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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_ALLOCATION_OBSERVER_H_
#define V8_HEAP_ALLOCATION_OBSERVER_H_
#include <cstdint>
#include <unordered_set>
#include <vector>
#include "src/common/globals.h"
namespace v8 {
namespace internal {
class AllocationObserver;
class AllocationCounter {
public:
AllocationCounter()
: paused_(false),
current_counter_(0),
next_counter_(0),
step_in_progress_(false) {}
V8_EXPORT_PRIVATE void AddAllocationObserver(AllocationObserver* observer);
V8_EXPORT_PRIVATE void RemoveAllocationObserver(AllocationObserver* observer);
bool IsActive() { return !IsPaused() && observers_.size() > 0; }
void Pause() {
DCHECK(!paused_);
DCHECK(!step_in_progress_);
paused_ = true;
}
void Resume() {
DCHECK(paused_);
DCHECK(!step_in_progress_);
paused_ = false;
}
V8_EXPORT_PRIVATE void AdvanceAllocationObservers(size_t allocated);
V8_EXPORT_PRIVATE void InvokeAllocationObservers(Address soon_object,
size_t object_size,
size_t aligned_object_size);
size_t NextBytes() {
DCHECK(IsActive());
return next_counter_ - current_counter_;
}
bool IsStepInProgress() { return step_in_progress_; }
private:
bool IsPaused() { return paused_; }
struct AllocationObserverCounter {
AllocationObserverCounter(AllocationObserver* observer, size_t prev_counter,
size_t next_counter)
: observer_(observer),
prev_counter_(prev_counter),
next_counter_(next_counter) {}
AllocationObserver* observer_;
size_t prev_counter_;
size_t next_counter_;
};
std::vector<AllocationObserverCounter> observers_;
std::vector<AllocationObserverCounter> pending_added_;
std::unordered_set<AllocationObserver*> pending_removed_;
bool paused_;
size_t current_counter_;
size_t next_counter_;
bool step_in_progress_;
};
// -----------------------------------------------------------------------------
// Allows observation of allocations.
class AllocationObserver {
public:
explicit AllocationObserver(intptr_t step_size) : step_size_(step_size) {
DCHECK_LE(kTaggedSize, step_size);
}
virtual ~AllocationObserver() = default;
AllocationObserver(const AllocationObserver&) = delete;
AllocationObserver& operator=(const AllocationObserver&) = delete;
protected:
// Pure virtual method provided by the subclasses that gets called when at
// least step_size bytes have been allocated. soon_object is the address just
// allocated (but not yet initialized.) size is the size of the object as
// requested (i.e. w/o the alignment fillers). Some complexities to be aware
// of:
// 1) soon_object will be nullptr in cases where we end up observing an
// allocation that happens to be a filler space (e.g. page boundaries.)
// 2) size is the requested size at the time of allocation. Right-trimming
// may change the object size dynamically.
// 3) soon_object may actually be the first object in an allocation-folding
// group. In such a case size is the size of the group rather than the
// first object.
virtual void Step(int bytes_allocated, Address soon_object, size_t size) = 0;
// Subclasses can override this method to make step size dynamic.
virtual intptr_t GetNextStepSize() { return step_size_; }
private:
intptr_t step_size_;
friend class AllocationCounter;
};
class V8_EXPORT_PRIVATE V8_NODISCARD PauseAllocationObserversScope {
public:
explicit PauseAllocationObserversScope(Heap* heap);
~PauseAllocationObserversScope();
PauseAllocationObserversScope(const PauseAllocationObserversScope&) = delete;
PauseAllocationObserversScope& operator=(
const PauseAllocationObserversScope&) = delete;
private:
Heap* heap_;
};
} // namespace internal
} // namespace v8
#endif // V8_HEAP_ALLOCATION_OBSERVER_H_
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