gecko-dev/xpcom/ds/TimeStamp.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla code.
*
* The Initial Developer of the Original Code is the Mozilla Corporation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Robert O'Callahan <robert@ocallahan.org>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
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* ***** END LICENSE BLOCK ***** */
#include "mozilla/TimeStamp.h"
#include "prlock.h"
namespace mozilla {
struct TimeStampInitialization
{
TimeStampInitialization() {
TimeStamp::Startup();
}
~TimeStampInitialization() {
TimeStamp::Shutdown();
}
};
static TimeStampInitialization initOnce;
static PRLock* gTimeStampLock = 0;
static PRUint32 gRolloverCount;
static PRIntervalTime gLastNow;
double
TimeDuration::ToSeconds() const
{
return double(mValue)/PR_TicksPerSecond();
}
double
TimeDuration::ToSecondsSigDigits() const
{
return ToSeconds();
}
TimeDuration
TimeDuration::FromMilliseconds(double aMilliseconds)
{
static double kTicksPerMs = double(PR_TicksPerSecond()) / 1000.0;
return TimeDuration::FromTicks(aMilliseconds * kTicksPerMs);
}
TimeDuration
TimeDuration::Resolution()
{
// This is grossly nonrepresentative of actual system capabilities
// on some platforms
return TimeDuration::FromTicks(PRInt64(1));
}
nsresult
TimeStamp::Startup()
{
if (gTimeStampLock)
return NS_OK;
// TimeStamp has to use bare PRLock instead of mozilla::Mutex
// because TimeStamp can be used very early in startup.
gTimeStampLock = PR_NewLock();
gRolloverCount = 1;
gLastNow = 0;
return gTimeStampLock ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
}
void
TimeStamp::Shutdown()
{
if (gTimeStampLock) {
PR_DestroyLock(gTimeStampLock);
gTimeStampLock = nsnull;
}
}
TimeStamp
TimeStamp::Now()
{
// XXX this could be considerably simpler and faster if we had
// 64-bit atomic operations
PR_Lock(gTimeStampLock);
PRIntervalTime now = PR_IntervalNow();
if (now < gLastNow) {
++gRolloverCount;
// This can't happen unless you've been running for millions of years
NS_ASSERTION(gRolloverCount > 0, "Rollover in rollover count???");
}
gLastNow = now;
TimeStamp result((PRUint64(gRolloverCount) << 32) + now);
PR_Unlock(gTimeStampLock);
return result;
}
}