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/*
* Copyright (C) 2020 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <memory>
#include <chrono>
#include <utility>
#include <condition_variable>
#include <mutex>
#include <stdint.h>
namespace android {
namespace hardware {
namespace audio {
namespace V6_0 {
namespace implementation {
// A one-producer-one-consumer ring buffer.
struct RingBuffer {
typedef std::chrono::time_point<std::chrono::high_resolution_clock> Timepoint;
RingBuffer(size_t capacity);
size_t capacity() const { return mCapacity; }
size_t availableToProduce() const;
size_t availableToConsume() const;
struct ContiniousChunk {
void *data;
size_t size;
std::unique_lock<std::mutex> lock;
};
struct ContiniousLockedChunk : public ContiniousChunk{
std::unique_lock<std::mutex> lock;
};
size_t makeRoomForProduce(size_t atLeast);
bool waitForProduceAvailable(Timepoint blockUntil) const;
// `getProduceChunk` is a non-blocking function which returns a pointer
// (`result.data`) inside RingBuffer's buffer, `result.size` is the
// size of the continious chunk (can be smaller than availableToProduce()).
ContiniousChunk getProduceChunk() const;
// Tries to move the `produce` cursor by `size`, returns the actual size
// moved.
size_t produce(size_t size);
// Tried to write `size` bytes into the internal buffer from `data`,
// returns the actual size written.
size_t produce(const void *data, size_t size);
bool waitForConsumeAvailable(Timepoint blockUntil) const;
// `getConsumeChunk` is a non-blocking function which a pointer
// (`result.data`) inside RingBuffer's buffer, `result.size` is the
// size of the continious chunk (can be smaller than availableToConsume()).
// IMPORTANT: do not call long running functions while have an instance of
// ContiniousLockedChunk, it might block the producer because
// it need to drop the stale audio data to replace it with
// more recent one.
// NOTE: ContiniousLockedChunk holds a lock inside, it might deadlock
// if you calling other RingBuffer's functions that assume it is
// unlocked, in this case you want to introduce a function like
// `consume` below.
ContiniousLockedChunk getConsumeChunk() const;
// Tries to move the `consume` cursor by `size`, returns the actual size
// moved.
size_t consume(const ContiniousLockedChunk&, size_t size);
private:
std::unique_ptr<uint8_t[]> mBuffer;
mutable std::condition_variable mProduceAvailable;
mutable std::condition_variable mConsumeAvailable;
mutable std::mutex mMutex;
const int mCapacity;
int mAvailableToConsume = 0;
int mProducePos = 0;
int mConsumePos = 0;
};
} // namespace implementation
} // namespace V6_0
} // namespace audio
} // namespace hardware
} // namespace android
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