mpv/misc/rendezvous.h

#ifndef MP_RENDEZVOUS_H_
#define MP_RENDEZVOUS_H_

#include <stdint.h>

intptr_t mp_rendezvous(void *tag, intptr_t value);

#endif
Add Plan 9-style barriers Plan 9 has a very interesting synchronization mechanism, the rendezvous() call. A good property of this is that you don't need to explicitly initialize and destroy a barrier object, unlike as with e.g. POSIX barriers (which are mandatory to begin with). Upon "meeting", they can exchange a value. This mechanism will be nice to synchronize certain stages of initialization between threads in the following commit. Unlike Plan 9 rendezvous(), this is not implemented with a hashtable, because that would require additional effort (especially if you want to make it actually scele). Unlike the Plan 9 variant, we use intptr_t instead of void* as type for the value, because I expect that we will be mostly passing a status code as value and not a pointer. Converting an integer to void* requires two cast (because the integer needs to be intptr_t), the other way around it's only one cast. We don't particularly care about performance in this case either. It's simply not important for our use-case. So a simple linked list is used for waiters, and on wakeup, all waiters are temporarily woken up. 2014-07-26 18:29:48 +00:00			`#ifndef MP_RENDEZVOUS_H_`
			`#define MP_RENDEZVOUS_H_`

			`#include <stdint.h>`

			`intptr_t mp_rendezvous(void *tag, intptr_t value);`

			`#endif`