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--source include/have_innodb.inc
--source include/have_debug_sync.inc
--source include/count_sessions.inc
--connect(cancel_purge,localhost,root,,)
# Purge can cause deadlock in the test, requesting page's RW_X_LATCH for trx
# ids reseting, after trx 2 acqured RW_S_LATCH and suspended in debug sync point
# lock_trx_handle_wait_enter, waiting for upd_cont signal, which must be
# emitted after the last SELECT in this test. The last SELECT will hang waiting
# for purge RW_X_LATCH releasing, and trx 2 will be rolled back by timeout.
# The last SELECT will then be successfully executed instead of finishing by
# lock wait timeout.
START TRANSACTION WITH CONSISTENT SNAPSHOT;
--connection default
CREATE TABLE t (a int PRIMARY KEY, b int) engine = InnoDB;
CREATE TABLE t2 (a int PRIMARY KEY) engine = InnoDB;
INSERT INTO t VALUES (10, 10), (20, 20), (30, 30);
INSERT INTO t2 VALUES (10), (20), (30);
BEGIN; # trx 1
SELECT * FROM t WHERE a = 20 FOR UPDATE;
# Locking order:
# (10,10) (20,20) (30,30)
# ^
# trx 1
--connect(con_2,localhost,root,,)
# RC is neccessary to do semi-consistent read
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
BEGIN; # trx 2
# The first time it will be hit on trying to lock (20,20), the second hit
# will be on (30,30).
SET DEBUG_SYNC = 'lock_trx_handle_wait_enter SIGNAL upd_locked WAIT_FOR upd_cont EXECUTE 2';
# We must not modify primary key fields to cause rr_sequential() read record
# function choosing in mysql_update(), i.e. both query_plan.using_filesort and
# query_plan.using_io_buffer must be false during init_read_record() call.
--send UPDATE t SET b = 100
--connect(con_3,localhost,root,,)
BEGIN; # trx 3
# The following update is necessary to increase the transaction weight, which is
# calculated as the number of locks + the number of undo records during deadlock
# report. Victim's transaction should have minimum weight. We need trx 2 to be
# choosen as victim, that's why we need to increase the current transaction
# weight.
UPDATE t2 SET a = a + 100;
SELECT * FROM t WHERE a = 30 FOR UPDATE;
SET DEBUG_SYNC='now WAIT_FOR upd_locked';
# Locking queue:
# (10,10) (20,20) (30,30)
# ^ ^ ^
# trx 2 trx 1 trx 3
# trx 2 (waiting for 1)
SET DEBUG_SYNC = 'lock_wait_start SIGNAL sel_locked';
--send SELECT * FROM t WHERE a = 20 FOR UPDATE
--connection default
SET DEBUG_SYNC='now WAIT_FOR sel_locked';
# Locking queue:
# (10,10) (20,20) (30,30)
# ^ ^ ^
# trx 2 trx 1 trx 3
# trx 2 (waiting for 1)
# trx 3 (waiting for 1)
#
# Note trx 1 must grant lock to trx2 before trx 2 checks the lock state in
# lock_trx_handle_wait(), i.e. the function must return DB_SUCCESS, that's why
# the following ROLLBACK must be executed before sending upd_cont signal.
ROLLBACK;
SET DEBUG_SYNC='now SIGNAL upd_cont';
SET DEBUG_SYNC="now WAIT_FOR upd_locked";
# Locking queue:
# (10,10) (20,20) (30,30)
# ^ ^ ^
# trx 2 trx 2 trx 3
# trx 3 (waiting for 2) trx 2 (waiting for 3)
#
# Deadlock happened after trx 1 granted lock to trx 2, and trx2 continued
# sequential read (with rr_sequential() read record function), and requested
# lock on (30,30). But the deadlock has not been determined yet.
SET SESSION innodb_lock_wait_timeout=1;
--error ER_LOCK_WAIT_TIMEOUT
# The deadlock will be determined in lock_wait() after lock wait timeout
# expired.
SELECT * FROM t WHERE a = 10 FOR UPDATE;
SET DEBUG_SYNC="now SIGNAL upd_cont";
--connection con_3
--reap
--connection con_2
# As lock_trx_handle_wait() wrongly returned DB_SUCCESS instead of
# DB_DEADLOCK, row_search_mvcc() of trx 2 behaves so as if (30,30) was locked.
# But the waiting(for trx 3) lock was cancelled by deadlock checker after
# trx 2 was choosen as a victim (see lock_cancel_waiting_and_release() call
# from Deadlock::report() for details). The try to update non-locked record
# will cause assertion if the bug is not fixed.
--error ER_LOCK_DEADLOCK
--reap
--disconnect con_3
--disconnect con_2
--connection default
SET DEBUG_SYNC = 'RESET';
DROP TABLE t;
DROP TABLE t2;
--disconnect cancel_purge
--source include/wait_until_count_sessions.inc
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