[core] Minor ACK variables clean up.

* m_ullACKInt_tk used at initialization
* Removed unused m_iACKPeriod from FileCC
* ACK event variant type changed to signed integer
* SrtCongestionControlBase: renamed ACKInterval() -> ACKMaxPackets()
* SrtCongestionControlBase: renamed ACKPeriod() -> ACKTimeout_us()

srtcore/common.h

@@ -210,7 +210,7 @@ struct EventVariant
     union U
     {
         CPacket* packet;
-        uint32_t ack;
+        int32_t ack;
         struct
         {
             int32_t* ptr;
@@ -238,7 +238,7 @@ struct EventVariant
     }
 
     void operator=(CPacket* arg) { Assign<PACKET>(arg); };
-    void operator=(uint32_t arg) { Assign<ACK>(arg); };
+    void operator=(int32_t  arg) { Assign<ACK>(arg); };
     void operator=(ECheckTimerStage arg) { Assign<STAGE>(arg); };
     void operator=(EInitEvent arg) { Assign<INIT>(arg); };
 
@@ -323,7 +323,7 @@ template<> struct EventVariant::VariantFor<EventVariant::PACKET>
 
 template<> struct EventVariant::VariantFor<EventVariant::ACK>
 {
-    typedef uint32_t type;
+    typedef int32_t type;
     static type U::*field() { return &U::ack; }
 };
 

srtcore/congctl.cpp

@@ -248,9 +248,6 @@ class FileCC : public SrtCongestionControlBase
 {
     typedef FileCC Me; // Required by SSLOT macro
 
-    // Fields from CCC not used by FileCC
-    int m_iACKPeriod;
-
     // Fields from CUDTCC
     int m_iRCInterval;          // UDT Rate control interval
     uint64_t m_LastRCTime;      // last rate increase time
@@ -270,7 +267,6 @@ class FileCC : public SrtCongestionControlBase
 
     FileCC(CUDT* parent)
         : SrtCongestionControlBase(parent)
-        , m_iACKPeriod(CUDT::COMM_SYN_INTERVAL_US)
         , m_iRCInterval(CUDT::COMM_SYN_INTERVAL_US)
         , m_LastRCTime(CTimer::getTime())
         , m_bSlowStart(true)
@@ -497,13 +493,11 @@ class FileCC : public SrtCongestionControlBase
         m_bLoss = true;
 
         const int pktsInFlight = m_parent->RTT() / m_dPktSndPeriod;
-        const int ackSeqno = m_iLastAck;// m_parent->sndLastDataAck();
-        const int sentSeqno = m_parent->sndSeqNo();
         const int numPktsLost = m_parent->sndLossLength();
         const int lost_pcent_x10 = (numPktsLost * 1000) / pktsInFlight;
 
         HLOGC(mglog.Debug, log << "FileSmootherV2: LOSS: "
-            << "sent=" << CSeqNo::seqlen(ackSeqno, sentSeqno) << ", inFlight=" << pktsInFlight
+            << "sent=" << CSeqNo::seqlen(m_iLastAck, m_parent->sndSeqNo()) << ", inFlight=" << pktsInFlight
             << ", lost=" << numPktsLost << " ("
             << lost_pcent_x10 / 10 << "." << lost_pcent_x10 % 10 << "\%)");
         if (lost_pcent_x10 < 20)    // 2.0%

srtcore/congctl.h

@@ -156,19 +156,17 @@ class SrtCongestionControlBase
     // If not, it will be internally calculated.
     virtual int RTO() { return 0; }
 
-    // How many packets to send one ACK, in packets.
-    // If user-defined, will return nonzero value.  It can enforce extra ACKs
-    // beside those calculated by ACK, sent only when the number of packets
-    // received since the last EXP that fired "fat" ACK does not exceed this
-    // value.
-    virtual int ACKInterval() { return 0; }
-
-    // Periodical timer to send an ACK, in microseconds.
-    // If user-defined, this value in microseconds will be used to calculate
+    // Maximum number of packets to trigger ACK sending.
+    // Specifies the number of packets to receive before sending the ACK.
+    // Used by CUDT together with ACKTimeout_us() to trigger ACK packet sending.
+    virtual int ACKMaxPackets() const { return 0; }
+
+    // Periodical interval to send an ACK, in microseconds.
+    // If user-defined, this value will be used to calculate
     // the next ACK time every time ACK is considered to be sent (see CUDT::checkTimers).
     // Otherwise this will be calculated internally in CUDT, normally taken
-    // from CPacket::SYN_INTERVAL.
-    virtual int ACKPeriod() { return 0; }
+    // from CUDT::COMM_SYN_INTERVAL_US.
+    virtual int ACKTimeout_us() const { return 0; }
 
