If anyone is interested the following code has been used safely on Windows
and Linux for thread safe reference counting. You can paste it into a
header file if you want, or use it as a guide. It uses pthreads on Linux
and the Win32 thread functions on Windows with InterlockedIncrement() and
InterlockedDecrement().
Best regards,
Martin
#ifndef Increment_h
#define Increment_h
#define _WINDOWS_
#ifndef _WINDOWS_
#include <pthread.h>
#include <bits/pthreadtypes.h>
#endif
class CIncrement
{
public:
#ifdef _WINDOWS_
CRITICAL_SECTION m_CS;
#endif
CIncrement()
{
#ifndef _WINDOWS_
pthread_mutex_init(&m_Mutex, NULL);
#endif
#ifdef _WINDOWS_
InitializeCriticalSection(&m_CS);
#endif
#ifdef _WINDOWS_
EnterCriticalSection(&m_CS);
#endif
m_nVal = 0;
#ifdef _WINDOWS_
LeaveCriticalSection(&m_CS);
#endif
}
~CIncrement()
{
#ifndef _WINDOWS_
pthread_mutex_destroy (&m_Mutex);
#endif
#ifdef _WINDOWS_
DeleteCriticalSection(&m_CS);
#endif
}
CIncrement& operator=(const CIncrement& thread)
{
if (this == &thread)
return *this;
#ifndef _WINDOWS_
pthread_mutex_lock(&m_Mutex);
#endif
#ifdef _WINDOWS_
EnterCriticalSection(&m_CS);
#endif
m_nVal = thread.m_nVal;
#ifdef _WINDOWS_
DeleteCriticalSection(&m_CS);
#endif
#ifndef _WINDOWS_
pthread_mutex_unlock(&m_Mutex);
#endif
return *this;
}
int operator++(int nVal)
{
return Add(1, true);
}
int operator++()
{
return Add(1, false);
}
int operator--(int nVal)
{
return Add(-1, true);
}
int operator--()
{
return Add(-1, false);
}
bool operator==(const int nVal)
{
#ifndef _WINDOWS_
pthread_mutex_lock(&m_Mutex);
#endif
#ifdef _WINDOWS_
EnterCriticalSection(&m_CS);
#endif
bool bReturn = (m_nVal == nVal);
#ifdef _WINDOWS_
LeaveCriticalSection(&m_CS);
#endif
#ifndef _WINDOWS_
pthread_mutex_unlock(&m_Mutex);
#endif
return bReturn;
}
int Add(int nNum, bool bReturnNew)
{
int rtn = 0;
#ifdef _WINDOWS_
return nNum > 0 ? InterlockedIncrement((volatile LONG*) &m_nVal)
: InterlockedDecrement((volatile
LONG*) &m_nVal);
#else
pthread_mutex_lock(&m_Mutex);
int oVal = m_nVal;
m_nVal += nNum;
rtn = bReturnNew ? m_nVal : oVal;
pthread_mutex_unlock(&m_Mutex);
#endif
return rtn;
}
protected:
int m_nVal;
#ifdef _WINDOWS_
void* m_Mutex;
#else
pthread_mutex_t m_Mutex;
#endif
};
#endif
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Tamas Szekeres
Sent: Saturday, November 01, 2008 5:40 PM
To: [email protected]
Subject: [gdal-dev] GDAL reference counting is thread unsafe
Folks,
I've found the following issue with the current refcounting
implementation in GDAL:
http://trac.osgeo.org/gdal/ticket/2648
Do you have idea whether we could handle this problem possibly for the
next release?
Best regards,
Tamas
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