hazptr: Add singleton CPUThreadPoolExecutor for default domain asynchronous reclamation

Summary: Add function to make the default hazptr domain use a CPUThreadPoolExecutor.

Reviewed By: davidtgoldblatt

Differential Revision: D19107084

fbshipit-source-id: 873779d7b9314e5920f2542ef23bb707b47a4e10

folly/synchronization/HazptrThreadPoolExecutor.cpp

+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <folly/synchronization/HazptrThreadPoolExecutor.h>
+
+#include <folly/Singleton.h>
+#include <folly/executors/CPUThreadPoolExecutor.h>
+
+namespace {
+
+struct HazptrTPETag {};
+folly::Singleton<folly::CPUThreadPoolExecutor, HazptrTPETag> hazptr_tpe_([] {
+  return new folly::CPUThreadPoolExecutor(1);
+});
+
+folly::Executor* get_hazptr_tpe() {
+  auto ex = hazptr_tpe_.try_get();
+  return ex ? ex.get() : nullptr;
+}
+
+} // namespace
+
+namespace folly {
+
+void start_hazptr_thread_pool_executor() {
+  if (FLAGS_folly_hazptr_use_executor) {
+    default_hazptr_domain().set_executor(&get_hazptr_tpe);
+  }
+}
+
+} // namespace folly

folly/synchronization/HazptrThreadPoolExecutor.h

+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <folly/synchronization/Hazptr.h>
+
+namespace folly {
+
+void start_hazptr_thread_pool_executor();
+
+} // namespace folly

folly/synchronization/test/HazptrTest.cpp

@@ -21,9 +21,9 @@
 #include <folly/synchronization/test/Barrier.h>
 
 #include <folly/Singleton.h>
-#include <folly/executors/CPUThreadPoolExecutor.h>
 #include <folly/portability/GFlags.h>
 #include <folly/portability/GTest.h>
+#include <folly/synchronization/HazptrThreadPoolExecutor.h>
 #include <folly/test/DeterministicSchedule.h>
 
 #include <atomic>
@@ -899,18 +899,8 @@ void recursive_destruction_test() {
   ASSERT_EQ(c_.dtors(), total);
 }
 
-struct TPETag {};
-folly::Singleton<folly::CPUThreadPoolExecutor, TPETag> cputpe_([] {
-  return new folly::CPUThreadPoolExecutor(1);
-});
-
-folly::Executor* get_cputpe() {
-  auto ex = cputpe_.try_get();
-  return ex ? ex.get() : nullptr;
-}
-
 void fork_test() {
-  folly::default_hazptr_domain().set_executor(&get_cputpe);
+  folly::start_hazptr_thread_pool_executor();
   auto trigger_reclamation = [] {
     hazptr_obj_batch b;
     for (int i = 0; i < 2001; ++i) {