Increase the stun ping interval.

webrtc/p2p/base/p2ptransportchannel_unittest.cc

 /*
  *  Copyright 2009 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 26 matching lines @@
 using cricket::kDefaultStepDelay;
 using cricket::PORTALLOCATOR_ENABLE_SHARED_SOCKET;
 using cricket::ServerAddresses;
 using cricket::MIN_PINGS_AT_WEAK_PING_INTERVAL;
 using rtc::SocketAddress;
 
 static const int kDefaultTimeout = 1000;
 static const int kOnlyLocalPorts = cricket::PORTALLOCATOR_DISABLE_STUN |
                                    cricket::PORTALLOCATOR_DISABLE_RELAY |
                                    cricket::PORTALLOCATOR_DISABLE_TCP;
+static const int LOW_RTT = 20;
 // Addresses on the public internet.
 static const SocketAddress kPublicAddrs[2] =
     { SocketAddress("11.11.11.11", 0), SocketAddress("22.22.22.22", 0) };
 // IPv6 Addresses on the public internet.
 static const SocketAddress kIPv6PublicAddrs[2] = {
     SocketAddress("2400:4030:1:2c00:be30:abcd:efab:cdef", 0),
     SocketAddress("2620:0:1000:1b03:2e41:38ff:fea6:f2a4", 0)
 };
 // For configuring multihomed clients.
 static const SocketAddress kAlternateAddrs[2] =
@@ skipping 2013 matching lines @@
   ch.AddRemoteCandidate(CreateHostCandidate("1.1.1.1", 1, 1));
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 2));
 
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn1 != nullptr);
   ASSERT_TRUE(conn2 != nullptr);
 
   // Low-priority connection becomes writable so that the other connection
   // is not pruned.
-  conn1->ReceivedPingResponse();
+  conn1->ReceivedPingResponse(LOW_RTT);
   EXPECT_TRUE_WAIT(
       conn1->num_pings_sent() >= MIN_PINGS_AT_WEAK_PING_INTERVAL &&
           conn2->num_pings_sent() >= MIN_PINGS_AT_WEAK_PING_INTERVAL,
       kDefaultTimeout);
 }
 
