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https://github.com/ossrs/srs.git
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c5e067fb0b
fix https://github.com/ossrs/srs/issues/3155 Build srt-1-fit fails with `standard attributes in middle of decl-specifiers` on GCC 12,Arch Linux. See https://github.com/Haivision/srt/releases/tag/v1.5.3
392 lines
16 KiB
C++
392 lines
16 KiB
C++
/*
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* SRT - Secure, Reliable, Transport
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* Copyright (c) 2020 Haivision Systems Inc.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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*/
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#ifndef INC_SRT_BUFFER_RCV_H
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#define INC_SRT_BUFFER_RCV_H
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#include "buffer_tools.h" // AvgBufSize
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#include "common.h"
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#include "queue.h"
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#include "tsbpd_time.h"
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namespace srt
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{
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/*
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* Circular receiver buffer.
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*
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* |<------------------- m_szSize ---------------------------->|
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* | |<------------ m_iMaxPosOff ----------->| |
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* | | | |
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* +---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+
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* | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 0 |...| 0 | m_pUnit[]
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* +---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+
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* | |
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* | \__last pkt received
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* |
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* \___ m_iStartPos: first message to read
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*
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* m_pUnit[i]->status_: 0: free, 1: good, 2: read, 3: dropped (can be combined with read?)
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*
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* thread safety:
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* start_pos_: CUDT::m_RecvLock
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* first_unack_pos_: CUDT::m_AckLock
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* max_pos_inc_: none? (modified on add and ack
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* first_nonread_pos_:
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*/
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class CRcvBuffer
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{
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typedef sync::steady_clock::time_point time_point;
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typedef sync::steady_clock::duration duration;
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public:
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CRcvBuffer(int initSeqNo, size_t size, CUnitQueue* unitqueue, bool bMessageAPI);
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~CRcvBuffer();
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public:
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/// Insert a unit into the buffer.
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/// Similar to CRcvBuffer::addData(CUnit* unit, int offset)
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///
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/// @param [in] unit pointer to a data unit containing new packet
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/// @param [in] offset offset from last ACK point.
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///
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/// @return 0 on success, -1 if packet is already in buffer, -2 if packet is before m_iStartSeqNo.
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/// -3 if a packet is offset is ahead the buffer capacity.
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// TODO: Previously '-2' also meant 'already acknowledged'. Check usage of this value.
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int insert(CUnit* unit);
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/// Drop packets in the receiver buffer from the current position up to the seqno (excluding seqno).
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/// @param [in] seqno drop units up to this sequence number
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/// @return number of dropped packets.
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int dropUpTo(int32_t seqno);
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/// @brief Drop all the packets in the receiver buffer.
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/// The starting position and seqno are shifted right after the last packet in the buffer.
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/// @return the number of dropped packets.
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int dropAll();
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enum DropActionIfExists {
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DROP_EXISTING = 0,
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KEEP_EXISTING = 1
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};
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/// @brief Drop a sequence of packets from the buffer.
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/// If @a msgno is valid, sender has requested to drop the whole message by TTL. In this case it has to also provide a pkt seqno range.
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/// However, if a message has been partially acknowledged and already removed from the SND buffer,
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/// the @a seqnolo might specify some position in the middle of the message, not the very first packet.
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/// If those packets have been acknowledged, they must exist in the receiver buffer unless already read.
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/// In this case the @a msgno should be used to determine starting packets of the message.
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/// Some packets of the message can be missing on the receiver, therefore the actual drop should still be performed by pkt seqno range.
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/// If message number is 0 or SRT_MSGNO_NONE, then use sequence numbers to locate sequence range to drop [seqnolo, seqnohi].
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/// A SOLO message packet can be kept depending on @a actionOnExisting value.
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/// TODO: A message in general can be kept if all of its packets are in the buffer, depending on @a actionOnExisting value.
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/// This is done to avoid dropping existing packet when the sender was asked to re-transmit a packet from an outdated loss report,
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/// which is already not available in the SND buffer.
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/// @param seqnolo sequence number of the first packet in the dropping range.
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/// @param seqnohi sequence number of the last packet in the dropping range.
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/// @param msgno message number to drop (0 if unknown)
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/// @param actionOnExisting Should an exising SOLO packet be dropped from the buffer or preserved?
