[heap] Add inlined fast path for JSArrayBuffer (un)register in tracker

src/heap/array-buffer-tracker-inl.h

Index: src/heap/array-buffer-tracker-inl.h
diff --git a/src/heap/array-buffer-tracker-inl.h b/src/heap/array-buffer-tracker-inl.h
new file mode 100644
index 0000000000000000000000000000000000000000..7f6e43af58720c3dc8258f6ebd975178c92f8c58
--- /dev/null
+++ b/src/heap/array-buffer-tracker-inl.h
@@ -0,0 +1,68 @@
+// Copyright 2016 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/conversions-inl.h"
+#include "src/heap/array-buffer-tracker.h"
+#include "src/heap/heap.h"
+#include "src/objects.h"
+
+namespace v8 {
+namespace internal {
+
+void ArrayBufferTracker::RegisterNew(Heap* heap, JSArrayBuffer* buffer) {
+  void* data = buffer->backing_store();
+  if (!data) return;
+
+  size_t length = NumberToSize(heap->isolate(), buffer->byte_length());
+  Page* page = Page::FromAddress(buffer->address());
+  {
+    base::LockGuard<base::Mutex> guard(page->mutex());
+    LocalArrayBufferTracker* tracker = page->local_tracker();
+    if (tracker == nullptr) {
+      page->AllocateLocalTracker();
+      tracker = page->local_tracker();
+    }
+    DCHECK_NOT_NULL(tracker);
+    tracker->Add(buffer, std::make_pair(data, length));
+  }
+  // We may go over the limit of externally allocated memory here. We call the
+  // api function to trigger a GC in this case.
+  reinterpret_cast<v8::Isolate*>(heap->isolate())
+      ->AdjustAmountOfExternalAllocatedMemory(length);
+}
+
+void ArrayBufferTracker::Unregister(Heap* heap, JSArrayBuffer* buffer) {
+  void* data = buffer->backing_store();
+  if (!data) return;
+
+  Page* page = Page::FromAddress(buffer->address());
+  size_t length = 0;
+  {
+    base::LockGuard<base::Mutex> guard(page->mutex());
+    LocalArrayBufferTracker* tracker = page->local_tracker();
+    DCHECK_NOT_NULL(tracker);
+    length = tracker->Remove(buffer).second;
+  }
+  heap->update_amount_of_external_allocated_memory(
+      -static_cast<intptr_t>(length));
+}
+
+void LocalArrayBufferTracker::Add(Key key, const Value& value) {
+  auto ret = array_buffers_.insert(std::make_pair(key, value));
+  USE(ret);
+  // Check that we indeed inserted a new value and did not overwrite an existing
+  // one (which would be a bug).
+  DCHECK(ret.second);
+}
+
+LocalArrayBufferTracker::Value LocalArrayBufferTracker::Remove(Key key) {
+  TrackingMap::iterator it = array_buffers_.find(key);
+  DCHECK(it != array_buffers_.end());
+  Value value = it->second;
+  array_buffers_.erase(it);
+  return value;
+}
+
+}  // namespace internal
+}  // namespace v8