Fix issue #18: slave crash on update with row based binary logging

Summary:
ha_rocksdb::position() should not return rowid of the last read row,
it should get the rowid of the record passed as parameter.

Differential Revision: https://reviews.facebook.net/D31983

fbshipit-source-id: 93a5004

mysql-test/suite/rocksdb/rpl_row_rocksdb.result

@@ -16,4 +16,19 @@ pk
 2
 3
 drop table t1;
+#
+# Issue #18: slave crash on update with row based binary logging
+#
+create table t1 (id int primary key, value int, value2 int, index(value)) engine=rocksdb;
+insert into t1 values (1,1,1);
+insert into t1 values (2,1,1);
+insert into t1 values (3,1,1);
+insert into t1 values (4,1,1);
+insert into t1 values (5,1,1);
+update t1 set value2=100 where id=1;
+include/sync_slave_sql_with_master.inc
+select * from t1 where id=1;
+id	value	value2
+1	1	100
+drop table t1;
 include/rpl_end.inc

mysql-test/suite/rocksdb/rpl_row_rocksdb.test

@@ -19,5 +19,23 @@ select * from t1;
 connection master;
 drop table t1;
 
+--echo #
+--echo # Issue #18: slave crash on update with row based binary logging
+--echo #
+create table t1 (id int primary key, value int, value2 int, index(value)) engine=rocksdb; 
+insert into t1 values (1,1,1); 
+insert into t1 values (2,1,1); 
+insert into t1 values (3,1,1); 
+insert into t1 values (4,1,1); 
+insert into t1 values (5,1,1); 
+update t1 set value2=100 where id=1;
+
+--source include/sync_slave_sql_with_master.inc
+connection slave;
+select * from t1 where id=1;
+
+connection master;
+drop table t1;
+
 --source include/rpl_end.inc
 

storage/rocksdb/ha_rocksdb.cc

@@ -3271,8 +3271,14 @@ int ha_rocksdb::info(uint flag)
 void ha_rocksdb::position(const uchar *record)
 {
   DBUG_ENTER("ha_rocksdb::position");
-
-  memcpy(ref, last_rowkey.ptr(), ref_length);
+  /*
+    Get packed primary key value from the record.
+    (Note: last_rowkey has the packed PK of last-read-row, which allows to
+    handle most cases, but there is an exception to this: when slave applies
+    RBR events, it fills the record and then calls position(); rnd_pos())
+  */
+  pk_descr->pack_record(table, pack_buffer, record, ref,
+                        NULL, NULL);
   DBUG_VOID_RETURN;
 }