1 76193d7c 2003-09-30 devnull #include "threadimpl.h"
  2 76193d7c 2003-09-30 devnull 
  3 76193d7c 2003-09-30 devnull static Lock chanlock;		/* central channel access lock */
  4 76193d7c 2003-09-30 devnull 
  5 76193d7c 2003-09-30 devnull static void enqueue(Alt*, Channel**);
  6 76193d7c 2003-09-30 devnull static void dequeue(Alt*);
  7 76193d7c 2003-09-30 devnull static int altexec(Alt*, int);
  8 76193d7c 2003-09-30 devnull 
  9 76193d7c 2003-09-30 devnull int _threadhighnentry;
 10 76193d7c 2003-09-30 devnull int _threadnalt;
 11 76193d7c 2003-09-30 devnull 
 12 76193d7c 2003-09-30 devnull static int
 13 76193d7c 2003-09-30 devnull canexec(Alt *a)
 14 76193d7c 2003-09-30 devnull {
 15 76193d7c 2003-09-30 devnull 	int i, otherop;
 16 76193d7c 2003-09-30 devnull 	Channel *c;
 17 76193d7c 2003-09-30 devnull 
 18 76193d7c 2003-09-30 devnull 	c = a->c;
 19 76193d7c 2003-09-30 devnull 	/* are there senders or receivers blocked? */
 20 76193d7c 2003-09-30 devnull 	otherop = (CHANSND+CHANRCV) - a->op;
 21 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
 22 76193d7c 2003-09-30 devnull 		if(c->qentry[i] && c->qentry[i]->op==otherop && *c->qentry[i]->tag==nil){
 23 76193d7c 2003-09-30 devnull 			_threaddebug(DBGCHAN, "can rendez alt %p chan %p", a, c);
 24 76193d7c 2003-09-30 devnull 			return 1;
 25 76193d7c 2003-09-30 devnull 		}
 26 76193d7c 2003-09-30 devnull 
 27 76193d7c 2003-09-30 devnull 	/* is there room in the channel? */
 28 76193d7c 2003-09-30 devnull 	if((a->op==CHANSND && c->n < c->s)
 29 76193d7c 2003-09-30 devnull 	|| (a->op==CHANRCV && c->n > 0)){
 30 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "can buffer alt %p chan %p", a, c);
 31 76193d7c 2003-09-30 devnull 		return 1;
 32 76193d7c 2003-09-30 devnull 	}
 33 76193d7c 2003-09-30 devnull 
 34 76193d7c 2003-09-30 devnull 	return 0;
 35 76193d7c 2003-09-30 devnull }
 36 76193d7c 2003-09-30 devnull 
 37 76193d7c 2003-09-30 devnull static void
 38 76193d7c 2003-09-30 devnull _chanfree(Channel *c)
 39 76193d7c 2003-09-30 devnull {
 40 76193d7c 2003-09-30 devnull 	int i, inuse;
 41 76193d7c 2003-09-30 devnull 
 42 76193d7c 2003-09-30 devnull 	inuse = 0;
 43 76193d7c 2003-09-30 devnull 	for(i = 0; i < c->nentry; i++)
 44 76193d7c 2003-09-30 devnull 		if(c->qentry[i])
 45 76193d7c 2003-09-30 devnull 			inuse = 1;
 46 76193d7c 2003-09-30 devnull 	if(inuse)
 47 76193d7c 2003-09-30 devnull 		c->freed = 1;
 48 76193d7c 2003-09-30 devnull 	else{
 49 76193d7c 2003-09-30 devnull 		if(c->qentry)
 50 76193d7c 2003-09-30 devnull 			free(c->qentry);
 51 76193d7c 2003-09-30 devnull 		free(c);
 52 76193d7c 2003-09-30 devnull 	}
