SequencedExecutor

Reviewed By: phoad

Differential Revision: D7220254

fbshipit-source-id: 3a2a49fd17d0aca4acc590c1c16db75ace472216

folly/executors/ManualExecutor.h

@@ -23,6 +23,7 @@
 
 #include <folly/executors/DrivableExecutor.h>
 #include <folly/executors/ScheduledExecutor.h>
+#include <folly/executors/SequencedExecutor.h>
 #include <folly/synchronization/LifoSem.h>
 
 namespace folly {
@@ -35,7 +36,8 @@ namespace folly {
   /// NB No attempt has been made to make anything other than add and schedule
   /// threadsafe.
   class ManualExecutor : public DrivableExecutor,
-                         public ScheduledExecutor {
+                         public ScheduledExecutor,
+                         public SequencedExecutor {
    public:
     void add(Func) override;
 

folly/executors/NotificationQueueExecutor.h

@@ -18,11 +18,13 @@
 #include <folly/ExceptionString.h>
 #include <folly/Function.h>
 #include <folly/executors/DrivableExecutor.h>
+#include <folly/executors/SequencedExecutor.h>
 #include <folly/io/async/NotificationQueue.h>
 
 namespace folly {
 
-class NotificationQueueExecutor : public folly::DrivableExecutor {
+class NotificationQueueExecutor : public DrivableExecutor,
+                                  public SequencedExecutor {
  public:
   using Func = folly::Func;
 

folly/executors/SequencedExecutor.h

+/*
+ * Copyright 2018-present Facebook, Inc.
+ *
+ * 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/Executor.h>
+
+namespace folly {
+
+// An SequencedExecutor is an executor that provides the following guarantee:
+// if add(A) and add(B) were sequenced then execution of A and B will be
+// sequenced too.
+class SequencedExecutor : public virtual Executor {
+ public:
+  ~SequencedExecutor() override = default;
+};
+
+} // namespace folly

folly/executors/SerialExecutor.h

@@ -18,8 +18,8 @@
 
 #include <memory>
 
-#include <folly/Executor.h>
 #include <folly/executors/GlobalExecutor.h>
+#include <folly/executors/SequencedExecutor.h>
 
 namespace folly {
 
@@ -46,7 +46,7 @@ namespace folly {
  * parent executor is executing tasks.
  */
 
-class SerialExecutor : public folly::Executor {
+class SerialExecutor : public SequencedExecutor {
  public:
   ~SerialExecutor() override = default;
   SerialExecutor(SerialExecutor const&) = delete;

folly/io/async/EventBase.h

@@ -39,6 +39,7 @@
 #include <folly/Portability.h>
 #include <folly/ScopeGuard.h>
 #include <folly/executors/DrivableExecutor.h>
+#include <folly/executors/SequencedExecutor.h>
 #include <folly/experimental/ExecutionObserver.h>
 #include <folly/io/async/AsyncTimeout.h>
 #include <folly/io/async/HHWheelTimer.h>
@@ -126,7 +127,8 @@ class VirtualEventBase;
  */
 class EventBase : private boost::noncopyable,
                   public TimeoutManager,
-                  public DrivableExecutor {
+                  public DrivableExecutor,
+                  public SequencedExecutor {
  public:
   using Func = folly::Function<void()>;