Split out QuicAlarm creation from QuicConnectionHelper to new QuicAlarmFactory.

net/quic/quic_chromium_alarm_factory.cc

Index: net/quic/quic_chromium_alarm_factory.cc
diff --git a/net/quic/quic_chromium_alarm_factory.cc b/net/quic/quic_chromium_alarm_factory.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ce8b101a872a2191d3ec03f6bccfeb31cf86cfb9
--- /dev/null
+++ b/net/quic/quic_chromium_alarm_factory.cc
@@ -0,0 +1,117 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/quic/quic_chromium_alarm_factory.h"
+
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/metrics/sparse_histogram.h"
+#include "base/task_runner.h"
+#include "base/time/time.h"
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "net/quic/quic_utils.h"
+
+namespace net {
+
+namespace {
+
+class QuicChromeAlarm : public QuicAlarm {
+ public:
+  QuicChromeAlarm(const QuicClock* clock,
+                  base::TaskRunner* task_runner,
+                  QuicArenaScopedPtr<QuicAlarm::Delegate> delegate)
+      : QuicAlarm(std::move(delegate)),
+        clock_(clock),
+        task_runner_(task_runner),
+        task_deadline_(QuicTime::Zero()),
+        weak_factory_(this) {}
+
+ protected:
+  void SetImpl() override {
+    DCHECK(deadline().IsInitialized());
+    if (task_deadline_.IsInitialized()) {
+      if (task_deadline_ <= deadline()) {
+        // Since tasks can not be un-posted, OnAlarm will be invoked which
+        // will notice that deadline has not yet been reached, and will set
+        // the alarm for the new deadline.
+        return;
+      }
+      // The scheduled task is after new deadline.  Invalidate the weak ptrs
+      // so that task does not execute when we're not expecting it.
+      weak_factory_.InvalidateWeakPtrs();
+    }
+
+    int64_t delay_us = deadline().Subtract(clock_->Now()).ToMicroseconds();
+    if (delay_us < 0) {
+      delay_us = 0;
+    }
+    task_runner_->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(&QuicChromeAlarm::OnAlarm, weak_factory_.GetWeakPtr()),
+        base::TimeDelta::FromMicroseconds(delay_us));
+    task_deadline_ = deadline();
+  }
+
+  void CancelImpl() override {
+    DCHECK(!deadline().IsInitialized());
+    // Since tasks can not be un-posted, OnAlarm will be invoked which
+    // will notice that deadline is not Initialized and will do nothing.
+  }
+
+ private:
+  void OnAlarm() {
+    DCHECK(task_deadline_.IsInitialized());
+    task_deadline_ = QuicTime::Zero();
+    // 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();
+  }
+
+  const QuicClock* clock_;
+  base::TaskRunner* task_runner_;
+  // If a task has been posted to the message loop, this is the time it
+  // was scheduled to fire.  Tracking this allows us to avoid posting a
+  // new tast if the new deadline is in the future, but permits us to
+  // post a new task when the new deadline now earlier than when
+  // previously posted.
+  QuicTime task_deadline_;
+  base::WeakPtrFactory<QuicChromeAlarm> weak_factory_;
+};
+
+}  // namespace
+
+QuicChromiumAlarmFactory::QuicChromiumAlarmFactory(
+    base::TaskRunner* task_runner,
+    const QuicClock* clock)
+    : task_runner_(task_runner), clock_(clock) {}
+
+QuicArenaScopedPtr<QuicAlarm> QuicChromiumAlarmFactory::CreateAlarm(
+    QuicArenaScopedPtr<QuicAlarm::Delegate> delegate,
+    QuicConnectionArena* arena) {
+  if (arena != nullptr) {
+    return arena->New<QuicChromeAlarm>(clock_, task_runner_,
+                                       std::move(delegate));
+  } else {
+    return QuicArenaScopedPtr<QuicAlarm>(
+        new QuicChromeAlarm(clock_, task_runner_, std::move(delegate)));
+  }
+}
+
+QuicAlarm* QuicChromiumAlarmFactory::CreateAlarm(
+    QuicAlarm::Delegate* delegate) {
+  return new QuicChromeAlarm(clock_, task_runner_,
+                             QuicArenaScopedPtr<QuicAlarm::Delegate>(delegate));
+}
+
+}  // namespace net