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.cc

@@ -0,0 +1,112 @@
+/*
+ *  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.
+ */
+
+#include "webrtc/base/timing.h"
+#include "webrtc/base/timeutils.h"
+
+#if defined(WEBRTC_POSIX)
+#include <errno.h>
+#include <math.h>
+#include <sys/time.h>
+#if defined(WEBRTC_MAC) && !defined(WEBRTC_IOS)
+#include <mach/mach.h>
+#include <mach/clock.h>
+#endif
+#elif defined(WEBRTC_WIN)
+#include <sys/timeb.h>
+#include "webrtc/base/win32.h"
+#endif
+
+namespace rtc {
+
+Timing::Timing() {
+#if defined(WEBRTC_WIN)
+  // This may fail, but we handle failure gracefully in the methods
+  // that use it (use alternative sleep method).
+  //
+  // TODO: Make it possible for user to tell if IdleWait will
+  // be done at lesser resolution because of this.
+  timer_handle_ = CreateWaitableTimer(NULL,     // Security attributes.
+                                      FALSE,    // Manual reset?
+                                      NULL);    // Timer name.
+#endif
+}
+
+Timing::~Timing() {
+#if defined(WEBRTC_WIN)
+  if (timer_handle_ != NULL)
+    CloseHandle(timer_handle_);
+#endif
+}
+
+double Timing::WallTimeNow() {
+#if defined(WEBRTC_POSIX)
+  struct timeval time;
+  gettimeofday(&time, NULL);
+  // Convert from second (1.0) and microsecond (1e-6).
+  return (static_cast<double>(time.tv_sec) +
+          static_cast<double>(time.tv_usec) * 1.0e-6);
+
+#elif defined(WEBRTC_WIN)
+  struct _timeb time;
+  _ftime(&time);
+  // Convert from second (1.0) and milliseconds (1e-3).
+  return (static_cast<double>(time.time) +
+          static_cast<double>(time.millitm) * 1.0e-3);
+#endif
+}
+
+double Timing::TimerNow() {
+  return (static_cast<double>(TimeNanos()) / kNumNanosecsPerSec);
+}
+
+double Timing::BusyWait(double period) {
+  double start_time = TimerNow();
+  while (TimerNow() - start_time < period) {
+  }
+  return TimerNow() - start_time;
+}
+
+double Timing::IdleWait(double period) {
+  double start_time = TimerNow();
+
+#if defined(WEBRTC_POSIX)
+  double sec_int, sec_frac = modf(period, &sec_int);
+  struct timespec ts;
+  ts.tv_sec = static_cast<time_t>(sec_int);
+  ts.tv_nsec = static_cast<long>(sec_frac * 1.0e9);  // NOLINT
+
+  // NOTE(liulk): for the NOLINT above, long is the appropriate POSIX
+  // type.
+
+  // POSIX nanosleep may be interrupted by signals.
+  while (nanosleep(&ts, &ts) == -1 && errno == EINTR) {
+  }
+
+#elif defined(WEBRTC_WIN)
+  if (timer_handle_ != NULL) {
+    LARGE_INTEGER due_time;
+
+    // Negative indicates relative time.  The unit is 100 nanoseconds.
+    due_time.QuadPart = -LONGLONG(period * 1.0e7);
+
+    SetWaitableTimer(timer_handle_, &due_time, 0, NULL, NULL, TRUE);
+    WaitForSingleObject(timer_handle_, INFINITE);
+  } else {
+    // Still attempts to sleep with lesser resolution.
+    // The unit is in milliseconds.
+    Sleep(DWORD(period * 1.0e3));
+  }
+#endif
+
+  return TimerNow() - start_time;
+}
+
+}  // namespace rtc