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/*
* ip tunnel/ethertap device for MacOSX.
*
* Locking is not as straightforward for Tiger. So declare our own locking class.
*/
/*
* Copyright (c) 2011 Mattias Nissler <mattias.nissler@gmx.de>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other materials provided
* with the distribution.
* 3. The name of the author may not be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __LOCK_H__
#define __LOCK_H__
extern "C" {
#include <kern/locks.h>
#include <sys/param.h>
}
/* our own locking class. declares the common interface of the locking primitives. */
class tt_lock {
protected:
/* locking group */
static lck_grp_t *tt_lck_grp;
public:
/* be virtual */
virtual ~tt_lock() { };
/* static intialization (inits the locking group) */
static bool initialize();
static void shutdown();
/* locking */
virtual void lock() = 0;
virtual void unlock() = 0;
/* monitor primitives */
virtual void sleep(void* cond) = 0;
virtual void sleep(void* cond, uint64_t) = 0;
virtual void wakeup(void* cond) = 0;
};
/* simple mutex */
class tt_mutex : public tt_lock {
private:
/* underlying darwin lock */
lck_rw_t *lck;
public:
tt_mutex();
virtual ~tt_mutex();
void lock();
void unlock();
/* monitor primitives */
void sleep(void* cond);
void sleep(void* cond, uint64_t);
void wakeup(void* cond);
};
/* A very special locking class that we use to track threads that enter and leave the character
* device service functions. They call enter() before entering the actual service routinge and
* exit() when done. enter() only permits them to pass when the gate isn't locked. Furthermore, the
* gate assigns ticket numbers to everyone that passes the gate, so you can check whether more
* threads came through. See tuntap_mgr::shutdown() for how we use that stuff.
*/
class tt_gate : public tt_lock {
private:
/* synchronization lock */
tt_mutex slock;
/* ticket number */
unsigned int ticket_number;
/* count of threads that are in */
unsigned int population;
public:
/* construct a new gate */
tt_gate();
/* enter - pass the gate */
void enter();
/* exit - pass the gate */
void exit();
/* check whether anyone is in */
bool is_anyone_in();
/* gets the next ticket number */
unsigned int get_ticket_number();
/* lock the gate */
void lock();
/* unlock the gate */
void unlock();
/* monitor primitives */
void sleep(void* cond);
void sleep(void* cond, uint64_t);
void wakeup(void* cond);
};
/* auto_lock and auto_rwlock serve as automatic lock managers: Create an object, passing the
* tt_[rw]lock you want to lock to have it grab the lock. When the object goes out of scope, the
* destructor of the class will release the lock.
*/
class auto_lock {
protected:
/* the lock we hold */
tt_lock *l;
public:
auto_lock(tt_lock *m)
: l(m)
{
lock();
}
~auto_lock()
{
unlock();
}
void lock()
{
l->lock();
}
void unlock()
{
l->unlock();
}
};
#endif /* __LOCK_H__ */
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