Add avoid_flush_during_shutdown DB option

Summary:
Add avoid_flush_during_shutdown DB option.
Closes https://github.com/facebook/rocksdb/pull/1451

Differential Revision: D4108643

Pulled By: yiwu-arbug

fbshipit-source-id: abdaf4d

HISTORY.md

@@ -3,6 +3,9 @@
 ### Public API Change
 * Options::max_bytes_for_level_multiplier is now a double along with all getters and setters.
 
+### New Features
+* Add avoid_flush_during_shutdown option, which speeds up DB shutdown by not flushing unpersisted data (i.e. with disableWAL = true). Unpersisted data will be lost. The options is dynamically changeable.
+
 ## 4.13.0 (10/18/2016)
 ### Public API Change
 * DB::GetOptions() reflect dynamic changed options (i.e. through DB::SetOptions()) and return copy of options instead of reference.

db/db_impl.cc

@@ -375,7 +375,8 @@ void DBImpl::CancelAllBackgroundWork(bool wait) {
   InstrumentedMutexLock l(&mutex_);
 
   if (!shutting_down_.load(std::memory_order_acquire) &&
-      has_unpersisted_data_) {
+      has_unpersisted_data_ &&
+      !mutable_db_options_.avoid_flush_during_shutdown) {
     for (auto cfd : *versions_->GetColumnFamilySet()) {
       if (!cfd->IsDropped() && !cfd->mem()->IsEmpty()) {
         cfd->Ref();

db/db_options_test.cc

@@ -256,6 +256,28 @@ TEST_F(DBOptionsTest, SetBackgroundCompactionThreads) {
   ASSERT_EQ(3, dbfull()->TEST_BGCompactionsAllowed());
 }
 
+TEST_F(DBOptionsTest, AvoidFlushDuringShutdown) {
+  Options options;
+  options.create_if_missing = true;
+  options.disable_auto_compactions = true;
+  WriteOptions write_without_wal;
+  write_without_wal.disableWAL = true;
+
+  ASSERT_FALSE(options.avoid_flush_during_shutdown);
+  DestroyAndReopen(options);
+  ASSERT_OK(Put("foo", "v1", write_without_wal));
+  Reopen(options);
+  ASSERT_EQ("v1", Get("foo"));
+  ASSERT_EQ("1", FilesPerLevel());
+
+  DestroyAndReopen(options);
+  ASSERT_OK(Put("foo", "v2", write_without_wal));
+  ASSERT_OK(dbfull()->SetDBOptions({{"avoid_flush_during_shutdown", "true"}}));
+  Reopen(options);
+  ASSERT_EQ("NOT_FOUND", Get("foo"));
+  ASSERT_EQ("", FilesPerLevel());
+}
+
 #endif  // ROCKSDB_LITE
 
 }  // namespace rocksdb

include/rocksdb/options.h

@@ -1354,6 +1354,15 @@ struct DBOptions {
   //
   // DEFAULT: false
   bool avoid_flush_during_recovery;
+
+  // By default RocksDB will flush all memtables on DB close if there are
+  // unpersisted data (i.e. with WAL disabled) The flush can be skip to speedup
+  // DB close. Unpersisted data WILL BE LOST.
+  //
+  // DEFAULT: false
+  //
+  // Dynamically changeable through SetDBOptions() API.
+  bool avoid_flush_during_shutdown;
 };
 
 // Options to control the behavior of a database (passed to DB::Open)

util/db_options.cc

@@ -224,17 +224,22 @@ void ImmutableDBOptions::Dump(Logger* log) const {
 }
 
 MutableDBOptions::MutableDBOptions()
-    : base_background_compactions(1), max_background_compactions(1) {}
+    : base_background_compactions(1),
+      max_background_compactions(1),
+      avoid_flush_during_shutdown(false) {}
 
 MutableDBOptions::MutableDBOptions(const DBOptions& options)
     : base_background_compactions(options.base_background_compactions),
-      max_background_compactions(options.max_background_compactions) {}
+      max_background_compactions(options.max_background_compactions),
+      avoid_flush_during_shutdown(options.avoid_flush_during_shutdown) {}
 
 void MutableDBOptions::Dump(Logger* log) const {
   Header(log, "            Options.base_background_compactions: %d",
          base_background_compactions);
   Header(log, "             Options.max_background_compactions: %d",
          max_background_compactions);
+  Header(log, "            Options.avoid_flush_during_shutdown: %d",
+         avoid_flush_during_shutdown);
 }
 
