#ifdef UNIV_DEBUG
-	dict_sync_check check(true);
-
-	ut_ad(!sync_check_iterate(check));
-#endif /* UNIV_DEBUG */
+	ut_ad(!sync_check_iterate(dict_sync_check()));
 
 	ut_ad(err != DB_SUCCESS || btr_validate_index(m_index, NULL, false));
 	return(err);

storage/innobase/buf/buf0flu.cc

@@ -1870,15 +1870,8 @@ buf_flush_batch(
 					counts  */
 {
 	ut_ad(flush_type == BUF_FLUSH_LRU || flush_type == BUF_FLUSH_LIST);
-
-#ifdef UNIV_DEBUG
-	{
-		dict_sync_check	check(true);
-
-		ut_ad(flush_type != BUF_FLUSH_LIST
-		      || !sync_check_iterate(check));
-	}
-#endif /* UNIV_DEBUG */
+	ut_ad(flush_type == BUF_FLUSH_LRU
+	      || !sync_check_iterate(dict_sync_check()));
 
 	buf_pool_mutex_enter(buf_pool);
 

storage/innobase/dict/dict0dict.cc

@@ -6113,14 +6113,7 @@ dict_set_corrupted(
 	ut_ad(mutex_own(&dict_sys->mutex));
 	ut_ad(!dict_table_is_comp(dict_sys->sys_tables));
 	ut_ad(!dict_table_is_comp(dict_sys->sys_indexes));
-
-#ifdef UNIV_DEBUG
-	{
-		dict_sync_check	check(true);
-
-		ut_ad(!sync_check_iterate(check));
-	}
-#endif /* UNIV_DEBUG */
+	ut_ad(!sync_check_iterate(dict_sync_check()));
 
 	/* Mark the table as corrupted only if the clustered index
 	is corrupted */

storage/innobase/handler/ha_innodb.cc

@@ -1869,6 +1869,8 @@ void
 innobase_srv_conc_exit_innodb(
 	row_prebuilt_t*	prebuilt)
 {
+	ut_ad(!sync_check_iterate(sync_check()));
+
 #ifdef WITH_WSREP
 	if (wsrep_on(prebuilt->trx->mysql_thd) &&
 	    wsrep_thd_is_BF(prebuilt->trx->mysql_thd, FALSE)) {
@@ -1877,13 +1879,6 @@ innobase_srv_conc_exit_innodb(
 #endif /* WITH_WSREP */
 
 	trx_t*			trx = prebuilt->trx;
-#ifdef BTR_CUR_HASH_ADAPT
-# ifdef UNIV_DEBUG
-	btrsea_sync_check	check(trx->has_search_latch);
-
-	ut_ad(!sync_check_iterate(check));
-# endif /* UNIV_DEBUG */
-#endif /* BTR_CUR_HASH_ADAPT */
 
 	/* This is to avoid making an unnecessary function call. */
 	if (trx->declared_to_be_inside_innodb
@@ -1901,13 +1896,7 @@ innobase_srv_conc_force_exit_innodb(
 /*================================*/
 	trx_t*	trx)	/*!< in: transaction handle */
 {
-#ifdef BTR_CUR_HASH_ADAPT
-# ifdef UNIV_DEBUG
-	btrsea_sync_check	check(trx->has_search_latch);
-
-	ut_ad(!sync_check_iterate(check));
-# endif /* UNIV_DEBUG */
-#endif /* BTR_CUR_HASH_ADAPT */
+	ut_ad(!sync_check_iterate(sync_check()));
 
 	/* This is to avoid making an unnecessary function call. */
 	if (trx->declared_to_be_inside_innodb) {
@@ -1994,13 +1983,7 @@ const char*
 thd_innodb_tmpdir(
 	THD*	thd)
 {
-#ifdef BTR_CUR_HASH_ADAPT
-# ifdef UNIV_DEBUG
-	trx_t*	trx = thd_to_trx(thd);
-	btrsea_sync_check	check(trx->has_search_latch);
-	ut_ad(!sync_check_iterate(check));
-# endif /* UNIV_DEBUG */
-#endif /* BTR_CUR_HASH_ADAPT */
+	ut_ad(!sync_check_iterate(sync_check()));
 
 	const char*	tmp_dir = THDVAR(thd, tmpdir);
 
@@ -3360,7 +3343,6 @@ innobase_query_caching_of_table_permitted(
 		return(false);
 	}
 
-	trx_assert_no_search_latch(trx);
 	innobase_srv_conc_force_exit_innodb(trx);
 
 	if (!thd_test_options(thd, OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)
@@ -3668,8 +3650,6 @@ ha_innobase::init_table_handle_for_HANDLER(void)
 	/* Initialize the m_prebuilt struct much like it would be inited in
 	external_lock */
 
-	trx_assert_no_search_latch(m_prebuilt->trx);
-
 	innobase_srv_conc_force_exit_innodb(m_prebuilt->trx);
 
