Adds a modified copy of talk/base to webrtc/base. It is the first step in migrating talk/base to webrtc/base.

BUG=N/A
R=andrew@webrtc.org, wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/12199004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6107 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/timing.h

@@ -0,0 +1,59 @@
+/*
+ *  Copyright 2008 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.
+ */
+
+#ifndef WEBRTC_BASE_TIMING_H_
+#define WEBRTC_BASE_TIMING_H_
+
+#if defined(WEBRTC_WIN)
+#include "webrtc/base/win32.h"
+#endif
+
+namespace rtc {
+
+class Timing {
+ public:
+  Timing();
+  virtual ~Timing();
+
+  // WallTimeNow() returns the current wall-clock time in seconds,
+  // within 10 milliseconds resolution.
+  virtual double WallTimeNow();
+
+  // TimerNow() is like WallTimeNow(), but is monotonically
+  // increasing.  It returns seconds in resolution of 10 microseconds
+  // or better.  Although timer and wall-clock time have the same
+  // timing unit, they do not necessarily correlate because wall-clock
+  // time may be adjusted backwards, hence not monotonic.
+  // Made virtual so we can make a fake one.
+  virtual double TimerNow();
+
+  // BusyWait() exhausts CPU as long as the time elapsed is less than
+  // the specified interval in seconds.  Returns the actual waiting
+  // time based on TimerNow() measurement.
+  double BusyWait(double period);
+
+  // IdleWait() relinquishes control of CPU for specified period in
+  // seconds.  It uses highest resolution sleep mechanism as possible,
+  // but does not otherwise guarantee the accuracy.  Returns the
+  // actual waiting time based on TimerNow() measurement.
+  //
+  // This function is not re-entrant for an object.  Create a fresh
+  // Timing object for each thread.
+  double IdleWait(double period);
+
+ private:
+#if defined(WEBRTC_WIN)
+  HANDLE timer_handle_;
+#endif
+};
+
+}  // namespace rtc
+
+#endif // WEBRTC_BASE_TIMING_H_