pjs/xpcom/ds/TimeStamp.cpp

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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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 * 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
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 * The Original Code is Mozilla code.
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 * Contributor(s):
 *  Robert O'Callahan <robert@ocallahan.org>
 *
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#include "mozilla/TimeStamp.h"
#include "prlock.h"

namespace mozilla {

static PRLock* gTimeStampLock;
static PRUint32 gRolloverCount;
static PRIntervalTime gLastNow;

nsresult TimeStamp::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;
}

}