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 02a1a5c1 2004-03-05 devnull static void
 13 02a1a5c1 2004-03-05 devnull setuserpc(ulong pc)
 14 02a1a5c1 2004-03-05 devnull {
 15 02a1a5c1 2004-03-05 devnull 	Thread *t;
 16 02a1a5c1 2004-03-05 devnull 
 17 02a1a5c1 2004-03-05 devnull 	t = _threadgetproc()->thread;
 18 02a1a5c1 2004-03-05 devnull 	if(t)
 19 02a1a5c1 2004-03-05 devnull 		t->userpc = pc;
 20 02a1a5c1 2004-03-05 devnull }
 21 02a1a5c1 2004-03-05 devnull 
 22 76193d7c 2003-09-30 devnull static int
 23 76193d7c 2003-09-30 devnull canexec(Alt *a)
 24 76193d7c 2003-09-30 devnull {
 25 76193d7c 2003-09-30 devnull 	int i, otherop;
 26 76193d7c 2003-09-30 devnull 	Channel *c;
 27 76193d7c 2003-09-30 devnull 
 28 76193d7c 2003-09-30 devnull 	c = a->c;
 29 76193d7c 2003-09-30 devnull 	/* are there senders or receivers blocked? */
 30 76193d7c 2003-09-30 devnull 	otherop = (CHANSND+CHANRCV) - a->op;
 31 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
 32 76193d7c 2003-09-30 devnull 		if(c->qentry[i] && c->qentry[i]->op==otherop && *c->qentry[i]->tag==nil){
 33 76193d7c 2003-09-30 devnull 			_threaddebug(DBGCHAN, "can rendez alt %p chan %p", a, c);
 34 76193d7c 2003-09-30 devnull 			return 1;
 35 76193d7c 2003-09-30 devnull 		}
 36 76193d7c 2003-09-30 devnull 
 37 76193d7c 2003-09-30 devnull 	/* is there room in the channel? */
 38 76193d7c 2003-09-30 devnull 	if((a->op==CHANSND && c->n < c->s)
 39 76193d7c 2003-09-30 devnull 	|| (a->op==CHANRCV && c->n > 0)){
 40 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "can buffer alt %p chan %p", a, c);
 41 76193d7c 2003-09-30 devnull 		return 1;
 42 76193d7c 2003-09-30 devnull 	}
 43 76193d7c 2003-09-30 devnull 
 44 76193d7c 2003-09-30 devnull 	return 0;
 45 76193d7c 2003-09-30 devnull }
 46 76193d7c 2003-09-30 devnull 
 47 76193d7c 2003-09-30 devnull static void
 48 76193d7c 2003-09-30 devnull _chanfree(Channel *c)
 49 76193d7c 2003-09-30 devnull {
 50 76193d7c 2003-09-30 devnull 	int i, inuse;
 51 76193d7c 2003-09-30 devnull 
 52 76193d7c 2003-09-30 devnull 	inuse = 0;
 53 76193d7c 2003-09-30 devnull 	for(i = 0; i < c->nentry; i++)
 54 76193d7c 2003-09-30 devnull 		if(c->qentry[i])
 55 76193d7c 2003-09-30 devnull 			inuse = 1;
 56 76193d7c 2003-09-30 devnull 	if(inuse)
 57 76193d7c 2003-09-30 devnull 		c->freed = 1;
 58 76193d7c 2003-09-30 devnull 	else{
 59 76193d7c 2003-09-30 devnull 		if(c->qentry)
 60 76193d7c 2003-09-30 devnull 			free(c->qentry);
 61 76193d7c 2003-09-30 devnull 		free(c);
 62 76193d7c 2003-09-30 devnull 	}
 63 76193d7c 2003-09-30 devnull }
 64 76193d7c 2003-09-30 devnull 
 65 76193d7c 2003-09-30 devnull void
 66 76193d7c 2003-09-30 devnull chanfree(Channel *c)
 67 76193d7c 2003-09-30 devnull {
 68 76193d7c 2003-09-30 devnull 	lock(&chanlock);
 69 76193d7c 2003-09-30 devnull 	_chanfree(c);
 70 76193d7c 2003-09-30 devnull 	unlock(&chanlock);
 71 76193d7c 2003-09-30 devnull }
 72 76193d7c 2003-09-30 devnull 
 73 76193d7c 2003-09-30 devnull int
 74 76193d7c 2003-09-30 devnull chaninit(Channel *c, int elemsize, int elemcnt)
 75 76193d7c 2003-09-30 devnull {
 76 76193d7c 2003-09-30 devnull 	if(elemcnt < 0 || elemsize <= 0 || c == nil)
 77 76193d7c 2003-09-30 devnull 		return -1;
 78 5a8e63b2 2004-02-29 devnull 	memset(c, 0, sizeof *c);
 79 76193d7c 2003-09-30 devnull 	c->e = elemsize;
 80 76193d7c 2003-09-30 devnull 	c->s = elemcnt;
 81 76193d7c 2003-09-30 devnull 	_threaddebug(DBGCHAN, "chaninit %p", c);
 82 76193d7c 2003-09-30 devnull 	return 1;
 83 76193d7c 2003-09-30 devnull }
 84 76193d7c 2003-09-30 devnull 
 85 76193d7c 2003-09-30 devnull Channel*
 86 76193d7c 2003-09-30 devnull chancreate(int elemsize, int elemcnt)
 87 76193d7c 2003-09-30 devnull {
 88 76193d7c 2003-09-30 devnull 	Channel *c;
