Add the COM STA Task Runner

base/task_scheduler/scheduler_single_thread_task_runner_manager.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/task_scheduler/scheduler_single_thread_task_runner_manager.h"
 
 #include <algorithm>
 #include <memory>
 #include <string>
+#include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/ptr_util.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/atomic_flag.h"
 #include "base/task_scheduler/delayed_task_manager.h"
 #include "base/task_scheduler/scheduler_worker.h"
 #include "base/task_scheduler/sequence.h"
 #include "base/task_scheduler/task.h"
 #include "base/task_scheduler/task_tracker.h"
 #include "base/task_scheduler/task_traits.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 
+#if defined(OS_WIN)
+#include <windows.h>
+
+#include "base/win/scoped_com_initializer.h"
+#endif  // defined(OS_WIN)
+
 namespace base {
 namespace internal {
 
 namespace {
 
 // Allows for checking the PlatformThread::CurrentRef() against a set
 // PlatformThreadRef atomically without using locks.
 class AtomicThreadRefChecker {
  public:
   AtomicThreadRefChecker() = default;
@@ skipping 86 matching lines @@
   // Synchronizes access to |sequence_| and |has_work_|.
   SchedulerLock sequence_lock_;
   scoped_refptr<Sequence> sequence_ = new Sequence;
   bool has_work_ = false;
 
   AtomicThreadRefChecker thread_ref_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(SchedulerWorkerDelegate);
 };
 
+#if defined(OS_WIN)
+
+class SchedulerWorkerCOMDelegate : public SchedulerWorkerDelegate {
+ public:
+  SchedulerWorkerCOMDelegate(const std::string& thread_name,
+                             TaskTracker* task_tracker)
+      : SchedulerWorkerDelegate(thread_name), task_tracker_(task_tracker) {}
+
+  ~SchedulerWorkerCOMDelegate() override { DCHECK(!scoped_com_initializer_); }
+
+  // SchedulerWorker::Delegate:
+  void OnMainEntry(SchedulerWorker* worker) override {
+    SchedulerWorkerDelegate::OnMainEntry(worker);
+
+    scoped_com_initializer_ = MakeUnique<win::ScopedCOMInitializer>();
+  }
+
+  scoped_refptr<Sequence> GetWork(SchedulerWorker* worker) override {
+    // This scheme below allows us to cover the following scenarios:
+    // * Only SchedulerWorkerDelegate::GetWork() has work:
+    //   Always return the sequence from GetWork().
+    // * Only the Windows Message Queue has work:
+    //   Always return the sequence from GetWorkFromWindowsMessageQueue();
+    // * Both SchedulerWorkerDelegate::GetWork() and the Windows Message Queue
+    //   have work:
+    //   Process sequences from each source round-robin style.
+    scoped_refptr<Sequence> sequence;
+    if (get_work_first_) {
+      sequence = SchedulerWorkerDelegate::GetWork(worker);
+      if (sequence)
+        get_work_first_ = false;
+    }
+
+    if (!sequence) {
+      sequence = GetWorkFromWindowsMessageQueue();
+      if (sequence)
+        get_work_first_ = true;
+    }
+
+    if (!sequence && !get_work_first_) {
+      // This case is important if we checked the Windows Message Queue first
+      // and found there was no work. We don't want to return null immediately
+      // as that could cause the thread to go to sleep while work is waiting via
+      // SchedulerWorkerDelegate::GetWork().
+      sequence = SchedulerWorkerDelegate::GetWork(worker);
+    }
+    return sequence;
+  }
+
+  void OnMainExit() override { scoped_com_initializer_.reset(); }
+
+  void WaitForWork(WaitableEvent* wake_up_event) override {
+    DCHECK(wake_up_event);
+    const TimeDelta sleep_time = GetSleepTimeout();
+    const DWORD milliseconds_wait =
+        sleep_time.is_max() ? INFINITE : sleep_time.InMilliseconds();
+    HANDLE wake_up_event_handle = wake_up_event->handle();
+    DWORD result = MsgWaitForMultipleObjectsEx(
+        1, &wake_up_event_handle, milliseconds_wait, QS_ALLINPUT, 0);
+    if (result == WAIT_OBJECT_0) {
+      // Reset the event since we woke up due to it.
+      wake_up_event->Reset();
+    }
+  }
+
+ private:
+  scoped_refptr<Sequence> GetWorkFromWindowsMessageQueue() {
+    MSG msg;
+    if (PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE) != FALSE) {
+      auto pump_message_task =
+          MakeUnique<Task>(FROM_HERE,
+                           Bind(
+                               [](MSG msg) {
+                                 TranslateMessage(&msg);
+                                 DispatchMessage(&msg);
+                               },
+                               std::move(msg)),
+                           TaskTraits().MayBlock(), TimeDelta());
+      if (task_tracker_->WillPostTask(pump_message_task.get())) {
+        bool was_empty =
+            message_pump_sequence_->PushTask(std::move(pump_message_task));
+        DCHECK(was_empty) << "GetWorkFromWindowsMessageQueue() does not expect "
+                             "queueing of pump tasks.";
+        return message_pump_sequence_;
+      }
+    }
+    return nullptr;
+  }
+
+  bool get_work_first_ = true;
+  const scoped_refptr<Sequence> message_pump_sequence_ = new Sequence;
+  TaskTracker* const task_tracker_;
+  std::unique_ptr<win::ScopedCOMInitializer> scoped_com_initializer_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerWorkerCOMDelegate);
+};
+
+#endif  // defined(OS_WIN)
+
 }  // namespace
 
