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/* syncobj.h
*
* $Id$
*
* Synchronization objects.
*
* This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
* project.
*
* Copyright (C) 1998-2018 OpenLink Software
*
* This project 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; only version 2 of the License, dated June 1991.
*
* 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.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*
*/
#ifndef SYNCOBJ_H
#define SYNCOBJ_H
/*
* Mutual exclusion synchronization object.
*/
class SyncObj
{
public:
SyncObj();
~SyncObj();
void EnterCriticalSection();
void LeaveCriticalSection();
private:
#if DEBUG
long m_id;
static long m_last_id;
#endif
CRITICAL_SECTION critical_section;
// forbid copying
SyncObj(const SyncObj&);
SyncObj& operator=(const SyncObj&);
};
/*
* An utility class to be used jointly with a SyncObj. The only good
* of it is that it calls Leave() on the respective sync object in the
* destructor. So it comes in handy when used as an automatic variable
* in functions that require mutual exclusion.
*
* Example:
*
* SyncObj obj;
*
* void f1()
* {
* CriticalSection cs(obj);
* ...
* }
*
* An explicit call to the Leave() method allows to release the sync
* object before the end of the containing block (it might be desired
* for the sake of efficiency). The Enter() method allows to reacquire
* the sync object later on.
*
* void f2()
* {
* CriticalSection cs(obj);
* ...
* cs.Leave();
* ...
* }
*
*/
class CriticalSection
{
public:
CriticalSection(SyncObj *obj)
: entered(false), object(obj)
{
Enter();
}
~CriticalSection()
{
Leave();
}
void Enter();
void Leave();
private:
bool entered;
SyncObj *object;
};
class NotReentrantObj
{
public:
NotReentrantObj()
{
m_iEntranceCnt = 0;
}
bool
EnterNotReentrantObj()
{
LONG iEntranceCnt = InterlockedIncrement(&m_iEntranceCnt);
return (iEntranceCnt == 0);
}
void
LeaveNotReentrantObj()
{
InterlockedDecrement(&m_iEntranceCnt);
}
private:
LONG m_iEntranceCnt;
};
class EntranceChecker
{
public:
EntranceChecker(NotReentrantObj* pObj)
{
m_pObj = pObj;
if (m_pObj != NULL)
m_fCanEnter = m_pObj->EnterNotReentrantObj();
}
~EntranceChecker()
{
if (m_pObj != NULL)
m_pObj->LeaveNotReentrantObj();
}
bool
CanEnter()
{
return m_fCanEnter;
}
private:
bool m_fCanEnter;
NotReentrantObj* m_pObj;
};
#endif
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