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/*
* Copyright (C) 2001-2008 Jacek Sieka, arnetheduck on gmail point 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(CRITICAL_SECTION_H)
#define CRITICAL_SECTION_H
#include "Thread.h"
namespace dcpp {
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_init(&ma);
pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_RECURSIVE);
pthread_mutex_init(&mtx, &ma);
}
~CriticalSection() throw() {
pthread_mutex_destroy(&mtx);
pthread_mutexattr_destroy(&ma);
}
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;
pthread_mutexattr_t ma;
#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:
volatile long state;
#else
// We have to use a pthread (nonrecursive) mutex, didn't find any test_and_set on linux...
FastCriticalSection() {
static pthread_mutex_t fastmtx = PTHREAD_MUTEX_INITIALIZER;
mtx = fastmtx;
}
~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 T>
class LockBase {
public:
LockBase(T& aCs) throw() : cs(aCs) { cs.enter(); }
~LockBase() throw() { cs.leave(); }
private:
LockBase& operator=(const LockBase&);
T& cs;
};
typedef LockBase<CriticalSection> Lock;
typedef LockBase<FastCriticalSection> FastLock;
} // namespace dcpp
#endif // !defined(CRITICAL_SECTION_H)
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