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/*
* $Revision: 3840 $
*
* last checkin:
* $Author: gutwenger $
* $Date: 2013-11-19 08:27:44 +0100 (Tue, 19 Nov 2013) $
***************************************************************/
/** \file
* \brief Implementation of criticial sections.
*
* \author Carsten Gutwenger
*
* \par License:
* This file is part of the Open Graph Drawing Framework (OGDF).
*
* \par
* Copyright (C)<br>
* See README.txt in the root directory of the OGDF installation for details.
*
* \par
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* Version 2 or 3 as published by the Free Software Foundation;
* see the file LICENSE.txt included in the packaging of this file
* for details.
*
* \par
* 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.
*
* \par
* 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., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
* \see http://www.gnu.org/copyleft/gpl.html
***************************************************************/
// must be included first here
#include <ogdf/basic/basic.h>
#ifdef _MSC_VER
#pragma once
#endif
#ifndef OGDF_CRITICAL_SECTION_H
#define OGDF_CRITICAL_SECTION_H
#if !defined(OGDF_SYSTEM_WINDOWS)
#include <pthread.h>
#include <errno.h>
#endif
#include <ogdf/basic/System.h>
namespace ogdf {
#if defined(OGDF_SYSTEM_WINDOWS)
//! Representation of a critical section.
/**
* Critical sections are used to synchronize access to resources shared by
* several threads. It can be used to protect an object or a piece of code
* allowing always one thread at a time access.
*/
class OGDF_EXPORT CriticalSection
{
public:
//! Creates a critical section object.
CriticalSection() {
#if _WIN32_WINNT >= 0x0600
InitializeSRWLock(&m_srwLock);
#else
InitializeCriticalSection(&m_cs);
#endif
}
//! Creates a critical section object with spin count.
/**
* The spin count determines how many times the calling thread spins
* when the critical section is unavailable, before it performs a wait.
* \remark The spin count is only used on multiprocessor systems;
* otherwise it makes no sense.
*/
explicit CriticalSection(int spinCount) {
#if _WIN32_WINNT >= 0x0600
#pragma warning( suppress : 4100 )
InitializeSRWLock(&m_srwLock);
#else
InitializeCriticalSectionAndSpinCount(&m_cs, spinCount);
#endif
}
~CriticalSection() {
#if _WIN32_WINNT < 0x0600
DeleteCriticalSection(&m_cs);
#endif
}
//! Enters the critical section.
void enter() {
#if _WIN32_WINNT >= 0x0600
AcquireSRWLockExclusive(&m_srwLock);
#else
EnterCriticalSection(&m_cs);
#endif
}
//! Tries to enter the critical section; returns true on success.
bool tryEnter() {
#if _WIN32_WINNT >= 0x0600
return (TryAcquireSRWLockExclusive(&m_srwLock) != 0);
#else
return (TryEnterCriticalSection(&m_cs) != 0);
#endif
}
//! Leaves the critical section.
void leave() {
#if _WIN32_WINNT >= 0x0600
ReleaseSRWLockExclusive(&m_srwLock);
#else
LeaveCriticalSection(&m_cs);
#endif
}
private:
#if _WIN32_WINNT >= 0x0600
SRWLOCK m_srwLock;
#else
CRITICAL_SECTION m_cs; //!< The Windows critical section object.
#endif
};
#else
class OGDF_EXPORT CriticalSection
{
public:
CriticalSection() : m_spinCount(0) {
pthread_mutex_init(&m_mutex, NULL);
}
explicit CriticalSection(int spinCount) {
m_spinCount = (System::numberOfProcessors() >= 2) ? spinCount : 0;
int ret = pthread_mutex_init(&m_mutex, NULL);
if(ret != 0)
cout << "initialization of mutex failed: " << ret << endl;
}
~CriticalSection() {
pthread_mutex_destroy(&m_mutex);
}
void enter() {
if(m_spinCount > 0) {
for(int i = m_spinCount; i > 0; --i)
if(pthread_mutex_trylock(&m_mutex) != EBUSY)
return;
}
pthread_mutex_lock(&m_mutex);
}
bool tryEnter() {
return (pthread_mutex_trylock(&m_mutex) != EBUSY);
}
void leave() {
pthread_mutex_unlock(&m_mutex);
}
private:
pthread_mutex_t m_mutex;
int m_spinCount;
};
#endif
} // end namespace ogdf
#endif
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