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/*
* Copyright 2019 The WebRTC 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 in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef RTC_BASE_MEMORY_FIFO_BUFFER_H_
#define RTC_BASE_MEMORY_FIFO_BUFFER_H_
#include <cstddef>
#include <cstdint>
#include <memory>
#include "api/array_view.h"
#include "api/sequence_checker.h"
#include "api/task_queue/pending_task_safety_flag.h"
#include "rtc_base/stream.h"
#include "rtc_base/thread.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
// FifoBuffer allows for efficient, thread-safe buffering of data between
// writer and reader.
class FifoBuffer final : public StreamInterface {
public:
// Creates a FIFO buffer with the specified capacity.
explicit FifoBuffer(size_t length);
// Creates a FIFO buffer with the specified capacity and owner
FifoBuffer(size_t length, Thread* owner);
~FifoBuffer() override;
FifoBuffer(const FifoBuffer&) = delete;
FifoBuffer& operator=(const FifoBuffer&) = delete;
// Gets the amount of data currently readable from the buffer.
bool GetBuffered(size_t* data_len) const;
// StreamInterface methods
StreamState GetState() const override;
StreamResult Read(ArrayView<uint8_t> buffer,
size_t& bytes_read,
int& error) override;
StreamResult Write(ArrayView<const uint8_t> buffer,
size_t& bytes_written,
int& error) override;
void Close() override;
// Seek to a byte offset from the beginning of the stream. Returns false if
// the stream does not support seeking, or cannot seek to the specified
// position.
bool SetPosition(size_t position);
// Get the byte offset of the current position from the start of the stream.
// Returns false if the position is not known.
bool GetPosition(size_t* position) const;
// Seek to the start of the stream.
bool Rewind() { return SetPosition(0); }
// GetReadData returns a pointer to a buffer which is owned by the stream.
// The buffer contains data_len bytes. null is returned if no data is
// available, or if the method fails. If the caller processes the data, it
// must call ConsumeReadData with the number of processed bytes. GetReadData
// does not require a matching call to ConsumeReadData if the data is not
// processed. Read and ConsumeReadData invalidate the buffer returned by
// GetReadData.
const void* GetReadData(size_t* data_len);
void ConsumeReadData(size_t used);
// GetWriteBuffer returns a pointer to a buffer which is owned by the stream.
// The buffer has a capacity of buf_len bytes. null is returned if there is
// no buffer available, or if the method fails. The call may write data to
// the buffer, and then call ConsumeWriteBuffer with the number of bytes
// written. GetWriteBuffer does not require a matching call to
// ConsumeWriteData if no data is written. Write and
// ConsumeWriteData invalidate the buffer returned by GetWriteBuffer.
void* GetWriteBuffer(size_t* buf_len);
void ConsumeWriteBuffer(size_t used);
private:
void PostEvent(int events, int err) {
RTC_DCHECK_RUN_ON(owner_);
owner_->PostTask(SafeTask(task_safety_.flag(), [this, events, err]() {
RTC_DCHECK_RUN_ON(&callback_sequence_);
FireEvent(events, err);
}));
}
// Helper method that implements Read. Caller must acquire a lock
// when calling this method.
StreamResult ReadLocked(void* buffer, size_t bytes, size_t* bytes_read)
RTC_EXCLUSIVE_LOCKS_REQUIRED(callback_sequence_);
// Helper method that implements Write. Caller must acquire a lock
// when calling this method.
StreamResult WriteLocked(const void* buffer,
size_t bytes,
size_t* bytes_written)
RTC_EXCLUSIVE_LOCKS_REQUIRED(callback_sequence_);
ScopedTaskSafety task_safety_;
// keeps the opened/closed state of the stream
StreamState state_ RTC_GUARDED_BY(callback_sequence_);
// the allocated buffer
std::unique_ptr<char[]> buffer_ RTC_GUARDED_BY(callback_sequence_);
// size of the allocated buffer
const size_t buffer_length_;
// amount of readable data in the buffer
size_t data_length_ RTC_GUARDED_BY(callback_sequence_);
// offset to the readable data
size_t read_position_ RTC_GUARDED_BY(callback_sequence_);
// stream callbacks are dispatched on this thread
Thread* const owner_;
};
} // namespace webrtc
#endif // RTC_BASE_MEMORY_FIFO_BUFFER_H_
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