Removes PostStop from RepeatingTaskHandle.

It isn't used and can easily be replaced with posting a task, as shown
in the changes to the unit test.

Also removing the sequenced task checker that no longer adds any value.
We now ensure that the task can only be stopped with a reference to the
 task queue it runs on.

Bug: webrtc:10365
Change-Id: Ie8aef6f742c55db1fb686f20c2a28c606c721fa0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/129725
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27292}

rtc_base/task_utils/repeating_task.cc

@@ -54,38 +54,16 @@ void RepeatingTaskBase::Stop() {
   next_run_time_ = Timestamp::PlusInfinity();
 }
 
-void RepeatingTaskBase::PostStop() {
-  if (task_queue_->IsCurrent()) {
-    RTC_DLOG(LS_INFO) << "Using PostStop() from the task queue running the "
-                         "repeated task. Consider calling Stop() instead.";
-  }
-  task_queue_->PostTask(ToQueuedTask([this] {
-    RTC_DCHECK_RUN_ON(task_queue_);
-    Stop();
-  }));
-}
-
 }  // namespace webrtc_repeating_task_impl
-RepeatingTaskHandle::RepeatingTaskHandle() {
-  sequence_checker_.Detach();
-}
-RepeatingTaskHandle::~RepeatingTaskHandle() {
-  sequence_checker_.Detach();
-}
 
 RepeatingTaskHandle::RepeatingTaskHandle(RepeatingTaskHandle&& other)
     : repeating_task_(other.repeating_task_) {
-  RTC_DCHECK_RUN_ON(&sequence_checker_);
   other.repeating_task_ = nullptr;
 }
 
 RepeatingTaskHandle& RepeatingTaskHandle::operator=(
     RepeatingTaskHandle&& other) {
-  RTC_DCHECK_RUN_ON(&other.sequence_checker_);
-  {
-    RTC_DCHECK_RUN_ON(&sequence_checker_);
-    repeating_task_ = other.repeating_task_;
-  }
+  repeating_task_ = other.repeating_task_;
   other.repeating_task_ = nullptr;
   return *this;
 }
@@ -95,7 +73,6 @@ RepeatingTaskHandle::RepeatingTaskHandle(
     : repeating_task_(repeating_task) {}
 
 void RepeatingTaskHandle::Stop() {
-  RTC_DCHECK_RUN_ON(&sequence_checker_);
   if (repeating_task_) {
     RTC_DCHECK_RUN_ON(repeating_task_->task_queue_);
     repeating_task_->Stop();
@@ -103,16 +80,7 @@ void RepeatingTaskHandle::Stop() {
   }
 }
 
-void RepeatingTaskHandle::PostStop() {
-  RTC_DCHECK_RUN_ON(&sequence_checker_);
-  if (repeating_task_) {
-    repeating_task_->PostStop();
-    repeating_task_ = nullptr;
-  }
-}
-
 bool RepeatingTaskHandle::Running() const {
-  RTC_DCHECK_RUN_ON(&sequence_checker_);
   return repeating_task_ != nullptr;
 }
 

rtc_base/task_utils/repeating_task.h

@@ -38,7 +38,6 @@ class RepeatingTaskBase : public QueuedTask {
 
   bool Run() final;
   void Stop() RTC_RUN_ON(task_queue_);
-  void PostStop();
 
   TaskQueueBase* const task_queue_;
   // This is always finite, except for the special case where it's PlusInfinity
@@ -77,8 +76,8 @@ class RepeatingTaskImpl final : public RepeatingTaskBase {
 // not thread safe.
 class RepeatingTaskHandle {
  public:
-  RepeatingTaskHandle();
-  ~RepeatingTaskHandle();
+  RepeatingTaskHandle() = default;
+  ~RepeatingTaskHandle() = default;
   RepeatingTaskHandle(RepeatingTaskHandle&& other);
   RepeatingTaskHandle& operator=(RepeatingTaskHandle&& other);
   RepeatingTaskHandle(const RepeatingTaskHandle&) = delete;
@@ -122,11 +121,6 @@ class RepeatingTaskHandle {
   // closure itself.
   void Stop();
 