 53 76193d7c 2003-09-30 devnull }
 54 76193d7c 2003-09-30 devnull 
 55 76193d7c 2003-09-30 devnull void
 56 76193d7c 2003-09-30 devnull chanfree(Channel *c)
 57 76193d7c 2003-09-30 devnull {
 58 76193d7c 2003-09-30 devnull 	lock(&chanlock);
 59 76193d7c 2003-09-30 devnull 	_chanfree(c);
 60 76193d7c 2003-09-30 devnull 	unlock(&chanlock);
 61 76193d7c 2003-09-30 devnull }
 62 76193d7c 2003-09-30 devnull 
 63 76193d7c 2003-09-30 devnull int
 64 76193d7c 2003-09-30 devnull chaninit(Channel *c, int elemsize, int elemcnt)
 65 76193d7c 2003-09-30 devnull {
 66 76193d7c 2003-09-30 devnull 	if(elemcnt < 0 || elemsize <= 0 || c == nil)
 67 76193d7c 2003-09-30 devnull 		return -1;
 68 76193d7c 2003-09-30 devnull 	c->f = 0;
 69 76193d7c 2003-09-30 devnull 	c->n = 0;
 70 76193d7c 2003-09-30 devnull 	c->freed = 0;
 71 76193d7c 2003-09-30 devnull 	c->e = elemsize;
 72 76193d7c 2003-09-30 devnull 	c->s = elemcnt;
 73 76193d7c 2003-09-30 devnull 	_threaddebug(DBGCHAN, "chaninit %p", c);
 74 76193d7c 2003-09-30 devnull 	return 1;
 75 76193d7c 2003-09-30 devnull }
 76 76193d7c 2003-09-30 devnull 
 77 76193d7c 2003-09-30 devnull Channel*
 78 76193d7c 2003-09-30 devnull chancreate(int elemsize, int elemcnt)
 79 76193d7c 2003-09-30 devnull {
 80 76193d7c 2003-09-30 devnull 	Channel *c;
 81 76193d7c 2003-09-30 devnull 
 82 76193d7c 2003-09-30 devnull 	if(elemcnt < 0 || elemsize <= 0)
 83 76193d7c 2003-09-30 devnull 		return nil;
 84 76193d7c 2003-09-30 devnull 	c = _threadmalloc(sizeof(Channel)+elemsize*elemcnt, 1);
 85 76193d7c 2003-09-30 devnull 	c->e = elemsize;
 86 76193d7c 2003-09-30 devnull 	c->s = elemcnt;
 87 76193d7c 2003-09-30 devnull 	_threaddebug(DBGCHAN, "chancreate %p", c);
 88 76193d7c 2003-09-30 devnull 	return c;
 89 76193d7c 2003-09-30 devnull }
 90 76193d7c 2003-09-30 devnull 
 91 76193d7c 2003-09-30 devnull int
 92 76193d7c 2003-09-30 devnull alt(Alt *alts)
 93 76193d7c 2003-09-30 devnull {
 94 76193d7c 2003-09-30 devnull 	Alt *a, *xa;
 95 76193d7c 2003-09-30 devnull 	Channel *volatile c;
 96 76193d7c 2003-09-30 devnull 	int n, s;
 97 76193d7c 2003-09-30 devnull 	ulong r;
 98 76193d7c 2003-09-30 devnull 	Thread *t;
 99 76193d7c 2003-09-30 devnull 
100 76193d7c 2003-09-30 devnull 	/*
101 76193d7c 2003-09-30 devnull 	 * The point of going splhi here is that note handlers
102 76193d7c 2003-09-30 devnull 	 * might reasonably want to use channel operations,
103 76193d7c 2003-09-30 devnull 	 * but that will hang if the note comes while we hold the
104 76193d7c 2003-09-30 devnull 	 * chanlock.  Instead, we delay the note until we've dropped
105 76193d7c 2003-09-30 devnull 	 * the lock.
