ZLMediaKit/srt/PacketQueue.cpp

#include "PacketQueue.hpp"

namespace SRT {

#define MAX_SEQ  0x7fffffff
#define MAX_TS   0xffffffff
inline uint32_t genExpectedSeq(uint32_t seq){
    return MAX_SEQ & seq;
}
inline bool isSeqEdge(uint32_t seq,uint32_t cap){
    if(seq >(MAX_SEQ - cap)){
        return true;
    }
    return false;
}

inline bool isTSCycle(uint32_t first,uint32_t second){
    uint32_t diff;
    if(first>second){
        diff = first - second;
    }else{
        diff = second - first;
    }

    if(diff > (MAX_TS>>1)){
        return true;
    }else{
        return false;
    }
}
PacketQueue::PacketQueue(uint32_t max_size, uint32_t init_seq, uint32_t lantency)
    : _pkt_expected_seq(init_seq)
    , _pkt_cap(max_size)
    , _pkt_lantency(lantency) {
}
void PacketQueue::tryInsertPkt(DataPacket::Ptr pkt){

    if (_pkt_expected_seq <= pkt->packet_seq_number) {
        auto diff = pkt->packet_seq_number - _pkt_expected_seq;
        if(diff >= (MAX_SEQ>>1)){
            TraceL << "drop packet too later for cycle "<< "expected seq=" << _pkt_expected_seq << " pkt seq=" << pkt->packet_seq_number;
            return;
        }else{
            _pkt_map.emplace(pkt->packet_seq_number, pkt);
        }
    } else {
        auto diff = _pkt_expected_seq - pkt->packet_seq_number;
        if(diff >= (MAX_SEQ>>1)){
             _pkt_map.emplace(pkt->packet_seq_number, pkt);
             TraceL<<" cycle packet "<<"expected seq=" << _pkt_expected_seq << " pkt seq=" << pkt->packet_seq_number;
        }else{
            TraceL << "drop packet too later "<< "expected seq=" << _pkt_expected_seq << " pkt seq=" << pkt->packet_seq_number;
        }
    }
}
bool PacketQueue::inputPacket(DataPacket::Ptr pkt,std::list<DataPacket::Ptr>& out) {
    tryInsertPkt(pkt);
    auto it = _pkt_map.find(_pkt_expected_seq);
    while ( it != _pkt_map.end()) {
        out.push_back(it->second);
        _pkt_map.erase(it);
        _pkt_expected_seq = genExpectedSeq(_pkt_expected_seq+1);
        it = _pkt_map.find(_pkt_expected_seq);
    }

    while (_pkt_map.size() > _pkt_cap) {
        // 防止回环
        it = _pkt_map.find(_pkt_expected_seq);
        if(it != _pkt_map.end()){
            out.push_back(it->second);
            _pkt_map.erase(it);
        }
        _pkt_expected_seq = genExpectedSeq(_pkt_expected_seq + 1);
    }

     while (timeLantency() > _pkt_lantency) {
        it = _pkt_map.find(_pkt_expected_seq);
        if(it != _pkt_map.end()){
            out.push_back(it->second);
            _pkt_map.erase(it);
        }
        _pkt_expected_seq = genExpectedSeq(_pkt_expected_seq + 1);
    }

    return true;
}

bool PacketQueue::drop(uint32_t first, uint32_t last,std::list<DataPacket::Ptr>& out){
    uint32_t end = genExpectedSeq(last+1);
    decltype(_pkt_map.end()) it;
    for(uint32_t i =_pkt_expected_seq;i< end;){
            it = _pkt_map.find(i);
            if(it != _pkt_map.end()){
                out.push_back(it->second);
                _pkt_map.erase(it);
            }
            i = genExpectedSeq(i+1);
    }
    _pkt_expected_seq = end;
    return true;
}

uint32_t PacketQueue::timeLantency() {
    if (_pkt_map.empty()) {
        return 0;
    }

    auto first = _pkt_map.begin()->second->timestamp;
    auto last = _pkt_map.rbegin()->second->timestamp;
    uint32_t dur;
    if(last>first){
        dur = last - first;
    }else{
        dur = first - last;
    }

    if(dur > 0x80000000){
        dur = MAX_TS - dur;
        WarnL<<"cycle dur "<<dur;
    }

    return dur;
}

std::list<PacketQueue::LostPair> PacketQueue::getLostSeq() {
    std::list<PacketQueue::LostPair> re;
    if(_pkt_map.empty()){
        return re;
    }
    
    if(getExpectedSize() == getSize()){
        return re;
    }

    uint32_t end = 0;
    uint32_t first,last;

    first = _pkt_map.begin()->second->packet_seq_number;
    last = _pkt_map.rbegin()->second->packet_seq_number;
    if ((last - first) > (MAX_SEQ >> 1)) {
        TraceL << " cycle seq first " << first << " last " << last << " size " << _pkt_map.size();
        end = first;
    } else {
        end = last;
    }
    PacketQueue::LostPair lost;
    lost.first = 0;
    lost.second = 0;

    uint32_t i = _pkt_expected_seq;
    bool finish = true;
    for(i = _pkt_expected_seq;i<=end;){
        if(_pkt_map.find(i) == _pkt_map.end()){
            if(finish){
                finish = false;
                lost.first = i;
                lost.second = i+1;
            }else{
                lost.second = i+1;
            }
        }else{
            if(!finish){
                finish = true;
                re.push_back(lost);
            }
        }
        i = genExpectedSeq(i+1);
    }

    return re;
}

size_t PacketQueue::getSize(){
    return _pkt_map.size();
}

size_t PacketQueue::getExpectedSize() {
    if(_pkt_map.empty()){
        return 0;
    }

    uint32_t max = _pkt_map.rbegin()->first;
    uint32_t min = _pkt_map.begin()->first;
    if((max-min)>=(MAX_SEQ>>1)){
         TraceL<<"cycle "<<"expected seq "<<_pkt_expected_seq<<" min "<<min<<" max "<<max<<" size "<<_pkt_map.size();
        return MAX_SEQ-_pkt_expected_seq+min+1;
    }else{
        return max-_pkt_expected_seq+1;
    }
}

size_t PacketQueue::getAvailableBufferSize(){
    auto size =  getExpectedSize();
    if(_pkt_cap > size){
        return _pkt_cap - size;
    }

    if(_pkt_cap > _pkt_map.size()){
        return _pkt_cap - _pkt_map.size();
    }
    WarnL<<" cap "<<_pkt_cap<<" expected size "<<size<<" map size "<<_pkt_map.size();
    return _pkt_cap;
}

uint32_t PacketQueue::getExpectedSeq(){
    return _pkt_expected_seq;
}
std::string PacketQueue::dump(){
     _StrPrinter printer;
     if(_pkt_map.empty()){
         printer<<" expected seq :"<<_pkt_expected_seq;
     }else{
        printer<<" expected seq :"<<_pkt_expected_seq<<" size:"<<_pkt_map.size()<<" first:"<<_pkt_map.begin()->second->packet_seq_number;
        printer<<" last:"<<_pkt_map.rbegin()->second->packet_seq_number;
        printer<<" latency:"<<timeLantency()/1e3;
     }
     return std::move(printer);
}
} // namespace SRT