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/// @return the number of packets actually dropped.
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int dropMessage(int32_t seqnolo, int32_t seqnohi, int32_t msgno, DropActionIfExists actionOnExisting);
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/// Read the whole message from one or several packets.
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///
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/// @param [in,out] data buffer to write the message into.
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/// @param [in] len size of the buffer.
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/// @param [in,out] message control data
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///
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/// @return actual number of bytes extracted from the buffer.
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/// 0 if nothing to read.
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/// -1 on failure.
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int readMessage(char* data, size_t len, SRT_MSGCTRL* msgctrl = NULL);
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/// Read acknowledged data into a user buffer.
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/// @param [in, out] dst pointer to the target user buffer.
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/// @param [in] len length of user buffer.
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/// @return size of data read. -1 on error.
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int readBuffer(char* dst, int len);
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/// Read acknowledged data directly into file.
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/// @param [in] ofs C++ file stream.
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/// @param [in] len expected length of data to write into the file.
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/// @return size of data read. -1 on error.
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int readBufferToFile(std::fstream& ofs, int len);
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public:
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/// Get the starting position of the buffer as a packet sequence number.
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int getStartSeqNo() const { return m_iStartSeqNo; }
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/// Sets the start seqno of the buffer.
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/// Must be used with caution and only when the buffer is empty.
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void setStartSeqNo(int seqno) { m_iStartSeqNo = seqno; }
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/// Given the sequence number of the first unacknowledged packet
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/// tells the size of the buffer available for packets.
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/// Effective returns capacity of the buffer minus acknowledged packet still kept in it.
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// TODO: Maybe does not need to return minus one slot now to distinguish full and empty buffer.
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size_t getAvailSize(int iFirstUnackSeqNo) const
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{
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// Receiver buffer allows reading unacknowledged packets.
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// Therefore if the first packet in the buffer is ahead of the iFirstUnackSeqNo
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// then it does not have acknowledged packets and its full capacity is available.
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// Otherwise subtract the number of acknowledged but not yet read packets from its capacity.
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const int iRBufSeqNo = getStartSeqNo();
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if (CSeqNo::seqcmp(iRBufSeqNo, iFirstUnackSeqNo) >= 0) // iRBufSeqNo >= iFirstUnackSeqNo
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{
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// Full capacity is available.
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return capacity();
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}
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// Note: CSeqNo::seqlen(n, n) returns 1.
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return capacity() - CSeqNo::seqlen(iRBufSeqNo, iFirstUnackSeqNo) + 1;
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}
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/// @brief Checks if the buffer has packets available for reading regardless of the TSBPD.
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/// A message is available for reading only if all of its packets are present in the buffer.
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/// @return true if there are packets available for reading, false otherwise.
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bool hasAvailablePackets() const;
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/// Query how many data has been continuously received (for reading) and available for reading out
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/// regardless of the TSBPD.
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/// TODO: Rename to countAvailablePackets().
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/// @return size of valid (continuous) data for reading.
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int getRcvDataSize() const;
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/// Get the number of packets, bytes and buffer timespan.
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/// Differs from getRcvDataSize() that it counts all packets in the buffer, not only continious.
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int getRcvDataSize(int& bytes, int& timespan) const;
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struct PacketInfo
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{
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int seqno;
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bool seq_gap; //< true if there are missing packets in the buffer, preceding current packet
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time_point tsbpd_time;
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};
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/// Get information on the 1st message in queue.
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/// Similar to CRcvBuffer::getRcvFirstMsg
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/// Parameters (of the 1st packet queue, ready to play or not):
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/// @param [out] tsbpdtime localtime-based (uSec) packet time stamp including buffering delay of 1st packet or 0 if
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/// none
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/// @param [out] passack true if 1st ready packet is not yet acknowledged (allowed to be delivered to the app)
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/// @param [out] skipseqno -1 or sequence number of 1st unacknowledged packet (after one or more missing packets) that is ready to play.
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/// @retval true 1st packet ready to play (tsbpdtime <= now). Not yet acknowledged if passack == true
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/// @retval false IF tsbpdtime = 0: rcv buffer empty; ELSE:
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/// IF skipseqno != -1, packet ready to play preceded by missing packets.;
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/// IF skipseqno == -1, no missing packet but 1st not ready to play.