-  // Stops future invocations of the repeating task closure. The closure might
-  // still be running when PostStop() returns, but there will be no future
-  // invocation.
-  void PostStop();
-
   // Returns true if Start() or DelayedStart() was called most recently. Returns
   // false initially and if Stop() or PostStop() was called most recently.
   bool Running() const;
@@ -134,10 +128,8 @@ class RepeatingTaskHandle {
  private:
   explicit RepeatingTaskHandle(
       webrtc_repeating_task_impl::RepeatingTaskBase* repeating_task);
-  rtc::SequencedTaskChecker sequence_checker_;
   // Owned by the task queue.
-  webrtc_repeating_task_impl::RepeatingTaskBase* repeating_task_
-      RTC_GUARDED_BY(sequence_checker_) = nullptr;
+  webrtc_repeating_task_impl::RepeatingTaskBase* repeating_task_ = nullptr;
 };
 
 }  // namespace webrtc

rtc_base/task_utils/repeating_task_unittest.cc

@@ -60,6 +60,18 @@ class MoveOnlyClosure {
  private:
   MockClosure* mock_;
 };
+
+// Helper closure class to stop repeating task on a task queue. This is
+// equivalent to [handle{move(handle)}] { handle.Stop(); } in c++14.
+class TaskHandleStopper {
+ public:
+  explicit TaskHandleStopper(RepeatingTaskHandle handle)
+      : handle_(std::move(handle)) {}
+  void operator()() { handle_.Stop(); }
+
+ private:
+  RepeatingTaskHandle handle_;
+};
 }  // namespace
 
 TEST(RepeatingTaskTest, TaskIsStoppedOnStop) {
@@ -79,7 +91,7 @@ TEST(RepeatingTaskTest, TaskIsStoppedOnStop) {
   Sleep(kShortInterval * (kShortIntervalCount + kMargin));
   EXPECT_EQ(counter.load(), kShortIntervalCount);
 
-  handle.PostStop();
+  task_queue.PostTask(TaskHandleStopper(std::move(handle)));
   // Sleep long enough that the task would run at least once more if not
   // stopped.
   Sleep(kLongInterval * 2);
@@ -132,7 +144,7 @@ TEST(RepeatingTaskTest, CancelDelayedTaskBeforeItRuns) {
   TaskQueueForTest task_queue("queue");
   auto handle = RepeatingTaskHandle::DelayedStart(
       task_queue.Get(), TimeDelta::ms(100), MoveOnlyClosure(&mock));
-  handle.PostStop();
+  task_queue.PostTask(TaskHandleStopper(std::move(handle)));
   EXPECT_TRUE(done.Wait(kTimeout.ms()));
 }
 
@@ -144,7 +156,7 @@ TEST(RepeatingTaskTest, CancelTaskAfterItRuns) {
   TaskQueueForTest task_queue("queue");
   auto handle =
       RepeatingTaskHandle::Start(task_queue.Get(), MoveOnlyClosure(&mock));
-  handle.PostStop();
+  task_queue.PostTask(TaskHandleStopper(std::move(handle)));
   EXPECT_TRUE(done.Wait(kTimeout.ms()));
 }
 
@@ -211,9 +223,9 @@ TEST(RepeatingTaskTest, Example) {
   RepeatingTaskHandle handle;
   object->StartPeriodicTask(&handle, task_queue.Get());
   // Restart the task
-  handle.PostStop();
+  task_queue.PostTask(TaskHandleStopper(std::move(handle)));
   object->StartPeriodicTask(&handle, task_queue.Get());
-  handle.PostStop();
+  task_queue.PostTask(TaskHandleStopper(std::move(handle)));
   struct Destructor {
     void operator()() { object.reset(); }
     std::unique_ptr<ObjectOnTaskQueue> object;