106 76193d7c 2003-09-30 devnull 	 */
107 76193d7c 2003-09-30 devnull 	t = _threadgetproc()->thread;
108 76193d7c 2003-09-30 devnull 	if(t->moribund || _threadexitsallstatus)
109 76193d7c 2003-09-30 devnull 		yield();	/* won't return */
110 76193d7c 2003-09-30 devnull 	s = _procsplhi();
111 76193d7c 2003-09-30 devnull 	lock(&chanlock);
112 76193d7c 2003-09-30 devnull 	t->alt = alts;
113 76193d7c 2003-09-30 devnull 	t->chan = Chanalt;
114 76193d7c 2003-09-30 devnull 
115 76193d7c 2003-09-30 devnull 	/* test whether any channels can proceed */
116 76193d7c 2003-09-30 devnull 	n = 0;
117 76193d7c 2003-09-30 devnull 	a = nil;
118 76193d7c 2003-09-30 devnull 
119 76193d7c 2003-09-30 devnull 	for(xa=alts; xa->op!=CHANEND && xa->op!=CHANNOBLK; xa++){
120 76193d7c 2003-09-30 devnull 		xa->entryno = -1;
121 76193d7c 2003-09-30 devnull 		if(xa->op == CHANNOP)
122 76193d7c 2003-09-30 devnull 			continue;
123 76193d7c 2003-09-30 devnull 		
124 76193d7c 2003-09-30 devnull 		c = xa->c;
125 76193d7c 2003-09-30 devnull 		if(c==nil){
126 76193d7c 2003-09-30 devnull 			unlock(&chanlock);
127 76193d7c 2003-09-30 devnull 			_procsplx(s);
128 76193d7c 2003-09-30 devnull 			t->chan = Channone;
129 76193d7c 2003-09-30 devnull 			return -1;
130 76193d7c 2003-09-30 devnull 		}
131 76193d7c 2003-09-30 devnull 		if(canexec(xa))
132 76193d7c 2003-09-30 devnull 			if(nrand(++n) == 0)
133 76193d7c 2003-09-30 devnull 				a = xa;
134 76193d7c 2003-09-30 devnull 	}
135 76193d7c 2003-09-30 devnull 
136 76193d7c 2003-09-30 devnull 	if(a==nil){
137 76193d7c 2003-09-30 devnull 		/* nothing can proceed */
138 76193d7c 2003-09-30 devnull 		if(xa->op == CHANNOBLK){
139 76193d7c 2003-09-30 devnull 			unlock(&chanlock);
140 76193d7c 2003-09-30 devnull 			_procsplx(s);
141 76193d7c 2003-09-30 devnull 			t->chan = Channone;
142 76193d7c 2003-09-30 devnull _threadnalt++;
143 76193d7c 2003-09-30 devnull 			return xa - alts;
144 76193d7c 2003-09-30 devnull 		}
145 76193d7c 2003-09-30 devnull 
146 76193d7c 2003-09-30 devnull 		/* enqueue on all channels. */
147 76193d7c 2003-09-30 devnull 		c = nil;
148 76193d7c 2003-09-30 devnull 		for(xa=alts; xa->op!=CHANEND; xa++){
149 76193d7c 2003-09-30 devnull 			if(xa->op==CHANNOP)
150 76193d7c 2003-09-30 devnull 				continue;
151 76193d7c 2003-09-30 devnull 			enqueue(xa, (Channel**)&c);
152 76193d7c 2003-09-30 devnull 		}
153 76193d7c 2003-09-30 devnull 
154 76193d7c 2003-09-30 devnull 		/*
155 76193d7c 2003-09-30 devnull 		 * wait for successful rendezvous.
156 76193d7c 2003-09-30 devnull 		 * we can't just give up if the rendezvous
157 76193d7c 2003-09-30 devnull 		 * is interrupted -- someone else might come
158 76193d7c 2003-09-30 devnull 		 * along and try to rendezvous with us, so
159 76193d7c 2003-09-30 devnull 		 * we need to be here.