 }  // namespace rocksdb

util/db_options.h

@@ -94,6 +94,7 @@ struct MutableDBOptions {
 
   int base_background_compactions;
   int max_background_compactions;
+  bool avoid_flush_during_shutdown;
 };
 
 }  // namespace rocksdb

util/options.cc

@@ -228,7 +228,8 @@ DBOptions::DBOptions()
 #endif  // ROCKSDB_LITE
       fail_if_options_file_error(false),
       dump_malloc_stats(false),
-      avoid_flush_during_recovery(false) {
+      avoid_flush_during_recovery(false),
+      avoid_flush_during_shutdown(false) {
 }
 
 DBOptions::DBOptions(const Options& options)
@@ -301,7 +302,8 @@ DBOptions::DBOptions(const Options& options)
 #endif  // ROCKSDB_LITE
       fail_if_options_file_error(options.fail_if_options_file_error),
       dump_malloc_stats(options.dump_malloc_stats),
-      avoid_flush_during_recovery(options.avoid_flush_during_recovery) {
+      avoid_flush_during_recovery(options.avoid_flush_during_recovery),
+      avoid_flush_during_shutdown(options.avoid_flush_during_shutdown) {
 }
 
 static const char* const access_hints[] = {

util/options_helper.cc

@@ -118,6 +118,8 @@ DBOptions BuildDBOptions(const ImmutableDBOptions& immutable_db_options,
   options.dump_malloc_stats = immutable_db_options.dump_malloc_stats;
   options.avoid_flush_during_recovery =
       immutable_db_options.avoid_flush_during_recovery;
+  options.avoid_flush_during_shutdown =
+      mutable_db_options.avoid_flush_during_shutdown;
 
   return options;
 }

util/options_helper.h

@@ -343,7 +343,11 @@ static std::unordered_map<std::string, OptionTypeInfo> db_options_type_info = {
       OptionVerificationType::kNormal, false, 0}},
     {"avoid_flush_during_recovery",
      {offsetof(struct DBOptions, avoid_flush_during_recovery),
-      OptionType::kBoolean, OptionVerificationType::kNormal, false, 0}}};
+      OptionType::kBoolean, OptionVerificationType::kNormal, false, 0}},
+    {"avoid_flush_during_shutdown",
+     {offsetof(struct DBOptions, avoid_flush_during_shutdown),
+      OptionType::kBoolean, OptionVerificationType::kNormal, true,
+      offsetof(struct MutableDBOptions, avoid_flush_during_shutdown)}}};
 
 static std::unordered_map<std::string, OptionTypeInfo> cf_options_type_info = {
     /* not yet supported

util/options_settable_test.cc

@@ -288,7 +288,8 @@ TEST_F(OptionsSettableTest, DBOptionsAllFieldsSettable) {
                              "info_log_level=DEBUG_LEVEL;"
                              "dump_malloc_stats=false;"
                              "allow_2pc=false;"
-                             "avoid_flush_during_recovery=false;",
+                             "avoid_flush_during_recovery=false;"
+                             "avoid_flush_during_shutdown=false;",
                              new_options));
 
   ASSERT_EQ(unset_bytes_base, NumUnsetBytes(new_options_ptr, sizeof(DBOptions),

util/testutil.cc

@@ -253,6 +253,8 @@ void RandomInitDBOptions(DBOptions* db_opt, Random* rnd) {
   db_opt->use_adaptive_mutex = rnd->Uniform(2);
   db_opt->use_fsync = rnd->Uniform(2);
   db_opt->recycle_log_file_num = rnd->Uniform(2);
+  db_opt->avoid_flush_during_recovery = rnd->Uniform(2);
+  db_opt->avoid_flush_during_shutdown = rnd->Uniform(2);
 
   // int options
   db_opt->max_background_compactions = rnd->Uniform(100);