[core] Fixed CRcvBuffer::getAvailSize() may jump around. (#2490)

gou4shi1 · web-flow · commit b76c8b2e3bf2 · 2022-11-08T15:07:25.000+01:00
diff --git a/srtcore/buffer_rcv.h b/srtcore/buffer_rcv.h
@@ -128,9 +128,8 @@ class CRcvBuffer
         const int iRBufSeqNo  = getStartSeqNo();
         if (CSeqNo::seqcmp(iRBufSeqNo, iFirstUnackSeqNo) >= 0) // iRBufSeqNo >= iFirstUnackSeqNo
         {
-            // Full capacity is available, still don't want to encourage extra packets to come.
-            // Note: CSeqNo::seqlen(n, n) returns 1.
-            return capacity() - CSeqNo::seqlen(iFirstUnackSeqNo, iRBufSeqNo) + 1;
+            // Full capacity is available.
+            return capacity();
         }
 
         // Note: CSeqNo::seqlen(n, n) returns 1.
diff --git a/srtcore/core.cpp b/srtcore/core.cpp
@@ -7993,6 +7993,8 @@ int srt::CUDT::sendCtrlAck(CPacket& ctrlpkt, int size)
         data[ACKD_RCVLASTACK] = m_iRcvLastAck;
         data[ACKD_RTT] = m_iSRTT;
         data[ACKD_RTTVAR] = m_iRTTVar;
+        // The ackDataUpTo() above ensures this condition.
+        SRT_ASSERT(m_iRcvLastSkipAck == m_iRcvLastAck);
         data[ACKD_BUFFERLEFT] = (int) getAvailRcvBufferSizeNoLock();
         // a minimum flow window of 2 is used, even if buffer is full, to break potential deadlock
         if (data[ACKD_BUFFERLEFT] < 2)
diff --git a/test/test_buffer_rcv.cpp b/test/test_buffer_rcv.cpp
@@ -803,14 +803,14 @@ TEST_F(CRcvBufferReadStream, ReadFractional)
     const size_t num_bytes1 = nfull_pkts * m_payload_sz + m_payload_sz / 2;
     const int res1 = m_rcv_buffer->readBuffer(buff.data(), num_bytes1);
     EXPECT_TRUE(size_t(res1) == num_bytes1);
-    EXPECT_EQ(getAvailBufferSize(), m_buff_size_pkts - nfull_pkts - 1);
+    EXPECT_EQ(getAvailBufferSize(), m_buff_size_pkts - 1);
     EXPECT_TRUE(hasAvailablePackets());
 
     const size_t num_bytes2 = m_payload_sz * (num_pkts - nfull_pkts - 1) + m_payload_sz / 2;
 
     const int res2 = m_rcv_buffer->readBuffer(buff.data() + num_bytes1, buff.size() - num_bytes1);
     EXPECT_TRUE(size_t(res2) == num_bytes2);
-    EXPECT_EQ(getAvailBufferSize(), m_buff_size_pkts - num_pkts - 1);
+    EXPECT_EQ(getAvailBufferSize(), m_buff_size_pkts - 1);
     EXPECT_FALSE(hasAvailablePackets());
     ackPackets(num_pkts); // Move the reference ACK position.
     EXPECT_EQ(getAvailBufferSize(), m_buff_size_pkts - 1);

Original file line number	Diff line number	Diff line change
`@@ -128,9 +128,8 @@ class CRcvBuffer`
`128`	`128`	`const int iRBufSeqNo = getStartSeqNo();`
`129`	`129`	`if (CSeqNo::seqcmp(iRBufSeqNo, iFirstUnackSeqNo) >= 0) // iRBufSeqNo >= iFirstUnackSeqNo`
`130`	`130`	`{`
`131`		`- // Full capacity is available, still don't want to encourage extra packets to come.`
`132`		`- // Note: CSeqNo::seqlen(n, n) returns 1.`
`133`		`- return capacity() - CSeqNo::seqlen(iFirstUnackSeqNo, iRBufSeqNo) + 1;`
	`131`	`+ // Full capacity is available.`
	`132`	`+ return capacity();`
`134`	`133`	`}`
`135`	`134`
`136`	`135`	`// Note: CSeqNo::seqlen(n, n) returns 1.`