kc3-lang/angle/src/libANGLE/WorkerThread.cpp

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• Hash : 7ae70d8f
  Author :
  Date : 2018-07-06T13:47:01
  

  ParallelCompile: Parallelize D3D linking
  
  This adds a new linking state to Program. If a Program is in linking
  state, on the one hand the foreground thread may continue issuing more
  GL calls, and on the other hand the background linking threads may be
  accessing Program internally too. Without a proper constraint there
  must be conflicts between them. For this purpose, we block any further
  GL calls to Program until it's actually linked. In addition, we
  prohibit parallel linking an active program, so that ProgramD3D does
  not have to worry about such similar conflicts.
  
  Also changes the WorkerThread to support limiting the number of
  concurrently running worker threads.
  
  BUG=chromium:849576
  
  Change-Id: I52618647539323f8bf27201320bdf7301c4982e6
  Reviewed-on: https://chromium-review.googlesource.com/1127495
  Commit-Queue: Jie A Chen <jie.a.chen@intel.com>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  

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• src/libANGLE/WorkerThread.cpp

• //
  // Copyright 2016 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  // WorkerThread:
  //   Task running thread for ANGLE, similar to a TaskRunner in Chromium.
  //   Might be implemented differently depending on platform.
  //
  
  #include "libANGLE/WorkerThread.h"
  
  #if (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
  #include <condition_variable>
  #include <future>
  #include <mutex>
  #include <queue>
  #include <thread>
  #endif  // (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
  
  namespace angle
  {
  
  WaitableEvent::WaitableEvent()  = default;
  WaitableEvent::~WaitableEvent() = default;
  
  WorkerThreadPool::WorkerThreadPool()  = default;
  WorkerThreadPool::~WorkerThreadPool() = default;
  
  class SingleThreadedWaitableEvent final : public WaitableEvent
  {
    public:
      SingleThreadedWaitableEvent()  = default;
      ~SingleThreadedWaitableEvent() = default;
  
      void wait() override;
      bool isReady() override;
  };
  
  void SingleThreadedWaitableEvent::wait()
  {
  }
  
  bool SingleThreadedWaitableEvent::isReady()
  {
      return true;
  }
  
  class SingleThreadedWorkerPool final : public WorkerThreadPool
  {
    public:
      std::shared_ptr<WaitableEvent> postWorkerTask(std::shared_ptr<Closure> task) override;
      void setMaxThreads(size_t maxThreads) override;
  };
  
  // SingleThreadedWorkerPool implementation.
  std::shared_ptr<WaitableEvent> SingleThreadedWorkerPool::postWorkerTask(
      std::shared_ptr<Closure> task)
  {
      (*task)();
      return std::make_shared<SingleThreadedWaitableEvent>();
  }
  
  void SingleThreadedWorkerPool::setMaxThreads(size_t maxThreads)
  {
  }
  
  #if (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
  class AsyncWaitableEvent final : public WaitableEvent
  {
    public:
      AsyncWaitableEvent() : mIsPending(true) {}
      ~AsyncWaitableEvent() = default;
  
      void wait() override;
      bool isReady() override;
  
    private:
      friend class AsyncWorkerPool;
      void setFuture(std::future<void> &&future);
  
      // To block wait() when the task is stil in queue to be run.
      // Also to protect the concurrent accesses from both main thread and
      // background threads to the member fields.
      std::mutex mMutex;
  
      bool mIsPending;
      std::condition_variable mCondition;
      std::future<void> mFuture;
  };
  
  void AsyncWaitableEvent::setFuture(std::future<void> &&future)
  {
      mFuture = std::move(future);
  }
  
  void AsyncWaitableEvent::wait()
  {
      {
          std::unique_lock<std::mutex> lock(mMutex);
          mCondition.wait(lock, [this] { return !mIsPending; });
      }
  
      ASSERT(mFuture.valid());
      mFuture.wait();
  }
  
  bool AsyncWaitableEvent::isReady()
  {
      std::lock_guard<std::mutex> lock(mMutex);
      if (mIsPending)
      {
          return false;
      }
      ASSERT(mFuture.valid());
      return mFuture.wait_for(std::chrono::seconds(0)) == std::future_status::ready;
  }
  
  class AsyncWorkerPool final : public WorkerThreadPool
  {
    public:
      AsyncWorkerPool(size_t maxThreads) : mMaxThreads(maxThreads), mRunningThreads(0){};
      ~AsyncWorkerPool() = default;
  
      std::shared_ptr<WaitableEvent> postWorkerTask(std::shared_ptr<Closure> task) override;
      void setMaxThreads(size_t maxThreads) override;
  
    private:
      void checkToRunPendingTasks();
  
      // To protect the concurrent accesses from both main thread and background
      // threads to the member fields.
      std::mutex mMutex;
  
      size_t mMaxThreads;
      size_t mRunningThreads;
      std::queue<std::pair<std::shared_ptr<AsyncWaitableEvent>, std::shared_ptr<Closure>>> mTaskQueue;
  };
  
  // AsyncWorkerPool implementation.
  std::shared_ptr<WaitableEvent> AsyncWorkerPool::postWorkerTask(std::shared_ptr<Closure> task)
  {
      ASSERT(mMaxThreads > 0);
  
      auto waitable = std::make_shared<AsyncWaitableEvent>();
      {
          std::lock_guard<std::mutex> lock(mMutex);
          mTaskQueue.push(std::make_pair(waitable, task));
      }
      checkToRunPendingTasks();
      return waitable;
  }
  
  void AsyncWorkerPool::setMaxThreads(size_t maxThreads)
  {
      {
          std::lock_guard<std::mutex> lock(mMutex);
          mMaxThreads = (maxThreads == 0xFFFFFFFF ? std::thread::hardware_concurrency() : maxThreads);
      }
      checkToRunPendingTasks();
  }
  
  void AsyncWorkerPool::checkToRunPendingTasks()
  {
      std::lock_guard<std::mutex> lock(mMutex);
      while (mRunningThreads < mMaxThreads && !mTaskQueue.empty())
      {
          auto task = mTaskQueue.front();
          mTaskQueue.pop();
          auto waitable = task.first;
          auto closure  = task.second;
  
          auto future = std::async(std::launch::async, [closure, this] {
              (*closure)();
              {
                  std::lock_guard<std::mutex> lock(mMutex);
                  ASSERT(mRunningThreads != 0);
                  --mRunningThreads;
              }
              checkToRunPendingTasks();
          });
  
          ++mRunningThreads;
  
          {
              std::lock_guard<std::mutex> waitableLock(waitable->mMutex);
              waitable->mIsPending = false;
              waitable->setFuture(std::move(future));
          }
          waitable->mCondition.notify_all();
      }
  }
  #endif  // (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
  
  // static
  std::shared_ptr<WorkerThreadPool> WorkerThreadPool::Create(bool multithreaded)
  {
      std::shared_ptr<WorkerThreadPool> pool(nullptr);
  #if (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
      if (multithreaded)
      {
          pool = std::shared_ptr<WorkerThreadPool>(static_cast<WorkerThreadPool *>(
              new AsyncWorkerPool(std::thread::hardware_concurrency())));
      }
  #endif
      if (!pool)
      {
          return std::shared_ptr<WorkerThreadPool>(
              static_cast<WorkerThreadPool *>(new SingleThreadedWorkerPool()));
      }
      return pool;
  }
  
  }  // namespace angle
  

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