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// Copyright 2020 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_SWEEPER_H_
#define V8_HEAP_ARRAY_BUFFER_SWEEPER_H_
#include "src/base/platform/mutex.h"
#include "src/objects/js-array-buffer.h"
#include "src/tasks/cancelable-task.h"
namespace v8 {
namespace internal {
class ArrayBufferExtension;
class Heap;
// Singly linked-list of ArrayBufferExtensions that stores head and tail of the
// list to allow for concatenation of lists.
struct ArrayBufferList {
ArrayBufferList() : head_(nullptr), tail_(nullptr), bytes_(0) {}
ArrayBufferExtension* head_;
ArrayBufferExtension* tail_;
size_t bytes_;
bool IsEmpty() {
DCHECK_IMPLIES(head_, tail_);
return head_ == nullptr;
}
size_t Bytes() { return bytes_; }
size_t BytesSlow();
void Reset() {
head_ = tail_ = nullptr;
bytes_ = 0;
}
void Append(ArrayBufferExtension* extension);
void Append(ArrayBufferList* list);
V8_EXPORT_PRIVATE bool Contains(ArrayBufferExtension* extension);
};
// The ArrayBufferSweeper iterates and deletes ArrayBufferExtensions
// concurrently to the application.
class ArrayBufferSweeper {
public:
explicit ArrayBufferSweeper(Heap* heap)
: heap_(heap),
sweeping_in_progress_(false),
freed_bytes_(0),
young_bytes_(0),
old_bytes_(0) {}
~ArrayBufferSweeper() { ReleaseAll(); }
void EnsureFinished();
void RequestSweepYoung();
void RequestSweepFull();
// Track the given ArrayBufferExtension for the given JSArrayBuffer.
void Append(JSArrayBuffer object, ArrayBufferExtension* extension);
// Detaches an ArrayBufferExtension from a JSArrayBuffer.
void Detach(JSArrayBuffer object, ArrayBufferExtension* extension);
ArrayBufferList young() { return young_; }
ArrayBufferList old() { return old_; }
size_t YoungBytes();
size_t OldBytes();
private:
enum class SweepingScope { kYoung, kFull };
enum class SweepingState { kInProgress, kDone };
struct SweepingJob {
ArrayBufferSweeper* sweeper_;
CancelableTaskManager::Id id_;
std::atomic<SweepingState> state_;
ArrayBufferList young_;
ArrayBufferList old_;
SweepingScope scope_;
SweepingJob(ArrayBufferSweeper* sweeper, ArrayBufferList young,
ArrayBufferList old, SweepingScope scope)
: sweeper_(sweeper),
id_(0),
state_(SweepingState::kInProgress),
young_(young),
old_(old),
scope_(scope) {}
void Sweep();
void SweepYoung();
void SweepFull();
ArrayBufferList SweepListFull(ArrayBufferList* list);
};
base::Optional<SweepingJob> job_;
void Merge();
void MergeBackExtensionsWhenSwept();
void UpdateCountersForConcurrentlySweptExtensions();
void IncrementExternalMemoryCounters(size_t bytes);
void DecrementExternalMemoryCounters(size_t bytes);
void IncrementFreedBytes(size_t bytes);
void RequestSweep(SweepingScope sweeping_task);
void Prepare(SweepingScope sweeping_task);
ArrayBufferList SweepYoungGen();
void SweepOldGen(ArrayBufferExtension* extension);
void ReleaseAll();
void ReleaseAll(ArrayBufferList* extension);
Heap* const heap_;
bool sweeping_in_progress_;
base::Mutex sweeping_mutex_;
base::ConditionVariable job_finished_;
std::atomic<size_t> freed_bytes_;
ArrayBufferList young_;
ArrayBufferList old_;
size_t young_bytes_;
size_t old_bytes_;
};
} // namespace internal
} // namespace v8
#endif // V8_HEAP_ARRAY_BUFFER_SWEEPER_H_
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