+// Verify that the connections are pinged at the right time.
+TEST_F(P2PTransportChannelPingTest, TestStunPingIntervals) {
+  rtc::ScopedFakeClock clock;
+  int RTT_RATIO = 4;
+  int SCHEDULING_RANGE = 200;
+  int RTT_RANGE = 10;
+
+  cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
+  cricket::P2PTransportChannel ch("TestChannel", 1, &pa);
+  PrepareChannel(&ch);
+  ch.Connect();
+  ch.MaybeStartGathering();
+  ch.AddRemoteCandidate(CreateHostCandidate("1.1.1.1", 1, 1));
+  cricket::Connection* conn = WaitForConnectionTo(&ch, "1.1.1.1", 1);
+
+  ASSERT_TRUE(conn != nullptr);
+  SIMULATED_WAIT(conn->num_pings_sent() == 1, kDefaultTimeout, clock);
+
+  // Initializing.
+
+  int64_t start = clock.TimeNanos();
+  SIMULATED_WAIT(conn->num_pings_sent() >= MIN_PINGS_AT_WEAK_PING_INTERVAL,
+                 kDefaultTimeout, clock);
+  int64_t ping_interval_ms = (clock.TimeNanos() - start) /
+                             rtc::kNumNanosecsPerMillisec /
+                             (MIN_PINGS_AT_WEAK_PING_INTERVAL - 1);
+  EXPECT_EQ(ping_interval_ms, cricket::WEAK_PING_INTERVAL);
+
+  // Stabilizing.
+
+  conn->ReceivedPingResponse(LOW_RTT);
+  int ping_sent_before = conn->num_pings_sent();
+  start = clock.TimeNanos();
+  // The connection becomes strong but not stable because we haven't been able
+  // to converge the RTT.
+  SIMULATED_WAIT(conn->num_pings_sent() == ping_sent_before + 1, 3000, clock);
+  ping_interval_ms = (clock.TimeNanos() - start) / rtc::kNumNanosecsPerMillisec;
+  EXPECT_GE(ping_interval_ms,
+            cricket::STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL);
+  EXPECT_LE(ping_interval_ms,
+            cricket::STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL +
+                SCHEDULING_RANGE);
+
+  // Stabilized.
+
+  // The connection becomes stable after receiving more than RTT_RATIO rtt
+  // samples.
+  for (int i = 0; i < RTT_RATIO; i++) {
+    conn->ReceivedPingResponse(LOW_RTT);
+  }
+  ping_sent_before = conn->num_pings_sent();
+  start = clock.TimeNanos();
+  SIMULATED_WAIT(conn->num_pings_sent() == ping_sent_before + 1, 3000, clock);
+  ping_interval_ms = (clock.TimeNanos() - start) / rtc::kNumNanosecsPerMillisec;
+  EXPECT_GE(ping_interval_ms,
+            cricket::STABLE_WRITABLE_CONNECTION_PING_INTERVAL);
+  EXPECT_LE(
+      ping_interval_ms,
+      cricket::STABLE_WRITABLE_CONNECTION_PING_INTERVAL + SCHEDULING_RANGE);
+
+  // Destabilized.
+
+  conn->ReceivedPingResponse(LOW_RTT);
+  // Create a in-flight ping.
+  conn->Ping(clock.TimeNanos() / rtc::kNumNanosecsPerMillisec);
+  start = clock.TimeNanos();
+  // In-flight ping timeout and the connection will be unstable.
+  SIMULATED_WAIT(
+      !conn->stable(clock.TimeNanos() / rtc::kNumNanosecsPerMillisec), 3000,
+      clock);
+  int64_t duration_ms =
+      (clock.TimeNanos() - start) / rtc::kNumNanosecsPerMillisec;
+  EXPECT_GE(duration_ms, 2 * conn->rtt() - RTT_RANGE);
+  EXPECT_LE(duration_ms, 2 * conn->rtt() + RTT_RANGE);
+  // The connection become unstable due to not receiving ping responses.
+  ping_sent_before = conn->num_pings_sent();
+  SIMULATED_WAIT(conn->num_pings_sent() == ping_sent_before + 1, 3000, clock);
+  // The interval is expected to be
+  // STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL.
+  start = clock.TimeNanos();
+  ping_sent_before = conn->num_pings_sent();
+  SIMULATED_WAIT(conn->num_pings_sent() == ping_sent_before + 1, 3000, clock);
+  ping_interval_ms = (clock.TimeNanos() - start) / rtc::kNumNanosecsPerMillisec;
+  EXPECT_GE(ping_interval_ms,
+            cricket::STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL);
+  EXPECT_LE(ping_interval_ms,
+            cricket::STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL +
+                SCHEDULING_RANGE);
+}
+
 TEST_F(P2PTransportChannelPingTest, TestNoTriggeredChecksWhenWritable) {
   cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
   cricket::P2PTransportChannel ch("trigger checks", 1, &pa);
   PrepareChannel(&ch);
   ch.Connect();
   ch.MaybeStartGathering();
   ch.AddRemoteCandidate(CreateHostCandidate("1.1.1.1", 1, 1));
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 2));
 
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn1 != nullptr);
   ASSERT_TRUE(conn2 != nullptr);
 
   EXPECT_EQ(conn2, FindNextPingableConnectionAndPingIt(&ch));
   EXPECT_EQ(conn1, FindNextPingableConnectionAndPingIt(&ch));
-  conn1->ReceivedPingResponse();
+  conn1->ReceivedPingResponse(LOW_RTT);
   ASSERT_TRUE(conn1->writable());
   conn1->ReceivedPing();
 
   // Ping received, but the connection is already writable, so no
   // "triggered check" and conn2 is pinged before conn1 because it has
   // a higher priority.
   EXPECT_EQ(conn2, FindNextPingableConnectionAndPingIt(&ch));
 }
 
 TEST_F(P2PTransportChannelPingTest, TestSignalStateChanged) {
@@ skipping 79 matching lines @@
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   ASSERT_TRUE(conn1 != nullptr);
   uint32_t remote_priority = conn1->remote_candidate().priority();
 
   // Create a higher priority candidate and make the connection
   // receiving/writable. This will prune conn1.
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 2));
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn2 != nullptr);
   conn2->ReceivedPing();
-  conn2->ReceivedPingResponse();
+  conn2->ReceivedPingResponse(LOW_RTT);
 
