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* Copyright (C) 2012 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <time.h>
#include <audio_utils/fifo.h>
#include <media/SingleStateQueue.h>
#include <media/nbaio/NBAIO.h>
namespace android {
typedef SingleStateQueue<ExtendedTimestamp> ExtendedTimestampSingleStateQueue;
// MonoPipe is similar to Pipe except:
// - supports only a single reader, called MonoPipeReader
// - write() cannot overrun; instead it will return a short actual count if insufficient space
// - write() can optionally block if the pipe is full
// Like Pipe, it is not multi-thread safe for either writer or reader
// but writer and reader can be different threads.
class MonoPipe : public NBAIO_Sink {
friend class MonoPipeReader;
// reqFrames will be rounded up to a power of 2, and all slots are available. Must be >= 2.
// Note: whatever shares this object with another thread needs to do so in an SMP-safe way (like
// creating it the object before creating the other thread, or storing the object with a
// release_store). Otherwise the other thread could see a partially-constructed object.
MonoPipe(size_t reqFrames, const NBAIO_Format& format, bool writeCanBlock = false);
virtual ~MonoPipe();
// NBAIO_Port interface
//virtual ssize_t negotiate(const NBAIO_Format offers[], size_t numOffers,
// NBAIO_Format counterOffers[], size_t& numCounterOffers);
//virtual NBAIO_Format format() const;
// NBAIO_Sink interface
//virtual int64_t framesWritten() const;
//virtual int64_t framesUnderrun() const;
//virtual int64_t underruns() const;
// returns n where 0 <= n <= mMaxFrames, or a negative status_t
// including the private status codes in NBAIO.h
virtual ssize_t availableToWrite();
virtual ssize_t write(const void *buffer, size_t count);
//virtual ssize_t writeVia(writeVia_t via, size_t total, void *user, size_t block);
// average number of frames present in the pipe under normal conditions.
// See throttling mechanism in MonoPipe::write()
size_t getAvgFrames() const { return mSetpoint; }
void setAvgFrames(size_t setpoint);
size_t maxFrames() const { return mMaxFrames; }
// Set the shutdown state for the write side of a pipe.
// This may be called by an unrelated thread. When shutdown state is 'true',
// a write that would otherwise block instead returns a short transfer count.
// There is no guarantee how long it will take for the shutdown to be recognized,
// but it will not be an unbounded amount of time.
// The state can be restored to normal by calling shutdown(false).
void shutdown(bool newState = true);
// Return true if the write side of a pipe is currently shutdown.
bool isShutdown();
// Return NO_ERROR if there is a timestamp available
status_t getTimestamp(ExtendedTimestamp &timestamp);
const size_t mMaxFrames; // as requested in constructor, rounded up to a power of 2
void * const mBuffer;
audio_utils_fifo mFifo;
audio_utils_fifo_writer mFifoWriter;
bool mWriteTsValid; // whether mWriteTs is valid
struct timespec mWriteTs; // time that the previous write() completed
size_t mSetpoint; // target value for pipe fill depth
const bool mWriteCanBlock; // whether write() should block if the pipe is full
bool mIsShutdown; // whether shutdown(true) was called, no barriers are needed
ExtendedTimestampSingleStateQueue::Shared mTimestampShared;
ExtendedTimestampSingleStateQueue::Mutator mTimestampMutator;
ExtendedTimestampSingleStateQueue::Observer mTimestampObserver;
} // namespace android