160 76193d7c 2003-09-30 devnull 		 */
161 76193d7c 2003-09-30 devnull 	    Again:
162 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
163 76193d7c 2003-09-30 devnull 		_procsplx(s);
164 76193d7c 2003-09-30 devnull 		r = _threadrendezvous((ulong)&c, 0);
165 76193d7c 2003-09-30 devnull 		s = _procsplhi();
166 76193d7c 2003-09-30 devnull 		lock(&chanlock);
167 76193d7c 2003-09-30 devnull 
168 76193d7c 2003-09-30 devnull 		if(r==~0){		/* interrupted */
169 76193d7c 2003-09-30 devnull 			if(c!=nil)		/* someone will meet us; go back */
170 76193d7c 2003-09-30 devnull 				goto Again;
171 76193d7c 2003-09-30 devnull 			c = (Channel*)~0;	/* so no one tries to meet us */
172 76193d7c 2003-09-30 devnull 		}
173 76193d7c 2003-09-30 devnull 
174 76193d7c 2003-09-30 devnull 		/* dequeue from channels, find selected one */
175 76193d7c 2003-09-30 devnull 		a = nil;
176 76193d7c 2003-09-30 devnull 		for(xa=alts; xa->op!=CHANEND; xa++){
177 76193d7c 2003-09-30 devnull 			if(xa->op==CHANNOP)
178 76193d7c 2003-09-30 devnull 				continue;
179 76193d7c 2003-09-30 devnull 			if(xa->c == c)
180 76193d7c 2003-09-30 devnull 				a = xa;
181 76193d7c 2003-09-30 devnull 			dequeue(xa);
182 76193d7c 2003-09-30 devnull 		}
183 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
184 76193d7c 2003-09-30 devnull 		_procsplx(s);
185 76193d7c 2003-09-30 devnull 		if(a == nil){	/* we were interrupted */
186 76193d7c 2003-09-30 devnull 			assert(c==(Channel*)~0);
187 76193d7c 2003-09-30 devnull 			return -1;
188 76193d7c 2003-09-30 devnull 		}
189 76193d7c 2003-09-30 devnull 	}else{
190 76193d7c 2003-09-30 devnull 		altexec(a, s);	/* unlocks chanlock, does splx */
191 76193d7c 2003-09-30 devnull 	}
192 76193d7c 2003-09-30 devnull 	_sched();
193 76193d7c 2003-09-30 devnull 	t->chan = Channone;
194 76193d7c 2003-09-30 devnull _threadnalt++;
195 76193d7c 2003-09-30 devnull 	return a - alts;
196 76193d7c 2003-09-30 devnull }
197 76193d7c 2003-09-30 devnull 
198 76193d7c 2003-09-30 devnull static int
199 76193d7c 2003-09-30 devnull runop(int op, Channel *c, void *v, int nb)
200 76193d7c 2003-09-30 devnull {
201 76193d7c 2003-09-30 devnull 	int r;
202 76193d7c 2003-09-30 devnull 	Alt a[2];
203 76193d7c 2003-09-30 devnull 
204 76193d7c 2003-09-30 devnull 	/*
205 76193d7c 2003-09-30 devnull 	 * we could do this without calling alt,
206 76193d7c 2003-09-30 devnull 	 * but the only reason would be performance,
207 76193d7c 2003-09-30 devnull 	 * and i'm not convinced it matters.
208 76193d7c 2003-09-30 devnull 	 */
209 76193d7c 2003-09-30 devnull 	a[0].op = op;
210 76193d7c 2003-09-30 devnull 	a[0].c = c;
211 76193d7c 2003-09-30 devnull 	a[0].v = v;
212 76193d7c 2003-09-30 devnull 	a[1].op = CHANEND;
213 76193d7c 2003-09-30 devnull 	if(nb)
214 76193d7c 2003-09-30 devnull 		a[1].op = CHANNOBLK;
215 76193d7c 2003-09-30 devnull 	switch(r=alt(a)){
216 76193d7c 2003-09-30 devnull 	case -1:	/* interrupted */
217 76193d7c 2003-09-30 devnull 		return -1;
218 76193d7c 2003-09-30 devnull 	case 1:	/* nonblocking, didn't accomplish anything */
219 76193d7c 2003-09-30 devnull 		assert(nb);
220 76193d7c 2003-09-30 devnull 		return 0;
221 76193d7c 2003-09-30 devnull 	case 0:
222 76193d7c 2003-09-30 devnull 		return 1;