     // Called when the settings concerning m_llMaxBW were changed.
     // Arg 1: value of CUDT::m_llMaxBW

srtcore/core.cpp

@@ -1371,8 +1371,6 @@ void CUDT::open()
    m_iRTTVar = m_iRTT >> 1;
    m_ullCPUFrequency = CTimer::getCPUFrequency();
 
-   // set up the timers
-   m_ullSYNInt_tk = COMM_SYN_INTERVAL_US * m_ullCPUFrequency;
 
    // set minimum NAK and EXP timeout to 300ms
    /*
@@ -1387,16 +1385,17 @@ void CUDT::open()
    else
 #endif
 */
+   // Set up timers
    m_ullMinNakInt_tk = 300000 * m_ullCPUFrequency;
    m_ullMinExpInt_tk = 300000 * m_ullCPUFrequency;
 
-   m_ullACKInt_tk = m_ullSYNInt_tk;
+   m_ullACKInt_tk = COMM_SYN_INTERVAL_US * m_ullCPUFrequency;
    m_ullNAKInt_tk = m_ullMinNakInt_tk;
 
    uint64_t currtime_tk;
    CTimer::rdtsc(currtime_tk);
    m_ullLastRspTime_tk    = currtime_tk;
-   m_ullNextACKTime_tk    = currtime_tk + m_ullSYNInt_tk;
+   m_ullNextACKTime_tk    = currtime_tk + m_ullACKInt_tk;
    m_ullNextNAKTime_tk    = currtime_tk + m_ullNAKInt_tk;
    m_ullLastRspAckTime_tk = currtime_tk;
    m_ullLastSndTime_tk    = currtime_tk;
@@ -5090,7 +5089,7 @@ SRT_REJECT_REASON CUDT::setupCC()
     uint64_t currtime_tk;
     CTimer::rdtsc(currtime_tk);
     m_ullLastRspTime_tk    = currtime_tk;
-    m_ullNextACKTime_tk    = currtime_tk + m_ullSYNInt_tk;
+    m_ullNextACKTime_tk    = currtime_tk + m_ullACKInt_tk;
     m_ullNextNAKTime_tk    = currtime_tk + m_ullNAKInt_tk;
     m_ullLastRspAckTime_tk = currtime_tk;
     m_ullLastSndTime_tk    = currtime_tk;
@@ -6956,7 +6955,8 @@ void CUDT::sendCtrl(UDTMessageType pkttype, void* lparam, void* rparam, int size
          if (data[ACKD_BUFFERLEFT] < 2)
             data[ACKD_BUFFERLEFT] = 2;
 
-         if (currtime_tk - m_ullLastAckTime_tk > m_ullSYNInt_tk)
+         // NOTE: m_CongCtl->ACKTimeout_us() should be taken into account.
+         if (currtime_tk - m_ullLastAckTime_tk > m_ullACKInt_tk)
          {
              int rcvRate;
              int ctrlsz = ACKD_TOTAL_SIZE_UDTBASE * ACKD_FIELD_SIZE; // Minimum required size
@@ -6976,7 +6976,6 @@ void CUDT::sendCtrl(UDTMessageType pkttype, void* lparam, void* rparam, int size
                  // Normal, currently expected version.
                  data[ACKD_RCVRATE] = rcvRate; //bytes/sec
                  ctrlsz = ACKD_FIELD_SIZE * ACKD_TOTAL_SIZE_VER101;
-
              }
              // ELSE: leave the buffer with ...UDTBASE size.
 
@@ -9185,17 +9184,17 @@ void CUDT::addLossRecord(std::vector<int32_t>& lr, int32_t lo, int32_t hi)
 void CUDT::checkACKTimer(uint64_t currtime_tk)
 {
     if (currtime_tk > m_ullNextACKTime_tk  // ACK time has come
-        // OR the number of sent packets since last ACK has reached
-        // the congctl-defined value of ACK Interval
-        // (note that none of the builtin congctls defines ACK Interval)
-        || (m_CongCtl->ACKInterval() > 0 && m_iPktCount >= m_CongCtl->ACKInterval()))
+            // OR the number of sent packets since last ACK has reached
+            // the congctl-defined value of ACK Interval
+            // (note that none of the builtin congctls defines ACK Interval)
+            || (m_CongCtl->ACKMaxPackets() > 0 && m_iPktCount >= m_CongCtl->ACKMaxPackets()))
     {
         // ACK timer expired or ACK interval is reached
         sendCtrl(UMSG_ACK);
         CTimer::rdtsc(currtime_tk);
 