 class SchedulerSingleThreadTaskRunnerManager::SchedulerSingleThreadTaskRunner
     : public SingleThreadTaskRunner {
  public:
   // Constructs a SchedulerSingleThreadTaskRunner that indirectly controls the
   // lifetime of a dedicated |worker| for |traits|.
   SchedulerSingleThreadTaskRunner(
       SchedulerSingleThreadTaskRunnerManager* const outer,
       const TaskTraits& traits,
@@ skipping 18 matching lines @@
     } else {
       outer_->delayed_task_manager_->AddDelayedTask(
           std::move(task), Bind(&SchedulerSingleThreadTaskRunner::PostTaskNow,
                                 Unretained(this)));
     }
     return true;
   }
 
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
                                   const Closure& closure,
-                                  base::TimeDelta delay) override {
+                                  TimeDelta delay) override {
     // Tasks are never nested within the task scheduler.
     return PostDelayedTask(from_here, closure, delay);
   }
 
   bool RunsTasksOnCurrentThread() const override {
     return GetDelegate()->RunsTasksOnCurrentThread();
   }
 
  private:
   ~SchedulerSingleThreadTaskRunner() override {
@@ skipping 49 matching lines @@
       subtle::NoBarrier_Load(&workers_unregistered_during_join_);
   DCHECK_EQ(workers_unregistered_during_join, workers_.size())
       << "There cannot be outstanding SingleThreadTaskRunners upon destruction "
          "of SchedulerSingleThreadTaskRunnerManager or the Task Scheduler";
 #endif
 }
 
 scoped_refptr<SingleThreadTaskRunner>
 SchedulerSingleThreadTaskRunnerManager::CreateSingleThreadTaskRunnerWithTraits(
     const TaskTraits& traits) {
-  size_t index = worker_pool_index_for_traits_callback_.Run(traits);
-  DCHECK_LT(index, worker_pool_params_vector_.size());
-  return new SchedulerSingleThreadTaskRunner(
-      this, traits,
-      CreateAndRegisterSchedulerWorker(worker_pool_params_vector_[index]));
+  return CreateSingleThreadTaskRunnerWithDelegate<SchedulerWorkerDelegate>(
+      traits);
 }
 