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PacketInfo getFirstValidPacketInfo() const;
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PacketInfo getFirstReadablePacketInfo(time_point time_now) const;
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/// Get information on packets available to be read.
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/// @returns a pair of sequence numbers (first available; first unavailable).
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///
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/// @note CSeqNo::seqoff(first, second) is 0 if nothing to read.
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std::pair<int, int> getAvailablePacketsRange() const;
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size_t countReadable() const;
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bool empty() const
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{
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return (m_iMaxPosOff == 0);
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}
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/// Return buffer capacity.
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/// One slot had to be empty in order to tell the difference between "empty buffer" and "full buffer".
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/// E.g. m_iFirstNonreadPos would again point to m_iStartPos if m_szSize entries are added continiously.
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/// TODO: Old receiver buffer capacity returns the actual size. Check for conflicts.
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size_t capacity() const
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{
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return m_szSize - 1;
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}
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int64_t getDrift() const { return m_tsbpd.drift(); }
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// TODO: make thread safe?
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int debugGetSize() const
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{
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return getRcvDataSize();
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}
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/// Zero time to include all available packets.
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/// TODO: Rename to 'canRead`.
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bool isRcvDataReady(time_point time_now = time_point()) const;
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int getRcvAvgDataSize(int& bytes, int& timespan);
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void updRcvAvgDataSize(const time_point& now);
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unsigned getRcvAvgPayloadSize() const { return m_uAvgPayloadSz; }
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void getInternalTimeBase(time_point& w_timebase, bool& w_wrp, duration& w_udrift)
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{
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return m_tsbpd.getInternalTimeBase(w_timebase, w_wrp, w_udrift);
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}
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public: // Used for testing
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/// Peek unit in position of seqno
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const CUnit* peek(int32_t seqno);
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private:
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inline int incPos(int pos, int inc = 1) const { return (pos + inc) % m_szSize; }
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inline int decPos(int pos) const { return (pos - 1) >= 0 ? (pos - 1) : int(m_szSize - 1); }
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inline int offPos(int pos1, int pos2) const { return (pos2 >= pos1) ? (pos2 - pos1) : int(m_szSize + pos2 - pos1); }
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inline int cmpPos(int pos2, int pos1) const
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{
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// XXX maybe not the best implementation, but this keeps up to the rule
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const int off1 = pos1 >= m_iStartPos ? pos1 - m_iStartPos : pos1 + (int)m_szSize - m_iStartPos;
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const int off2 = pos2 >= m_iStartPos ? pos2 - m_iStartPos : pos2 + (int)m_szSize - m_iStartPos;
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return off2 - off1;
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}
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// NOTE: Assumes that pUnit != NULL
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CPacket& packetAt(int pos) { return m_entries[pos].pUnit->m_Packet; }
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const CPacket& packetAt(int pos) const { return m_entries[pos].pUnit->m_Packet; }
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private:
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void countBytes(int pkts, int bytes);
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void updateNonreadPos();
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void releaseUnitInPos(int pos);
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/// @brief Drop a unit from the buffer.
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/// @param pos position in the m_entries of the unit to drop.
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/// @return false if nothing to drop, true if the unit was dropped successfully.
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bool dropUnitInPos(int pos);
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/// Release entries following the current buffer position if they were already
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/// read out of order (EntryState_Read) or dropped (EntryState_Drop).
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void releaseNextFillerEntries();
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bool hasReadableInorderPkts() const { return (m_iFirstNonreadPos != m_iStartPos); }
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/// Find position of the last packet of the message.
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int findLastMessagePkt();
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/// Scan for availability of out of order packets.
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void onInsertNotInOrderPacket(int insertpos);
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// Check if m_iFirstReadableOutOfOrder is still readable.
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bool checkFirstReadableOutOfOrder();
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void updateFirstReadableOutOfOrder();
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int scanNotInOrderMessageRight(int startPos, int msgNo) const;
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int scanNotInOrderMessageLeft(int startPos, int msgNo) const;
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typedef bool copy_to_dst_f(char* data, int len, int dst_offset, void* arg);
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/// Read acknowledged data directly into file.
