Bug #31310404 I_S_FTS_INDEX_CACHE_FILL_ONE_INDEX() IS NOT PROTECTED

BY THE LOCK

Problem:
FTS SYNC write data from fts index cache to the FTS auxiliary index
table and clear the cache (word by word) at the end.
when FTS SYNC thread is freeing a word, if at the same time, user
read from INFORMATION_SCHEMA.INNODB_FT_INDEX_CACHE. then we may try
read a word from the cache which has been freed.

Fix:
Before start filling INFORMATION_SCHEMA.INNODB_FT_INDEX_CACHE table,
if FTS SYNC is in progress then we will wait for SYNC to finish.

RB: 25079
Reviewed by : Rahul Agarkar <[email protected]>

Author: sachinagarwal1111

mysql-test/suite/innodb_fts/r/sync.result

@@ -13,15 +13,16 @@ SET DEBUG_SYNC= 'now WAIT_FOR written';
 SET GLOBAL innodb_ft_aux_table="test/t1";
 SELECT * FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_CACHE;
 WORD	FIRST_DOC_ID	LAST_DOC_ID	DOC_COUNT	DOC_ID	POSITION
+SELECT * FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_TABLE;
+WORD	FIRST_DOC_ID	LAST_DOC_ID	DOC_COUNT	DOC_ID	POSITION
 database	2	3	2	2	0
 database	2	3	2	3	6
 mysql	1	3	2	1	0
 mysql	1	3	2	3	0
-SELECT * FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_TABLE;
-WORD	FIRST_DOC_ID	LAST_DOC_ID	DOC_COUNT	DOC_ID	POSITION
 SET GLOBAL innodb_ft_aux_table=default;
 SELECT * FROM t1 WHERE MATCH(title) AGAINST('mysql database');
 FTS_DOC_ID	title
+3	mysql database
 1	mysql
 2	database
 SET DEBUG_SYNC= 'now SIGNAL selected';
@@ -130,3 +131,32 @@ id	title
 2	database
 3	good
 DROP TABLE t1;
+#
+# Bug #31310404 I_S_FTS_INDEX_CACHE_FILL_ONE_INDEX() IS NOT PROTECT BY THE LOCK
+#
+CREATE TABLE t1 (
+FTS_DOC_ID BIGINT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
+title VARCHAR(200),
+FULLTEXT(title)
+) ENGINE = InnoDB;
+INSERT INTO t1(title) VALUES('mysql');
+INSERT INTO t1(title) VALUES('database');
+SET SESSION debug="+d,fts_instrument_sync_request";
+INSERT INTO t1(title) VALUES('mysql database');
+SET SESSION debug="-d,fts_instrument_sync_request";
+SET GLOBAL innodb_ft_aux_table="test/t1";
+SELECT * FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_CACHE;
+WORD	FIRST_DOC_ID	LAST_DOC_ID	DOC_COUNT	DOC_ID	POSITION
+SELECT * FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_TABLE;
+WORD	FIRST_DOC_ID	LAST_DOC_ID	DOC_COUNT	DOC_ID	POSITION
+database	2	3	2	2	0
+database	2	3	2	3	6
+mysql	1	3	2	1	0
+mysql	1	3	2	3	0
+SET GLOBAL innodb_ft_aux_table=default;
+SELECT * FROM t1 WHERE MATCH(title) AGAINST('mysql database');
+FTS_DOC_ID	title
+3	mysql database
+1	mysql
+2	database
+DROP TABLE t1;

mysql-test/suite/innodb_fts/t/sync.test

@@ -168,3 +168,31 @@ SELECT * FROM t1 WHERE MATCH(title) AGAINST ('mysql database good');
 DROP TABLE t1;
 
 --source include/wait_until_count_sessions.inc
+
+--echo #
+--echo # Bug #31310404 I_S_FTS_INDEX_CACHE_FILL_ONE_INDEX() IS NOT PROTECT BY THE LOCK
+--echo #
+
+CREATE TABLE t1 (
+        FTS_DOC_ID BIGINT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
+        title VARCHAR(200),
+        FULLTEXT(title)
+) ENGINE = InnoDB;
+
+INSERT INTO t1(title) VALUES('mysql');
+INSERT INTO t1(title) VALUES('database');
+
+SET SESSION debug="+d,fts_instrument_sync_request";
+INSERT INTO t1(title) VALUES('mysql database');
+SET SESSION debug="-d,fts_instrument_sync_request";
+
+SET GLOBAL innodb_ft_aux_table="test/t1";
+
+# If FTS SYNC is in progress then wait for SYNC to finish.
+SELECT * FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_CACHE;
+SELECT * FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_TABLE;
+SET GLOBAL innodb_ft_aux_table=default;
+
+SELECT * FROM t1 WHERE MATCH(title) AGAINST('mysql database');
+
+DROP TABLE t1;

storage/innobase/handler/i_s.cc

@@ -3474,6 +3474,11 @@ i_s_fts_index_cache_fill(
 
 	ut_a(cache);
 
+	/* Check if cache is being synced.
+	Note: we wait till cache is being synced. */
+	while (cache->sync->in_progress) {
+		os_event_wait(cache->sync->event);
+	}
 	for (ulint i = 0; i < ib_vector_size(cache->indexes); i++) {
 		fts_index_cache_t*      index_cache;