 	/* If the transaction is not started yet, start it */
@@ -4781,12 +4761,6 @@ innobase_commit_ordered(
 	trx = check_trx_exists(thd);
 	TrxInInnoDB	trx_in_innodb(trx);
 
-	/* Since we will reserve the kernel mutex, we must not be holding the
-	search system latch, or we will disobey the latching order. But we
-	already released it in innobase_xa_prepare() (if not before), so just
-	have an assert here.*/
-	trx_assert_no_search_latch(trx);
-
 	if (!trx_is_registered_for_2pc(trx) && trx_is_started(trx)) {
 		/* We cannot throw error here; instead we will catch this error
 		again in innobase_commit() and report it from there. */
@@ -4998,12 +4972,6 @@ innobase_rollback_trx(
 	DBUG_ENTER("innobase_rollback_trx");
 	DBUG_PRINT("trans", ("aborting transaction"));
 
-	/* Release a possible FIFO ticket and search latch. Since we will
-	reserve the trx_sys->mutex, we have to release the search system
-	latch first to obey the latching order. */
-
-	trx_assert_no_search_latch(trx);
-
 	innobase_srv_conc_force_exit_innodb(trx);
 
 	/* If we had reserved the auto-inc lock for some table (if
@@ -13101,10 +13069,6 @@ create_table_info_t::initialize()
 
 	parent_trx = check_trx_exists(m_thd);
 
-	/* In case MySQL calls this in the middle of a SELECT query, release
-	possible adaptive hash latch to avoid deadlocks of threads */
-
-	trx_assert_no_search_latch(parent_trx);
 	DBUG_RETURN(0);
 }
 
@@ -13953,12 +13917,6 @@ innobase_drop_database(
 
 	THD*	thd = current_thd;
 
-	/* In case MySQL calls this in the middle of a SELECT
-	query, release possible adaptive hash latch to avoid
-	deadlocks of threads */
-
-	trx_assert_no_search_latch(check_trx_exists(thd));
-
 	ulint	len = 0;
 	char*	ptr = strend(path) - 2;
 
@@ -14692,12 +14650,7 @@ ha_innobase::info_low(
 
 	update_thd(ha_thd());
 
-	/* In case MySQL calls this in the middle of a SELECT query, release
-	possible adaptive hash latch to avoid deadlocks of threads */
-
-	m_prebuilt->trx->op_info = (char*)"returning various info to MariaDB";
-
-	trx_assert_no_search_latch(m_prebuilt->trx);
+	m_prebuilt->trx->op_info = "returning various info to MariaDB";
 
 	ib_table = m_prebuilt->table;
 	DBUG_ASSERT(ib_table->n_ref_count > 0);
@@ -15544,12 +15497,7 @@ ha_innobase::update_table_comment(
 
 	update_thd(ha_thd());
 
-	m_prebuilt->trx->op_info = (char*)"returning table comment";
-
-	/* In case MySQL calls this in the middle of a SELECT query, release
-	possible adaptive hash latch to avoid deadlocks of threads */
-
-	trx_assert_no_search_latch(m_prebuilt->trx);
+	m_prebuilt->trx->op_info = "returning table comment";
 
 #define SSTR( x ) reinterpret_cast< std::ostringstream & >(		\
         ( std::ostringstream() << std::dec << x ) ).str()
@@ -15605,22 +15553,14 @@ ha_innobase::get_foreign_key_create_info(void)
 
 	update_thd(ha_thd());
 
-	m_prebuilt->trx->op_info = (char*)"getting info on foreign keys";
-
-	/* In case MySQL calls this in the middle of a SELECT query,
-	release possible adaptive hash latch to avoid
-	deadlocks of threads */
-
-	trx_assert_no_search_latch(m_prebuilt->trx);
-
-
+	m_prebuilt->trx->op_info = "getting info on foreign keys";
 
 	/* Output the data to a temporary string */
 	std::string str = dict_print_info_on_foreign_keys(
 		TRUE, m_prebuilt->trx,
 		m_prebuilt->table);
 
-	m_prebuilt->trx->op_info = (char*)"";
+	m_prebuilt->trx->op_info = "";
 
 	/* Allocate buffer for the string */
 	char* fk_str = (char*) my_malloc(str.length() + 1, MYF(0));
@@ -16624,8 +16564,6 @@ innodb_show_status(
 
 	trx_t*	trx = check_trx_exists(thd);
 
-	trx_assert_no_search_latch(trx);
-
 	innobase_srv_conc_force_exit_innodb(trx);
 
 	TrxInInnoDB	trx_in_innodb(trx);
@@ -17936,12 +17874,6 @@ innobase_xa_prepare(
 
 	thd_get_xid(thd, (MYSQL_XID*) trx->xid);
 
-	/* Release a possible FIFO ticket and search latch. Since we will
-	reserve the trx_sys->mutex, we have to release the search system
-	latch first to obey the latching order. */
-
-	trx_assert_no_search_latch(trx);
-
 	innobase_srv_conc_force_exit_innodb(trx);
 
