Hi Paul and Robert,
don't know if it'll help as a reference or not, but I make a fair
bit of use of the free ZThreads API in the day-job and it seems
to fairly well implemented in WIN32. I've attached the impl
of FastMutex which has an "acquire" and "tryAcquire". See
http://zthread.sourceforge.net/ for the rest.
Cheers,
Colin.
----- Original Message -----
From: "Paul Martz" <[EMAIL PROTECTED]>
To: "'osg users'" <osg-users@openscenegraph.net>
Sent: Saturday, August 12, 2006 8:28 PM
Subject: RE: [osg-users] Windows users please test OpenThreads CVS
Don't know, I haven't been party to the Windows OpenThreds
implementation, but my guess is that the contributors were
learning threading/MS's thread API while developing the code.
Alot of code is developed this way, OpenSceneGraph wouldn't
exist if it weren't for the spirit of having a go at
something you've never done before ;-)
Well, in THAT spirit, then let me give it a whack... :-)
I've rewritten Mutex using a CRITICAL_SECTION which eliminates the need for
spinning so it should address the performance issues. While I'm rebuilding
OSG for testing I thought I'd post some questions and see how bad I screwed
things up.
With a Win32 CRITICAL_SECTION, we call EnterCriticalSection to hold a lock
and LeaveCriticalSection to release the lock. The problem is, these are
paired calls; if a thread calls EnterCriticalSection twice, it must then
call LeaveCriticalSection twice to release the lock. If I'm not mistaken,
this is what osgDB::ReentrantMutex does, which implies that
OpenThreads::Mutex should not work this way. Correct? If so, then I'll need
to add some additional code to prevent this from happening.
I'm also unsure of what the semantics and return code should be for
trylock():
* Should this function take the lock if it can? What should the return code
be in this case?
* If the current thread can't take the lock, what should the return code
be?
* Finally, if the current thread already owns the lock, what should the
return code be?
Thanks,
-Paul
_______________________________________________
osg-users mailing list
osg-users@openscenegraph.net
http://openscenegraph.net/mailman/listinfo/osg-users
http://www.openscenegraph.org/
/*
* Copyright (c) 2005, Eric Crahen
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
furnished
* to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#ifndef __ZTFASTRECURSIVELOCK_H__
#define __ZTFASTRECURSIVELOCK_H__
#include "zthread/Exceptions.h"
#include "zthread/NonCopyable.h"
#include <windows.h>
#include <assert.h>
namespace ZThread {
/**
* @class FastRecursiveLock
*
* @author Eric Crahen <http://www.code-foo.com>
* @date <2003-07-16T23:32:56-0400>
* @version 2.2.11
*
* This FastRecursiveLock implementation is based on a Win32 Mutex
* object. This will perform better under high contention,
* but will not be as fast as the spin lock under reasonable
* circumstances.
*/
class FastRecursiveLock : private NonCopyable {
HANDLE _hMutex;
volatile unsigned int _count;
public:
/**
* Create a new FastRecursiveLock
*/
FastRecursiveLock() : _count(0) {
_hMutex = ::CreateMutex(0, 0, 0);
assert(_hMutex != NULL);
if(_hMutex == NULL)
throw Initialization_Exception();
}
~FastRecursiveLock() {
::CloseHandle(_hMutex);
}
void acquire() {
if(::WaitForSingleObject(_hMutex, INFINITE) != WAIT_OBJECT_0) {
assert(0);
throw Synchronization_Exception();
}
}
void release() {
if(::ReleaseMutex(_hMutex) == 0) {
assert(0);
throw Synchronization_Exception();
}
}
bool tryAcquire(unsigned long) {
switch(::WaitForSingleObject(_hMutex, 0)) {
case WAIT_OBJECT_0:
return true;
case WAIT_TIMEOUT:
return false;
default:
break;
}
assert(0);
throw Synchronization_Exception();
}
}; /* FastRecursiveLock */
} // namespace ZThread
#endif
/*
* Copyright (c) 2005, Eric Crahen
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
furnished
* to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#ifndef __ZTFASTLOCK_H__
#define __ZTFASTLOCK_H__
#include "zthread/Exceptions.h"
#include "zthread/NonCopyable.h"
#include "../ThreadOps.h"
#include <windows.h>
#include <assert.h>
namespace ZThread {
/**
* @class FastLock
*
* @author Eric Crahen <http://www.code-foo.com>
* @date <2003-07-16T23:32:44-0400>
* @version 2.2.11
*
* This FastLock implementation is based on a Win32 Mutex
* object. This will perform better under high contention,
* but will not be as fast as the spin lock under reasonable
* circumstances.
*/
class FastLock : private NonCopyable {
HANDLE _hMutex;
#ifndef NDEBUG
volatile bool _locked;
#endif
public:
/**
* Create a new FastLock
*/
FastLock() {
#ifndef NDEBUG
_locked = false;
#endif
_hMutex = ::CreateMutex(0, 0, 0);
assert(_hMutex != NULL);
if(_hMutex == NULL)
throw Initialization_Exception();
}
~FastLock() {
::CloseHandle(_hMutex);
}
void acquire() {
if(::WaitForSingleObject(_hMutex, INFINITE) != WAIT_OBJECT_0) {
assert(0);
throw Synchronization_Exception();
}
#ifndef NDEBUG
// Simulate deadlock to provide consistent behavior. This
// will help avoid errors when porting. Avoiding situations
// where a FastMutex mistakenly behaves as a recursive lock.
while(_locked)
ThreadOps::yield();
_locked = true;
#endif
}
void release() {
#ifndef NDEBUG
_locked = false;
#endif
if(::ReleaseMutex(_hMutex) == 0) {
assert(0);
throw Synchronization_Exception();
}
}
bool tryAcquire(unsigned long timeout = 0) {
switch(::WaitForSingleObject(_hMutex, timeout)) {
case WAIT_OBJECT_0:
#ifndef NDEBUG
// Simulate deadlock to provide consistent behavior. This
// will help avoid errors when porting. Avoiding situations
// where a FastMutex mistakenly behaves as a recursive lock.
while(_locked)
ThreadOps::yield();
_locked = true;
#endif
return true;
case WAIT_TIMEOUT:
return false;
default:
break;
}
assert(0);
throw Synchronization_Exception();
}
};
} // namespace ZThread
#endif
_______________________________________________
osg-users mailing list
osg-users@openscenegraph.net
http://openscenegraph.net/mailman/listinfo/osg-users
http://www.openscenegraph.org/
