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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <stdint.h>
#include <memory>
#include <string>
#include <vector>
#include "base/containers/circular_deque.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/read_only_shared_memory_region.h"
#include "base/sync_socket.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "media/audio/audio_input_controller.h"
#include "media/base/audio_bus.h"
#include "media/base/audio_parameters.h"
#include "media/base/media_export.h"
#if defined(OS_POSIX)
#include "base/file_descriptor_posix.h"
namespace media {
// A AudioInputController::SyncWriter implementation using SyncSocket. This
// is used by AudioInputController to provide a low latency data source for
// transmitting audio packets between the browser process and the renderer
// process.
class MEDIA_EXPORT AudioInputSyncWriter
: public AudioInputController::SyncWriter {
// Maximum fifo size (|overflow_buses_| and |overflow_params_|) in number of
// AudioBuses.
enum { kMaxOverflowBusesSize = 100 };
// Create() automatically initializes the AudioInputSyncWriter correctly,
// and should be strongly preferred over calling the constructor directly!
base::RepeatingCallback<void(const std::string&)> log_callback,
base::MappedReadOnlyRegion shared_memory,
std::unique_ptr<base::CancelableSyncSocket> socket,
uint32_t shared_memory_segment_count,
const AudioParameters& params);
~AudioInputSyncWriter() override;
static std::unique_ptr<AudioInputSyncWriter> Create(
base::RepeatingCallback<void(const std::string&)> log_callback,
uint32_t shared_memory_segment_count,
const AudioParameters& params,
base::CancelableSyncSocket* foreign_socket);
// Transfers shared memory region ownership to a caller. It shouldn't be
// called more than once.
base::ReadOnlySharedMemoryRegion TakeSharedMemoryRegion();
size_t shared_memory_segment_count() const { return audio_buses_.size(); }
// AudioInputController::SyncWriter implementation.
void Write(const AudioBus* data,
double volume,
bool key_pressed,
base::TimeTicks capture_time) override;
void Close() override;
friend class AudioInputSyncWriterTest;
// Called by Write(). Checks the time since last called and if larger than a
// threshold logs info about that.
void CheckTimeSinceLastWrite();
// Push |data| and metadata to |audio_buffer_fifo_|. Returns true if
// successful. Logs error and returns false if the fifo already reached the
// maximum size.
bool PushDataToFifo(const AudioBus* data,
double volume,
bool key_pressed,
base::TimeTicks capture_time);
// Writes as much data as possible from the fifo (|overflow_buses_|) to the
// shared memory ring buffer. Returns true if all operations were successful,
// otherwise false.
bool WriteDataFromFifoToSharedMemory();
// Write audio parameters to current segment in shared memory.
void WriteParametersToCurrentSegment(double volume,
bool key_pressed,
base::TimeTicks capture_time);
// Signals over the socket that data has been written to the current segment.
// Updates counters and returns true if successful. Logs error and returns
// false if failure.
bool SignalDataWrittenAndUpdateCounters();
const base::RepeatingCallback<void(const std::string&)> log_callback_;
// Socket used to signal that audio data is ready.
const std::unique_ptr<base::CancelableSyncSocket> socket_;
// Shared memory for audio data and associated metadata.
base::ReadOnlySharedMemoryRegion shared_memory_region_;
const base::WritableSharedMemoryMapping shared_memory_mapping_;
// The size in bytes of a single audio segment in the shared memory.
const uint32_t shared_memory_segment_size_;
// Index of next segment to write.
uint32_t current_segment_id_ = 0;
// The time of the creation of this object.
base::TimeTicks creation_time_;
// The time of the last Write call.
base::TimeTicks last_write_time_;
// Size in bytes of each audio bus.
const int audio_bus_memory_size_;
// Increasing ID used for checking audio buffers are in correct sequence at
// read side.
uint32_t next_buffer_id_ = 0;
// Next expected audio buffer index to have been read at the other side. We
// will get the index read at the other side over the socket. Note that this
// index does not correspond to |next_buffer_id_|, it's two separate counters.
uint32_t next_read_buffer_index_ = 0;
// Keeps track of number of filled buffer segments in the ring buffer to
// ensure the we don't overwrite data that hasn't been read yet.
size_t number_of_filled_segments_ = 0;
// Counts the total number of calls to Write().
size_t write_count_ = 0;
// Counts the number of writes to the fifo instead of to the shared memory.
size_t write_to_fifo_count_ = 0;
// Counts the number of errors that causes data to be dropped, due to either
// the fifo or the socket buffer being full.
size_t write_error_count_ = 0;
// Denotes that the most recent socket error has been logged. Used to avoid
// log spam.
bool had_socket_error_ = false;
// Counts the fifo writes and errors we get during renderer process teardown
// so that we can account for that (subtract) when we calculate the overall
// counts.
size_t trailing_write_to_fifo_count_ = 0;
size_t trailing_write_error_count_ = 0;
// Vector of audio buses allocated during construction and deleted in the
// destructor.
std::vector<std::unique_ptr<AudioBus>> audio_buses_;
// Fifo for audio that is used in case there isn't room in the shared memory.
// This can for example happen under load when the consumer side is starved.
// It should ideally be rare, but we need to guarantee that the data arrives
// since audio processing such as echo cancelling requires that to perform
// properly.
struct OverflowData {
OverflowData(double volume,
bool key_pressed,
base::TimeTicks capture_time,
std::unique_ptr<AudioBus> audio_bus);
OverflowData& operator=(OverflowData&& other);
double volume_;
bool key_pressed_;
base::TimeTicks capture_time_;
std::unique_ptr<AudioBus> audio_bus_;
std::vector<OverflowData> overflow_data_;
} // namespace media