223 76193d7c 2003-09-30 devnull 	default:
224 76193d7c 2003-09-30 devnull 		fprint(2, "ERROR: channel alt returned %d\n", r);
225 76193d7c 2003-09-30 devnull 		abort();
226 76193d7c 2003-09-30 devnull 		return -1;
227 76193d7c 2003-09-30 devnull 	}
228 76193d7c 2003-09-30 devnull }
229 76193d7c 2003-09-30 devnull 
230 76193d7c 2003-09-30 devnull int
231 76193d7c 2003-09-30 devnull recv(Channel *c, void *v)
232 76193d7c 2003-09-30 devnull {
233 76193d7c 2003-09-30 devnull 	return runop(CHANRCV, c, v, 0);
234 76193d7c 2003-09-30 devnull }
235 76193d7c 2003-09-30 devnull 
236 76193d7c 2003-09-30 devnull int
237 76193d7c 2003-09-30 devnull nbrecv(Channel *c, void *v)
238 76193d7c 2003-09-30 devnull {
239 76193d7c 2003-09-30 devnull 	return runop(CHANRCV, c, v, 1);
240 76193d7c 2003-09-30 devnull }
241 76193d7c 2003-09-30 devnull 
242 76193d7c 2003-09-30 devnull int
243 76193d7c 2003-09-30 devnull send(Channel *c, void *v)
244 76193d7c 2003-09-30 devnull {
245 76193d7c 2003-09-30 devnull 	return runop(CHANSND, c, v, 0);
246 76193d7c 2003-09-30 devnull }
247 76193d7c 2003-09-30 devnull 
248 76193d7c 2003-09-30 devnull int
249 76193d7c 2003-09-30 devnull nbsend(Channel *c, void *v)
250 76193d7c 2003-09-30 devnull {
251 76193d7c 2003-09-30 devnull 	return runop(CHANSND, c, v, 1);
252 76193d7c 2003-09-30 devnull }
253 76193d7c 2003-09-30 devnull 
254 76193d7c 2003-09-30 devnull static void
255 76193d7c 2003-09-30 devnull channelsize(Channel *c, int sz)
256 76193d7c 2003-09-30 devnull {
257 76193d7c 2003-09-30 devnull 	if(c->e != sz){
258 76193d7c 2003-09-30 devnull 		fprint(2, "expected channel with elements of size %d, got size %d",
259 76193d7c 2003-09-30 devnull 			sz, c->e);
260 76193d7c 2003-09-30 devnull 		abort();
261 76193d7c 2003-09-30 devnull 	}
262 76193d7c 2003-09-30 devnull }
263 76193d7c 2003-09-30 devnull 
264 76193d7c 2003-09-30 devnull int
265 76193d7c 2003-09-30 devnull sendul(Channel *c, ulong v)
266 76193d7c 2003-09-30 devnull {
267 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
268 76193d7c 2003-09-30 devnull 	return send(c, &v);
269 76193d7c 2003-09-30 devnull }
270 76193d7c 2003-09-30 devnull 
271 76193d7c 2003-09-30 devnull ulong
272 76193d7c 2003-09-30 devnull recvul(Channel *c)
273 76193d7c 2003-09-30 devnull {
274 76193d7c 2003-09-30 devnull 	ulong v;
275 76193d7c 2003-09-30 devnull 
276 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
277 76193d7c 2003-09-30 devnull 	if(recv(c, &v) < 0)
278 76193d7c 2003-09-30 devnull 		return ~0;
279 76193d7c 2003-09-30 devnull 	return v;
280 76193d7c 2003-09-30 devnull }
281 76193d7c 2003-09-30 devnull 
282 76193d7c 2003-09-30 devnull int
283 76193d7c 2003-09-30 devnull sendp(Channel *c, void *v)
284 76193d7c 2003-09-30 devnull {
285 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
286 76193d7c 2003-09-30 devnull 	return send(c, &v);
287 76193d7c 2003-09-30 devnull }
288 76193d7c 2003-09-30 devnull 
289 76193d7c 2003-09-30 devnull void*
290 76193d7c 2003-09-30 devnull recvp(Channel *c)
291 76193d7c 2003-09-30 devnull {
292 76193d7c 2003-09-30 devnull 	void *v;
293 76193d7c 2003-09-30 devnull 
294 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
