[heap] Reland "Add a guard for restarting the memory reducer after mark-compact."

src/heap/memory-reducer.h

 // 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.
 
 #ifndef V8_HEAP_memory_reducer_H
 #define V8_HEAP_memory_reducer_H
 
 #include "include/v8-platform.h"
 #include "src/base/macros.h"
 #include "src/cancelable-task.h"
@@ skipping 68 matching lines @@
 //
 // now_ms is the current time,
 // t' is t if the current event is not a GC event and is now_ms otherwise,
 // long_delay_ms, short_delay_ms, and watchdog_delay_ms are constants.
 class V8_EXPORT_PRIVATE MemoryReducer {
  public:
   enum Action { kDone, kWait, kRun };
 
   struct State {
     State(Action action, int started_gcs, double next_gc_start_ms,
-          double last_gc_time_ms)
+          double last_gc_time_ms, size_t committed_memory_at_last_run)
         : action(action),
           started_gcs(started_gcs),
           next_gc_start_ms(next_gc_start_ms),
-          last_gc_time_ms(last_gc_time_ms) {}
+          last_gc_time_ms(last_gc_time_ms),
+          committed_memory_at_last_run(committed_memory_at_last_run) {}
     Action action;
     int started_gcs;
     double next_gc_start_ms;
     double last_gc_time_ms;
+    size_t committed_memory_at_last_run;
   };
 
   enum EventType { kTimer, kMarkCompact, kPossibleGarbage };
 
   struct Event {
     EventType type;
     double time_ms;
+    size_t committed_memory;
     bool next_gc_likely_to_collect_more;
     bool should_start_incremental_gc;
     bool can_start_incremental_gc;
   };
 
   explicit MemoryReducer(Heap* heap)
       : heap_(heap),
-        state_(kDone, 0, 0.0, 0.0),
+        state_(kDone, 0, 0.0, 0.0, 0),
         js_calls_counter_(0),
         js_calls_sample_time_ms_(0.0) {}
   // Callbacks.
   void NotifyMarkCompact(const Event& event);
   void NotifyPossibleGarbage(const Event& event);
   void NotifyBackgroundIdleNotification(const Event& event);
   // The step function that computes the next state from the current state and
   // the incoming event.
   static State Step(const State& state, const Event& event);
   // Posts a timer task that will call NotifyTimer after the given delay.
   void ScheduleTimer(double time_ms, double delay_ms);
   void TearDown();
   static const int kLongDelayMs;
   static const int kShortDelayMs;
   static const int kWatchdogDelayMs;
   static const int kMaxNumberOfGCs;
+  // The committed memory has to increase by at least this factor since the
+  // last run in order to trigger a new run after mark-compact.
+  static const double kCommittedMemoryFactor;
+  // The committed memory has to increase by at least this amount since the
+  // last run in order to trigger a new run after mark-compact.
+  static const size_t kCommittedMemoryDelta;
 
   Heap* heap() { return heap_; }
 
   bool ShouldGrowHeapSlowly() {
     return state_.action == kDone && state_.started_gcs > 0;
   }
 
  private:
   class TimerTask : public v8::internal::CancelableTask {
    public:
@@ skipping 17 matching lines @@
 
   // Used in cctest.
   friend class HeapTester;
   DISALLOW_COPY_AND_ASSIGN(MemoryReducer);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_memory_reducer_H