Bug #32709: Assertion failed: trx_data->empty(), file log.cc

The assertion indicates that some data was left in the transaction
cache when the server was shut down, which means that a previous
statement did not commit or rollback correctly.

What happened was that a bug in the rollback of a transactional
table caused the transaction cache to be emptied, but not reset.
The error can be triggered by having a failing UPDATE or INSERT,
on a transactional table, causing an implicit rollback.

Fixed by always flushing the pending event to reset the state
properly.


mysql-test/extra/rpl_tests/rpl_row_basic.test:
  Testing that a failed update (that writes some rows to the
  transaction cache) does not cause the transaction cache to
  hold on to the data or forget to reset the transaction cache.
sql/log.cc:
  Added call to remove pending event when the transaction cache
  is emptied instead of written to binary log. The call will also
  clear the outstanding table map count so that the cache is not
  left it in a state of "empty but not reset".
  
  Added function MYSQL_BIN_LOG::remove_pending_rows_event().
sql/log.h:
  Added function MYSQL_BIN_LOG::remove_pending_rows_event().
sql/sql_class.cc:
  Adding function THD::binlog_remove_pending_rows_event().
sql/sql_class.h:
  Adding function THD::binlog_remove_pending_rows_event().

mysql-test/extra/rpl_tests/rpl_row_basic.test

@@ -451,3 +451,23 @@ connection master;
 drop table t1, t2, t3, t4, t5, t6, t7;
 sync_slave_with_master;
 
+#
+# BUG#32709: Assertion failed: trx_data->empty(), file .\log.cc, line 1293
+#
+
+connection master;
+eval CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=$type;
+
+INSERT INTO t1 VALUES (1), (2), (3);
+--error ER_DUP_ENTRY
+UPDATE t1 SET a = 10;
+INSERT INTO t1 VALUES (4);
+sync_slave_with_master;
+
+let $diff_table_1=master:test.t1;
+let $diff_table_2=slave:test.t1;
+source include/diff_tables.inc;
+
+connection master;
+drop table t1;
+sync_slave_with_master;

mysql-test/suite/rpl/r/rpl_row_basic_2myisam.result

@@ -520,3 +520,10 @@ INSERT INTO t7 VALUES (1, "", 1);
 INSERT INTO t7 VALUES (2, repeat(_utf8'a', 255), 2);
 Comparing tables master:test.t7 and slave:test.t7
 drop table t1, t2, t3, t4, t5, t6, t7;
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE='MYISAM' ;
+INSERT INTO t1 VALUES (1), (2), (3);
+UPDATE t1 SET a = 10;
+ERROR 23000: Duplicate entry '10' for key 'PRIMARY'
+INSERT INTO t1 VALUES (4);
+Comparing tables master:test.t1 and slave:test.t1
+drop table t1;

mysql-test/suite/rpl/r/rpl_row_basic_3innodb.result

@@ -520,3 +520,10 @@ INSERT INTO t7 VALUES (1, "", 1);
 INSERT INTO t7 VALUES (2, repeat(_utf8'a', 255), 2);
 Comparing tables master:test.t7 and slave:test.t7
 drop table t1, t2, t3, t4, t5, t6, t7;
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE='INNODB' ;
+INSERT INTO t1 VALUES (1), (2), (3);
+UPDATE t1 SET a = 10;
+ERROR 23000: Duplicate entry '10' for key 'PRIMARY'
+INSERT INTO t1 VALUES (4);
+Comparing tables master:test.t1 and slave:test.t1
+drop table t1;

sql/log.cc

@@ -1421,6 +1421,7 @@ binlog_end_trans(THD *thd, binlog_trx_data *trx_data,
       If rolling back a statement in a transaction, we truncate the
       transaction cache to remove the statement.
      */
+    thd->binlog_remove_pending_rows_event(TRUE);
     if (all || !(thd->options & (OPTION_BEGIN | OPTION_NOT_AUTOCOMMIT)))
       trx_data->reset();
     else                                        // ...statement
@@ -3769,6 +3770,31 @@ THD::binlog_set_pending_rows_event(Rows_log_event* ev)
 }
 
 
+/**
+  Remove the pending rows event, discarding any outstanding rows.
+
+  If there is no pending rows event available, this is effectively a
+  no-op.
+ */
+int
+MYSQL_BIN_LOG::remove_pending_rows_event(THD *thd)
+{
+  DBUG_ENTER(__FUNCTION__);
+
+  binlog_trx_data *const trx_data=
+    (binlog_trx_data*) thd_get_ha_data(thd, binlog_hton);
+
+  DBUG_ASSERT(trx_data);
+
+  if (Rows_log_event* pending= trx_data->pending())
+  {
+    delete pending;
+    trx_data->set_pending(NULL);
+  }
+
+  DBUG_RETURN(0);
+}
+
 /*
   Moves the last bunch of rows from the pending Rows event to the binlog
   (either cached binlog if transaction, or disk binlog). Sets a new pending

sql/log.h

@@ -307,6 +307,7 @@ public:
   void update_table_map_version() { ++m_table_map_version; }
 
   int flush_and_set_pending_rows_event(THD *thd, Rows_log_event* event);
+  int remove_pending_rows_event(THD *thd);
 
 #endif /* !defined(MYSQL_CLIENT) */
   void reset_bytes_written()

sql/sql_class.cc

@@ -3502,6 +3502,21 @@ int THD::binlog_delete_row(TABLE* table, bool is_trans,
 }
 
 
+int THD::binlog_remove_pending_rows_event(bool clear_maps)
+{
+  DBUG_ENTER(__FUNCTION__);
+
+  if (!mysql_bin_log.is_open())
+    DBUG_RETURN(0);
+
+  mysql_bin_log.remove_pending_rows_event(this);
+
+  if (clear_maps)
+    binlog_table_maps= 0;
+
+  DBUG_RETURN(0);
+}
+
 int THD::binlog_flush_pending_rows_event(bool stmt_end)
 {
   DBUG_ENTER("THD::binlog_flush_pending_rows_event");

sql/sql_class.h

@@ -1360,6 +1360,7 @@ public:
   Rows_log_event* binlog_get_pending_rows_event() const;
   void            binlog_set_pending_rows_event(Rows_log_event* ev);
   int binlog_flush_pending_rows_event(bool stmt_end);
+  int binlog_remove_pending_rows_event(bool clear_maps);
 
 private:
   uint binlog_table_maps; // Number of table maps currently in the binlog