295 76193d7c 2003-09-30 devnull 	if(recv(c, &v) < 0)
296 76193d7c 2003-09-30 devnull 		return nil;
297 76193d7c 2003-09-30 devnull 	return v;
298 76193d7c 2003-09-30 devnull }
299 76193d7c 2003-09-30 devnull 
300 76193d7c 2003-09-30 devnull int
301 76193d7c 2003-09-30 devnull nbsendul(Channel *c, ulong v)
302 76193d7c 2003-09-30 devnull {
303 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
304 76193d7c 2003-09-30 devnull 	return nbsend(c, &v);
305 76193d7c 2003-09-30 devnull }
306 76193d7c 2003-09-30 devnull 
307 76193d7c 2003-09-30 devnull ulong
308 76193d7c 2003-09-30 devnull nbrecvul(Channel *c)
309 76193d7c 2003-09-30 devnull {
310 76193d7c 2003-09-30 devnull 	ulong v;
311 76193d7c 2003-09-30 devnull 
312 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
313 76193d7c 2003-09-30 devnull 	if(nbrecv(c, &v) == 0)
314 76193d7c 2003-09-30 devnull 		return 0;
315 76193d7c 2003-09-30 devnull 	return v;
316 76193d7c 2003-09-30 devnull }
317 76193d7c 2003-09-30 devnull 
318 76193d7c 2003-09-30 devnull int
319 76193d7c 2003-09-30 devnull nbsendp(Channel *c, void *v)
320 76193d7c 2003-09-30 devnull {
321 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
322 76193d7c 2003-09-30 devnull 	return nbsend(c, &v);
323 76193d7c 2003-09-30 devnull }
324 76193d7c 2003-09-30 devnull 
325 76193d7c 2003-09-30 devnull void*
326 76193d7c 2003-09-30 devnull nbrecvp(Channel *c)
327 76193d7c 2003-09-30 devnull {
328 76193d7c 2003-09-30 devnull 	void *v;
329 76193d7c 2003-09-30 devnull 
330 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
331 76193d7c 2003-09-30 devnull 	if(nbrecv(c, &v) == 0)
332 76193d7c 2003-09-30 devnull 		return nil;
333 76193d7c 2003-09-30 devnull 	return v;
334 76193d7c 2003-09-30 devnull }
335 76193d7c 2003-09-30 devnull 
336 76193d7c 2003-09-30 devnull static int
337 76193d7c 2003-09-30 devnull emptyentry(Channel *c)
338 76193d7c 2003-09-30 devnull {
339 76193d7c 2003-09-30 devnull 	int i, extra;
340 76193d7c 2003-09-30 devnull 
341 76193d7c 2003-09-30 devnull 	assert((c->nentry==0 && c->qentry==nil) || (c->nentry && c->qentry));
342 76193d7c 2003-09-30 devnull 
343 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
344 76193d7c 2003-09-30 devnull 		if(c->qentry[i]==nil)
345 76193d7c 2003-09-30 devnull 			return i;
346 76193d7c 2003-09-30 devnull 
347 76193d7c 2003-09-30 devnull 	extra = 16;
348 76193d7c 2003-09-30 devnull 	c->nentry += extra;
349 76193d7c 2003-09-30 devnull if(c->nentry > _threadhighnentry) _threadhighnentry = c->nentry;
350 76193d7c 2003-09-30 devnull 	c->qentry = realloc((void*)c->qentry, c->nentry*sizeof(c->qentry[0]));
351 76193d7c 2003-09-30 devnull 	if(c->qentry == nil)
352 76193d7c 2003-09-30 devnull 		sysfatal("realloc channel entries: %r");
353 76193d7c 2003-09-30 devnull 	_threadmemset(&c->qentry[i], 0, extra*sizeof(c->qentry[0]));
354 76193d7c 2003-09-30 devnull 	return i;
355 76193d7c 2003-09-30 devnull }
356 76193d7c 2003-09-30 devnull 
357 76193d7c 2003-09-30 devnull static void
358 76193d7c 2003-09-30 devnull enqueue(Alt *a, Channel **c)
359 76193d7c 2003-09-30 devnull {
360 76193d7c 2003-09-30 devnull 	int i;
361 76193d7c 2003-09-30 devnull 
362 76193d7c 2003-09-30 devnull 	_threaddebug(DBGCHAN, "Queuing alt %p on channel %p", a, a->c);