   // Wait for conn1 to be pruned.
   EXPECT_TRUE_WAIT(conn1->pruned(), 3000);
   // Destroy the connection to test SignalUnknownAddress.
   conn1->Destroy();
   EXPECT_TRUE_WAIT(GetConnectionTo(&ch, "1.1.1.1", 1) == nullptr, 1000);
 
   // Create a minimal STUN message with prflx priority.
   cricket::IceMessage request;
   request.SetType(cricket::STUN_BINDING_REQUEST);
@@ skipping 82 matching lines @@
 
   // If a stun request with use-candidate attribute arrives, the receiving
   // connection will be set as the best connection, even though
   // its priority is lower.
   SendData(ch, data, len, ++last_packet_id);
   ch.AddRemoteCandidate(CreateHostCandidate("3.3.3.3", 3, 1));
   cricket::Connection* conn3 = WaitForConnectionTo(&ch, "3.3.3.3", 3);
   ASSERT_TRUE(conn3 != nullptr);
   // Because it has a lower priority, the best connection is still conn2.
   EXPECT_EQ(conn2, ch.best_connection());
-  conn3->ReceivedPingResponse();  // Become writable.
+  conn3->ReceivedPingResponse(LOW_RTT);  // Become writable.
   // But if it is nominated via use_candidate, it is chosen as the best
   // connection.
   conn3->set_nominated(true);
   conn3->SignalNominated(conn3);
   EXPECT_EQ(conn3, ch.best_connection());
   EXPECT_EQ(conn3, last_selected_candidate_pair());
   EXPECT_EQ(last_packet_id, last_sent_packet_id());
   EXPECT_TRUE(channel_ready_to_send());
 
   // Even if another higher priority candidate arrives,
   // it will not be set as the best connection because the best connection
   // is nominated by the controlling side.
   SendData(ch, data, len, ++last_packet_id);
   ch.AddRemoteCandidate(CreateHostCandidate("4.4.4.4", 4, 100));
   cricket::Connection* conn4 = WaitForConnectionTo(&ch, "4.4.4.4", 4);
   ASSERT_TRUE(conn4 != nullptr);
   EXPECT_EQ(conn3, ch.best_connection());
   // But if it is nominated via use_candidate and writable, it will be set as
   // the best connection.
   conn4->set_nominated(true);
   conn4->SignalNominated(conn4);
   // Not switched yet because conn4 is not writable.
   EXPECT_EQ(conn3, ch.best_connection());
   reset_channel_ready_to_send();
   // The best connection switches after conn4 becomes writable.
-  conn4->ReceivedPingResponse();
+  conn4->ReceivedPingResponse(LOW_RTT);
   EXPECT_EQ(conn4, ch.best_connection());
   EXPECT_EQ(conn4, last_selected_candidate_pair());
   EXPECT_EQ(last_packet_id, last_sent_packet_id());
   // SignalReadyToSend is fired again because conn4 is writable.
   EXPECT_TRUE(channel_ready_to_send());
 }
 
 // The controlled side will select a connection as the "best connection" based
 // on requests from an unknown address before the controlling side nominates
 // a connection, and will nominate a connection from an unknown address if the
@@ skipping 14 matching lines @@
   uint32_t prflx_priority = cricket::ICE_TYPE_PREFERENCE_PRFLX << 24;
   request.AddAttribute(new cricket::StunUInt32Attribute(
       cricket::STUN_ATTR_PRIORITY, prflx_priority));
   cricket::TestUDPPort* port = static_cast<cricket::TestUDPPort*>(GetPort(&ch));
   port->SignalUnknownAddress(port, rtc::SocketAddress("1.1.1.1", 1),
                              cricket::PROTO_UDP, &request, kIceUfrag[1], false);
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   ASSERT_TRUE(conn1 != nullptr);
   EXPECT_TRUE(port->sent_binding_response());
   EXPECT_EQ(conn1, ch.best_connection());
-  conn1->ReceivedPingResponse();
+  conn1->ReceivedPingResponse(LOW_RTT);
   EXPECT_EQ(conn1, ch.best_connection());
   port->set_sent_binding_response(false);
 
   // Another connection is nominated via use_candidate.
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 1));
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn2 != nullptr);
   // Because it has a lower priority, the best connection is still conn1.
   EXPECT_EQ(conn1, ch.best_connection());
   // When it is nominated via use_candidate and writable, it is chosen as the
   // best connection.
-  conn2->ReceivedPingResponse();  // Become writable.
+  conn2->ReceivedPingResponse(LOW_RTT);  // Become writable.
   conn2->set_nominated(true);
   conn2->SignalNominated(conn2);
   EXPECT_EQ(conn2, ch.best_connection());
 
