1 #include "threadimpl.h"
2 
3 Rgrp _threadrgrp;
4 static int isdirty;
5 int _threadhighnrendez;
6 int _threadnrendez;
7 static int nrendez;
8 
9 static ulong
10 finish(Thread *t, ulong val)
11 {
12 	ulong ret;
13 
14 	ret = t->rendval;
15 	t->rendval = val;
16 	while(t->state == Running)
17 		sleep(0);
18 	lock(&t->proc->lock);
19 	if(t->state == Rendezvous){	/* not always true: might be Dead */
20 		t->state = Ready;
21 		_threadready(t);
22 	}
23 	unlock(&t->proc->lock);
24 	return ret;
25 }
26 
27 ulong
28 _threadrendezvous(ulong tag, ulong val)
29 {
30 	ulong ret;
31 	Thread *t, **l;
32 
33 	lock(&_threadrgrp.lock);
34 _threadnrendez++;
35 	l = &_threadrgrp.hash[tag%nelem(_threadrgrp.hash)];
36 	for(t=*l; t; l=&t->rendhash, t=*l){
37 		if(t->rendtag==tag){
38 			_threaddebug(DBGREND, "Rendezvous with thread %d.%d", t->proc->pid, t->id);
39 			*l = t->rendhash;
40 			ret = finish(t, val);
41 			--nrendez;
42 			unlock(&_threadrgrp.lock);
43 			return ret;
44 		}
45 	}
46 
47 	/* Going to sleep here. */
48 	t = _threadgetproc()->thread;
49 	t->rendbreak = 0;
50 	t->inrendez = 1;
51 	t->rendtag = tag;
52 	t->rendval = val;
53 	t->rendhash = *l;
54 	*l = t;
55 	t->nextstate = Rendezvous;
56 	++nrendez;
57 	if(nrendez > _threadhighnrendez)
58 		_threadhighnrendez = nrendez;
59 	_threaddebug(DBGREND, "Rendezvous for tag %lud", t->rendtag);
60 	unlock(&_threadrgrp.lock);
61 	_sched();
62 	t->inrendez = 0;
63 	_threaddebug(DBGREND, "Woke after rendezvous; val is %lud", t->rendval);
64 	return t->rendval;
65 }
66 
67 /*
68  * This is called while holding _threadpq.lock and p->lock,
69  * so we can't lock _threadrgrp.lock.  Instead our caller has 
70  * to call _threadbreakrendez after dropping those locks.
71  */
72 void
73 _threadflagrendez(Thread *t)
74 {
75 	t->rendbreak = 1;
76 	isdirty = 1;
77 }
78 
79 void
80 _threadbreakrendez(void)
81 {
82 	int i;
83 	Thread *t, **l;
84 
85 	if(isdirty == 0)
86 		return;
87 	lock(&_threadrgrp.lock);
88 	if(isdirty == 0){
89 		unlock(&_threadrgrp.lock);
90 		return;
91 	}
92 	isdirty = 0;
93 	for(i=0; i<nelem(_threadrgrp.hash); i++){
94 		l = &_threadrgrp.hash[i];
95 		for(t=*l; t; t=*l){
96 			if(t->rendbreak){
97 				*l = t->rendhash;
98 				finish(t, ~0);
99 			}else
100 				 l=&t->rendhash;
101 		}
102 	}
103 	unlock(&_threadrgrp.lock);
104 }