Add a new NetworkActivityMonitor to track network activity

net/base/network_activity_monitor.cc

+// 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
+// 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.)
+NetworkActivityMonitor* g_network_activity_monitor = NULL;
+
+}  // namespace
+
+NetworkActivityMonitor::NetworkActivityMonitor()
+    : bytes_read_(0),
+      bytes_written_(0) {
+}
+
+NetworkActivityMonitor::~NetworkActivityMonitor() {
+}
+
+// static
+NetworkActivityMonitor* NetworkActivityMonitor::GetInstance() {
+  if (!g_network_activity_monitor) {
+    g_network_activity_monitor = new NetworkActivityMonitor();

[eroman, 2014/11/13 22:18:39]

This not a good pattern as it leads to a race when initializing (could allocate
g_network_activity_monitor).

Try something like this instead:

base::LazyInstance<NetworkActivityMonitor>::Leaky g_network_activity_monitor =
    LAZY_INSTANCE_INITIALIZER;

[Ryan Hamilton, 2014/11/13 23:38:17]

Done! I should have discovered this on my own.

+  }
+  return g_network_activity_monitor;
+}
+
+void NetworkActivityMonitor::AddBytesRead(uint64 bytes_read) {

[eroman, 2014/11/13 22:18:39]

Not sure if it will be useful, but you may consider making these return a uint64
(either the previous total, or the new total).

[Ryan Hamilton, 2014/11/13 23:38:17]

I thought about this, and am happy to do so if we ever have a need. However, I
think that the only callers of the Add() methods will be sockets, and the
callers of the Get() methods will never be sockets. So if it's cool with you, I
think I'll leave it as is?

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

sgtm

+  base::AutoLock lock(bytes_read_lock_);
+  bytes_read_ += bytes_read;
+}
+
+void NetworkActivityMonitor::AddBytesWritten(uint64 bytes_written) {
+  base::AutoLock lock(bytes_written_lock_);
+  bytes_written_ += bytes_written;
+}
+
+
+uint64 NetworkActivityMonitor::GetBytesRead() {
+  base::AutoLock lock(bytes_read_lock_);
+  return bytes_read_;
+}
+
+uint64 NetworkActivityMonitor::GetBytesWritten() {
+  base::AutoLock lock(bytes_written_lock_);
+  return bytes_written_;
+}
+
+}  // namespace net