   // Another request with unknown address, it will not be set as the best
   // connection because the best connection was nominated by the controlling
   // side.
   port->SignalUnknownAddress(port, rtc::SocketAddress("3.3.3.3", 3),
                              cricket::PROTO_UDP, &request, kIceUfrag[1], false);
   cricket::Connection* conn3 = WaitForConnectionTo(&ch, "3.3.3.3", 3);
   ASSERT_TRUE(conn3 != nullptr);
   EXPECT_TRUE(port->sent_binding_response());
-  conn3->ReceivedPingResponse();  // Become writable.
+  conn3->ReceivedPingResponse(LOW_RTT);  // Become writable.
   EXPECT_EQ(conn2, ch.best_connection());
   port->set_sent_binding_response(false);
 
   // However if the request contains use_candidate attribute, it will be
   // selected as the best connection.
   request.AddAttribute(
       new cricket::StunByteStringAttribute(cricket::STUN_ATTR_USE_CANDIDATE));
   port->SignalUnknownAddress(port, rtc::SocketAddress("4.4.4.4", 4),
                              cricket::PROTO_UDP, &request, kIceUfrag[1], false);
   cricket::Connection* conn4 = WaitForConnectionTo(&ch, "4.4.4.4", 4);
   ASSERT_TRUE(conn4 != nullptr);
   EXPECT_TRUE(port->sent_binding_response());
   // conn4 is not the best connection yet because it is not writable.
   EXPECT_EQ(conn2, ch.best_connection());
-  conn4->ReceivedPingResponse();  // Become writable.
+  conn4->ReceivedPingResponse(LOW_RTT);  // Become writable.
   EXPECT_EQ(conn4, ch.best_connection());
 
   // Test that the request from an unknown address contains a ufrag from an old
   // generation.
   port->set_sent_binding_response(false);
   ch.SetRemoteIceCredentials(kIceUfrag[2], kIcePwd[2]);
   ch.SetRemoteIceCredentials(kIceUfrag[3], kIcePwd[3]);
   port->SignalUnknownAddress(port, rtc::SocketAddress("5.5.5.5", 5),
                              cricket::PROTO_UDP, &request, kIceUfrag[2], false);
   cricket::Connection* conn5 = WaitForConnectionTo(&ch, "5.5.5.5", 5);
@@ skipping 22 matching lines @@
   // switch to conn2 because the controlled side must mirror the media path
   // chosen by the controlling side.
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 1));
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn2 != nullptr);
   conn2->ReceivedPing();  // Start receiving.
   // Do not switch because it is not writable.
   conn2->OnReadPacket("ABC", 3, rtc::CreatePacketTime(0));
   EXPECT_EQ(conn1, ch.best_connection());
 
-  conn2->ReceivedPingResponse();  // Become writable.
+  conn2->ReceivedPingResponse(LOW_RTT);  // Become writable.
   // Switch because it is writable.
   conn2->OnReadPacket("DEF", 3, rtc::CreatePacketTime(0));
   EXPECT_EQ(conn2, ch.best_connection());
 
   // Now another STUN message with an unknown address and use_candidate will
   // nominate the best connection.
   cricket::IceMessage request;
   request.SetType(cricket::STUN_BINDING_REQUEST);
   request.AddAttribute(new cricket::StunByteStringAttribute(
       cricket::STUN_ATTR_USERNAME, kIceUfrag[1]));
   uint32_t prflx_priority = cricket::ICE_TYPE_PREFERENCE_PRFLX << 24;
   request.AddAttribute(new cricket::StunUInt32Attribute(
       cricket::STUN_ATTR_PRIORITY, prflx_priority));
   request.AddAttribute(
       new cricket::StunByteStringAttribute(cricket::STUN_ATTR_USE_CANDIDATE));
   cricket::Port* port = GetPort(&ch);
   port->SignalUnknownAddress(port, rtc::SocketAddress("3.3.3.3", 3),
                              cricket::PROTO_UDP, &request, kIceUfrag[1], false);
   cricket::Connection* conn3 = WaitForConnectionTo(&ch, "3.3.3.3", 3);
   ASSERT_TRUE(conn3 != nullptr);
   EXPECT_EQ(conn2, ch.best_connection());  // Not writable yet.
-  conn3->ReceivedPingResponse();           // Become writable.
+  conn3->ReceivedPingResponse(LOW_RTT);    // Become writable.
   EXPECT_EQ(conn3, ch.best_connection());
 
