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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef GPU_COMMAND_BUFFER_COMMON_SHM_COUNT_H_
#define GPU_COMMAND_BUFFER_COMMON_SHM_COUNT_H_
#include <atomic>
#include "base/memory/raw_ptr.h"
#include "base/memory/shared_memory_mapping.h"
#include "base/memory/unsafe_shared_memory_region.h"
#include "gpu/command_buffer/common/gpu_command_buffer_common_export.h"
namespace gpu {
// Base class for GpuProcessShmCount and GpuProcessHostShmCount,
// can not be used directly.
class GPU_COMMAND_BUFFER_COMMON_EXPORT ShmCountBase {
public:
using CountType = int32_t;
protected:
using AtomicType = std::atomic<CountType>;
ShmCountBase();
ShmCountBase(ShmCountBase&& other);
ShmCountBase& operator=(ShmCountBase&& other);
~ShmCountBase();
void Initialize(base::UnsafeSharedMemoryRegion region);
bool IsInitialized() const;
const base::UnsafeSharedMemoryRegion& region() const { return region_; }
volatile AtomicType* AsAtomic();
private:
base::UnsafeSharedMemoryRegion region_;
base::WritableSharedMemoryMapping mapping_;
};
// Provides write-only access to the count for the gpu process.
// It is safe to use ScopedIncrement from multiple threads on the same instance
// of GpuProcessShmCount.
class GPU_COMMAND_BUFFER_COMMON_EXPORT GpuProcessShmCount
: public ShmCountBase {
public:
class ScopedIncrement {
public:
explicit ScopedIncrement(GpuProcessShmCount* shm_count)
: shm_count_(shm_count) {
CHECK(shm_count_);
shm_count_->Increment();
}
~ScopedIncrement() { shm_count_->Decrement(); }
private:
const raw_ptr<GpuProcessShmCount> shm_count_;
};
GpuProcessShmCount();
explicit GpuProcessShmCount(base::UnsafeSharedMemoryRegion region);
protected:
// Virtual for testing.
virtual void Increment();
virtual void Decrement();
};
// Provides read-only access to the count for the browser process.
// GpuProcessHostShmCount will initialize a new mojo shared buffer. The
// handle to this buffer should be passed to the GPU process via CloneHandle.
// The GPU process will then increment the count, which can be read via this
// class.
class GPU_COMMAND_BUFFER_COMMON_EXPORT GpuProcessHostShmCount
: public ShmCountBase {
public:
GpuProcessHostShmCount();
CountType GetCount();
base::UnsafeSharedMemoryRegion CloneRegion() { return region().Duplicate(); }
};
} // namespace gpu
#endif // GPU_COMMAND_BUFFER_COMMON_SHM_COUNT_H_
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