[heap] Do more incremental marking work in tasks.

src/heap/incremental-marking-job.h

 // Copyright 2012 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.
 
 #ifndef V8_HEAP_INCREMENTAL_MARKING_JOB_H_
 #define V8_HEAP_INCREMENTAL_MARKING_JOB_H_
 
 #include "src/cancelable-task.h"
 
 namespace v8 {
 namespace internal {
 
 class Heap;
 class Isolate;
 
 // The incremental marking job uses platform tasks to perform incremental
-// marking steps. The job posts an idle and a delayed task with a large delay.
-// The delayed task performs steps only if the idle task is not making progress.
-// We expect this to be a rare event since incremental marking should finish
-// quickly with the help of the mutator and the idle task.
-// The delayed task guarantees that we eventually finish incremental marking
-// even if the mutator becomes idle and the platform stops running idle tasks,
-// which can happen for background tabs in Chrome.
+// marking steps. The job posts a foreground task that makes a small (~1ms)
+// step and posts another task until the marking is completed.
 class IncrementalMarkingJob {
  public:
-  class IdleTask : public CancelableIdleTask {
+  class Task : public CancelableTask {
    public:
-    explicit IdleTask(Isolate* isolate, IncrementalMarkingJob* job)
-        : CancelableIdleTask(isolate), job_(job) {}
-    enum Progress { kDone, kMoreWork };
-    static Progress Step(Heap* heap, double deadline_in_ms);
-    // CancelableIdleTask overrides.
-    void RunInternal(double deadline_in_seconds) override;
-
-   private:
-    IncrementalMarkingJob* job_;
-  };
-
-  class DelayedTask : public CancelableTask {
-   public:
-    explicit DelayedTask(Isolate* isolate, IncrementalMarkingJob* job)
+    explicit Task(Isolate* isolate, IncrementalMarkingJob* job)
         : CancelableTask(isolate), job_(job) {}
     static void Step(Heap* heap);
     // CancelableTask overrides.
     void RunInternal() override;
 
    private:
     IncrementalMarkingJob* job_;
   };
 
-  // Delay of the delayed task.
-  static const double kLongDelayInSeconds;
-  static const double kShortDelayInSeconds;
+  IncrementalMarkingJob() : task_pending_(false) {}
 
-  IncrementalMarkingJob()
-      : idle_task_pending_(false),
-        delayed_task_pending_(false),
-        made_progress_since_last_delayed_task_(false) {}
-
-  bool ShouldForceMarkingStep() {
-    return !made_progress_since_last_delayed_task_;
-  }
-
-  bool IdleTaskPending() { return idle_task_pending_; }
+  bool TaskPending() { return task_pending_; }
 
   void Start(Heap* heap);
 
-  void NotifyIdleTask();
-  void NotifyDelayedTask();
-  void NotifyIdleTaskProgress();
-  void ScheduleIdleTask(Heap* heap);
-  void ScheduleDelayedTask(Heap* heap);
+  void NotifyTask();
+
+  void ScheduleTask(Heap* heap);
 
  private:
-  bool idle_task_pending_;
-  bool delayed_task_pending_;
-  bool made_progress_since_last_delayed_task_;
+  bool task_pending_;
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_INCREMENTAL_MARKING_JOB_H_