   // Now another data packet will not switch the best connection because the
   // best connection was nominated by the controlling side.
   conn2->ReceivedPing();
-  conn2->ReceivedPingResponse();
+  conn2->ReceivedPingResponse(LOW_RTT);
   conn2->OnReadPacket("XYZ", 3, rtc::CreatePacketTime(0));
   EXPECT_EQ(conn3, ch.best_connection());
 }
 
 // Test that if a new remote candidate has the same address and port with
 // an old one, it will be used to create a new connection.
 TEST_F(P2PTransportChannelPingTest, TestAddRemoteCandidateWithAddressReuse) {
   cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
   cricket::P2PTransportChannel ch("candidate reuse", 1, &pa);
   PrepareChannel(&ch);
@@ skipping 36 matching lines @@
   cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
   cricket::P2PTransportChannel ch("test channel", 1, &pa);
   PrepareChannel(&ch);
   ch.SetIceRole(cricket::ICEROLE_CONTROLLED);
   ch.Connect();
   ch.MaybeStartGathering();
   ch.AddRemoteCandidate(CreateHostCandidate("1.1.1.1", 1, 1));
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   ASSERT_TRUE(conn1 != nullptr);
   EXPECT_EQ(conn1, ch.best_connection());
-  conn1->ReceivedPingResponse();  // Becomes writable and receiving
+  conn1->ReceivedPingResponse(LOW_RTT);  // Becomes writable and receiving
 
   // When a higher-priority, nominated candidate comes in, the connections with
   // lower-priority are pruned.
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 10));
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn2 != nullptr);
-  conn2->ReceivedPingResponse();  // Becomes writable and receiving
+  conn2->ReceivedPingResponse(LOW_RTT);  // Becomes writable and receiving
   conn2->set_nominated(true);
   conn2->SignalNominated(conn2);
   EXPECT_TRUE_WAIT(conn1->pruned(), 3000);
 
   ch.SetIceConfig(CreateIceConfig(500, false));
   // Wait until conn2 becomes not receiving.
   EXPECT_TRUE_WAIT(!conn2->receiving(), 3000);
 
   ch.AddRemoteCandidate(CreateHostCandidate("3.3.3.3", 3, 1));
   cricket::Connection* conn3 = WaitForConnectionTo(&ch, "3.3.3.3", 3);
@@ skipping 15 matching lines @@
   EXPECT_EQ(cricket::TransportChannelState::STATE_INIT, ch.GetState());
   ch.AddRemoteCandidate(CreateHostCandidate("1.1.1.1", 1, 100));
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 1));
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn1 != nullptr);
   ASSERT_TRUE(conn2 != nullptr);
   // Now there are two connections, so the transport channel is connecting.
   EXPECT_EQ(cricket::TransportChannelState::STATE_CONNECTING, ch.GetState());
   // |conn1| becomes writable and receiving; it then should prune |conn2|.
-  conn1->ReceivedPingResponse();
+  conn1->ReceivedPingResponse(LOW_RTT);
   EXPECT_TRUE_WAIT(conn2->pruned(), 1000);
   EXPECT_EQ(cricket::TransportChannelState::STATE_COMPLETED, ch.GetState());
   conn1->Prune();  // All connections are pruned.
   // Need to wait until the channel state is updated.
   EXPECT_EQ_WAIT(cricket::TransportChannelState::STATE_FAILED, ch.GetState(),
                  1000);
 }
 
 // Test that when a low-priority connection is pruned, it is not deleted
 // right away, and it can become active and be pruned again.
 TEST_F(P2PTransportChannelPingTest, TestConnectionPrunedAgain) {
   cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
   cricket::P2PTransportChannel ch("test channel", 1, &pa);
   PrepareChannel(&ch);
   ch.SetIceConfig(CreateIceConfig(1000, false));
   ch.Connect();
   ch.MaybeStartGathering();
   ch.AddRemoteCandidate(CreateHostCandidate("1.1.1.1", 1, 100));
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   ASSERT_TRUE(conn1 != nullptr);
   EXPECT_EQ(conn1, ch.best_connection());
-  conn1->ReceivedPingResponse();  // Becomes writable and receiving
+  conn1->ReceivedPingResponse(LOW_RTT);  // Becomes writable and receiving
 
