xpcom/ds/TimeStamp.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is Mozilla code.
  17  *
  18  * The Initial Developer of the Original Code is the Mozilla Corporation.
  19  * Portions created by the Initial Developer are Copyright (C) 2009
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *  Robert O'Callahan <robert@ocallahan.org>
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either the GNU General Public License Version 2 or later (the "GPL"), or
  27  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28  * in which case the provisions of the GPL or the LGPL are applicable instead
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  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #include "mozilla/TimeStamp.h"
  40 #include "prlock.h"
  41
  42 namespace mozilla {
  43
  44 struct TimeStampInitialization
  45 {
  46   TimeStampInitialization() {
  47     TimeStamp::Startup();
  48   }
  49   ~TimeStampInitialization() {
  50     TimeStamp::Shutdown();
  51   }
  52 };
  53
  54 static TimeStampInitialization initOnce;
  55
  56 static PRLock* gTimeStampLock = 0;
  57 static PRUint32 gRolloverCount;
  58 static PRIntervalTime gLastNow;
  59
  60 double
  61 TimeDuration::ToSeconds() const
  62 {
  63  return double(mValue)/PR_TicksPerSecond();
  64 }
  65
  66 double
  67 TimeDuration::ToSecondsSigDigits() const
  68 {
  69   return ToSeconds();
  70 }
  71
  72 TimeDuration
  73 TimeDuration::FromSeconds(PRInt32 aSeconds)
  74 {
  75   // No overflow is possible here
  76   return TimeDuration::FromTicks(PRInt64(aSeconds)*PR_TicksPerSecond());
  77 }
  78
  79 TimeDuration
  80 TimeDuration::FromMilliseconds(PRInt32 aMilliseconds)
  81 {
  82   // No overflow is possible here
  83   return TimeDuration::FromTicks(PRInt64(aMilliseconds)*PR_TicksPerSecond()/1000);
  84 }
  85
  86 TimeDuration
  87 TimeDuration::Resolution()
  88 {
  89   // This is grossly nonrepresentative of actual system capabilities
  90   // on some platforms
  91   return TimeDuration::FromTicks(1);
  92 }
  93
  94 nsresult
  95 TimeStamp::Startup()
  96 {
  97   if (gTimeStampLock)
  98     return NS_OK;
  99
 100   gTimeStampLock = PR_NewLock();
 101   gRolloverCount = 1;
 102   gLastNow = 0;
 103   return gTimeStampLock ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
 104 }
 105
 106 void
 107 TimeStamp::Shutdown()
 108 {
 109   if (gTimeStampLock) {
 110     PR_DestroyLock(gTimeStampLock);
 111     gTimeStampLock = nsnull;
 112   }
 113 }
 114
 115 TimeStamp
 116 TimeStamp::Now()
 117 {
 118   // XXX this could be considerably simpler and faster if we had
 119   // 64-bit atomic operations
 120   PR_Lock(gTimeStampLock);
 121
 122   PRIntervalTime now = PR_IntervalNow();
 123   if (now < gLastNow) {
 124     ++gRolloverCount;
 125     // This can't happen unless you've been running for millions of years
 126     NS_ASSERTION(gRolloverCount > 0, "Rollover in rollover count???");
 127   }
 128
 129   gLastNow = now;
 130   TimeStamp result((PRUint64(gRolloverCount) << 32) + now);
 131
 132   PR_Unlock(gTimeStampLock);
 133   return result;
 134 }
 135
 136 }