/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <thread.h>#include "threadimpl.h" Rgrp _threadrgrp;static int isdirty; static void*finish(Thread *t, void *val){	void *ret; 	ret = t->rendval;	t->rendval = val;	while(t->state == Running)		sleep(0);	lock(&t->proc->lock);	if(t->state == Rendezvous){	/* not always true: might be Dead */		t->state = Ready;		_threadready(t);	}	unlock(&t->proc->lock);	return ret;} void*_threadrendezvous(void *tag, void *val){	void *ret;	Thread *t, **l; 	lock(&_threadrgrp.lock);	l = &_threadrgrp.hash[((uintptr)tag)%nelem(_threadrgrp.hash)];	for(t=*l; t; l=&t->rendhash, t=*l){		if(t->rendtag==tag){			_threaddebug(DBGREND, "Rendezvous with thread %d.%d", t->proc->pid, t->id);			*l = t->rendhash;			ret = finish(t, val);			unlock(&_threadrgrp.lock);			return ret;		}	} 	/* Going to sleep here. */	t = _threadgetproc()->thread;	t->rendbreak = 0;	t->inrendez = 1;	t->rendtag = tag;	t->rendval = val;	t->rendhash = *l;	*l = t;	t->nextstate = Rendezvous;	_threaddebug(DBGREND, "Rendezvous for tag %p", t->rendtag);	unlock(&_threadrgrp.lock);	_sched();	t->inrendez = 0;	_threaddebug(DBGREND, "Woke after rendezvous; val is %p", t->rendval);	return t->rendval;} /* * This is called while holding _threadpq.lock and p->lock, * so we can't lock _threadrgrp.lock.  Instead our caller has  * to call _threadbreakrendez after dropping those locks. */void_threadflagrendez(Thread *t){	t->rendbreak = 1;	isdirty = 1;} void_threadbreakrendez(void){	int i;	Thread *t, **l; 	if(isdirty == 0)		return;	lock(&_threadrgrp.lock);	if(isdirty == 0){		unlock(&_threadrgrp.lock);		return;	}	isdirty = 0;	for(i=0; i<nelem(_threadrgrp.hash); i++){		l = &_threadrgrp.hash[i];		for(t=*l; t; t=*l){			if(t->rendbreak){				*l = t->rendhash;				finish(t, (void*)~0);			}else				 l=&t->rendhash;		}	}	unlock(&_threadrgrp.lock);}