   // Add a low-priority connection |conn2|, which will be pruned, but it will
   // not be deleted right away. Once the current best connection becomes not
   // receiving, |conn2| will start to ping and upon receiving the ping response,
   // it will become the best connection.
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 1));
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn2 != nullptr);
   EXPECT_TRUE_WAIT(!conn2->active(), 1000);
   // |conn2| should not send a ping yet.
   EXPECT_EQ(cricket::Connection::STATE_WAITING, conn2->state());
   EXPECT_EQ(cricket::TransportChannelState::STATE_COMPLETED, ch.GetState());
   // Wait for |conn1| becoming not receiving.
   EXPECT_TRUE_WAIT(!conn1->receiving(), 3000);
   // Make sure conn2 is not deleted.
   conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn2 != nullptr);
   EXPECT_EQ_WAIT(cricket::Connection::STATE_INPROGRESS, conn2->state(), 1000);
-  conn2->ReceivedPingResponse();
+  conn2->ReceivedPingResponse(LOW_RTT);
   EXPECT_EQ_WAIT(conn2, ch.best_connection(), 1000);
   EXPECT_EQ(cricket::TransportChannelState::STATE_CONNECTING, ch.GetState());
 
   // When |conn1| comes back again, |conn2| will be pruned again.
-  conn1->ReceivedPingResponse();
+  conn1->ReceivedPingResponse(LOW_RTT);
   EXPECT_EQ_WAIT(conn1, ch.best_connection(), 1000);
   EXPECT_TRUE_WAIT(!conn2->active(), 1000);
   EXPECT_EQ(cricket::TransportChannelState::STATE_COMPLETED, ch.GetState());
 }
 
 // Test that if all connections in a channel has timed out on writing, they
 // will all be deleted. We use Prune to simulate write_time_out.
 TEST_F(P2PTransportChannelPingTest, TestDeleteConnectionsIfAllWriteTimedout) {
   cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
   cricket::P2PTransportChannel ch("test channel", 1, &pa);
@@ skipping 30 matching lines @@
 TEST_F(P2PTransportChannelPingTest, TestStopPortAllocatorSessions) {
   cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
   cricket::P2PTransportChannel ch("test channel", 1, &pa);
   PrepareChannel(&ch);
   ch.SetIceConfig(CreateIceConfig(2000, false));
   ch.Connect();
   ch.MaybeStartGathering();
   ch.AddRemoteCandidate(CreateHostCandidate("1.1.1.1", 1, 100));
   cricket::Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   ASSERT_TRUE(conn1 != nullptr);
-  conn1->ReceivedPingResponse();  // Becomes writable and receiving
+  conn1->ReceivedPingResponse(LOW_RTT);  // Becomes writable and receiving
   EXPECT_TRUE(!ch.allocator_session()->IsGettingPorts());
 
   // Start a new session. Even though conn1, which belongs to an older
   // session, becomes unwritable and writable again, it should not stop the
   // current session.
   ch.SetIceCredentials(kIceUfrag[1], kIcePwd[1]);
   ch.MaybeStartGathering();
   conn1->Prune();
-  conn1->ReceivedPingResponse();
+  conn1->ReceivedPingResponse(LOW_RTT);
   EXPECT_TRUE(ch.allocator_session()->IsGettingPorts());
 
   // But if a new connection created from the new session becomes writable,
   // it will stop the current session.
   ch.AddRemoteCandidate(CreateHostCandidate("2.2.2.2", 2, 100));
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   ASSERT_TRUE(conn2 != nullptr);
-  conn2->ReceivedPingResponse();  // Becomes writable and receiving
+  conn2->ReceivedPingResponse(LOW_RTT);  // Becomes writable and receiving
   EXPECT_TRUE(!ch.allocator_session()->IsGettingPorts());
 }
 