 	TrxInInnoDB	trx_in_innodb(trx);

storage/innobase/handler/ha_innopart.cc

@@ -3020,11 +3020,6 @@ ha_innopart::records_in_range(
 
 	m_prebuilt->trx->op_info = (char*)"estimating records in index range";
 
-	/* In case MySQL calls this in the middle of a SELECT query, release
-	possible adaptive hash latch to avoid deadlocks of threads. */
-
-	trx_assert_no_search_latch(m_prebuilt->trx);
-
 	active_index = keynr;
 
 	key = table->key_info + active_index;
@@ -3159,11 +3154,6 @@ ha_innopart::estimate_rows_upper_bound()
 
 	m_prebuilt->trx->op_info = "calculating upper bound for table rows";
 
-	/* In case MySQL calls this in the middle of a SELECT query, release
-	possible adaptive hash latch to avoid deadlocks of threads. */
-
-	trx_assert_no_search_latch(m_prebuilt->trx);
-
 	for (uint i = m_part_info->get_first_used_partition();
 	     i < m_tot_parts;
 	     i = m_part_info->get_next_used_partition(i)) {
@@ -3275,12 +3265,7 @@ ha_innopart::info_low(
 
 	update_thd(ha_thd());
 
-	/* In case MySQL calls this in the middle of a SELECT query, release
-	possible adaptive hash latch to avoid deadlocks of threads. */
-
-	m_prebuilt->trx->op_info = (char*)"returning various info to MySQL";
-
-	trx_assert_no_search_latch(m_prebuilt->trx);
+	m_prebuilt->trx->op_info = "returning various info to MySQL";
 
 	ut_ad(m_part_share->get_table_part(0)->n_ref_count > 0);
 

storage/innobase/handler/handler0alter.cc

@@ -591,7 +591,6 @@ ha_innobase::check_if_supported_inplace_alter(
 	}
 
 	update_thd();
-	trx_assert_no_search_latch(m_prebuilt->trx);
 
 	/* Change on engine specific table options require rebuild of the
 	table */

storage/innobase/handler/i_s.cc

@@ -699,8 +699,7 @@ fill_innodb_trx_from_cache(
 
 #ifdef BTR_CUR_HASH_ADAPT
 		/* trx_adaptive_hash_latched */
-		OK(fields[IDX_TRX_ADAPTIVE_HASH_LATCHED]->store(
-			   row->trx_has_search_latch, true));
+		OK(fields[IDX_TRX_ADAPTIVE_HASH_LATCHED]->store(0, true));
 #endif /* BTR_CUR_HASH_ADAPT */
 
 		/* trx_is_read_only*/

storage/innobase/include/log0log.ic

@@ -1,6 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 1995, 2015, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 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 the Free Software
@@ -479,25 +480,24 @@ void
 log_free_check(void)
 /*================*/
 {
-#ifdef UNIV_DEBUG
 	/* During row_log_table_apply(), this function will be called while we
 	are holding some latches. This is OK, as long as we are not holding
 	any latches on buffer blocks. */
 
+#ifdef UNIV_DEBUG
 	static const latch_level_t latches[] = {
 		SYNC_DICT,		/* dict_sys->mutex during
 					commit_try_rebuild() */
 		SYNC_DICT_OPERATION,	/* dict_operation_lock X-latch during
 					commit_try_rebuild() */
 		SYNC_INDEX_TREE		/* index->lock */
 	};
-
-	sync_allowed_latches check(
-		latches, latches + sizeof(latches)/sizeof(*latches));
-
-        ut_ad(!sync_check_iterate(check));
 #endif /* UNIV_DEBUG */
 
+	ut_ad(!sync_check_iterate(
+		      sync_allowed_latches(latches,
+					   latches + UT_ARR_SIZE(latches))));
+
 	if (log_sys->check_flush_or_checkpoint) {
 
 		log_check_margins();

storage/innobase/include/sync0debug.h

@@ -1,7 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 2013, 2015, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2017, MariaDB Corporation. All Rights Reserved.
+Copyright (c) 2017, MariaDB Corporation.
 
 Portions of this file contain modifications contributed and copyrighted by
 Google, Inc. Those modifications are gratefully acknowledged and are described
@@ -84,10 +84,10 @@ sync_check_find(latch_level_t level);
 
 /** Checks that the level array for the current thread is empty.
 Terminate iteration if the functor returns true.
-@param[in,out]	 functor	called for each element.
-@return true if the functor returns true */
+@param[in]	 functor	called for each element.
+@return true if the functor returns true for any element */
 bool
-sync_check_iterate(sync_check_functor_t& functor);
+sync_check_iterate(const sync_check_functor_t& functor);
 
 /** Acquires the debug mutex. We cannot use the mutex defined in sync0sync,
 because the debug mutex is also acquired in sync0arr while holding the OS