folly/wangle/concurrent/IOThreadPoolExecutor.h

   1 /*
   2  * Copyright 2015 Facebook, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *   http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #pragma once
  18
  19 #include <folly/io/async/EventBaseManager.h>
  20 #include <folly/wangle/concurrent/IOExecutor.h>
  21 #include <folly/wangle/concurrent/ThreadPoolExecutor.h>
  22
  23 namespace folly { namespace wangle {
  24
  25 // N.B. For this thread pool, stop() behaves like join() because outstanding
  26 // tasks belong to the event base and will be executed upon its destruction.
  27 class IOThreadPoolExecutor : public ThreadPoolExecutor, public IOExecutor {
  28  public:
  29   explicit IOThreadPoolExecutor(
  30       size_t numThreads,
  31       std::shared_ptr<ThreadFactory> threadFactory =
  32           std::make_shared<NamedThreadFactory>("IOThreadPool"),
  33       EventBaseManager* ebm = folly::EventBaseManager::get());
  34
  35   ~IOThreadPoolExecutor();
  36
  37   void add(Func func) override;
  38   void add(
  39       Func func,
  40       std::chrono::milliseconds expiration,
  41       Func expireCallback = nullptr) override;
  42
  43   EventBase* getEventBase() override;
  44
  45   static EventBase* getEventBase(ThreadPoolExecutor::ThreadHandle*);
  46
  47   EventBaseManager* getEventBaseManager();
  48
  49  private:
  50   struct FOLLY_ALIGN_TO_AVOID_FALSE_SHARING IOThread : public Thread {
  51     IOThread(IOThreadPoolExecutor* pool)
  52       : Thread(pool),
  53         shouldRun(true),
  54         pendingTasks(0) {};
  55     std::atomic<bool> shouldRun;
  56     std::atomic<size_t> pendingTasks;
  57     EventBase* eventBase;
  58   };
  59
  60   ThreadPtr makeThread() override;
  61   std::shared_ptr<IOThread> pickThread();
  62   void threadRun(ThreadPtr thread) override;
  63   void stopThreads(size_t n) override;
  64   uint64_t getPendingTaskCount() override;
  65
  66   size_t nextThread_;
  67   ThreadLocal<std::shared_ptr<IOThread>> thisThread_;
  68   EventBaseManager* eventBaseManager_;
  69 };
  70
  71 }} // folly::wangle