Time for Java

Question

Hey,
I've been developing a Timing and Synchronisation package, I've just discovered that System.currentTimeMillis() is too inaccurate, so i've implemented something using jni and the windows libraries. On desktop machines it works perfect but on a Dell laptop running xp of mine the results are erratic and hidiously unhelpfully! I know that this is most likely a hardware issue, but i'm under presssure to produce something releasable shortly.
Does anyone have ANY ideas on the issue?
Thanks,
M
ps all machines are using 1.4.2 and it works proberly on desktops running w2k and xp

Answer 1

The more i look into it the more seems to be specific to my personel laptop! The only difference i can think that might be causing the problem is that the machine has a kind-of pusedo-dual-processer set up which i read on the msdn site can cause problems when using the methods below. Anyway I have included a copy of the c++ code below
It doesn't feel right posting c code here but hey...
#include <jni.h>
#include "HiResTimer.h"
#include <windows.h>
// HiResCounter
class _HiResCounter{
public:
_HiResCounter()
{ m_bExists = QueryPerformanceFrequency(
&m_Freq ); }
BOOL Exists()
{ return m_bExists; }
double Freq()
{ return (double)(m_Freq.QuadPart); }
protected:
BOOL m_bExists;
LARGE_INTEGER m_Freq;
static _HiResCounter HiResCounter;
// Class: HiResTimer
// Method: isHighResTimerAvailable
// Signature: ()Z
JNIEXPORT jboolean JNICALL
Java_HiResTimer_isHighResTimerAvailable
(JNIEnv *, jobject)
return HiResCounter.Exists();
// Class: HiResTimer
// Method: startTiming
// Signature: ()D
JNIEXPORT jdouble JNICALL Java_HiResTimer_startTiming
(JNIEnv *, jobject)
LARGE_INTEGER li;
if( HiResCounter.Exists() ) {
QueryPerformanceCounter( &li );
return (double)(li.QuadPart);
} else {
return (double)GetTickCount();
} // else
// Class: HiResTimer
// Method: endTiming
// Signature: (D)D
JNIEXPORT jdouble JNICALL Java_HiResTimer_endTiming
(JNIEnv *, jobject, jdouble dStart )
LARGE_INTEGER li;
if( HiResCounter.Exists() ) {
QueryPerformanceCounter( &li );
return ((li.QuadPart - dStart) * 1000.0 /
HiResCounter.Freq());
} else {
return (GetTickCount() - (DWORD) dStart);
} // else
// DllMain
BOOL APIENTRY DllMain(HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved)
switch (ul_reason_for_call)
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
return TRUE;