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/*
PowerDNS Versatile Database Driven Nameserver
Copyright (C) 2002 PowerDNS.COM BV
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2
as published by the Free Software Foundation
Additionally, the license of this program contains a special
exception which allows to distribute the program in binary form when
it is linked against OpenSSL.
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 LOCK_HH
#define LOCK_HH
#include <pthread.h>
#include <errno.h>
#include "misc.hh"
#include "pdnsexception.hh"
extern bool g_singleThreaded;
class Lock
{
pthread_mutex_t *d_lock;
public:
Lock(pthread_mutex_t *lock) : d_lock(lock)
{
if(g_singleThreaded)
return;
if((errno=pthread_mutex_lock(d_lock)))
throw PDNSException("error acquiring lock: "+stringerror());
}
~Lock()
{
if(g_singleThreaded)
return;
pthread_mutex_unlock(d_lock);
}
};
class WriteLock
{
pthread_rwlock_t *d_lock;
public:
WriteLock(pthread_rwlock_t *lock) : d_lock(lock)
{
if(g_singleThreaded)
return;
if((errno=pthread_rwlock_wrlock(d_lock))) {
throw PDNSException("error acquiring rwlock wrlock: "+stringerror());
}
}
~WriteLock()
{
if(g_singleThreaded)
return;
pthread_rwlock_unlock(d_lock);
}
};
class TryWriteLock
{
pthread_rwlock_t *d_lock;
bool d_havelock;
public:
TryWriteLock(pthread_rwlock_t *lock) : d_lock(lock)
{
if(g_singleThreaded) {
d_havelock=true;
return;
}
d_havelock=false;
if((errno=pthread_rwlock_trywrlock(d_lock)) && errno!=EBUSY)
throw PDNSException("error acquiring rwlock tryrwlock: "+stringerror());
d_havelock=(errno==0);
}
~TryWriteLock()
{
if(g_singleThreaded)
return;
if(d_havelock)
pthread_rwlock_unlock(d_lock);
}
bool gotIt()
{
if(g_singleThreaded)
return true;
return d_havelock;
}
};
class TryReadLock
{
pthread_rwlock_t *d_lock;
bool d_havelock;
public:
TryReadLock(pthread_rwlock_t *lock) : d_lock(lock)
{
if(g_singleThreaded) {
d_havelock=true;
return;
}
if((errno=pthread_rwlock_tryrdlock(d_lock)) && errno!=EBUSY)
throw PDNSException("error acquiring rwlock tryrdlock: "+stringerror());
d_havelock=(errno==0);
}
~TryReadLock()
{
if(g_singleThreaded)
return;
if(d_havelock)
pthread_rwlock_unlock(d_lock);
}
bool gotIt()
{
if(g_singleThreaded)
return true;
return d_havelock;
}
};
class ReadLock
{
pthread_rwlock_t *d_lock;
public:
ReadLock(pthread_rwlock_t *lock) : d_lock(lock)
{
if(g_singleThreaded)
return;
if((errno=pthread_rwlock_rdlock(d_lock)))
throw PDNSException("error acquiring rwlock tryrwlock: "+stringerror());
}
~ReadLock()
{
if(g_singleThreaded)
return;
pthread_rwlock_unlock(d_lock);
}
void upgrade()
{
if(g_singleThreaded)
return;
pthread_rwlock_unlock(d_lock);
pthread_rwlock_wrlock(d_lock);
}
};
#endif
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