Add a new NetworkActivityMonitor to track network activity

net/base/network_activity_monitor.cc

Index: net/base/network_activity_monitor.cc
diff --git a/net/base/network_activity_monitor.cc b/net/base/network_activity_monitor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c6432c627fb894ffdbe4f4683a9b1239f93a0809
--- /dev/null
+++ b/net/base/network_activity_monitor.cc
@@ -0,0 +1,72 @@
+// Copyright (c) 2014 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/base/network_activity_monitor.h"
+
+namespace net {
+
+namespace {
+
+// The actual singleton notifier.  The class contract forbids usage of the API

[eroman, 2014/11/14 00:06:16]

I am not sure what this comment means. I suggest deleting it.

[Ryan Hamilton, 2014/11/14 00:32:28]

Done.

+// in ways that would require us to place locks around access to this object.
+// (The prohibition on global non-POD objects makes it tricky to do such a thing
+// anyway.)
+
+base::LazyInstance<NetworkActivityMonitor>::Leaky g_network_activity_monitor =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+NetworkActivityMonitor::NetworkActivityMonitor()
+    : bytes_received_(0),
+      bytes_written_(0) {
+}
+
+NetworkActivityMonitor::~NetworkActivityMonitor() {
+}
+
+// static
+NetworkActivityMonitor* NetworkActivityMonitor::GetInstance() {
+  return g_network_activity_monitor.Pointer();
+}
+
+void NetworkActivityMonitor::IncrementBytesReceived(uint64 bytes_received) {
+  if (bytes_received != 0) {

[eroman, 2014/11/14 00:06:16]

meh, suggest removing.

[Ryan Hamilton, 2014/11/14 00:32:28]

Done.

+    base::AutoLock lock(lock_);
+    bytes_received_ += bytes_received;
+    last_received_ticks_ = base::TimeTicks::Now();

[eroman, 2014/11/14 00:06:15]

Can you move the call to TimeTicks::Now() outside of the lock?

(The implementation of that function is surprisingly complicated)

[Ryan Hamilton, 2014/11/14 00:32:28]

Done, I think. But I'm not sure if I need to use {}s to explicitly scope the
AutoLock?

+  }
+}
+
+void NetworkActivityMonitor::IncrementBytesWritten(uint64 bytes_written) {
+  if (bytes_written != 0) {

[eroman, 2014/11/14 00:06:16]

meh, suggest removing (just one more branch and line of code).

[Ryan Hamilton, 2014/11/14 00:32:28]

Done.

+    base::AutoLock lock(lock_);
+    bytes_written_ += bytes_written;
+    last_write_ticks_ = base::TimeTicks::Now();

[eroman, 2014/11/14 00:06:15]

Same thing here

[Ryan Hamilton, 2014/11/14 00:32:28]

Done.

+  }
+}
+
+
+uint64 NetworkActivityMonitor::GetBytesReceived() const {
+  base::AutoLock lock(lock_);
+  return bytes_received_;
+}
+
+uint64 NetworkActivityMonitor::GetBytesWritten() const {
+  base::AutoLock lock(lock_);
+  return bytes_written_;
+}
+
+base::TimeDelta NetworkActivityMonitor::GetTimeSinceLastReceived() const {
+  base::AutoLock lock(lock_);
+  return base::TimeTicks::Now() - last_received_ticks_;

[eroman, 2014/11/14 00:06:16]

Suggest moving Now() outside of lock

[Ryan Hamilton, 2014/11/14 00:32:28]

Done.

+}
+
+base::TimeDelta NetworkActivityMonitor::GetTimeSinceLastWrite() const {
+  base::AutoLock lock(lock_);
+  return base::TimeTicks::Now() - last_write_ticks_;

[eroman, 2014/11/14 00:06:15]

Same here.

[Ryan Hamilton, 2014/11/14 00:32:28]

Done.

+}
+
+
+}  // namespace net