MDEV-34122: Regression

In between the binlogging of a transaction and its wait, it is
possible that its entry in Active_tranx was removed if semi-sync was
switched off and on. This fires an assertion that checks before
awaiting an ACK that the entry must exist in Active_tranx.

mysql-test/suite/rpl/r/rpl_semi_sync_cond_var_per_thd.result

@@ -32,4 +32,57 @@ set @@global.binlog_commit_wait_count=@save_bgc_count;
 set @@global.binlog_commit_wait_usec=@save_bgc_usec;
 set @@global.debug_dbug=@save_debug_dbug;
 drop table t1, t2, t3;
+#
+# MDEV-34122
+# If semi-sync is switched off then on while a transaction is
+# in-between binlogging and waiting for an ACK, ensure that the
+# transaction skips the wait altogether (otherwise it would time-out).
+# Note that prior to MDEV-34122, there was a debug assertion that would
+# trigger if the transaction tried to wait but could not receive an ACK
+# signal.
+#
+# MDEV-34122.a: Test wait_point = AFTER_SYNC
+# Here, debug_sync is used to pause the leader thread between reporting
+# the binlogging to semi-sync, and starting the wait for ACK; and during
+# this pause, semi-sync is manually switched off and on.
+# Waiting for semi-sync to turn on..
+connection slave;
+connection master;
+set @old_master_wait_point= @@global.rpl_semi_sync_master_wait_point;
+set @@global.rpl_semi_sync_master_wait_point= AFTER_SYNC;
+create table t (a int) engine=innodb;
+connection slave;
+connection server_1;
+start transaction;
+insert into t values (0);
+set debug_sync= "commit_after_release_LOCK_log SIGNAL trx_binlogged WAIT_FOR continue_commit";
+commit;
+connection master;
+set debug_sync= "now WAIT_FOR trx_binlogged";
+# Switching semi-sync off/on
+set @@global.rpl_semi_sync_master_enabled= 0;
+set @@global.rpl_semi_sync_master_enabled= 1;
+# Resuming transaction to await ACK
+set debug_sync= "now SIGNAL continue_commit";
+connection server_1;
+# Cleanup
+connection master;
+drop table t;
+#
+# MDEV-34122.b: Test wait_point = AFTER_COMMIT
+# Here, use a transaction with a non-transactional statement to write to
+# the binlog directly, and turn off/on semi-sync before committing the
+# transaction.
+connection master;
+set @@global.rpl_semi_sync_master_wait_point= AFTER_COMMIT;
+create table tn (a int) engine=Aria;
+start transaction;
+insert into tn values (NULL);
+set @@global.rpl_semi_sync_master_enabled= 0;
+set @@global.rpl_semi_sync_master_enabled= 1;
+commit;
+# Cleanup
+connection master;
+drop table tn;
+set @@global.rpl_semi_sync_master_wait_point= @old_master_wait_point;
 include/rpl_end.inc

mysql-test/suite/rpl/t/rpl_semi_sync_cond_var_per_thd.test

@@ -19,9 +19,12 @@
 # References:
 #   MDEV-33551: Semi-sync Wait Point AFTER_COMMIT Slow on Workloads with Heavy
 #               Concurrency
+#   MDEV-34122: Assertion `entry' failed in Active_tranx::assert_thd_is_waiter
 #
 --source include/have_binlog_format_row.inc
+--source include/have_innodb.inc
 --source include/have_debug.inc
+--source include/have_debug_sync.inc
 --source include/master-slave.inc
 
 --connection master
@@ -77,4 +80,84 @@ set @@global.binlog_commit_wait_usec=@save_bgc_usec;
 set @@global.debug_dbug=@save_debug_dbug;
 drop table t1, t2, t3;
 
+
+--echo #
+--echo # MDEV-34122
+--echo # If semi-sync is switched off then on while a transaction is
+--echo # in-between binlogging and waiting for an ACK, ensure that the
+--echo # transaction skips the wait altogether (otherwise it would time-out).
+--echo # Note that prior to MDEV-34122, there was a debug assertion that would
+--echo # trigger if the transaction tried to wait but could not receive an ACK
+--echo # signal.
+
+--echo #
+--echo # MDEV-34122.a: Test wait_point = AFTER_SYNC
+--echo # Here, debug_sync is used to pause the leader thread between reporting
+--echo # the binlogging to semi-sync, and starting the wait for ACK; and during
+--echo # this pause, semi-sync is manually switched off and on.
+
+--echo # Waiting for semi-sync to turn on..
+--connection slave
+let $status_var= rpl_semi_sync_slave_status;
+let $status_var_value= ON;
+source include/wait_for_status_var.inc;
+
+--connection master
+set @old_master_wait_point= @@global.rpl_semi_sync_master_wait_point;
+set @@global.rpl_semi_sync_master_wait_point= AFTER_SYNC;
+let $status_var= rpl_semi_sync_master_status;
+let $status_var_value= ON;
+source include/wait_for_status_var.inc;
+
+create table t (a int) engine=innodb;
+--sync_slave_with_master
+
+--connection server_1
+start transaction;
+insert into t values (0);
+set debug_sync= "commit_after_release_LOCK_log SIGNAL trx_binlogged WAIT_FOR continue_commit";
+--send commit
+
+--connection master
+set debug_sync= "now WAIT_FOR trx_binlogged";
+
+--echo # Switching semi-sync off/on
+set @@global.rpl_semi_sync_master_enabled= 0;
+set @@global.rpl_semi_sync_master_enabled= 1;
+let $status_var= rpl_semi_sync_master_status;
+let $status_var_value= ON;
+source include/wait_for_status_var.inc;
+
+--echo # Resuming transaction to await ACK
+set debug_sync= "now SIGNAL continue_commit";
+
+--connection server_1
+--reap
+
+--echo # Cleanup
+--connection master
+drop table t;
+
+
+--echo #
+--echo # MDEV-34122.b: Test wait_point = AFTER_COMMIT
+--echo # Here, use a transaction with a non-transactional statement to write to
+--echo # the binlog directly, and turn off/on semi-sync before committing the
+--echo # transaction.
+
+--connection master
+set @@global.rpl_semi_sync_master_wait_point= AFTER_COMMIT;
+
+create table tn (a int) engine=Aria;
+start transaction;
+insert into tn values (NULL);
+set @@global.rpl_semi_sync_master_enabled= 0;
+set @@global.rpl_semi_sync_master_enabled= 1;
+commit;
+
+--echo # Cleanup
+--connection master
+drop table tn;
+set @@global.rpl_semi_sync_master_wait_point= @old_master_wait_point;
+
 --source include/rpl_end.inc