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#ifndef ANDROID_DVR_SERVICES_DISPLAYD_ACQUIRED_BUFFER_H_
#define ANDROID_DVR_SERVICES_DISPLAYD_ACQUIRED_BUFFER_H_
#include <pdx/file_handle.h>
#include <private/dvr/consumer_buffer.h>
#include <memory>
namespace android {
namespace dvr {
// Manages the ACQUIRE/RELEASE ownership cycle of a ConsumerBuffer.
class AcquiredBuffer {
public:
static constexpr int kEmptyFence = pdx::LocalHandle::kEmptyFileHandle;
AcquiredBuffer() : buffer_(nullptr), acquire_fence_(kEmptyFence) {}
// Constructs an AcquiredBuffer from a ConsumerBuffer pointer and an acquire
// fence. The ConsumerBuffer MUST be in the ACQUIRED state prior to calling
// this constructor; the constructor does not attempt to ACQUIRE the buffer
// itself.
AcquiredBuffer(const std::shared_ptr<ConsumerBuffer>& buffer,
pdx::LocalHandle acquire_fence, std::size_t slot = 0);
// Constructs an AcquiredBuffer from a ConsumerBuffer. The ConsumerBuffer MUST
// be in the POSTED state prior to calling this constructor, as this
// constructor attempts to ACQUIRE the buffer. If ACQUIRING the buffer fails
// this instance is left in the empty state. An optional error code is
// returned in |error|, which may be nullptr if not needed.
AcquiredBuffer(const std::shared_ptr<ConsumerBuffer>& buffer, int* error);
// Move constructor. Behaves similarly to the move assignment operator below.
AcquiredBuffer(AcquiredBuffer&& other) noexcept;
~AcquiredBuffer();
// Move assignment operator. Moves the ConsumerBuffer and acquire fence from
// |other| into this instance after RELEASING the current ConsumerBuffer and
// closing the acquire fence. After the move |other| is left in the empty
// state.
AcquiredBuffer& operator=(AcquiredBuffer&& other) noexcept;
// Accessors for the underlying ConsumerBuffer, the acquire fence, and the
// use-case specific sequence value from the acquisition (see
// private/dvr/consumer_buffer.h).
std::shared_ptr<ConsumerBuffer> buffer() const { return buffer_; }
int acquire_fence() const { return acquire_fence_.Get(); }
// When non-empty, returns true if the acquired fence was signaled (or if the
// fence is empty). Returns false when empty or if the fence is not signaled.
bool IsAvailable() const;
bool IsEmpty() const { return buffer_ == nullptr; }
// Returns the acquire fence, passing ownership to the caller.
pdx::LocalHandle ClaimAcquireFence();
// Returns the buffer, passing ownership to the caller. Caller is responsible
// for calling Release on the returned buffer.
std::shared_ptr<ConsumerBuffer> ClaimBuffer();
// Releases the ConsumerBuffer, passing the release fence in |release_fence|
// to the producer. On success, the ConsumerBuffer and acquire fence are set
// to empty state; if release fails, the ConsumerBuffer and acquire fence are
// left in place and a negative error code is returned.
int Release(pdx::LocalHandle release_fence = {});
// Returns the slot in the queue this buffer belongs to. Buffers that are not
// part of a queue return 0.
std::size_t slot() const { return slot_; }
private:
std::shared_ptr<ConsumerBuffer> buffer_;
// Mutable so that the fence can be closed when it is determined to be
// signaled during IsAvailable().
mutable pdx::LocalHandle acquire_fence_;
std::size_t slot_{0};
AcquiredBuffer(const AcquiredBuffer&) = delete;
void operator=(const AcquiredBuffer&) = delete;
};
} // namespace dvr
} // namespace android
#endif // ANDROID_DVR_SERVICES_DISPLAYD_ACQUIRED_BUFFER_H_
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