363 76193d7c 2003-09-30 devnull 	a->tag = c;
364 76193d7c 2003-09-30 devnull 	i = emptyentry(a->c);
365 76193d7c 2003-09-30 devnull 	a->c->qentry[i] = a;
366 76193d7c 2003-09-30 devnull }
367 76193d7c 2003-09-30 devnull 
368 76193d7c 2003-09-30 devnull static void
369 76193d7c 2003-09-30 devnull dequeue(Alt *a)
370 76193d7c 2003-09-30 devnull {
371 76193d7c 2003-09-30 devnull 	int i;
372 76193d7c 2003-09-30 devnull 	Channel *c;
373 76193d7c 2003-09-30 devnull 
374 76193d7c 2003-09-30 devnull 	c = a->c;
375 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
376 76193d7c 2003-09-30 devnull 		if(c->qentry[i]==a){
377 76193d7c 2003-09-30 devnull 			_threaddebug(DBGCHAN, "Dequeuing alt %p from channel %p", a, a->c);
378 76193d7c 2003-09-30 devnull 			c->qentry[i] = nil;
379 76193d7c 2003-09-30 devnull 			if(c->freed)
380 76193d7c 2003-09-30 devnull 				_chanfree(c);
381 76193d7c 2003-09-30 devnull 			return;
382 76193d7c 2003-09-30 devnull 		}
383 76193d7c 2003-09-30 devnull }
384 76193d7c 2003-09-30 devnull 
385 76193d7c 2003-09-30 devnull static void*
386 76193d7c 2003-09-30 devnull altexecbuffered(Alt *a, int willreplace)
387 76193d7c 2003-09-30 devnull {
388 76193d7c 2003-09-30 devnull 	uchar *v;
389 76193d7c 2003-09-30 devnull 	Channel *c;
390 76193d7c 2003-09-30 devnull 
391 76193d7c 2003-09-30 devnull 	c = a->c;
392 76193d7c 2003-09-30 devnull 	/* use buffered channel queue */
393 76193d7c 2003-09-30 devnull 	if(a->op==CHANRCV && c->n > 0){
394 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "buffer recv alt %p chan %p", a, c);
395 76193d7c 2003-09-30 devnull 		v = c->v + c->e*(c->f%c->s);
396 76193d7c 2003-09-30 devnull 		if(!willreplace)
397 76193d7c 2003-09-30 devnull 			c->n--;
398 76193d7c 2003-09-30 devnull 		c->f++;
399 76193d7c 2003-09-30 devnull 		return v;
400 76193d7c 2003-09-30 devnull 	}
401 76193d7c 2003-09-30 devnull 	if(a->op==CHANSND && c->n < c->s){
402 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "buffer send alt %p chan %p", a, c);
403 76193d7c 2003-09-30 devnull 		v = c->v + c->e*((c->f+c->n)%c->s);
404 76193d7c 2003-09-30 devnull 		if(!willreplace)
405 76193d7c 2003-09-30 devnull 			c->n++;
406 76193d7c 2003-09-30 devnull 		return v;
407 76193d7c 2003-09-30 devnull 	}
408 76193d7c 2003-09-30 devnull 	abort();
409 76193d7c 2003-09-30 devnull 	return nil;
410 76193d7c 2003-09-30 devnull }
411 76193d7c 2003-09-30 devnull 
412 76193d7c 2003-09-30 devnull static void
413 76193d7c 2003-09-30 devnull altcopy(void *dst, void *src, int sz)
414 76193d7c 2003-09-30 devnull {
415 76193d7c 2003-09-30 devnull 	if(dst){
416 76193d7c 2003-09-30 devnull 		if(src)
417 76193d7c 2003-09-30 devnull 			memmove(dst, src, sz);
418 76193d7c 2003-09-30 devnull 		else
419 76193d7c 2003-09-30 devnull 			_threadmemset(dst, 0, sz);
420 76193d7c 2003-09-30 devnull 	}
421 76193d7c 2003-09-30 devnull }
422 76193d7c 2003-09-30 devnull 
423 76193d7c 2003-09-30 devnull static int
424 76193d7c 2003-09-30 devnull altexec(Alt *a, int spl)
425 76193d7c 2003-09-30 devnull {
426 76193d7c 2003-09-30 devnull 	volatile Alt *b;
427 76193d7c 2003-09-30 devnull 	int i, n, otherop;
428 76193d7c 2003-09-30 devnull 	Channel *c;
