Do not stop a session unless the candidate of a writable connection belongs to the

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 2514 matching lines @@
   ch.AddRemoteCandidate(CreateHostCandidate("3.3.3.3", 3, 2));
   cricket::Connection* conn3 = WaitForConnectionTo(&ch, "3.3.3.3", 3);
   ASSERT_TRUE(conn3 != nullptr);
   conn3->ReceivedPing();  // Becomes receiving
   // Now prune both conn2 and conn3; they will be deleted soon.
   conn2->Prune();
   conn3->Prune();
   EXPECT_TRUE_WAIT(ch.connections().empty(), 1000);
 }
 
-// Test that after a port allocator session is started, it will be stopped
-// when a new connection becomes writable and receiving. Also test that this
-// holds even if the transport channel did not lose the writability.
+// Tests that after a port allocator session is started, it will be stopped
+// when a new connection becomes writable and receiving. Also tests that if a
+// connection belonging to an old session becomes writable, it won't stop
+// the current port allocator session.
 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
   EXPECT_TRUE(!ch.allocator_session()->IsGettingPorts());
 
-  // Restart gathering even if the transport channel is still writable.
-  // It should stop getting ports after a new connection becomes strongly
-  // connected.
+  // 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();
+  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
   EXPECT_TRUE(!ch.allocator_session()->IsGettingPorts());
 }
 
 class P2PTransportChannelMostLikelyToWorkFirstTest
     : public P2PTransportChannelPingTest {
  public:
@@ skipping 214 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);
 }