-        const int ack_interval_tk = m_CongCtl->ACKPeriod() > 0
-            ? m_CongCtl->ACKPeriod() * m_ullCPUFrequency
+        const int ack_interval_tk = m_CongCtl->ACKTimeout_us() > 0
+            ? m_CongCtl->ACKTimeout_us() * m_ullCPUFrequency
             : m_ullACKInt_tk;
         m_ullNextACKTime_tk = currtime_tk + ack_interval_tk;
 

srtcore/core.h

@@ -822,7 +822,6 @@ class CUDT
     uint64_t m_ullNextACKTime_tk;             // Next ACK time, in CPU clock cycles, same below
     uint64_t m_ullNextNAKTime_tk;             // Next NAK time
 
-    volatile uint64_t m_ullSYNInt_tk;         // SYN interval
     volatile uint64_t m_ullACKInt_tk;         // ACK interval
     volatile uint64_t m_ullNAKInt_tk;         // NAK interval
     volatile uint64_t m_ullLastRspTime_tk;    // time stamp of last response from the peer

srtcore/fec.h

@@ -242,7 +242,7 @@ class FECFilterBuiltin: public SrtPacketFilterBase
     // So extra 4 bytes are needed, 2 for flags, 2 for length clip.
     static const size_t EXTRA_SIZE = 4;
 
-    virtual SRT_ARQLevel arqLevel() { return m_fallback_level; }
+    virtual SRT_ARQLevel arqLevel() ATR_OVERRIDE { return m_fallback_level; }
 };
 
 #endif

srtcore/packet.h

@@ -385,7 +385,7 @@ friend class CRcvQueue;
    int32_t& m_iSeqNo;                   // alias: sequence number
    int32_t& m_iMsgNo;                   // alias: message number
    int32_t& m_iTimeStamp;               // alias: timestamp
-   int32_t& m_iID;			// alias: socket ID
+   int32_t& m_iID;                      // alias: socket ID
    char*& m_pcData;                     // alias: data/control information
 
    //static const int m_iPktHdrSize;	// packet header size

test/test_epoll.cpp

@@ -71,7 +71,6 @@ TEST(CEPoll, WaitEmptyCall)
     SRTSOCKET client_sock = srt_socket(AF_INET, SOCK_DGRAM, 0);
     ASSERT_NE(client_sock, SRT_ERROR);
 
-    const int yes = 1;
     const int no = 0;
     ASSERT_NE(srt_setsockopt(client_sock, 0, SRTO_RCVSYN, &no, sizeof no), SRT_ERROR); // for async connect
     ASSERT_NE(srt_setsockopt(client_sock, 0, SRTO_SNDSYN, &no, sizeof no), SRT_ERROR); // for async connect
@@ -96,7 +95,6 @@ TEST(CEPoll, UWaitEmptyCall)
     SRTSOCKET client_sock = srt_socket(AF_INET, SOCK_DGRAM, 0);
     ASSERT_NE(client_sock, SRT_ERROR);
 
-    const int yes = 1;
     const int no = 0;
     ASSERT_NE(srt_setsockopt(client_sock, 0, SRTO_RCVSYN, &no, sizeof no), SRT_ERROR); // for async connect
     ASSERT_NE(srt_setsockopt(client_sock, 0, SRTO_SNDSYN, &no, sizeof no), SRT_ERROR); // for async connect
@@ -186,12 +184,9 @@ TEST(CEPoll, WrongEpoll_idOnAddUSock)
     SRTSOCKET client_sock = srt_socket(AF_INET, SOCK_DGRAM, 0);
     ASSERT_NE(client_sock, SRT_ERROR);
 
-    const int yes = 1;
-    const int no = 0;
+    const int no  = 0;
     ASSERT_NE(srt_setsockopt(client_sock, 0, SRTO_RCVSYN, &no, sizeof no), SRT_ERROR); // for async connect
     ASSERT_NE(srt_setsockopt(client_sock, 0, SRTO_SNDSYN, &no, sizeof no), SRT_ERROR); // for async connect
-    ASSERT_NE(srt_setsockflag(client_sock, SRTO_SENDER, &yes, sizeof yes), SRT_ERROR);
-    ASSERT_NE(srt_setsockopt(client_sock, 0, SRTO_TSBPDMODE, &yes, sizeof yes), SRT_ERROR);
 
     const int epoll_id = srt_epoll_create();
     ASSERT_GE(epoll_id, 0);