prioritized_packet_queue.h

Enable keyboard shortcuts

/*

 *  Copyright (c) 2022 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 MODULES_PACING_PRIORITIZED_PACKET_QUEUE_H_

#define MODULES_PACING_PRIORITIZED_PACKET_QUEUE_H_

#include <stddef.h>

#include <array>

#include <cstdint>

#include <deque>

#include <list>

#include <memory>

#include <unordered_map>

#include "absl/container/inlined_vector.h"

#include "api/units/data_size.h"

#include "api/units/time_delta.h"

#include "api/units/timestamp.h"

#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"

#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"

namespace webrtc {

// Describes how long time a packet may stay in the queue before being dropped.

struct PacketQueueTTL {

  TimeDelta audio_retransmission = TimeDelta::PlusInfinity();

  TimeDelta video_retransmission = TimeDelta::PlusInfinity();

  TimeDelta video = TimeDelta::PlusInfinity();

};

class PrioritizedPacketQueue {

 public:

  explicit PrioritizedPacketQueue(

      Timestamp creation_time,

      bool prioritize_audio_retransmission = false,

      PacketQueueTTL packet_queue_ttl = PacketQueueTTL());

  PrioritizedPacketQueue(const PrioritizedPacketQueue&) = delete;

  PrioritizedPacketQueue& operator=(const PrioritizedPacketQueue&) = delete;

  // Add a packet to the queue. The enqueue time is used for queue time stats

  // and to report the leading packet enqueue time per packet type.

  void Push(Timestamp enqueue_time, std::unique_ptr<RtpPacketToSend> packet);

  // Remove the next packet from the queue. Packets a prioritized first

  // according to packet type, in the following order:

  // - audio, retransmissions, video / fec, padding

  // For each packet type, we use one FIFO-queue per SSRC and emit from

  // those queues in a round-robin fashion.

  std::unique_ptr<RtpPacketToSend> Pop();

  // Number of packets in the queue.

  int SizeInPackets() const;

  // Sum of all payload bytes in the queue, where the payload is calculated

  // as `packet->payload_size() + packet->padding_size()`.

  DataSize SizeInPayloadBytes() const;

  // Convenience method for `SizeInPackets() == 0`.

  bool Empty() const;

  // Total packets in the queue per media type (RtpPacketMediaType values are

  // used as lookup index).

  const std::array<int, kNumMediaTypes>& SizeInPacketsPerRtpPacketMediaType()

      const;

  // The enqueue time of the next packet this queue will return via the Pop()

  // method, for the given packet type. If queue has no packets, of that type,

  // returns Timestamp::MinusInfinity().

  Timestamp LeadingPacketEnqueueTime(RtpPacketMediaType type) const;

  Timestamp LeadingPacketEnqueueTimeForRetransmission() const;

  // Enqueue time of the oldest packet in the queue,

  // Timestamp::MinusInfinity() if queue is empty.

  Timestamp OldestEnqueueTime() const;

  // Average queue time for the packets currently in the queue.

  // The queuing time is calculated from Push() to the last UpdateQueueTime()

  // call - with any time spent in a paused state subtracted.

  // Returns TimeDelta::Zero() for an empty queue.

  TimeDelta AverageQueueTime() const;

  // Called during packet processing or when pause stats changes. Since the

  // AverageQueueTime() method does not look at the wall time, this method

  // needs to be called before querying queue time.

  void UpdateAverageQueueTime(Timestamp now);

  // Set the pause state, while `paused` is true queuing time is not counted.

  void SetPauseState(bool paused, Timestamp now);

  // Remove any packets matching the given SSRC.

  void RemovePacketsForSsrc(uint32_t ssrc);

  // Checks if the queue for the given SSRC has original (retransmissions not

  // counted) video packets containing keyframe data.

  bool HasKeyframePackets(uint32_t ssrc) const;

 private:

  static constexpr int kNumPriorityLevels = 5;

  class QueuedPacket {

   public:

    DataSize PacketSize() const;

    std::unique_ptr<RtpPacketToSend> packet;

    Timestamp enqueue_time;

    std::list<Timestamp>::iterator enqueue_time_iterator;

};

  // Class containing packets for an RTP stream.

  // For each priority level, packets are simply stored in a fifo queue.

  class StreamQueue {

   public:

    explicit StreamQueue(Timestamp creation_time);

    StreamQueue(StreamQueue&&) = default;

    StreamQueue& operator=(StreamQueue&&) = default;

    StreamQueue(const StreamQueue&) = delete;

    StreamQueue& operator=(const StreamQueue&) = delete;

    // Enqueue packet at the given priority level. Returns true if the packet

    // count for that priority level went from zero to non-zero.

    bool EnqueuePacket(QueuedPacket packet, int priority_level);

    QueuedPacket DequeuePacket(int priority_level);

    bool HasPacketsAtPrio(int priority_level) const;

    bool IsEmpty() const;

    Timestamp LeadingPacketEnqueueTime(int priority_level) const;

    Timestamp LastEnqueueTime() const;

    bool has_keyframe_packets() const { return num_keyframe_packets_ > 0; }

    std::array<std::deque<QueuedPacket>, kNumPriorityLevels> DequeueAll();

   private:

    std::deque<QueuedPacket> packets_[kNumPriorityLevels];

    Timestamp last_enqueue_time_;

    int num_keyframe_packets_;

};

  // Remove the packet from the internal state, e.g. queue time / size etc.

  void DequeuePacketInternal(QueuedPacket& packet);

  // Check if the queue pointed to by `top_active_prio_level_` is empty and

  // if so move it to the lowest non-empty index.

  void MaybeUpdateTopPrioLevel();

  void PurgeOldPacketsAtPriorityLevel(int prio_level, Timestamp now);

  static absl::InlinedVector<TimeDelta, kNumPriorityLevels> ToTtlPerPrio(

      PacketQueueTTL);

  const bool prioritize_audio_retransmission_;

  const absl::InlinedVector<TimeDelta, kNumPriorityLevels>

      time_to_live_per_prio_;

  // Cumulative sum, over all packets, of time spent in the queue.

  TimeDelta queue_time_sum_;

  // Cumulative sum of time the queue has spent in a paused state.

  TimeDelta pause_time_sum_;

  // Total number of packets stored in this queue.

  int size_packets_;

  // Total number of packets stored in this queue per RtpPacketMediaType.

  std::array<int, kNumMediaTypes> size_packets_per_media_type_;

  // Sum of payload sizes for all packts stored in this queue.

  DataSize size_payload_;

  // The last time queue/pause time sums were updated.

  Timestamp last_update_time_;

  bool paused_;

  // Last time `streams_` was culled for inactive streams.

  Timestamp last_culling_time_;

  // Map from SSRC to packet queues for the associated RTP stream.

  std::unordered_map<uint32_t, std::unique_ptr<StreamQueue>> streams_;

  // For each priority level, a queue of StreamQueues which have at least one

  // packet pending for that prio level.

  std::deque<StreamQueue*> streams_by_prio_[kNumPriorityLevels];

  // The first index into `stream_by_prio_` that is non-empty.

  int top_active_prio_level_;

  // Ordered list of enqueue times. Additions are always increasing and added to

  // the end. QueuedPacket instances have a iterators into this list for fast

  // removal.

  std::list<Timestamp> enqueue_times_;

};

}  // namespace webrtc

#endif  // MODULES_PACING_PRIORITIZED_PACKET_QUEUE_H_