 class P2PTransportChannelMostLikelyToWorkFirstTest
     : public P2PTransportChannelPingTest {
  public:
   P2PTransportChannelMostLikelyToWorkFirstTest()
       : turn_server_(rtc::Thread::Current(), kTurnUdpIntAddr, kTurnUdpExtAddr) {
     network_manager_.AddInterface(kPublicAddrs[0]);
     allocator_.reset(new cricket::BasicPortAllocator(
         &network_manager_, ServerAddresses(), rtc::SocketAddress(),
         rtc::SocketAddress(), rtc::SocketAddress()));
     allocator_->set_flags(allocator_->flags() |
                           cricket::PORTALLOCATOR_DISABLE_STUN |
                           cricket::PORTALLOCATOR_DISABLE_TCP);
     cricket::RelayServerConfig config(cricket::RELAY_TURN);
     config.credentials = kRelayCredentials;
     config.ports.push_back(
         cricket::ProtocolAddress(kTurnUdpIntAddr, cricket::PROTO_UDP, false));
     allocator_->AddTurnServer(config);
     allocator_->set_step_delay(kMinimumStepDelay);
   }
 
   cricket::P2PTransportChannel& StartTransportChannel(
       bool prioritize_most_likely_to_work,
-      int max_strong_interval) {
+      int stable_writable_connection_ping_interval) {
     channel_.reset(
         new cricket::P2PTransportChannel("checks", 1, nullptr, allocator()));
     cricket::IceConfig config = channel_->config();
     config.prioritize_most_likely_candidate_pairs =
         prioritize_most_likely_to_work;
-    config.max_strong_interval = max_strong_interval;
+    config.stable_writable_connection_ping_interval =
+        stable_writable_connection_ping_interval;
     channel_->SetIceConfig(config);
     PrepareChannel(channel_.get());
     channel_->Connect();
     channel_->MaybeStartGathering();
     return *channel_.get();
   }
 
   cricket::BasicPortAllocator* allocator() { return allocator_.get(); }
   cricket::TestTurnServer* turn_server() { return &turn_server_; }
 
@@ skipping 55 matching lines @@
   cricket::Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
   EXPECT_EQ(conn2->local_candidate().type(), cricket::LOCAL_PORT_TYPE);
   EXPECT_EQ(conn2->remote_candidate().type(), cricket::LOCAL_PORT_TYPE);
   conn2->ReceivedPing();
   EXPECT_EQ(conn2, FindNextPingableConnectionAndPingIt(&ch));
 
   // Make conn3 the best connection.
   cricket::Connection* conn3 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
   EXPECT_EQ(conn3->local_candidate().type(), cricket::LOCAL_PORT_TYPE);
   EXPECT_EQ(conn3->remote_candidate().type(), cricket::RELAY_PORT_TYPE);
-  conn3->ReceivedPingResponse();
+  conn3->ReceivedPingResponse(LOW_RTT);
   ASSERT_TRUE(conn3->writable());
   conn3->ReceivedPing();
 
   /*
 
   TODO(honghaiz): Re-enable this once we use fake clock for this test to fix
   the flakiness. The following test becomes flaky because we now ping the
   connections with fast rates until every connection is pinged at least three
   times. The best connection may have been pinged before |max_strong_interval|,
   so it may not be the next connection to be pinged as expected in the test.
 
   // Verify that conn3 will be the "best connection" since it is readable and
   // writable. After |MAX_CURRENT_STRONG_INTERVAL|, it should be the next
   // pingable connection.
   EXPECT_TRUE_WAIT(conn3 == ch.best_connection(), 5000);
   WAIT(false, max_strong_interval + 100);
-  conn3->ReceivedPingResponse();
+  conn3->ReceivedPingResponse(LOW_RTT);
   ASSERT_TRUE(conn3->writable());
   EXPECT_EQ(conn3, FindNextPingableConnectionAndPingIt(&ch));
 
   */
 }
 
 // Test that Relay/Relay connections will be pinged first when everything has
 // been pinged even if the Relay/Relay connection wasn't the first to be pinged
 // in the first round.
 TEST_F(P2PTransportChannelMostLikelyToWorkFirstTest,
@@ skipping 95 matching lines @@
 
   // TCP Relay/Relay is the next.
   VerifyNextPingableConnection(cricket::RELAY_PORT_TYPE,
                                cricket::RELAY_PORT_TYPE,
                                cricket::TCP_PROTOCOL_NAME);
 
   // Finally, Local/Relay will be pinged.
   VerifyNextPingableConnection(cricket::LOCAL_PORT_TYPE,
                                cricket::RELAY_PORT_TYPE);
 }