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      1 // Copyright 2012 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef V8_HEAP_INCREMENTAL_MARKING_JOB_H_
      6 #define V8_HEAP_INCREMENTAL_MARKING_JOB_H_
      7 
      8 #include "src/cancelable-task.h"
      9 
     10 namespace v8 {
     11 namespace internal {
     12 
     13 class Heap;
     14 class Isolate;
     15 
     16 // The incremental marking job uses platform tasks to perform incremental
     17 // marking steps. The job posts an idle and a delayed task with a large delay.
     18 // The delayed task performs steps only if the idle task is not making progress.
     19 // We expect this to be a rare event since incremental marking should finish
     20 // quickly with the help of the mutator and the idle task.
     21 // The delayed task guarantees that we eventually finish incremental marking
     22 // even if the mutator becomes idle and the platform stops running idle tasks,
     23 // which can happen for background tabs in Chrome.
     24 class IncrementalMarkingJob {
     25  public:
     26   class IdleTask : public CancelableIdleTask {
     27    public:
     28     explicit IdleTask(Isolate* isolate, IncrementalMarkingJob* job)
     29         : CancelableIdleTask(isolate), job_(job) {}
     30     enum Progress { kDone, kMoreWork };
     31     static Progress Step(Heap* heap, double deadline_in_ms);
     32     // CancelableIdleTask overrides.
     33     void RunInternal(double deadline_in_seconds) override;
     34 
     35    private:
     36     IncrementalMarkingJob* job_;
     37   };
     38 
     39   class DelayedTask : public CancelableTask {
     40    public:
     41     explicit DelayedTask(Isolate* isolate, IncrementalMarkingJob* job)
     42         : CancelableTask(isolate), job_(job) {}
     43     static void Step(Heap* heap);
     44     // CancelableTask overrides.
     45     void RunInternal() override;
     46 
     47    private:
     48     IncrementalMarkingJob* job_;
     49   };
     50 
     51   // Delay of the delayed task.
     52   static const int kDelayInSeconds = 5;
     53 
     54   IncrementalMarkingJob()
     55       : idle_task_pending_(false),
     56         delayed_task_pending_(false),
     57         made_progress_since_last_delayed_task_(false) {}
     58 
     59   bool ShouldForceMarkingStep() {
     60     return !made_progress_since_last_delayed_task_;
     61   }
     62 
     63   bool IdleTaskPending() { return idle_task_pending_; }
     64 
     65   void Start(Heap* heap);
     66 
     67   void NotifyIdleTask();
     68   void NotifyDelayedTask();
     69   void NotifyIdleTaskProgress();
     70   void ScheduleIdleTask(Heap* heap);
     71   void ScheduleDelayedTask(Heap* heap);
     72 
     73  private:
     74   bool idle_task_pending_;
     75   bool delayed_task_pending_;
     76   bool made_progress_since_last_delayed_task_;
     77 };
     78 }  // namespace internal
     79 }  // namespace v8
     80 
     81 #endif  // V8_HEAP_INCREMENTAL_MARKING_JOB_H_
     82