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/// @param [in] ofs C++ file stream.
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/// @param [in] len expected length of data to write into the file.
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/// @return size of data read.
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int readBufferTo(int len, copy_to_dst_f funcCopyToDst, void* arg);
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/// @brief Estimate timespan of the stored packets (acknowledged and unacknowledged).
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/// @return timespan in milliseconds
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int getTimespan_ms() const;
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private:
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// TODO: Call makeUnitTaken upon assignment, and makeUnitFree upon clearing.
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// TODO: CUnitPtr is not in use at the moment, but may be a smart pointer.
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// class CUnitPtr
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// {
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// public:
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// void operator=(CUnit* pUnit)
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// {
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// if (m_pUnit != NULL)
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// {
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// // m_pUnitQueue->makeUnitFree(m_entries[i].pUnit);
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// }
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// m_pUnit = pUnit;
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// }
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// private:
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// CUnit* m_pUnit;
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// };
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enum EntryStatus
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{
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EntryState_Empty, //< No CUnit record.
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EntryState_Avail, //< Entry is available for reading.
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EntryState_Read, //< Entry has already been read (out of order).
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EntryState_Drop //< Entry has been dropped.
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};
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struct Entry
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{
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Entry()
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: pUnit(NULL)
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, status(EntryState_Empty)
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{}
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CUnit* pUnit;
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EntryStatus status;
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};
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//static Entry emptyEntry() { return Entry { NULL, EntryState_Empty }; }
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FixedArray<Entry> m_entries;
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const size_t m_szSize; // size of the array of units (buffer)
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CUnitQueue* m_pUnitQueue; // the shared unit queue
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int m_iStartSeqNo;
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int m_iStartPos; // the head position for I/O (inclusive)
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int m_iFirstNonreadPos; // First position that can't be read (<= m_iLastAckPos)
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int m_iMaxPosOff; // the furthest data position
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int m_iNotch; // the starting read point of the first unit
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size_t m_numOutOfOrderPackets; // The number of stored packets with "inorder" flag set to false
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int m_iFirstReadableOutOfOrder; // In case of out ouf order packet, points to a position of the first such packet to
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// read
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bool m_bPeerRexmitFlag; // Needed to read message number correctly
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const bool m_bMessageAPI; // Operation mode flag: message or stream.
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public: // TSBPD public functions
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/// Set TimeStamp-Based Packet Delivery Rx Mode
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/// @param [in] timebase localtime base (uSec) of packet time stamps including buffering delay
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/// @param [in] wrap Is in wrapping period
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/// @param [in] delay agreed TsbPD delay
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///
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/// @return 0
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void setTsbPdMode(const time_point& timebase, bool wrap, duration delay);
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void setPeerRexmitFlag(bool flag) { m_bPeerRexmitFlag = flag; }
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void applyGroupTime(const time_point& timebase, bool wrp, uint32_t delay, const duration& udrift);
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void applyGroupDrift(const time_point& timebase, bool wrp, const duration& udrift);
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bool addRcvTsbPdDriftSample(uint32_t usTimestamp, const time_point& tsPktArrival, int usRTTSample);
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time_point getPktTsbPdTime(uint32_t usPktTimestamp) const;
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time_point getTsbPdTimeBase(uint32_t usPktTimestamp) const;
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void updateTsbPdTimeBase(uint32_t usPktTimestamp);
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bool isTsbPd() const { return m_tsbpd.isEnabled(); }
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/// Form a string of the current buffer fullness state.
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/// number of packets acknowledged, TSBPD readiness, etc.
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std::string strFullnessState(int iFirstUnackSeqNo, const time_point& tsNow) const;
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private:
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CTsbpdTime m_tsbpd;
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private: // Statistics
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AvgBufSize m_mavg;
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// TODO: m_BytesCountLock is probably not needed as the buffer has to be protected from simultaneous access.
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mutable sync::Mutex m_BytesCountLock; // used to protect counters operations
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int m_iBytesCount; // Number of payload bytes in the buffer
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int m_iPktsCount; // Number of payload bytes in the buffer
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unsigned m_uAvgPayloadSz; // Average payload size for dropped bytes estimation
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};
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} // namespace srt
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#endif // INC_SRT_BUFFER_RCV_H
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