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// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef SRC_MEDIA_AUDIO_AUDIO_CORE_AUDIO_LINK_PACKET_SOURCE_H_
#define SRC_MEDIA_AUDIO_AUDIO_CORE_AUDIO_LINK_PACKET_SOURCE_H_
#include <deque>
#include <memory>
#include <mutex>
#include <fbl/ref_ptr.h>
#include "src/lib/fxl/synchronization/thread_annotations.h"
#include "src/media/audio/audio_core/audio_link.h"
#include "src/media/audio/audio_core/audio_packet_ref.h"
#include "src/media/audio/audio_core/audio_renderer_format_info.h"
#include "src/media/audio/audio_core/fwd_decls.h"
#include "src/media/audio/audio_core/pending_flush_token.h"
namespace media::audio {
// TODO(johngro): docs
//
class AudioLinkPacketSource : public AudioLink {
public:
static fbl::RefPtr<AudioLinkPacketSource> Create(fbl::RefPtr<AudioObject> source,
fbl::RefPtr<AudioObject> dest,
fbl::RefPtr<AudioRendererFormatInfo> format);
~AudioLinkPacketSource() override;
// Accessor for the format info assigned to this link.
//
// TODO(johngro): Eliminate this. Format information belongs at the generic AudioLink level.
// Additionally, all sources should be able to to change or invalidate their format info without
// needing to destroy and re-create any links. Ideally, they should be able to do so without
// needing to obtain any locks. A lock-less single writer, single reader, triple-buffer object
// would be perfect for this (I have one of these lying around from a previous project, I just
// need to see if I am allowed to use it or not).
const AudioRendererFormatInfo& format_info() const { return *format_info_; }
// Common pending queue ops.
bool pending_queue_empty() const {
std::lock_guard<std::mutex> locker(pending_mutex_);
return pending_packet_queue_.empty();
}
// PendingQueue operations used by the packet source. Never call these from the destination.
void PushToPendingQueue(const fbl::RefPtr<AudioPacketRef>& packet);
void FlushPendingQueue(const fbl::RefPtr<PendingFlushToken>& flush_token = nullptr);
void CopyPendingQueue(const fbl::RefPtr<AudioLinkPacketSource>& other);
// PendingQueue operations used by the destination. Never call these from the source.
//
// When consuming audio, destinations must always pair their calls to LockPendingQueueFront and
// UnlockPendingQueueFront, passing the pointer to the reference to the front of the queue they
// obtained in the process (even if the front of the queue was nullptr).
//
// Doing so ensures that sources which are attempting to flush the pending queue are forced to
// wait if the front of the queue is involved in a mixing operation. This, in turn, guarantees
// that audio packets are always returned to the user in the order which they were queued in
// without forcing AudioRenderers to wait to queue new data if a mix operation is in progress.
fbl::RefPtr<AudioPacketRef> LockPendingQueueFront(bool* was_flushed);
void UnlockPendingQueueFront(bool release_packet);
private:
AudioLinkPacketSource(fbl::RefPtr<AudioObject> source, fbl::RefPtr<AudioObject> dest,
fbl::RefPtr<AudioRendererFormatInfo> format_info);
fbl::RefPtr<AudioRendererFormatInfo> format_info_;
std::mutex flush_mutex_;
mutable std::mutex pending_mutex_;
std::deque<fbl::RefPtr<AudioPacketRef>> pending_packet_queue_ FXL_GUARDED_BY(pending_mutex_);
std::deque<fbl::RefPtr<AudioPacketRef>> pending_flush_packet_queue_
FXL_GUARDED_BY(pending_mutex_);
std::deque<fbl::RefPtr<PendingFlushToken>> pending_flush_token_queue_
FXL_GUARDED_BY(pending_mutex_);
bool flushed_ FXL_GUARDED_BY(pending_mutex_) = true;
bool processing_in_progress_ FXL_GUARDED_BY(pending_mutex_) = false;
};
//
// Utility function used by packet-oriented AudioObjects (e.g. AudioRenderer)
inline AudioLinkPacketSource& AsPacketSource(AudioLink& link) {
FXL_DCHECK(link.source_type() == AudioLink::SourceType::Packet);
return static_cast<AudioLinkPacketSource&>(link);
}
} // namespace media::audio
#endif // SRC_MEDIA_AUDIO_AUDIO_CORE_AUDIO_LINK_PACKET_SOURCE_H_