www.pudn.com > DCPlusPlus-src.zip > CriticalSection.h

/*  
 * Copyright (C) 2001-2004 Jacek Sieka, j_s at telia com 
 * 
 * This program is free software; you can redistribute it and/or modify 
 * it under the terms of the GNU General Public License as published by 
 * the Free Software Foundation; either version 2 of the License, or 
 * (at your option) any later version. 
 * 
 * This program is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * GNU General Public License for more details. 
 * 
 * You should have received a copy of the GNU General Public License 
 * along with this program; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 */ 
 
#if !defined(AFX_CRITCALSECTION_H__1226AAB5_254F_4CBD_B384_5E8D3A23C346__INCLUDED_) 
#define AFX_CRITCALSECTION_H__1226AAB5_254F_4CBD_B384_5E8D3A23C346__INCLUDED_ 
 
#if _MSC_VER > 1000 
#pragma once 
#endif // _MSC_VER > 1000 
 
#include "Thread.h" 
 
class CriticalSection   
{ 
#ifdef _WIN32 
public: 
	void enter() throw() { 
		EnterCriticalSection(&cs); 
		dcdrun(counter++);	 
	} 
	void leave() throw() { 
		dcassert(--counter >= 0); 
		LeaveCriticalSection(&cs); 
	} 
	CriticalSection() throw() { 
		dcdrun(counter = 0;); 
		InitializeCriticalSection(&cs); 
	} 
	~CriticalSection() throw() { 
		dcassert(counter==0); 
		DeleteCriticalSection(&cs); 
	} 
private: 
	dcdrun(long counter;); 
	CRITICAL_SECTION cs; 
#else 
public: 
	CriticalSection() throw() { 
		pthread_mutexattr_t attr; 
		pthread_mutexattr_init(&attr); 
		pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE_NP); 
		pthread_mutex_init(&mtx, &attr); 
		pthread_mutexattr_destroy(&attr); 
	}; 
	~CriticalSection() throw() { pthread_mutex_destroy(&mtx); }; 
	void enter() throw() { pthread_mutex_lock(&mtx); }; 
	void leave() throw() { pthread_mutex_unlock(&mtx); }; 
	pthread_mutex_t& getMutex() { return mtx; }; 
private: 
	pthread_mutex_t mtx; 
#endif 
	CriticalSection(const CriticalSection&); 
	CriticalSection& operator=(const CriticalSection&); 
}; 
 
/** 
* A fast, non-recursive and unfair implementation of the Critical Section. 
* It is meant to be used in situations where the risk for lock conflict is very low,  
* i e locks that are held for a very short time. The lock is _not_ recursive, i e if  
* the same thread will try to grab the lock it'll hang in a never-ending loop. The lock 
* is not fair, i e the first to try to enter a locked lock is not guaranteed to be the 
* first to get it when it's freed... 
*/ 
class FastCriticalSection { 
public: 
#ifdef _WIN32 
	FastCriticalSection() : state(0) { }; 
 
	void enter() { 
		while(Thread::safeExchange(&state, 1) == 1) { 
			Thread::yield(); 
		} 
	} 
	void leave() { 
		Thread::safeDec(&state); 
	} 
private: 
	long state; 
 
#else 
	// We have to use a pthread (nonrecursive) mutex, didn't find any test_and_set on linux... 
	FastCriticalSection() {  
		pthread_mutexattr_t attr; 
		pthread_mutexattr_init(&attr); 
		pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_FAST_NP); 
		pthread_mutex_init(&mtx, &attr); 
		pthread_mutexattr_destroy(&attr); 
	}; 
	~FastCriticalSection() { pthread_mutex_destroy(&mtx); }; 
	void enter() { pthread_mutex_lock(&mtx); }; 
	void leave() { pthread_mutex_unlock(&mtx); }; 
private: 
	pthread_mutex_t mtx;	 
#endif 
}; 
 
template 
class SimpleLock { 
public: 
	SimpleLock(T& aCs) throw() : cs(aCs)  { cs.enter(); }; 
	~SimpleLock() throw() { cs.leave(); }; 
private: 
	T& cs; 
}; 
 
typedef SimpleLock Lock; 
typedef SimpleLock FastLock; 
 
class RWLock 
{ 
public: 
	RWLock() throw() : readers(0) { } 
	~RWLock() throw() { dcassert(readers==0); } 
 
	void enterRead() throw() { 
		Lock l(cs); 
		readers++; 
		dcassert(readers < 100); 
	} 
 
	void leaveRead() throw() { 
		Thread::safeDec(&readers); 
		dcassert(readers >= 0); 
	} 
	void enterWrite() throw() { 
		cs.enter(); 
		while(readers > 0) { 
			cs.leave(); 
			Thread::yield(); 
			 
			cs.enter(); 
		} 
	} 
	void leaveWrite() { 
		cs.leave(); 
	} 
private: 
	CriticalSection cs; 
	long readers; 
}; 
 
class RLock { 
public: 
	RLock(RWLock& aCs) throw() : cs(aCs)  { cs.enterRead(); }; 
	~RLock() throw() { cs.leaveRead(); }; 
private: 
	RWLock& cs; 
}; 
 
class WLock { 
public: 
	WLock(RWLock& aCs) throw() : cs(aCs)  { cs.enterWrite(); }; 
	~WLock() throw() { cs.leaveWrite(); }; 
private: 
	RWLock& cs; 
}; 
 
#endif // !defined(AFX_CRITCALSECTION_H__1226AAB5_254F_4CBD_B384_5E8D3A23C346__INCLUDED_) 
 
/** 
 * @file 
 * $Id: CriticalSection.h,v 1.22 2004/09/25 20:40:40 arnetheduck Exp $ 
 */