Reland "[heap] Uncommit marking deque in concurrent task."

src/cancelable-task.cc

 // Copyright 2015 the V8 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.
 
 #include "src/cancelable-task.h"
 
 #include "src/base/platform/platform.h"
 #include "src/isolate.h"
 
 namespace v8 {
@@ skipping 30 matching lines @@
 
 
 void CancelableTaskManager::RemoveFinishedTask(uint32_t id) {
   base::LockGuard<base::Mutex> guard(&mutex_);
   size_t removed = cancelable_tasks_.erase(id);
   USE(removed);
   DCHECK_NE(0, removed);
   cancelable_tasks_barrier_.NotifyOne();
 }
 
-
-bool CancelableTaskManager::TryAbort(uint32_t id) {
+CancelableTaskManager::TryAbortResult CancelableTaskManager::TryAbort(
+    uint32_t id) {
   base::LockGuard<base::Mutex> guard(&mutex_);
   auto entry = cancelable_tasks_.find(id);
   if (entry != cancelable_tasks_.end()) {
     Cancelable* value = entry->second;
     if (value->Cancel()) {
       // Cannot call RemoveFinishedTask here because of recursive locking.
       cancelable_tasks_.erase(entry);
       cancelable_tasks_barrier_.NotifyOne();
-      return true;
+      return kTaskAborted;
+    } else {
+      return kTaskRunning;
     }
   }
-  return false;
+  return kTaskRemoved;
 }
 
 
 void CancelableTaskManager::CancelAndWait() {
   // Clean up all cancelable fore- and background tasks. Tasks are canceled on
   // the way if possible, i.e., if they have not started yet.  After each round
   // of canceling we wait for the background tasks that have already been
   // started.
   base::LockGuard<base::Mutex> guard(&mutex_);
   canceled_ = true;
@@ skipping 19 matching lines @@
 
 CancelableTask::CancelableTask(Isolate* isolate)
     : Cancelable(isolate->cancelable_task_manager()), isolate_(isolate) {}
 
 
 CancelableIdleTask::CancelableIdleTask(Isolate* isolate)
     : Cancelable(isolate->cancelable_task_manager()), isolate_(isolate) {}
 
 }  // namespace internal
 }  // namespace v8