[core] Removed group syncing when sending control ACK.

The synchronisation is done upon reading from a group (CGroup::recv(..)).
Removed CUDT::dropToGroupRecvBase() function.

srtcore/core.cpp

@@ -7812,40 +7812,6 @@ void srt::CUDT::releaseSynch()
     leaveCS(m_RecvLock);
 }
 
-
-#if ENABLE_BONDING
-void srt::CUDT::dropToGroupRecvBase()
-{
-    int32_t group_recv_base = SRT_SEQNO_NONE;
-    if (m_parent->m_GroupOf)
-    {
-        // Check is first done before locking to avoid unnecessary
-        // mutex locking. The condition for this field is that it
-        // can be either never set, already reset, or ever set
-        // and possibly dangling. The re-check after lock eliminates
-        // the dangling case.
-        ScopedLock glock (uglobal().m_GlobControlLock);
-
-        // Note that getRcvBaseSeqNo() will lock m_GroupOf->m_GroupLock,
-        // but this is an intended order.
-        if (m_parent->m_GroupOf)
-            group_recv_base = m_parent->m_GroupOf->getRcvBaseSeqNo();
-    }
-    if (group_recv_base == SRT_SEQNO_NONE)
-        return;
-
-    ScopedLock lck(m_RcvBufferLock);
-    int cnt = rcvDropTooLateUpTo(CSeqNo::incseq(group_recv_base));
-    if (cnt > 0)
-    {
-        HLOGC(grlog.Debug,
-              log << CONID() << "dropToGroupRecvBase: dropped " << cnt << " packets before ACK: group_recv_base="
-                  << group_recv_base << " m_iRcvLastAck=" << m_iRcvLastAck
-                  << " m_iRcvCurrSeqNo=" << m_iRcvCurrSeqNo << " m_bTsbPd=" << m_bTsbPd);
-    }
-}
-#endif
-
 namespace srt {
 #if ENABLE_HEAVY_LOGGING
 static void DebugAck(string hdr, int prev, int ack)
@@ -8062,10 +8028,6 @@ int srt::CUDT::sendCtrlAck(CPacket& ctrlpkt, int size)
 #endif
     string reason; // just for "a reason" of giving particular % for ACK
 
-#if ENABLE_BONDING
-    dropToGroupRecvBase();
-#endif
-
     // The TSBPD thread may change the first lost sequence record (TLPKTDROP).
     // To avoid it the m_RcvBufferLock has to be acquired.
     UniqueLock bufflock(m_RcvBufferLock);

srtcore/core.h

@@ -1149,12 +1149,6 @@ class CUDT
     static void addLossRecord(std::vector<int32_t>& lossrecord, int32_t lo, int32_t hi);
     int32_t bake(const sockaddr_any& addr, int32_t previous_cookie = 0, int correction = 0);
 
-#if ENABLE_BONDING
-    /// @brief Drop packets in the recv buffer behind group_recv_base.
-    /// Updates m_iRcvLastSkipAck if it's behind group_recv_base.
-    void dropToGroupRecvBase();
-#endif
-
     void processKeepalive(const CPacket& ctrlpkt, const time_point& tsArrival);