Make CancelableTaskTracker sequence-safe.

base/task/cancelable_task_tracker.cc

 // Copyright 2014 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/cancelable_task_tracker.h"
 
 #include <stddef.h>
 
 #include <utility>
 
-#include "base/bind.h"
 #include "base/callback_helpers.h"
-#include "base/compiler_specific.h"
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
-#include "base/single_thread_task_runner.h"
 #include "base/synchronization/cancellation_flag.h"
 #include "base/task_runner.h"
-#include "base/threading/thread_task_runner_handle.h"
+#include "base/threading/sequenced_task_runner_handle.h"
 
-using base::Bind;
-using base::CancellationFlag;
-using base::Closure;
-using base::hash_map;
-using base::TaskRunner;
+namespace base {
 
 namespace {
 
 void RunIfNotCanceled(const CancellationFlag* flag, const Closure& task) {
   if (!flag->IsSet())
     task.Run();
 }
 
 void RunIfNotCanceledThenUntrack(const CancellationFlag* flag,
                                  const Closure& task,
@@ skipping 14 matching lines @@
 
 void RunOrPostToTaskRunner(TaskRunner* task_runner, const Closure& closure) {
   if (task_runner->RunsTasksOnCurrentThread())
     closure.Run();
   else
     task_runner->PostTask(FROM_HERE, closure);
 }
 
 }  // namespace
 
-namespace base {

[dcheng, 2016/12/20 19:14:36]

Oops.

-
 // static
 const CancelableTaskTracker::TaskId CancelableTaskTracker::kBadTaskId = 0;
 
 CancelableTaskTracker::CancelableTaskTracker()
     : next_id_(1),weak_factory_(this) {}
 
 CancelableTaskTracker::~CancelableTaskTracker() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
 
   TryCancelAll();
 }
 
 CancelableTaskTracker::TaskId CancelableTaskTracker::PostTask(
     TaskRunner* task_runner,
     const tracked_objects::Location& from_here,
     const Closure& task) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
 
   return PostTaskAndReply(task_runner, from_here, task, Bind(&base::DoNothing));
 }
 
 CancelableTaskTracker::TaskId CancelableTaskTracker::PostTaskAndReply(
     TaskRunner* task_runner,
     const tracked_objects::Location& from_here,
     const Closure& task,
     const Closure& reply) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
 
-  // We need a MessageLoop to run reply.
-  DCHECK(base::ThreadTaskRunnerHandle::IsSet());
+  // We need a SequencedTaskRunnerHandle to run |reply|.
+  DCHECK(base::SequencedTaskRunnerHandle::IsSet());
 
   // Owned by reply callback below.
   CancellationFlag* flag = new CancellationFlag();
 
   TaskId id = next_id_;
   next_id_++;  // int64_t is big enough that we ignore the potential overflow.
 
   const Closure& untrack_closure =
       Bind(&CancelableTaskTracker::Untrack, weak_factory_.GetWeakPtr(), id);
   bool success =
       task_runner->PostTaskAndReply(from_here,
                                     Bind(&RunIfNotCanceled, flag, task),
                                     Bind(&RunIfNotCanceledThenUntrack,
                                          base::Owned(flag),
                                          reply,
                                          untrack_closure));
 
   if (!success)
     return kBadTaskId;
 
   Track(id, flag);
   return id;
 }
 
 CancelableTaskTracker::TaskId CancelableTaskTracker::NewTrackedTaskId(
     IsCanceledCallback* is_canceled_cb) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(base::ThreadTaskRunnerHandle::IsSet());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
+  DCHECK(base::SequencedTaskRunnerHandle::IsSet());
 
   TaskId id = next_id_;
   next_id_++;  // int64_t is big enough that we ignore the potential overflow.
 
   // Will be deleted by |untrack_and_delete_flag| after Untrack().
   CancellationFlag* flag = new CancellationFlag();
 
   Closure untrack_and_delete_flag = Bind(
       &RunAndDeleteFlag,
       Bind(&CancelableTaskTracker::Untrack, weak_factory_.GetWeakPtr(), id),
       flag);
 
-  // Will always run |untrack_and_delete_flag| on current MessageLoop.
+  // Will always run |untrack_and_delete_flag| on current sequence.
   base::ScopedClosureRunner* untrack_and_delete_flag_runner =
       new base::ScopedClosureRunner(
           Bind(&RunOrPostToTaskRunner,
-               RetainedRef(base::ThreadTaskRunnerHandle::Get()),
+               RetainedRef(base::SequencedTaskRunnerHandle::Get()),
                untrack_and_delete_flag));
 
   *is_canceled_cb =
       Bind(&IsCanceled, flag, base::Owned(untrack_and_delete_flag_runner));
 
   Track(id, flag);
   return id;
 }
 
 void CancelableTaskTracker::TryCancel(TaskId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
 
   hash_map<TaskId, CancellationFlag*>::const_iterator it = task_flags_.find(id);
   if (it == task_flags_.end()) {
     // Two possibilities:
     //
     //   1. The task has already been untracked.
     //   2. The TaskId is bad or unknown.
     //
     // Since this function is best-effort, it's OK to ignore these.
     return;
   }
   it->second->Set();
 }
 
 void CancelableTaskTracker::TryCancelAll() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
 
   for (hash_map<TaskId, CancellationFlag*>::const_iterator it =
            task_flags_.begin();
        it != task_flags_.end();
        ++it) {
     it->second->Set();
   }
 }
 
 bool CancelableTaskTracker::HasTrackedTasks() const {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
   return !task_flags_.empty();
 }
 
 void CancelableTaskTracker::Track(TaskId id, CancellationFlag* flag) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
 
   bool success = task_flags_.insert(std::make_pair(id, flag)).second;
   DCHECK(success);
 }
 
 void CancelableTaskTracker::Untrack(TaskId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
   size_t num = task_flags_.erase(id);
   DCHECK_EQ(1u, num);
 }
 
 }  // namespace base