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/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* 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 Street, 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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