Create QuicSession

webrtc/p2p/base/quicconnectionhelper.cc

+/*
+ *  Copyright 2011 The WebRTC Project Authors. All rights reserved.

[pthatcher1, 2016/01/30 03:01:52]

2011??

[mikescarlett, 2016/02/03 17:41:01]

Changed to 2016.

+ *
+ *  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.
+ */
+
+#include "webrtc/p2p/base/quicconnectionhelper.h"
+
+namespace {
+
+// An alarm which will go off at a scheduled time, and execute the |OnAlarm|
+// method of the delegate
+class QuicWebrtcAlarm : public net::QuicAlarm, public rtc::MessageHandler {
+ public:
+  QuicWebrtcAlarm(const net::QuicClock* clock,

[pthatcher1, 2016/01/30 03:01:52]

Can you write a unit test for this class?

[mikescarlett, 2016/02/03 17:41:01]

Sure no problem.

+                  rtc::Thread* thread,
+                  QuicAlarm::Delegate* delegate)
+      : QuicAlarm(delegate),
+        clock_(clock),
+        thread_(thread),
+        in_message_queue_(false) {}
+
+  virtual ~QuicWebrtcAlarm() {}
+
+  void OnMessage(rtc::Message* msg) override {
+    DCHECK(in_message_queue_);

[pthatcher1, 2016/01/30 03:01:52]

Because this is called on a different thread, it may be executed before the 
"in_message_queue_ = true" after the message is posted in SetImpl().  So I
believe this may fail if the message queue wins the race.

But why do we even need in_message_queue_?  Is it so that we don't call
Thread::Clear when nothing is in the queue?  Because I think it's safe to call
Thread::Clear even if nothing is in there.

[mikescarlett, 2016/02/03 17:41:01]

You are correct. I looked at the source code and Thread::Clear simply ignores
cases when nothing is in the queue, so we don't need in_message_queue_. This is
also verified via unit test.

+    in_message_queue_ = false;
+    // The alarm may have been cancelled.
+    if (!deadline().IsInitialized()) {
+      return;
+    }
+
+    // The alarm may have been re-set to a later time.
+    if (clock_->Now() < deadline()) {
+      SetImpl();
+      return;
+    }
+
+    Fire();
+  }
+
+ protected:
+  void SetImpl() override {
+    DCHECK(deadline().IsInitialized());
+    CancelImpl();  // Unregister if already posted
+
+    int64 delay_ms = deadline().Subtract(clock_->Now()).ToMilliseconds();
+    if (delay_ms < 0) {
+      delay_ms = 0;
+    }
+    thread_->PostDelayed(delay_ms, this);
+    in_message_queue_ = true;
+  }
+
+  void CancelImpl() override {
+    if (in_message_queue_) {
+      thread_->Clear(this);
+      in_message_queue_ = false;
+    }
+  }
+
+ private:
+  const net::QuicClock* clock_;
+  rtc::Thread* thread_;
+  bool in_message_queue_;
+};
+
+}  // namespace
+
+namespace cricket {
+
+QuicConnectionHelper::QuicConnectionHelper(rtc::Thread* thread)
+    : thread_(thread) {}
+
+QuicConnectionHelper::~QuicConnectionHelper() {}
+
+const net::QuicClock* QuicConnectionHelper::GetClock() const {
+  return &clock_;
+}
+
+net::QuicRandom* QuicConnectionHelper::GetRandomGenerator() {
+  return net::QuicRandom::GetInstance();
+}
+
+net::QuicAlarm* QuicConnectionHelper::CreateAlarm(
+    net::QuicAlarm::Delegate* delegate) {
+  return new QuicWebrtcAlarm(GetClock(), thread_, delegate);
+}
+
+}  // namespace cricket