Check if there is still time before finalizing an incremental collection.

src/heap/incremental-marking.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/v8.h"
 
 #include "src/heap/incremental-marking.h"
 
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/conversions.h"
 #include "src/heap/objects-visiting.h"
 #include "src/heap/objects-visiting-inl.h"
 
 namespace v8 {
 namespace internal {
 
 
 IncrementalMarking::IncrementalMarking(Heap* heap)
     : heap_(heap),
       state_(STOPPED),
       marking_deque_memory_(NULL),
       marking_deque_memory_committed_(false),
       steps_count_(0),
       old_generation_space_available_at_start_of_incremental_(0),
       old_generation_space_used_at_start_of_incremental_(0),
       should_hurry_(false),
       marking_speed_(0),
       allocated_(0),
+      idle_marking_delay_counter_(0),
       no_marking_scope_depth_(0),
       unscanned_bytes_of_large_object_(0) {}
 
 
 void IncrementalMarking::TearDown() { delete marking_deque_memory_; }
 
 
 void IncrementalMarking::RecordWriteSlow(HeapObject* obj, Object** slot,
                                          Object* value) {
   if (BaseRecordWrite(obj, slot, value) && slot != NULL) {
@@ skipping 845 matching lines @@
       marking_speed_ = static_cast<int>(
           Min(kMaxMarkingSpeed, static_cast<intptr_t>(marking_speed_ * 1.3)));
       if (FLAG_trace_gc) {
         PrintPID("Marking speed increased to %d\n", marking_speed_);
       }
     }
   }
 }
 
 
-void IncrementalMarking::Step(intptr_t allocated_bytes, CompletionAction action,
-                              bool force_marking) {
+intptr_t IncrementalMarking::Step(intptr_t allocated_bytes,
+                                  CompletionAction action,
+                                  ForceMarkingAction marking,
+                                  ForceCompletionAction completion) {
   if (heap_->gc_state() != Heap::NOT_IN_GC || !FLAG_incremental_marking ||
       !FLAG_incremental_marking_steps ||
       (state_ != SWEEPING && state_ != MARKING)) {
-    return;
+    return 0;
   }
 
   allocated_ += allocated_bytes;
 
-  if (!force_marking && allocated_ < kAllocatedThreshold &&
+  if (marking == DO_NOT_FORCE_MARKING && allocated_ < kAllocatedThreshold &&
       write_barriers_invoked_since_last_step_ <
           kWriteBarriersInvokedThreshold) {
-    return;
+    return 0;
   }
 
-  if (state_ == MARKING && no_marking_scope_depth_ > 0) return;
+  if (state_ == MARKING && no_marking_scope_depth_ > 0) return 0;
 
+  intptr_t bytes_processed = 0;
   {
     HistogramTimerScope incremental_marking_scope(
         heap_->isolate()->counters()->gc_incremental_marking());
     double start = base::OS::TimeCurrentMillis();
 
     // The marking speed is driven either by the allocation rate or by the rate
     // at which we are having to check the color of objects in the write
     // barrier.
     // It is possible for a tight non-allocating loop to run a lot of write
     // barriers before we get here and check them (marking can only take place
     // on
     // allocation), so to reduce the lumpiness we don't use the write barriers
     // invoked since last step directly to determine the amount of work to do.
     intptr_t bytes_to_process =
         marking_speed_ *
         Max(allocated_, write_barriers_invoked_since_last_step_);
     allocated_ = 0;
     write_barriers_invoked_since_last_step_ = 0;
 
     bytes_scanned_ += bytes_to_process;
-    intptr_t bytes_processed = 0;
 
     if (state_ == SWEEPING) {
       if (heap_->mark_compact_collector()->sweeping_in_progress() &&
           heap_->mark_compact_collector()->IsSweepingCompleted()) {
         heap_->mark_compact_collector()->EnsureSweepingCompleted();
       }
       if (!heap_->mark_compact_collector()->sweeping_in_progress()) {
         bytes_scanned_ = 0;
         StartMarking(PREVENT_COMPACTION);
       }
     } else if (state_ == MARKING) {
       bytes_processed = ProcessMarkingDeque(bytes_to_process);
-      if (marking_deque_.IsEmpty()) MarkingComplete(action);
+      if (marking_deque_.IsEmpty()) {
+        if (completion == FORCE_COMPLETION ||
+            IsIdleMarkingDelayCounterLimitReached()) {
+          MarkingComplete(action);
+        } else {
+          IncrementIdleMarkingDelayCounter();
+        }
+      }
     }
 
     steps_count_++;
 
     // Speed up marking if we are marking too slow or if we are almost done
     // with marking.
     SpeedUp();
 
     double end = base::OS::TimeCurrentMillis();
     double duration = (end - start);
     // Note that we report zero bytes here when sweeping was in progress or
     // when we just started incremental marking. In these cases we did not
     // process the marking deque.
     heap_->tracer()->AddIncrementalMarkingStep(duration, bytes_processed);
   }
+  return bytes_processed;
 }
 
 
 void IncrementalMarking::ResetStepCounters() {
   steps_count_ = 0;
   old_generation_space_available_at_start_of_incremental_ =
       SpaceLeftInOldSpace();
   old_generation_space_used_at_start_of_incremental_ =
       heap_->PromotedTotalSize();
   bytes_rescanned_ = 0;
   marking_speed_ = kInitialMarkingSpeed;
   bytes_scanned_ = 0;
   write_barriers_invoked_since_last_step_ = 0;
 }
 
 
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects();
 }
+
+
+bool IncrementalMarking::IsIdleMarkingDelayCounterLimitReached() {
+  return idle_marking_delay_counter_ > kMaxIdleMarkingDelayCounter;
+}
+
+
+void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
+  idle_marking_delay_counter_++;
+}
+
+
+void IncrementalMarking::ClearIdleMarkingDelayCounter() {
+  idle_marking_delay_counter_ = 0;
+}
 }
 }  // namespace v8::internal