+#if defined(OS_WIN)
+scoped_refptr<SingleThreadTaskRunner>
+SchedulerSingleThreadTaskRunnerManager::CreateCOMSTATaskRunnerWithTraits(
+    const TaskTraits& traits) {
+  return CreateSingleThreadTaskRunnerWithDelegate<SchedulerWorkerCOMDelegate>(
+      traits);
+}
+#endif  // defined(OS_WIN)
+
 void SchedulerSingleThreadTaskRunnerManager::JoinForTesting() {
   decltype(workers_) local_workers;
   {
     AutoSchedulerLock auto_lock(workers_lock_);
     local_workers = std::move(workers_);
   }
 
   for (const auto& worker : local_workers)
     worker->JoinForTesting();
 
   {
     AutoSchedulerLock auto_lock(workers_lock_);
     DCHECK(workers_.empty())
         << "New worker(s) unexpectedly registered during join.";
     workers_ = std::move(local_workers);
   }
 }
 
+template <typename DelegateType>
+scoped_refptr<SingleThreadTaskRunner> SchedulerSingleThreadTaskRunnerManager::
+    CreateSingleThreadTaskRunnerWithDelegate(const TaskTraits& traits) {
+  size_t index = worker_pool_index_for_traits_callback_.Run(traits);
+  DCHECK_LT(index, worker_pool_params_vector_.size());
+  return new SchedulerSingleThreadTaskRunner(
+      this, traits,
+      CreateAndRegisterSchedulerWorker<DelegateType>(
+          worker_pool_params_vector_[index]));
+}
+
+template <>
+std::unique_ptr<SchedulerWorkerDelegate>
+SchedulerSingleThreadTaskRunnerManager::CreateSchedulerWorkerDelegate<
+    SchedulerWorkerDelegate>(const SchedulerWorkerPoolParams& params, int id) {
+  return MakeUnique<SchedulerWorkerDelegate>(StringPrintf(
+      "TaskSchedulerSingleThreadWorker%d%s", id, params.name().c_str()));
+}
+
+#if defined(OS_WIN)
+template <>
+std::unique_ptr<SchedulerWorkerDelegate>
+SchedulerSingleThreadTaskRunnerManager::CreateSchedulerWorkerDelegate<
+    SchedulerWorkerCOMDelegate>(const SchedulerWorkerPoolParams& params,
+                                int id) {
+  return MakeUnique<SchedulerWorkerCOMDelegate>(
+      StringPrintf("TaskSchedulerSingleThreadWorker%d%sCOMSTA", id,
+                   params.name().c_str()),
+      task_tracker_);
+}
+#endif  // defined(OS_WIN)
+
+template <typename DelegateType>
 SchedulerWorker*
 SchedulerSingleThreadTaskRunnerManager::CreateAndRegisterSchedulerWorker(
     const SchedulerWorkerPoolParams& params) {
   AutoSchedulerLock auto_lock(workers_lock_);
   int id = next_worker_id_++;
-  auto delegate = MakeUnique<SchedulerWorkerDelegate>(base::StringPrintf(
-      "TaskSchedulerSingleThreadWorker%d%s", id, params.name().c_str()));
+
   workers_.emplace_back(SchedulerWorker::Create(
-      params.priority_hint(), std::move(delegate), task_tracker_,
+      params.priority_hint(),
+      CreateSchedulerWorkerDelegate<DelegateType>(params, id), task_tracker_,
       SchedulerWorker::InitialState::DETACHED));
   return workers_.back().get();
 }
 
 void SchedulerSingleThreadTaskRunnerManager::UnregisterSchedulerWorker(
     SchedulerWorker* worker) {
   // Cleanup uses a SchedulerLock, so call Cleanup() after releasing
   // |workers_lock_|.
   scoped_refptr<SchedulerWorker> worker_to_destroy;
   {
@@ skipping 15 matching lines @@
                      });
     DCHECK(worker_iter != workers_.end());
     worker_to_destroy = std::move(*worker_iter);
     workers_.erase(worker_iter);
   }
   worker_to_destroy->Cleanup();
 }
 
 }  // namespace internal
 }  // namespace base