sem.cpp

这是一个完整的图书馆供销存管理系统

/***************************************************************************
                          sem.cpp  -  description
                             -------------------
    begin                : Fri Jul 20 2001
    copyright            : (C) 2001 by Mark
    email                : [e-mail]
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/


#include <errno.h>
#include <string.h>
#include <stdarg.h>

#include "sem.h"


CSem::CSem(key_t tKey, int iSems, int iMode)
				: m_iSems(iSems), m_tKey(tKey)
{
	GetSem(iMode);
}


CSem::~CSem()
{
}


void CSem::GetSem(int iMode)
{
	if ((m_iSemId = semget(m_tKey, m_iSems, IPC_CREAT | IPC_EXCL | iMode)) < 0)
	{
		if (errno != EEXIST)
			throw CSemException(strerror(errno), __FILE__, __LINE__);

		if ((m_iSemId = semget(m_tKey, 0, iMode)) < 0)
			throw CSemException(strerror(errno), __FILE__, __LINE__);
		
		m_bCreate = false;
		return;
	}

	m_bCreate = true;
}


void CSem::RemoveSem()
{
	union semun unSem;
	if (semctl(m_iSemId, 0, IPC_RMID, unSem) < 0)
		throw CSemException(strerror(errno), __FILE__, __LINE__);
}


bool CSem::SemOpWithUndo(int iSems, ...)
{
	struct sembuf* pstSemBuf = new struct sembuf [iSems];
	
	va_list ap;
	va_start(ap, iSems);
	for (int i = 0; i < iSems; i++)
	{
		pstSemBuf[i].sem_num = (unsigned short int)va_arg(ap, int);
		pstSemBuf[i].sem_op = (short int)va_arg(ap, int);
		pstSemBuf[i].sem_flg = SEM_UNDO;
	}
	va_end(ap);
	
	if (semop(m_iSemId, pstSemBuf, iSems) < 0)
	{
		if (errno == EAGAIN || errno == EINTR)
		{
			delete [] pstSemBuf;
			return false;
		}
			
		delete [] pstSemBuf;
		throw CSemException(strerror(errno), __FILE__, __LINE__);
	}
	
	delete [] pstSemBuf;
	return true;
}


bool CSem::SemOp(int iSems, ...)
{
	struct sembuf* pstSemBuf = new struct sembuf [iSems];
	
	va_list ap;
	va_start(ap, iSems);
	for (int i = 0; i < iSems; i++)
	{
		pstSemBuf[i].sem_num = (unsigned short int)va_arg(ap, int);
		pstSemBuf[i].sem_op = (short int)va_arg(ap, int);
		pstSemBuf[i].sem_flg = (short int)va_arg(ap, int);
	}
	va_end(ap);
	
	if (semop(m_iSemId, pstSemBuf, iSems) < 0)
	{
		if (errno == EAGAIN || errno == EINTR)
		{
			delete [] pstSemBuf;
			return false;
		}
		
		delete [] pstSemBuf;
		throw CSemException(strerror(errno), __FILE__, __LINE__);
	}
	
	delete [] pstSemBuf;
	return true;
}


bool CSem::Lock()
{
	struct sembuf* pstSemBuf = new struct sembuf [m_iSems];
	
	for (int i = 0; i < m_iSems; i++)
	{
		pstSemBuf[i].sem_num = i;
		pstSemBuf[i].sem_op = -1;
		pstSemBuf[i].sem_flg = SEM_UNDO;
	}
	
	if (semop(m_iSemId, pstSemBuf, m_iSems) < 0)
	{
		if (errno == EAGAIN || errno == EINTR)
		{
			delete [] pstSemBuf;
			return false;
		}
		
		delete [] pstSemBuf;
		throw CSemException(strerror(errno), __FILE__, __LINE__);	
	}
	
	delete [] pstSemBuf;
	return true;
}


void CSem::Unlock()
{
	struct sembuf* pstSemBuf = new struct sembuf [m_iSems];
	
	for (int i = 0; i < m_iSems; i++)
	{
		pstSemBuf[i].sem_num = i;
		pstSemBuf[i].sem_op = 1;
		pstSemBuf[i].sem_flg = SEM_UNDO;
	}
	
	if (semop(m_iSemId, pstSemBuf, m_iSems) < 0)
	{
		delete [] pstSemBuf;
		throw CSemException(strerror(errno), __FILE__, __LINE__);	
	}
	
	delete [] pstSemBuf;
}


void CSem::SetAll(int iSems, ...)
{
	if (iSems != m_iSems)
		throw CSemException("argument error.", __FILE__, __LINE__);
	
	unsigned short int* pusiValue = new unsigned short int [iSems];
	
	va_list ap;
	va_start(ap, iSems);
	for (int i = 0; i < iSems; i++)
		pusiValue[i] = (unsigned short int)va_arg(ap, int);
	va_end(ap);
	
	semun unSem;
	unSem.array = pusiValue;
	if (semctl(m_iSemId, 0, SETALL, unSem) < 0)
	{
		delete [] pusiValue;
		throw CSemException(strerror(errno), __FILE__, __LINE__);
	}
	
	delete [] pusiValue;
}


void CSem::SetValue(int iSemNum, int iValue)
{
	semun unSem;
	unSem.val = iValue;
	if (semctl(m_iSemId, iSemNum, SETVAL, unSem) < 0)
		throw CSemException(strerror(errno), __FILE__, __LINE__);
}


void CSem::GetAll(unsigned short int* pusiArray)
{
	semun unSem;
	unSem.array = pusiArray;
	if (semctl(m_iSemId, 0, GETALL, unSem) < 0)
		throw CSemException(strerror(errno), __FILE__, __LINE__);	
}


int CSem::GetValue(int iSemNum)
{
	semun unSem;
	int iValue = semctl(m_iSemId, iSemNum, GETVAL, unSem);
	if (iValue < 0)
		throw CSemException(strerror(errno), __FILE__, __LINE__);	
	
	return iValue;
}


void CSem::InitSem()
{
	unsigned short int* pusiValue = new unsigned short int [m_iSems];
	
	for (int i = 0; i < m_iSems; i++)
		pusiValue[i] = (unsigned short int)1;

	semun unSem;
	unSem.array = pusiValue;
	if (semctl(m_iSemId, 0, SETALL, unSem) < 0)
	{
		delete [] pusiValue;
		throw CSemException(strerror(errno), __FILE__, __LINE__);
	}
	
	delete [] pusiValue;
}