third_party/WebKit/Source/wtf/CurrentTime.h

   1 /*
   2  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
   3  * Copyright (C) 2008 Google Inc. All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met:
   8  *
   9  *     * Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *     * Redistributions in binary form must reproduce the above
  12  * copyright notice, this list of conditions and the following disclaimer
  13  * in the documentation and/or other materials provided with the
  14  * distribution.
  15  *     * Neither the name of Google Inc. nor the names of its
  16  * contributors may be used to endorse or promote products derived from
  17  * this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #ifndef CurrentTime_h
  33 #define CurrentTime_h
  34
  35 #include "wtf/WTFExport.h"
  36
  37 namespace WTF {
  38
  39 // Returns the current UTC time in seconds, counted from January 1, 1970.
  40 // Precision varies depending on platform but is usually as good or better
  41 // than a millisecond.
  42 WTF_EXPORT double currentTime();
  43
  44 // Same thing, in milliseconds.
  45 inline double currentTimeMS()
  46 {
  47     return currentTime() * 1000.0;
  48 }
  49
  50 // Provides a monotonically increasing time in seconds since an arbitrary point in the past.
  51 // On unsupported platforms, this function only guarantees the result will be non-decreasing.
  52 WTF_EXPORT double monotonicallyIncreasingTime();
  53
  54 // Provides a timestamp that aligns with system tracing utilities on the host operating
  55 // system.
  56 WTF_EXPORT double systemTraceTime();
  57
  58 typedef double(*TimeFunction)(void);
  59 void setCurrentTimeFunction(TimeFunction);
  60 WTF_EXPORT void setMonotonicallyIncreasingTimeFunction(TimeFunction);
  61 void setSystemTraceTimeFunction(TimeFunction);
  62
  63
  64 } // namespace WTF
  65
  66 using WTF::currentTime;
  67 using WTF::currentTimeMS;
  68 using WTF::monotonicallyIncreasingTime;
  69 using WTF::systemTraceTime;
  70
  71 #endif // CurrentTime_h