[core] Perf improvement of group reading.

Haivision · Aug 4, 2023 · 4db8260 · 4db8260
1 parent 207c1df
commit 4db8260
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Showing 4 changed files with 20 additions and 11 deletions.
diff --git a/srtcore/buffer_rcv.cpp b/srtcore/buffer_rcv.cpp
@@ -236,10 +236,14 @@ int CRcvBuffer::dropUpTo(int32_t seqno)
     m_iStartSeqNo = seqno;
     // Move forward if there are "read/drop" entries.
     releaseNextFillerEntries();
-    // Set nonread position to the starting position before updating,
-    // because start position was increased, and preceding packets are invalid.
-    m_iFirstNonreadPos = m_iStartPos;
-    updateNonreadPos();
+
+    // If the nonread position is now behind the starting position, set it to the starting position and update.
+	// Preceding packets were likely missing, and the non read position can probably be moved further now.
+    if (CSeqNo::seqcmp(m_iFirstNonreadPos, m_iStartPos) < 0)
+    {
+        m_iFirstNonreadPos = m_iStartPos;
+        updateNonreadPos();
+    }
     if (!m_tsbpd.isEnabled() && m_bMessageAPI)
         updateFirstReadableOutOfOrder();
     return iDropCnt;

diff --git a/srtcore/core.cpp b/srtcore/core.cpp
@@ -6804,6 +6804,11 @@ bool srt::CUDT::isRcvBufferReady() const
     return m_pRcvBuffer->isRcvDataReady(steady_clock::now());
 }
 
+bool srt::CUDT::isRcvBufferReadyNoLock() const
+{
+    return m_pRcvBuffer->isRcvDataReady(steady_clock::now());
+}
+
 // int by_exception: accepts values of CUDTUnited::ErrorHandling:
 // - 0 - by return value
 // - 1 - by exception

diff --git a/srtcore/core.h b/srtcore/core.h
@@ -720,6 +720,9 @@ class CUDT
     SRT_ATTR_EXCLUDES(m_RcvBufferLock)
     bool isRcvBufferReady() const;
 
+    SRT_ATTR_REQUIRES2(m_RcvBufferLock)
+    bool isRcvBufferReadyNoLock() const;
+
     // TSBPD thread main function.
     static void* tsbpd(void* param);
 

diff --git a/srtcore/group.cpp b/srtcore/group.cpp
@@ -2295,26 +2295,23 @@ int CUDTGroup::recv(char* buf, int len, SRT_MSGCTRL& w_mc)
         m_stats.recv.count(res);
         updateAvgPayloadSize(res);
 
+        bool canReadFurther = false;
         for (vector<CUDTSocket*>::const_iterator si = aliveMembers.begin(); si != aliveMembers.end(); ++si)
         {
             CUDTSocket* ps = *si;
             ScopedLock  lg(ps->core().m_RcvBufferLock);
             if (m_RcvBaseSeqNo != SRT_SEQNO_NONE)
             {
-                int cnt = ps->core().rcvDropTooLateUpTo(CSeqNo::incseq(m_RcvBaseSeqNo));
+                const int cnt = ps->core().rcvDropTooLateUpTo(CSeqNo::incseq(m_RcvBaseSeqNo));
                 if (cnt > 0)
                 {
                     HLOGC(grlog.Debug,
                           log << "grp/recv: $" << id() << ": @" << ps->m_SocketID << ": dropped " << cnt
                               << " packets after reading: m_RcvBaseSeqNo=" << m_RcvBaseSeqNo);
                 }
             }
-        }
-        bool canReadFurther = false;
-        for (vector<CUDTSocket*>::const_iterator si = aliveMembers.begin(); si != aliveMembers.end(); ++si)
-        {
-            CUDTSocket* ps = *si;
-            if (!ps->core().isRcvBufferReady())
+
+            if (!ps->core().isRcvBufferReadyNoLock())
                 m_Global.m_EPoll.update_events(ps->m_SocketID, ps->core().m_sPollID, SRT_EPOLL_IN, false);
             else
                 canReadFurther = true;