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/*
* Copyright (c) 2012 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_RTP_RTCP_SOURCE_RTP_PACKET_HISTORY_H_
#define MODULES_RTP_RTCP_SOURCE_RTP_PACKET_HISTORY_H_
#include <cstddef>
#include <cstdint>
#include <deque>
#include <memory>
#include <optional>
#include "api/array_view.h"
#include "api/environment/environment.h"
#include "api/function_view.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"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
class Clock;
class RtpPacketHistory {
public:
enum class StorageMode {
kDisabled, // Don't store any packets.
kStoreAndCull // Store up to `number_to_store` packets, but try to remove
// packets as they time out or as signaled as received.
};
enum class PaddingMode {
kDefault, // Last packet stored in the history that has not yet been
// culled.
kRecentLargePacket // Use the most recent large packet. Packet is kept for
// padding even after it has been culled from history.
};
// Maximum number of packets we ever allow in the history.
static constexpr size_t kMaxCapacity = 9600;
// Maximum number of entries in prioritized queue of padding packets.
static constexpr size_t kMaxPaddingHistory = 63;
// Don't remove packets within max(1 second, 3x RTT).
static constexpr TimeDelta kMinPacketDuration = TimeDelta::Seconds(1);
static constexpr int kMinPacketDurationRtt = 3;
// With kStoreAndCull, always remove packets after 3x max(1000ms, 3x rtt).
static constexpr int kPacketCullingDelayFactor = 3;
RtpPacketHistory(const Environment& env, PaddingMode padding_mode);
RtpPacketHistory() = delete;
RtpPacketHistory(const RtpPacketHistory&) = delete;
RtpPacketHistory& operator=(const RtpPacketHistory&) = delete;
~RtpPacketHistory();
// Set/get storage mode. Note that setting the state will clear the history,
// even if setting the same state as is currently used.
void SetStorePacketsStatus(StorageMode mode, size_t number_to_store);
StorageMode GetStorageMode() const;
// Set RTT, used to avoid premature retransmission and to prevent over-writing
// a packet in the history before we are reasonably sure it has been received.
void SetRtt(TimeDelta rtt);
void PutRtpPacket(std::unique_ptr<RtpPacketToSend> packet,
Timestamp send_time);
// Gets stored RTP packet corresponding to the input |sequence number|.
// Returns nullptr if packet is not found or was (re)sent too recently.
// If a packet copy is returned, it will be marked as pending transmission but
// does not update send time, that must be done by MarkPacketAsSent().
std::unique_ptr<RtpPacketToSend> GetPacketAndMarkAsPending(
uint16_t sequence_number);
// In addition to getting packet and marking as sent, this method takes an
// encapsulator function that takes a reference to the packet and outputs a
// copy that may be wrapped in a container, eg RTX.
// If the the encapsulator returns nullptr, the retransmit is aborted and the
// packet will not be marked as pending.
std::unique_ptr<RtpPacketToSend> GetPacketAndMarkAsPending(
uint16_t sequence_number,
FunctionView<std::unique_ptr<RtpPacketToSend>(const RtpPacketToSend&)>
encapsulate);
// Updates the send time for the given packet and increments the transmission
// counter. Marks the packet as no longer being in the pacer queue.
void MarkPacketAsSent(uint16_t sequence_number);
// Returns true if history contains packet with `sequence_number` and it can
// be retransmitted.
bool GetPacketState(uint16_t sequence_number) const;
// Get the packet (if any) from the history, that is deemed most likely to
// the remote side. This is calculated from heuristics such as packet age
// and times retransmitted. Updated the send time of the packet, so is not
// a const method.
std::unique_ptr<RtpPacketToSend> GetPayloadPaddingPacket();
// Same as GetPayloadPaddingPacket(void), but adds an encapsulation
// that can be used for instance to encapsulate the packet in an RTX
// container, or to abort getting the packet if the function returns
// nullptr.
std::unique_ptr<RtpPacketToSend> GetPayloadPaddingPacket(
FunctionView<std::unique_ptr<RtpPacketToSend>(const RtpPacketToSend&)>
encapsulate);
// Cull packets that have been acknowledged as received by the remote end.
void CullAcknowledgedPackets(ArrayView<const uint16_t> sequence_numbers);
// Remove all pending packets from the history, but keep storage mode and
// capacity.
void Clear();
private:
class StoredPacket {
public:
StoredPacket() = default;
StoredPacket(std::unique_ptr<RtpPacketToSend> packet,
Timestamp send_time,
uint64_t insert_order);
StoredPacket(StoredPacket&&);
StoredPacket& operator=(StoredPacket&&);
~StoredPacket();
uint64_t insert_order() const { return insert_order_; }
size_t times_retransmitted() const { return times_retransmitted_; }
void IncrementTimesRetransmitted();
// The time of last transmission, including retransmissions.
Timestamp send_time() const { return send_time_; }
void set_send_time(Timestamp value) { send_time_ = value; }
// The actual packet.
std::unique_ptr<RtpPacketToSend> packet_;
// True if the packet is currently in the pacer queue pending transmission.
bool pending_transmission_;
private:
Timestamp send_time_ = Timestamp::Zero();
// Unique number per StoredPacket, incremented by one for each added
// packet. Used to sort on insert order.
uint64_t insert_order_;
// Number of times RE-transmitted, ie excluding the first transmission.
size_t times_retransmitted_;
};
// Helper method to check if packet has too recently been sent.
bool VerifyRtt(const StoredPacket& packet) const
RTC_EXCLUSIVE_LOCKS_REQUIRED(lock_);
void Reset() RTC_EXCLUSIVE_LOCKS_REQUIRED(lock_);
void CullOldPackets() RTC_EXCLUSIVE_LOCKS_REQUIRED(lock_);
// Removes the packet from the history, and context/mapping that has been
// stored. Returns the RTP packet instance contained within the StoredPacket.
std::unique_ptr<RtpPacketToSend> RemovePacket(int packet_index)
RTC_EXCLUSIVE_LOCKS_REQUIRED(lock_);
int GetPacketIndex(uint16_t sequence_number) const
RTC_EXCLUSIVE_LOCKS_REQUIRED(lock_);
StoredPacket* GetStoredPacket(uint16_t sequence_number)
RTC_EXCLUSIVE_LOCKS_REQUIRED(lock_);
Clock* const clock_;
const PaddingMode padding_mode_;
mutable Mutex lock_;
size_t number_to_store_ RTC_GUARDED_BY(lock_);
StorageMode mode_ RTC_GUARDED_BY(lock_);
TimeDelta rtt_ RTC_GUARDED_BY(lock_);
// Queue of stored packets, ordered by sequence number, with older packets in
// the front and new packets being added to the back. Note that there may be
// wrap-arounds so the back may have a lower sequence number.
// Packets may also be removed out-of-order, in which case there will be
// instances of StoredPacket with `packet_` set to nullptr. The first and last
// entry in the queue will however always be populated.
std::deque<StoredPacket> packet_history_ RTC_GUARDED_BY(lock_);
// Total number of packets with inserted.
uint64_t packets_inserted_ RTC_GUARDED_BY(lock_);
std::optional<RtpPacketToSend> large_payload_packet_ RTC_GUARDED_BY(lock_);
};
} // namespace webrtc
#endif // MODULES_RTP_RTCP_SOURCE_RTP_PACKET_HISTORY_H_
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