Add memory pressure notification API

src/heap/incremental-marking-job.cc

 // 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.
 
 #include "src/heap/incremental-marking-job.h"
 
 #include "src/base/platform/time.h"
 #include "src/heap/heap-inl.h"
 #include "src/heap/heap.h"
 #include "src/heap/incremental-marking.h"
 #include "src/isolate.h"
 #include "src/v8.h"
 
 namespace v8 {
 namespace internal {
 
+const double IncrementalMarkingJob::kLongDelayInSeconds = 5;
+const double IncrementalMarkingJob::kShortDelayInSeconds = 0.5;
 
 void IncrementalMarkingJob::Start(Heap* heap) {
   DCHECK(!heap->incremental_marking()->IsStopped());
   // We don't need to reset the flags because tasks from the previous job
   // can still be pending. We just want to ensure that tasks are posted
   // if they are not pending.
   // If delayed task is pending and made_progress_since_last_delayed_task_ is
   // true, then the delayed task will clear that flag when it is rescheduled.
   ScheduleIdleTask(heap);
   ScheduleDelayedTask(heap);
@@ skipping 24 matching lines @@
   }
 }
 
 
 void IncrementalMarkingJob::ScheduleDelayedTask(Heap* heap) {
   if (!delayed_task_pending_ && FLAG_memory_reducer) {
     v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(heap->isolate());
     delayed_task_pending_ = true;
     made_progress_since_last_delayed_task_ = false;
     auto task = new DelayedTask(heap->isolate(), this);
+    double delay =
+        heap->HighMemoryPressure() ? kShortDelayInSeconds : kLongDelayInSeconds;
     V8::GetCurrentPlatform()->CallDelayedOnForegroundThread(isolate, task,
-                                                            kDelayInSeconds);
+                                                            delay);
   }
 }
 
 
 IncrementalMarkingJob::IdleTask::Progress IncrementalMarkingJob::IdleTask::Step(
     Heap* heap, double deadline_in_ms) {
   IncrementalMarking* incremental_marking = heap->incremental_marking();
   MarkCompactCollector* mark_compact_collector = heap->mark_compact_collector();
   if (incremental_marking->IsStopped()) {
     return kDone;
@@ skipping 63 matching lines @@
     }
     // The Step() above could have finished incremental marking.
     if (!incremental_marking->IsStopped()) {
       job_->ScheduleDelayedTask(heap);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8