From 5bc51bb454ba4e96e9bcbdc4106b6986a27eed6e Mon Sep 17 00:00:00 2001
From: erikcorry <erikcorry@chromium.org>
Date: Mon, 11 May 2015 03:57:55 -0700
Subject: [PATCH] Postpone counters triggered during GC, and use a HandleScope
 when calling back.

R=jkummerow@chromium.org,hpayer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1125383007

Cr-Commit-Position: refs/heads/master@{#28335}
---
 include/v8.h             |  1 +
 src/heap/heap.cc         | 25 +++++++++++++++++++++++++
 src/heap/heap.h          |  4 ++++
 src/isolate.cc           | 11 +++++++++--
 test/cctest/test-heap.cc | 25 +++++++++++++++++++++++++
 5 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/include/v8.h b/include/v8.h
index 910279b..3e173da 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -5107,6 +5107,7 @@ class V8_EXPORT Isolate {
     kStoreBufferOverflow = 4,
     kSlotsBufferOverflow = 5,
     kObjectObserve = 6,
+    kForcedGC = 7,
     kUseCounterFeatureCount  // This enum value must be last.
   };
 
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 54a8915..2ba75d0 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -395,6 +395,20 @@ void Heap::ReportStatisticsAfterGC() {
 #else
   if (FLAG_log_gc) new_space_.ReportStatistics();
 #endif  // DEBUG
+  for (int i = 0; i < static_cast<int>(v8::Isolate::kUseCounterFeatureCount);
+       ++i) {
+    int count = deferred_counters_[i];
+    deferred_counters_[i] = 0;
+    while (count > 0) {
+      count--;
+      isolate()->CountUsage(static_cast<v8::Isolate::UseCounterFeature>(i));
+    }
+  }
+}
+
+
+void Heap::IncrementDeferredCount(v8::Isolate::UseCounterFeature feature) {
+  deferred_counters_[feature]++;
 }
 
 
@@ -925,6 +939,11 @@ bool Heap::CollectGarbage(GarbageCollector collector, const char* gc_reason,
     tracer()->Stop(collector);
   }
 
+  if (collector == MARK_COMPACTOR &&
+      (gc_callback_flags & kGCCallbackFlagForced) != 0) {
+    isolate()->CountUsage(v8::Isolate::kForcedGC);
+  }
+
   // Start incremental marking for the next cycle. The heap snapshot
   // generator needs incremental marking to stay off after it aborted.
   if (!mark_compact_collector()->abort_incremental_marking() &&
@@ -5422,6 +5441,12 @@ bool Heap::SetUp() {
     }
   }
 
+  for (int i = 0; i < static_cast<int>(v8::Isolate::kUseCounterFeatureCount);
+       i++) {
+    deferred_counters_[i] = 0;
+  }
+
+
   LOG(isolate_, IntPtrTEvent("heap-capacity", Capacity()));
   LOG(isolate_, IntPtrTEvent("heap-available", Available()));
 
diff --git a/src/heap/heap.h b/src/heap/heap.h
index ff6a11e..58be0a2 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1311,6 +1311,8 @@ class Heap {
   // Returns minimal interval between two subsequent collections.
   double get_min_in_mutator() { return min_in_mutator_; }
 
+  void IncrementDeferredCount(v8::Isolate::UseCounterFeature feature);
+
   MarkCompactCollector* mark_compact_collector() {
     return &mark_compact_collector_;
   }
@@ -2047,6 +2049,8 @@ class Heap {
   // Total RegExp code ever generated
   double total_regexp_code_generated_;
 
+  int deferred_counters_[v8::Isolate::kUseCounterFeatureCount];
+
   GCTracer tracer_;
 
   // Creates and installs the full-sized number string cache.
diff --git a/src/isolate.cc b/src/isolate.cc
index d53d0d8..69a4f8d 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -2669,8 +2669,15 @@ void Isolate::SetUseCounterCallback(v8::Isolate::UseCounterCallback callback) {
 
 
 void Isolate::CountUsage(v8::Isolate::UseCounterFeature feature) {
-  if (use_counter_callback_) {
-    use_counter_callback_(reinterpret_cast<v8::Isolate*>(this), feature);
+  // The counter callback may cause the embedder to call into V8, which is not
+  // generally possible during GC.
+  if (heap_.gc_state() == Heap::NOT_IN_GC) {
+    if (use_counter_callback_) {
+      HandleScope handle_scope(this);
+      use_counter_callback_(reinterpret_cast<v8::Isolate*>(this), feature);
+    }
+  } else {
+    heap_.IncrementDeferredCount(feature);
   }
 }
 
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index cb08fb4..d8c89ae 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -3203,6 +3203,31 @@ TEST(ReleaseOverReservedPages) {
   CHECK_EQ(1, old_space->CountTotalPages());
 }
 
+static int forced_gc_counter = 0;
+
+void MockUseCounterCallback(v8::Isolate* isolate,
+                            v8::Isolate::UseCounterFeature feature) {
+  isolate->GetCallingContext();
+  if (feature == v8::Isolate::kForcedGC) {
+    forced_gc_counter++;
+  }
+}
+
+
+TEST(CountForcedGC) {
+  i::FLAG_expose_gc = true;
+  CcTest::InitializeVM();
+  Isolate* isolate = CcTest::i_isolate();
+  v8::HandleScope scope(CcTest::isolate());
+
+  isolate->SetUseCounterCallback(MockUseCounterCallback);
+
+  forced_gc_counter = 0;
+  const char* source = "gc();";
+  CompileRun(source);
+  CHECK_GT(forced_gc_counter, 0);
+}
+
 
 TEST(Regress2237) {
   i::FLAG_stress_compaction = false;
-- 
2.7.4