mirror of
https://github.com/ZLMediaKit/ZLMediaKit.git
synced 2024-11-22 19:00:01 +08:00
287 lines
8.0 KiB
C++
287 lines
8.0 KiB
C++
/*
|
||
* Copyright (c) 2016 The ZLMediaKit project authors. All Rights Reserved.
|
||
*
|
||
* This file is part of ZLMediaKit(https://github.com/ZLMediaKit/ZLMediaKit).
|
||
*
|
||
* Use of this source code is governed by MIT license that can be found in the
|
||
* LICENSE file in the root of the source tree. All contributing project authors
|
||
* may be found in the AUTHORS file in the root of the source tree.
|
||
*/
|
||
|
||
#include "Nack.h"
|
||
|
||
using namespace std;
|
||
using namespace toolkit;
|
||
|
||
namespace mediakit {
|
||
|
||
static constexpr uint32_t kMaxNackMS = 5 * 1000;
|
||
static constexpr uint32_t kRtpCacheCheckInterval = 100;
|
||
|
||
void NackList::pushBack(RtpPacket::Ptr rtp) {
|
||
auto seq = rtp->getSeq();
|
||
_nack_cache_seq.emplace_back(seq);
|
||
_nack_cache_pkt.emplace(seq, std::move(rtp));
|
||
if (++_cache_ms_check < kRtpCacheCheckInterval) {
|
||
return;
|
||
}
|
||
_cache_ms_check = 0;
|
||
while (getCacheMS() >= kMaxNackMS) {
|
||
// 需要清除部分nack缓存
|
||
popFront();
|
||
}
|
||
}
|
||
|
||
void NackList::forEach(const FCI_NACK &nack, const function<void(const RtpPacket::Ptr &rtp)> &func) {
|
||
auto seq = nack.getPid();
|
||
for (auto bit : nack.getBitArray()) {
|
||
if (bit) {
|
||
// 丢包
|
||
RtpPacket::Ptr *ptr = getRtp(seq);
|
||
if (ptr) {
|
||
func(*ptr);
|
||
}
|
||
}
|
||
++seq;
|
||
}
|
||
}
|
||
|
||
void NackList::popFront() {
|
||
if (_nack_cache_seq.empty()) {
|
||
return;
|
||
}
|
||
_nack_cache_pkt.erase(_nack_cache_seq.front());
|
||
_nack_cache_seq.pop_front();
|
||
}
|
||
|
||
RtpPacket::Ptr *NackList::getRtp(uint16_t seq) {
|
||
auto it = _nack_cache_pkt.find(seq);
|
||
if (it == _nack_cache_pkt.end()) {
|
||
return nullptr;
|
||
}
|
||
return &it->second;
|
||
}
|
||
|
||
uint32_t NackList::getCacheMS() {
|
||
while (_nack_cache_seq.size() > 2) {
|
||
auto back_stamp = getRtpStamp(_nack_cache_seq.back());
|
||
if (back_stamp == -1) {
|
||
_nack_cache_seq.pop_back();
|
||
continue;
|
||
}
|
||
|
||
auto front_stamp = getRtpStamp(_nack_cache_seq.front());
|
||
if (front_stamp == -1) {
|
||
_nack_cache_seq.pop_front();
|
||
continue;
|
||
}
|
||
|
||
if (back_stamp >= front_stamp) {
|
||
return back_stamp - front_stamp;
|
||
}
|
||
// 很有可能回环了
|
||
return back_stamp + (UINT32_MAX - front_stamp);
|
||
}
|
||
return 0;
|
||
}
|
||
|
||
int64_t NackList::getRtpStamp(uint16_t seq) {
|
||
auto it = _nack_cache_pkt.find(seq);
