[heap] introduce ArrayBufferTracker

src/heap/array-buffer-tracker.cc

+// 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.
+
+#include "src/heap/array-buffer-tracker.h"
+#include "src/heap/heap.h"
+#include "src/isolate.h"
+#include "src/objects.h"
+#include "src/objects-inl.h"
+#include "src/v8.h"
+
+namespace v8 {
+namespace internal {
+
+void ArrayBufferTracker::RegisterNew(bool in_new_space, void* data,
+                                     size_t length) {
+  if (!data) return;
+  if (in_new_space) {
+    live_array_buffers_for_scavenge_[data] = length;
+  } else {
+    live_array_buffers_[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(JSArrayBuffer* buffer) {
+  bool in_new_space = heap()->InNewSpace(buffer);
+  void* data = buffer->backing_store();
+  if (!data) return;
+
+  std::map<void*, size_t>* live_buffers =
+      in_new_space ? &live_array_buffers_for_scavenge_ : &live_array_buffers_;
+  std::map<void*, size_t>* not_yet_discovered_buffers =
+      in_new_space ? &not_yet_discovered_array_buffers_for_scavenge_
+                   : &not_yet_discovered_array_buffers_;
+
+  DCHECK(live_buffers->count(data) > 0);
+
+  size_t length = (*live_buffers)[data];
+  live_buffers->erase(data);
+  not_yet_discovered_buffers->erase(data);
+
+  heap()->update_amount_of_external_allocated_memory(
+      -static_cast<int64_t>(length));
+}
+
+
+void ArrayBufferTracker::MarkLive(JSArrayBuffer* buffer) {
+  void* data = buffer->backing_store();
+
+  // ArrayBuffer might be in the middle of being constructed.
+  if (data == heap()->undefined_value()) return;
+  if (heap()->InNewSpace(buffer)) {
+    not_yet_discovered_array_buffers_for_scavenge_.erase(data);
+  } else {
+    not_yet_discovered_array_buffers_.erase(data);
+  }
+}
+
+
+void ArrayBufferTracker::FreeDead(bool from_scavenge) {
+  size_t freed_memory = 0;
+  Isolate* isolate = heap()->isolate();
+  for (auto& buffer : not_yet_discovered_array_buffers_for_scavenge_) {
+    isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
+    freed_memory += buffer.second;
+    live_array_buffers_for_scavenge_.erase(buffer.first);
+  }
+
+  if (!from_scavenge) {
+    for (auto& buffer : not_yet_discovered_array_buffers_) {
+      isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
+      freed_memory += buffer.second;
+      live_array_buffers_.erase(buffer.first);
+    }
+  }
+
+  not_yet_discovered_array_buffers_for_scavenge_ =
+      live_array_buffers_for_scavenge_;
+  if (!from_scavenge) not_yet_discovered_array_buffers_ = live_array_buffers_;
+
+  // Do not call through the api as this code is triggered while doing a GC.
+  heap()->update_amount_of_external_allocated_memory(
+      -static_cast<int64_t>(freed_memory));
+}
+
+
+void ArrayBufferTracker::PrepareDiscoveryInNewSpace() {
+  not_yet_discovered_array_buffers_for_scavenge_ =
+      live_array_buffers_for_scavenge_;
+}
+
+
+void ArrayBufferTracker::Promote(JSArrayBuffer* buffer) {
+  if (buffer->is_external()) return;
+  void* data = buffer->backing_store();
+  if (!data) return;
+  // ArrayBuffer might be in the middle of being constructed.
+  if (data == heap()->undefined_value()) return;
+  DCHECK(live_array_buffers_for_scavenge_.count(data) > 0);
+  live_array_buffers_[data] = live_array_buffers_for_scavenge_[data];
+  live_array_buffers_for_scavenge_.erase(data);
+  not_yet_discovered_array_buffers_for_scavenge_.erase(data);
+}
+
+
+void ArrayBufferTracker::TearDown() {
+  Isolate* isolate = heap()->isolate();
+  size_t freed_memory = 0;
+  for (auto& buffer : live_array_buffers_) {
+    isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
+    freed_memory += buffer.second;
+  }
+  for (auto& buffer : live_array_buffers_for_scavenge_) {
+    isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
+    freed_memory += buffer.second;
+  }
+  live_array_buffers_.clear();
+  live_array_buffers_for_scavenge_.clear();
+  not_yet_discovered_array_buffers_.clear();
+  not_yet_discovered_array_buffers_for_scavenge_.clear();
+
+  if (freed_memory > 0) {
+    reinterpret_cast<v8::Isolate*>(isolate)
+        ->AdjustAmountOfExternalAllocatedMemory(
+            -static_cast<int64_t>(freed_memory));
+  }
+}
+}
+}  // namespace v8::internal