429 76193d7c 2003-09-30 devnull 	void *me, *waiter, *buf;
430 76193d7c 2003-09-30 devnull 
431 76193d7c 2003-09-30 devnull 	c = a->c;
432 76193d7c 2003-09-30 devnull 
433 76193d7c 2003-09-30 devnull 	/* rendezvous with others */
434 76193d7c 2003-09-30 devnull 	otherop = (CHANSND+CHANRCV) - a->op;
435 76193d7c 2003-09-30 devnull 	n = 0;
436 76193d7c 2003-09-30 devnull 	b = nil;
437 76193d7c 2003-09-30 devnull 	me = a->v;
438 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
439 76193d7c 2003-09-30 devnull 		if(c->qentry[i] && c->qentry[i]->op==otherop && *c->qentry[i]->tag==nil)
440 76193d7c 2003-09-30 devnull 			if(nrand(++n) == 0)
441 76193d7c 2003-09-30 devnull 				b = c->qentry[i];
442 76193d7c 2003-09-30 devnull 	if(b != nil){
443 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "rendez %s alt %p chan %p alt %p", a->op==CHANRCV?"recv":"send", a, c, b);
444 76193d7c 2003-09-30 devnull 		waiter = b->v;
445 76193d7c 2003-09-30 devnull 		if(c->s && c->n){
446 76193d7c 2003-09-30 devnull 			/*
447 76193d7c 2003-09-30 devnull 			 * if buffer is full and there are waiters
448 76193d7c 2003-09-30 devnull 			 * and we're meeting a waiter,
449 76193d7c 2003-09-30 devnull 			 * we must be receiving.
450 76193d7c 2003-09-30 devnull 			 *
451 76193d7c 2003-09-30 devnull 			 * we use the value in the channel buffer,
452 76193d7c 2003-09-30 devnull 			 * copy the waiter's value into the channel buffer
453 76193d7c 2003-09-30 devnull 			 * on behalf of the waiter, and then wake the waiter.
454 76193d7c 2003-09-30 devnull 			 */
455 76193d7c 2003-09-30 devnull 			if(a->op!=CHANRCV)
456 76193d7c 2003-09-30 devnull 				abort();
457 76193d7c 2003-09-30 devnull 			buf = altexecbuffered(a, 1);
458 76193d7c 2003-09-30 devnull 			altcopy(me, buf, c->e);
459 76193d7c 2003-09-30 devnull 			altcopy(buf, waiter, c->e);
460 76193d7c 2003-09-30 devnull 		}else{
461 76193d7c 2003-09-30 devnull 			if(a->op==CHANRCV)
462 76193d7c 2003-09-30 devnull 				altcopy(me, waiter, c->e);
463 76193d7c 2003-09-30 devnull 			else
464 76193d7c 2003-09-30 devnull 				altcopy(waiter, me, c->e);
465 76193d7c 2003-09-30 devnull 		}
466 76193d7c 2003-09-30 devnull 		*b->tag = c;	/* commits us to rendezvous */
467 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "unlocking the chanlock");
468 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
469 76193d7c 2003-09-30 devnull 		_procsplx(spl);
470 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "chanlock is %lud", *(ulong*)&chanlock);
471 76193d7c 2003-09-30 devnull 		while(_threadrendezvous((ulong)b->tag, 0) == ~0)
472 76193d7c 2003-09-30 devnull 			;
473 76193d7c 2003-09-30 devnull 		return 1;
474 76193d7c 2003-09-30 devnull 	}
475 76193d7c 2003-09-30 devnull 
476 76193d7c 2003-09-30 devnull 	buf = altexecbuffered(a, 0);
477 76193d7c 2003-09-30 devnull 	if(a->op==CHANRCV)
478 76193d7c 2003-09-30 devnull 		altcopy(me, buf, c->e);
479 76193d7c 2003-09-30 devnull 	else
480 76193d7c 2003-09-30 devnull 		altcopy(buf, me, c->e);
481 76193d7c 2003-09-30 devnull 
482 76193d7c 2003-09-30 devnull 	unlock(&chanlock);
483 76193d7c 2003-09-30 devnull 	_procsplx(spl);
484 76193d7c 2003-09-30 devnull 	return 1;
485 76193d7c 2003-09-30 devnull }