|
||
if (it == _nack_cache_pkt.end()) {
|
||
return -1;
|
||
}
|
||
return it->second->getStampMS(false);
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////////////////////
|
||
|
||
NackContext::NackContext() {
|
||
setOnNack(nullptr);
|
||
}
|
||
|
||
void NackContext::received(uint16_t seq, bool is_rtx) {
|
||
if (!_started) {
|
||
// 记录第一个seq
|
||
_started = true;
|
||
_nack_seq = seq - 1;
|
||
}
|
||
|
||
if (seq < _nack_seq && _nack_seq != UINT16_MAX && seq < 1024 && _nack_seq > UINT16_MAX - 1024) {
|
||
// seq回环,清空回环前状态
|
||
makeNack(UINT16_MAX, true);
|
||
_seq.emplace(seq);
|
||
return;
|
||
}
|
||
|
||
if (is_rtx || (seq < _nack_seq && _nack_seq != UINT16_MAX)) {
|
||
// seq非回环回退包，猜测其为重传包，清空其nack状态
|
||
clearNackStatus(seq);
|
||
return;
|
||
}
|
||
|
||
auto pr = _seq.emplace(seq);
|
||
if (!pr.second) {
|
||
// seq重复, 忽略
|
||
return;
|
||
}
|
||
|
||
auto max_seq = *_seq.rbegin();
|
||
auto min_seq = *_seq.begin();
|
||
auto diff = max_seq - min_seq;
|
||
if (diff > (UINT16_MAX >> 1)) {
|
||
// 回环后，收到回环前的大值seq, 忽略掉
|
||
_seq.erase(max_seq);
|
||
return;
|
||
}
|
||
if (min_seq == (uint16_t)(_nack_seq + 1) && _seq.size() == (size_t)diff + 1) {
|
||
// 都是连续的seq，未丢包
|
||
_seq.clear();
|
||
_nack_seq = max_seq;
|
||
} else {
|
||
// seq不连续，有丢包
|
||
makeNack(max_seq, false);
|
||
}
|
||
}
|
||
|
||
void NackContext::makeNack(uint16_t max_seq, bool flush) {
|
||
// 尝试移除前面部分连续的seq
|
||
eraseFrontSeq();
|
||
// 最多生成5个nack包，防止seq大幅跳跃导致一直循环
|
||
auto max_nack = 5u;
|
||
while (_nack_seq != max_seq && max_nack--) {
|
||
// 一次不能发送超过16+1个rtp的状态
|
||
uint16_t nack_rtp_count = std::min<uint16_t>(FCI_NACK::kBitSize, max_seq - (uint16_t)(_nack_seq + 1));
|
||
if (!flush && nack_rtp_count < kNackRtpSize) {
|
||
// 非flush状态下，seq个数不足以发送一次nack
|
||
break;
|
||
}
|
||
vector<bool> vec;
|
||
vec.resize(nack_rtp_count, false);
|
||
for (size_t i = 0; i < nack_rtp_count; ++i) {
|
||
vec[i] = _seq.find((uint16_t)(_nack_seq + i + 2)) == _seq.end();
|
||
}
|
||
doNack(FCI_NACK(_nack_seq + 1, vec), true);
|
||
_nack_seq += nack_rtp_count + 1;
|
||
// 返回第一个比_last_max_seq大的元素
|
||
auto it = _seq.upper_bound(_nack_seq);
|
||
// 移除 <=_last_max_seq 的seq
|
||
_seq.erase(_seq.begin(), it);
|
||
}
|
||
}
|
||
|
||
void NackContext::setOnNack(onNack cb) {
|
||
if (cb) {
|
||
_cb = std::move(cb);
|
||
} else {
|
||
_cb = [](const FCI_NACK &nack) {};
|
||
}
|
||
}
|
||
|
||
void NackContext::doNack(const FCI_NACK &nack, bool record_nack) {
|
||
if (record_nack) {
|
||
recordNack(nack);
|
||
}
|
||
_cb(nack);
|
||
