MyRocks: Flush memtables on clean shutdown (facebook#127)

Summary:
On clean shutdown, memtables were not flushed. This caused
data loss, if WAL was disabled. This diff flushes all
memtables before calling CancelAllBackgroundWork().

Differential Revision: https://reviews.facebook.net/D52257

mysql-test/suite/rocksdb/r/insert_optimized_config.result

@@ -0,0 +1,16 @@
+DROP TABLE IF EXISTS t1;
+create table t1(
+id bigint not null primary key,
+i1 bigint, #unique
+i2 bigint, #repeating
+c1 varchar(20), #unique
+c2 varchar(20), #repeating
+index t1_2(i1)
+) engine=rocksdb;
+select count(*), sum(id), sum(i1), sum(i2) from t1;
+count(*)	sum(id)	sum(i1)	sum(i2)
+50000	1250025000	1250025000	124980000
+select count(*), sum(id), sum(i1), sum(i2) from t1;
+count(*)	sum(id)	sum(i1)	sum(i2)
+50000	1250025000	1250025000	124980000
+drop table t1;

mysql-test/suite/rocksdb/t/insert_optimized_config-master.opt

@@ -0,0 +1,6 @@
+--rocksdb_write_disable_wal=1
+--rocksdb_default_cf_options=write_buffer_size=16k;target_file_size_base=16k;level0_file_num_compaction_trigger=4;level0_slowdown_writes_trigger=256;level0_stop_writes_trigger=256;max_write_buffer_number=16;compression_per_level=kNoCompression;memtable=vector:1024
+--rocksdb_override_cf_options=__system__={memtable=skip_list:16}
+--rocksdb_compaction_sequential_deletes=0
+--rocksdb_compaction_sequential_deletes_window=0
+

mysql-test/suite/rocksdb/t/insert_optimized_config.test

@@ -0,0 +1,41 @@
+--source include/have_rocksdb.inc
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+create table t1(
+       id bigint not null primary key,
+       i1 bigint, #unique
+       i2 bigint, #repeating
+       c1 varchar(20), #unique
+       c2 varchar(20), #repeating
+       index t1_2(i1)
+) engine=rocksdb;
+
+--disable_query_log
+set rocksdb_bulk_load=1;
+let $i=0;
+while ($i<50000)
+{
+  inc $i;
+  eval insert t1(id, i1, i2, c1, c2) values($i, $i, $i div 10, $i, $i div 10);
+}
+set rocksdb_bulk_load=0;
+--enable_query_log
+
+select count(*), sum(id), sum(i1), sum(i2) from t1;
+
+# reload without load optimized config
+let $restart_file= $MYSQLTEST_VARDIR/tmp/mysqld.1.expect;
+--exec echo "wait" > $restart_file
+--shutdown_server 10
+--source include/wait_until_disconnected.inc
+-- exec echo "restart:--rocksdb_write_disable_wal=0 --rocksdb_default_cf_options=write_buffer_size=64k;target_file_size_base=64k;max_bytes_for_level_base=1m;compression_per_level=kNoCompression;" > $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+-- enable_reconnect
+-- source include/wait_until_connected_again.inc
+
+select count(*), sum(id), sum(i1), sum(i2) from t1;
+
+drop table t1;
+

storage/rocksdb/ha_rocksdb.cc

@@ -148,6 +148,15 @@ background_thread_control bg_control;
 // collation check requirement.
 std::vector<std::string> collation_exception_list;
 
+static void
+rocksdb_flush_all_memtables()
+{
+  Column_family_manager& cf_manager = rocksdb_get_cf_manager();
+  for (auto cf_handle : cf_manager.get_all_cf()) {
+    rdb->Flush(rocksdb::FlushOptions(), cf_handle);
+  }
+}
+
 static void
 rocksdb_compact_column_family(THD* thd,
                               struct st_mysql_sys_var* var,
@@ -232,10 +241,7 @@ rocksdb_force_flush_memtable_now(THD* thd,
                                  const void* save)
 {
   sql_print_information("RocksDB: Manual memtable flush\n");
-  Column_family_manager& cf_manager = rocksdb_get_cf_manager();
-  for (auto cf_handle : cf_manager.get_all_cf()) {
-    rdb->Flush(rocksdb::FlushOptions(), cf_handle);
-  }
+  rocksdb_flush_all_memtables();
 }
 
 static void
@@ -2419,6 +2425,9 @@ static int rocksdb_done_func(void *p)
   // signal the drop index thread to stop
   signal_drop_index_thread(true);
 
+  // Flush all memtables for not lose data, even if WAL is disabled.
+  rocksdb_flush_all_memtables();
+
   // Stop all rocksdb background work
   CancelAllBackgroundWork(rdb->GetBaseDB(), true);