ha_innodb.cc:

  Fix a possible hang at the adaptive hash index latch if MySQL does query estimations also in the middle of a SELECT statement processing


sql/ha_innodb.cc:
  Fix a possible hang at the adaptive hash index latch if MySQL does query estimations also in the middle of a SELECT statement processing

sql/ha_innodb.cc

@@ -2994,6 +2994,7 @@ ha_innobase::create(
 {
 	int		error;
 	dict_table_t*	innobase_table;
+	trx_t*		parent_trx;
 	trx_t*		trx;
 	int		primary_key_no;
 	uint		i;
@@ -3005,6 +3006,16 @@ ha_innobase::create(
 
 	DBUG_ASSERT(thd != NULL);
 
+	/* Get the transaction associated with the current thd, or create one
+	if not yet created */
+	
+	parent_trx = check_trx_exists(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_search_latch_release_if_reserved(parent_trx);	
+	
 	trx = trx_allocate_for_mysql();
 
 	if (thd->options & OPTION_NO_FOREIGN_KEY_CHECKS) {
@@ -3165,11 +3176,22 @@ ha_innobase::delete_table(
 {
 	ulint	name_len;
 	int	error;
+	trx_t*	parent_trx;
 	trx_t*	trx;
 	char	norm_name[1000];
 
   	DBUG_ENTER("ha_innobase::delete_table");
 
+	/* Get the transaction associated with the current thd, or create one
+	if not yet created */
+	
+	parent_trx = check_trx_exists(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_search_latch_release_if_reserved(parent_trx);	
+
 	if (lower_case_table_names) {
 		srv_lower_case_table_names = TRUE;
 	} else {
@@ -3224,11 +3246,22 @@ innobase_drop_database(
 			the database name is 'test' */
 {
 	ulint	len		= 0;
+	trx_t*	parent_trx;
 	trx_t*	trx;
 	char*	ptr;
 	int	error;
 	char	namebuf[10000];
 
+	/* Get the transaction associated with the current thd, or create one
+	if not yet created */
+	
+	parent_trx = check_trx_exists(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_search_latch_release_if_reserved(parent_trx);	
+
 	ptr = strend(path) - 2;
 
 	while (ptr >= path && *ptr != '\\' && *ptr != '/') {
@@ -3280,12 +3313,23 @@ ha_innobase::rename_table(
 	ulint	name_len1;
 	ulint	name_len2;
 	int	error;
+	trx_t*	parent_trx;
 	trx_t*	trx;
 	char	norm_from[1000];
 	char	norm_to[1000];
 
   	DBUG_ENTER("ha_innobase::rename_table");
 
+	/* Get the transaction associated with the current thd, or create one
+	if not yet created */
+	
+	parent_trx = check_trx_exists(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_search_latch_release_if_reserved(parent_trx);	
+
 	if (lower_case_table_names) {
 		srv_lower_case_table_names = TRUE;
 	} else {
@@ -3332,8 +3376,8 @@ Estimates the number of index records in a range. */
 ha_rows
 ha_innobase::records_in_range(
 /*==========================*/
-						/* out: estimated number of rows,
-						currently 32-bit int or uint */
+						/* out: estimated number of
+						rows */
 	int 			keynr,		/* in: index number */
 	const mysql_byte*	start_key,	/* in: start key value of the
 						range, may also be empty */
@@ -3364,9 +3408,16 @@ ha_innobase::records_in_range(
 
    	DBUG_ENTER("records_in_range");
 
-	/* Warning: since it is not sure that MySQL calls external_lock
-	before calling this function, the trx field in prebuilt can be
-	obsolete! */
+	/* We do not know if MySQL can call this function before calling
+	external_lock(). To be safe, update the thd of the current table
+	handle. */
+
+	update_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_search_latch_release_if_reserved(prebuilt->trx);
 
 	active_index = keynr;
 
