Add kGCCallbackFlagCollectAllExternalMemory for external memory limit triggered gc

include/v8.h

 // 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.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 5220 matching lines @@
  *   - kGCCallbackFlagCollectAllAvailableGarbage: The GC callback is called
  *     in a phase where V8 is trying to collect all available garbage
  *     (e.g., handling a low memory notification).
  */
 enum GCCallbackFlags {
   kNoGCCallbackFlags = 0,
   kGCCallbackFlagConstructRetainedObjectInfos = 1 << 1,
   kGCCallbackFlagForced = 1 << 2,
   kGCCallbackFlagSynchronousPhantomCallbackProcessing = 1 << 3,
   kGCCallbackFlagCollectAllAvailableGarbage = 1 << 4,
+  kGCCallbackFlagCollectAllExternalMemory = 1 << 5,
 };
 
 typedef void (*GCCallback)(GCType type, GCCallbackFlags flags);
 
 typedef void (*InterruptCallback)(Isolate* isolate, void* data);
 
 
 /**
  * Collection of V8 heap information.
  *
@@ skipping 3536 matching lines @@
   typedef internal::Internals I;
   return I::kNumIsolateDataSlots;
 }
 
 
 int64_t Isolate::AdjustAmountOfExternalAllocatedMemory(
     int64_t change_in_bytes) {
   typedef internal::Internals I;
   int64_t* external_memory = reinterpret_cast<int64_t*>(
       reinterpret_cast<uint8_t*>(this) + I::kExternalMemoryOffset);
-  const int64_t external_memory_limit = *reinterpret_cast<int64_t*>(
+  int64_t* external_memory_limit = reinterpret_cast<int64_t*>(
       reinterpret_cast<uint8_t*>(this) + I::kExternalMemoryLimitOffset);
   const int64_t amount = *external_memory + change_in_bytes;
   *external_memory = amount;
-  if (change_in_bytes > 0 && amount > external_memory_limit) {
+  if (amount + 192 * 1024 * 1024 < *external_memory_limit) {

[Michael Lippautz, 2016/08/12 07:06:23]

Can we avoid polluting the API and instead adjust the external_memory_limit from
within V8?

The fast check here should merely be a comparison of a counter against a limit.

+    *external_memory_limit = amount + 192 * 1024 * 1024;

[Hannes Payer (out of office), 2016/08/12 14:06:09]

Why are you shrinking the limit here?

+  }
+  if (change_in_bytes > 0 && amount > *external_memory_limit) {
     ReportExternalAllocationLimitReached();
   }
   return *external_memory;
 }
 
 
 template<typename T>
 void Isolate::SetObjectGroupId(const Persistent<T>& object,
                                UniqueId id) {
   TYPE_CHECK(Value, T);
@@ skipping 154 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_