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