@@ -3420,12 +3471,19 @@ ha_innobase::estimate_number_of_rows(void)
 	ulonglong	estimate;
 	ulonglong	local_data_file_length;
 
-	/* Warning: since it is not sure that MySQL calls external_lock
-	before calling this function, the trx field in prebuilt can be
-	obsolete! */
-
  	DBUG_ENTER("info");
 
+	/* We do not know if MySQL can call this function before calling
+	external_lock(). To be safe, update the thd of the current table
+	handle. */
+
+	update_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_search_latch_release_if_reserved(prebuilt->trx);
+
 	index = dict_table_get_first_index_noninline(prebuilt->table);
 
 	local_data_file_length = ((ulonglong) index->stat_n_leaf_pages)
@@ -3489,9 +3547,16 @@ ha_innobase::info(
                 return;
         }
 
-	/* Warning: since it is not sure that MySQL calls external_lock
-	before calling this function, the trx field in prebuilt can be
-	obsolete! */
+	/* We do not know if MySQL can call this function before calling
+	external_lock(). To be safe, update the thd of the current table
+	handle. */
+
+	update_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_search_latch_release_if_reserved(prebuilt->trx);
 
  	ib_table = prebuilt->table;
 
@@ -3559,12 +3624,6 @@ ha_innobase::info(
 		}
 	}
 
-	/* The trx struct in InnoDB contains a pthread mutex embedded:
-	in the debug version of MySQL that it replaced by a 'safe mutex'
-	which is of a different size. We have to use a function to access
-	trx fields. Otherwise trx->error_info will be a random
-	pointer and cause a seg fault. */
-
   	if (flag & HA_STATUS_ERRKEY) {
 		ut_a(prebuilt->trx && prebuilt->trx->magic_n == TRX_MAGIC_N);
 
@@ -3630,9 +3689,16 @@ ha_innobase::update_table_comment(
   	char*		str 	= my_malloc(length + 16500, MYF(0));
   	char*		pos;
 
-	/* Warning: since it is not sure that MySQL calls external_lock
-	before calling this function, the trx field in prebuilt can be
-	obsolete! */
+	/* We do not know if MySQL can call this function before calling
+	external_lock(). To be safe, update the thd of the current table
+	handle. */
+
+	update_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_search_latch_release_if_reserved(prebuilt->trx);
    	
 	if (!str) {
     		return((char*)comment);
@@ -3674,6 +3740,17 @@ ha_innobase::get_foreign_key_create_info(void)
 	row_prebuilt_t* prebuilt = (row_prebuilt_t*)innobase_prebuilt;
 	char*	str;
 
+	/* We do not know if MySQL can call this function before calling
+	external_lock(). To be safe, update the thd of the current table
+	handle. */
+
+	update_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_search_latch_release_if_reserved(prebuilt->trx);
+	
 	if (prebuilt == NULL) {
 		fprintf(stderr,
 "InnoDB: Error: cannot get create info for foreign keys\n");
@@ -3752,9 +3829,10 @@ ha_innobase::reset(void)
 }
 
 /**********************************************************************
-When we create a temporary table inside MySQL LOCK TABLES, MySQL will
-not call external_lock for the temporary table when it uses it. Instead,
-it will call this function. */
+Inside LOCK TABLES MySQL will not call external_lock() between SQL
+statements. It will call this function at the start of each SQL statement.
+Note also a spacial case: if a temporary table is created inside LOCK
+TABLES, MySQL has not called external_lock() at all on that table. */
 
 int
 ha_innobase::start_stmt(
@@ -3892,8 +3970,8 @@ ha_innobase::external_lock(
 
 		  	trx->mysql_n_tables_locked = 0;
 
-			/* Here we release the search latch, auto_inc_lock,
-			and InnoDB thread FIFO ticket if they were reserved. */
+			/* Here we release the search latch and InnoDB
+			thread FIFO ticket if they were reserved. */
 
 			innobase_release_stat_resources(trx);