optimize send nack when check packet lost send nack immediately

2026-06-21 08:22:21 +08:00 · 2022-06-09 19:30:03 +08:00
parent e5ca3aa0fb
commit f58211fb08
6 changed files with 189 additions and 28 deletions
--- a/srt/NackContext.cpp
+++ b/srt/NackContext.cpp
@@ -0,0 +1,108 @@
+#include "NackContext.hpp"
+
+namespace SRT {
+void NackContext::update(TimePoint now, std::list<PacketQueue::LostPair> &lostlist) {
+    for (auto item : lostlist) {
+        mergeItem(now, item);
+    }
+}
+void NackContext::getLostList(
+    TimePoint now, uint32_t rtt, uint32_t rtt_variance, std::list<PacketQueue::LostPair> &lostlist) {
+    lostlist.clear();
+    std::list<uint32_t> tmp_list;
+
+    for (auto it = _nack_map.begin(); it != _nack_map.end(); ++it) {
+        if (!it->second._is_nack) {
+            tmp_list.push_back(it->first);
+            it->second._ts = now;
+            it->second._is_nack = true;
+        } else {
+            if (DurationCountMicroseconds(now - it->second._ts) > rtt) {
+                tmp_list.push_back(it->first);
+                it->second._ts = now;
+            }
+        }
+    }
+    tmp_list.sort();
+
+    if (tmp_list.empty()) {
+        return;
+    }
+
+    uint32_t min = *tmp_list.begin();
+    uint32_t max = *tmp_list.rbegin();
+
+    if ((max - min) >= (MAX_SEQ >> 1)) {
+        while ((max - tmp_list.front()) > (MAX_SEQ >> 1)) {
+            tmp_list.push_back(tmp_list.front());
+            tmp_list.pop_front();
+        }
+    }
+
+    PacketQueue::LostPair lost;
+    bool finish = true;
+    for (auto cur = tmp_list.begin(); cur != tmp_list.end(); ++cur) {
+        if (finish) {
+            lost.first = *cur;
+            lost.second = genExpectedSeq(*cur + 1);
+            finish = false;
+        } else {
+            if (lost.second == *cur) {
+                lost.second = genExpectedSeq(*cur + 1);
+            } else {
+                finish = true;
+                lostlist.push_back(lost);
+            }
+        }
+    }
+}
+void NackContext::drop(uint32_t seq) {
+    if (_nack_map.empty())
+        return;
+    uint32_t min = _nack_map.begin()->first;
+    uint32_t max = _nack_map.rbegin()->first;
+    bool is_cycle = false;
+    if ((max - min) >= (MAX_SEQ >> 1)) {
+        is_cycle = true;
+    }
+
+    for (auto it = _nack_map.begin(); it != _nack_map.end();) {
+        if (!is_cycle) {
+            // 不回环
+            if (it->first <= seq) {
+                it = _nack_map.erase(it);
+            } else {
+                it++;
+            }
+        } else {
+            if (it->first <= seq) {
+                if ((seq - it->first) >= (MAX_SEQ >> 1)) {
+                    WarnL << "cycle seq  " << seq << " " << it->first;
+                    it++;
+                } else {
+                    it = _nack_map.erase(it);
+                }
+            } else {
+                if ((it->first - seq) >= (MAX_SEQ >> 1)) {
+                    it = _nack_map.erase(it);
+                    WarnL << "cycle seq  " << seq << " " << it->first;
+                } else {
+                    it++;
+                }
+            }
+        }
+    }
+}
+
+void NackContext::mergeItem(TimePoint now, PacketQueue::LostPair &item) {
+    for (uint32_t i = item.first; i < item.second; ++i) {
+        auto it = _nack_map.find(i);
+        if (it != _nack_map.end()) {
+        } else {
+            NackItem tmp;
+            tmp._is_nack = false;
+            _nack_map.emplace(i, tmp);
+        }
+    }
+}
+} // namespace SRT