| // 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. |
| |
| #ifndef V8_HEAP_ARRAY_BUFFER_TRACKER_H_ |
| #define V8_HEAP_ARRAY_BUFFER_TRACKER_H_ |
| |
| #include <unordered_map> |
| |
| #include "src/base/platform/mutex.h" |
| #include "src/common/globals.h" |
| #include "src/objects/js-array-buffer.h" |
| #include "src/utils/allocation.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| class MarkingState; |
| class Page; |
| class Space; |
| |
| class ArrayBufferTracker : public AllStatic { |
| public: |
| enum ProcessingMode { |
| kUpdateForwardedRemoveOthers, |
| kUpdateForwardedKeepOthers, |
| }; |
| |
| // The following methods are used to track raw C++ pointers to externally |
| // allocated memory used as backing store in live array buffers. |
| |
| // Register/unregister a new JSArrayBuffer |buffer| for tracking. Guards all |
| // access to the tracker by taking the page lock for the corresponding page. |
| inline static void RegisterNew(Heap* heap, JSArrayBuffer buffer); |
| inline static void Unregister(Heap* heap, JSArrayBuffer buffer); |
| |
| // Identifies all backing store pointers for dead JSArrayBuffers in new space. |
| // Does not take any locks and can only be called during Scavenge. |
| static void PrepareToFreeDeadInNewSpace(Heap* heap); |
| |
| // Frees all backing store pointers for dead JSArrayBuffer on a given page. |
| // Requires marking information to be present. Requires the page lock to be |
| // taken by the caller. |
| template <typename MarkingState> |
| static void FreeDead(Page* page, MarkingState* marking_state); |
| |
| // Frees all remaining, live or dead, array buffers on a page. Only useful |
| // during tear down. |
| static void FreeAll(Page* page); |
| |
| // Processes all array buffers on a given page. |mode| specifies the action |
| // to perform on the buffers. Returns whether the tracker is empty or not. |
| static bool ProcessBuffers(Page* page, ProcessingMode mode); |
| |
| // Returns whether a buffer is currently tracked. |
| V8_EXPORT_PRIVATE static bool IsTracked(JSArrayBuffer buffer); |
| |
| // Tears down the tracker and frees up all registered array buffers. |
| static void TearDown(Heap* heap); |
| }; |
| |
| // LocalArrayBufferTracker tracks internalized array buffers. |
| // |
| // Never use directly but instead always call through |ArrayBufferTracker|. |
| class LocalArrayBufferTracker { |
| public: |
| enum CallbackResult { kKeepEntry, kUpdateEntry, kRemoveEntry }; |
| enum FreeMode { kFreeDead, kFreeAll }; |
| |
| explicit LocalArrayBufferTracker(Page* page) : page_(page) {} |
| ~LocalArrayBufferTracker(); |
| |
| inline void Add(JSArrayBuffer buffer, size_t length); |
| inline void Remove(JSArrayBuffer buffer, size_t length); |
| |
| // Frees up array buffers. |
| // |
| // Sample usage: |
| // Free([](HeapObject array_buffer) { |
| // if (should_free_internal(array_buffer)) return true; |
| // return false; |
| // }); |
| template <typename Callback> |
| void Free(Callback should_free); |
| |
| // Processes buffers one by one. The CallbackResult of the callback decides |
| // what action to take on the buffer. |
| // |
| // Callback should be of type: |
| // CallbackResult fn(JSArrayBuffer buffer, JSArrayBuffer* new_buffer); |
| template <typename Callback> |
| void Process(Callback callback); |
| |
| bool IsEmpty() const { return array_buffers_.empty(); } |
| |
| bool IsTracked(JSArrayBuffer buffer) const { |
| return array_buffers_.find(buffer) != array_buffers_.end(); |
| } |
| |
| private: |
| class Hasher { |
| public: |
| size_t operator()(JSArrayBuffer buffer) const { |
| return static_cast<size_t>(buffer.ptr() >> 3); |
| } |
| }; |
| |
| // Keep track of the backing store and the corresponding length at time of |
| // registering. The length is accessed from JavaScript and can be a |
| // HeapNumber. The reason for tracking the length is that in the case of |
| // length being a HeapNumber, the buffer and its length may be stored on |
| // different memory pages, making it impossible to guarantee order of freeing. |
| using TrackingData = |
| std::unordered_map<JSArrayBuffer, JSArrayBuffer::Allocation, Hasher>; |
| |
| // Internal version of add that does not update counters. Requires separate |
| // logic for updating external memory counters. |
| inline void AddInternal(JSArrayBuffer buffer, size_t length); |
| |
| Page* page_; |
| // The set contains raw heap pointers which are removed by the GC upon |
| // processing the tracker through its owning page. |
| TrackingData array_buffers_; |
| }; |
| |
| } // namespace internal |
| } // namespace v8 |
| #endif // V8_HEAP_ARRAY_BUFFER_TRACKER_H_ |