}
|
||
|
||
void NackContext::eraseFrontSeq() {
|
||
// 前面部分seq是连续的，未丢包，移除之
|
||
for (auto it = _seq.begin(); it != _seq.end();) {
|
||
if (*it != (uint16_t)(_nack_seq + 1)) {
|
||
// seq不连续，丢包了
|
||
break;
|
||
}
|
||
_nack_seq = *it;
|
||
it = _seq.erase(it);
|
||
}
|
||
}
|
||
|
||
void NackContext::clearNackStatus(uint16_t seq) {
|
||
auto it = _nack_send_status.find(seq);
|
||
if (it == _nack_send_status.end()) {
|
||
return;
|
||
}
|
||
//收到重传包与第一个nack包间的时间约等于rtt时间
|
||
auto rtt = getCurrentMillisecond() - it->second.first_stamp;
|
||
_nack_send_status.erase(it);
|
||
|
||
if (rtt >= 0) {
|
||
// rtt不能小于0
|
||
_rtt = rtt;
|
||
}
|
||
}
|
||
|
||
void NackContext::recordNack(const FCI_NACK &nack) {
|
||
auto now = getCurrentMillisecond();
|
||
auto i = nack.getPid();
|
||
for (auto flag : nack.getBitArray()) {
|
||
if (flag) {
|
||
auto &ref = _nack_send_status[i];
|
||
ref.first_stamp = now;
|
||
ref.update_stamp = now;
|
||
ref.nack_count = 1;
|
||
}
|
||
++i;
|
||
}
|
||
// 记录太多了，移除一部分早期的记录
|
||
while (_nack_send_status.size() > kNackMaxSize) {
|
||
_nack_send_status.erase(_nack_send_status.begin());
|
||
}
|
||
}
|
||
|
||
uint64_t NackContext::reSendNack() {
|
||
set<uint16_t> nack_rtp;
|
||
auto now = getCurrentMillisecond();
|
||
for (auto it = _nack_send_status.begin(); it != _nack_send_status.end();) {
|
||
if (now - it->second.first_stamp > kNackMaxMS) {
|
||
// 该rtp丢失太久了，不再要求重传
|
||
it = _nack_send_status.erase(it);
|
||
continue;
|
||
}
|
||
if (now - it->second.update_stamp < kNackIntervalRatio * _rtt) {
|
||
// 距离上次nack不足2倍的rtt，不用再发送nack
|
||
++it;
|
||
continue;
|
||
}
|
||
// 此rtp需要请求重传
|
||
nack_rtp.emplace(it->first);
|
||
// 更新nack发送时间戳
|
||
it->second.update_stamp = now;
|
||
if (++(it->second.nack_count) == kNackMaxCount) {
|
||
// nack次数太多，移除之
|
||
it = _nack_send_status.erase(it);
|
||
continue;
|
||
}
|
||
++it;
|
||
}
|
||
|
||
int pid = -1;
|
||
vector<bool> vec;
|
||
for (auto it = nack_rtp.begin(); it != nack_rtp.end();) {
|
||
if (pid == -1) {
|
||
pid = *it;
|
||
vec.resize(FCI_NACK::kBitSize, false);
|
||
++it;
|
||
continue;
|
||
}
|
||
auto inc = *it - pid;
|
||
if (inc > (ssize_t)FCI_NACK::kBitSize) {
|
||
// 新的nack包
|
||
doNack(FCI_NACK(pid, vec), false);
|
||
pid = -1;
|
||
continue;
|
||
}
|
||
// 这个包丢了
|
||
vec[inc - 1] = true;
|
||
++it;
|
||
}
|
||
if (pid != -1) {
|
||
doNack(FCI_NACK(pid, vec), false);
|
||
}
|
||
|
||
// 没有任何包需要重传时返回0，否则返回下次重传间隔(不得低于5ms)
|
||
return _nack_send_status.empty() ? 0 : max(_rtt, 5);
|
||
}
|
||
|
||
} // namespace mediakit
|