 89 76193d7c 2003-09-30 devnull 
 90 76193d7c 2003-09-30 devnull 	if(elemcnt < 0 || elemsize <= 0)
 91 76193d7c 2003-09-30 devnull 		return nil;
 92 76193d7c 2003-09-30 devnull 	c = _threadmalloc(sizeof(Channel)+elemsize*elemcnt, 1);
 93 76193d7c 2003-09-30 devnull 	c->e = elemsize;
 94 76193d7c 2003-09-30 devnull 	c->s = elemcnt;
 95 76193d7c 2003-09-30 devnull 	_threaddebug(DBGCHAN, "chancreate %p", c);
 96 76193d7c 2003-09-30 devnull 	return c;
 97 76193d7c 2003-09-30 devnull }
 98 76193d7c 2003-09-30 devnull 
 99 02a1a5c1 2004-03-05 devnull static int
100 02a1a5c1 2004-03-05 devnull _alt(Alt *alts)
101 76193d7c 2003-09-30 devnull {
102 76193d7c 2003-09-30 devnull 	Alt *a, *xa;
103 76193d7c 2003-09-30 devnull 	Channel *volatile c;
104 76193d7c 2003-09-30 devnull 	int n, s;
105 76193d7c 2003-09-30 devnull 	ulong r;
106 76193d7c 2003-09-30 devnull 	Thread *t;
107 76193d7c 2003-09-30 devnull 
108 76193d7c 2003-09-30 devnull 	/*
109 76193d7c 2003-09-30 devnull 	 * The point of going splhi here is that note handlers
110 76193d7c 2003-09-30 devnull 	 * might reasonably want to use channel operations,
111 76193d7c 2003-09-30 devnull 	 * but that will hang if the note comes while we hold the
112 76193d7c 2003-09-30 devnull 	 * chanlock.  Instead, we delay the note until we've dropped
113 76193d7c 2003-09-30 devnull 	 * the lock.
114 5a8e63b2 2004-02-29 devnull 	 */
115 5a8e63b2 2004-02-29 devnull 
116 5a8e63b2 2004-02-29 devnull 	/*
117 5a8e63b2 2004-02-29 devnull 	 * T might be nil here -- the scheduler sends on threadwaitchan
118 5a8e63b2 2004-02-29 devnull 	 * directly (in non-blocking mode, of course!).
119 76193d7c 2003-09-30 devnull 	 */
120 76193d7c 2003-09-30 devnull 	t = _threadgetproc()->thread;
121 5a8e63b2 2004-02-29 devnull 	if((t && t->moribund) || _threadexitsallstatus)
122 76193d7c 2003-09-30 devnull 		yield();	/* won't return */
123 76193d7c 2003-09-30 devnull 	s = _procsplhi();
124 76193d7c 2003-09-30 devnull 	lock(&chanlock);
125 76193d7c 2003-09-30 devnull 
126 76193d7c 2003-09-30 devnull 	/* test whether any channels can proceed */
127 76193d7c 2003-09-30 devnull 	n = 0;
128 76193d7c 2003-09-30 devnull 	a = nil;
129 76193d7c 2003-09-30 devnull 
130 76193d7c 2003-09-30 devnull 	for(xa=alts; xa->op!=CHANEND && xa->op!=CHANNOBLK; xa++){
131 76193d7c 2003-09-30 devnull 		xa->entryno = -1;
132 76193d7c 2003-09-30 devnull 		if(xa->op == CHANNOP)
133 76193d7c 2003-09-30 devnull 			continue;
134 76193d7c 2003-09-30 devnull 		
135 76193d7c 2003-09-30 devnull 		c = xa->c;
136 76193d7c 2003-09-30 devnull 		if(c==nil){
137 76193d7c 2003-09-30 devnull 			unlock(&chanlock);
138 76193d7c 2003-09-30 devnull 			_procsplx(s);
139 76193d7c 2003-09-30 devnull 			return -1;
140 76193d7c 2003-09-30 devnull 		}
141 76193d7c 2003-09-30 devnull 		if(canexec(xa))
142 76193d7c 2003-09-30 devnull 			if(nrand(++n) == 0)
143 76193d7c 2003-09-30 devnull 				a = xa;
144 76193d7c 2003-09-30 devnull 	}
145 76193d7c 2003-09-30 devnull 
146 76193d7c 2003-09-30 devnull 	if(a==nil){
147 76193d7c 2003-09-30 devnull 		/* nothing can proceed */
148 76193d7c 2003-09-30 devnull 		if(xa->op == CHANNOBLK){
149 76193d7c 2003-09-30 devnull 			unlock(&chanlock);
150 76193d7c 2003-09-30 devnull 			_procsplx(s);
151 76193d7c 2003-09-30 devnull _threadnalt++;
152 76193d7c 2003-09-30 devnull 			return xa - alts;
153 76193d7c 2003-09-30 devnull 		}
154 76193d7c 2003-09-30 devnull 
155 76193d7c 2003-09-30 devnull 		/* enqueue on all channels. */
156 76193d7c 2003-09-30 devnull 		c = nil;
157 76193d7c 2003-09-30 devnull 		for(xa=alts; xa->op!=CHANEND; xa++){
158 76193d7c 2003-09-30 devnull 			if(xa->op==CHANNOP)
159 76193d7c 2003-09-30 devnull 				continue;
160 76193d7c 2003-09-30 devnull 			enqueue(xa, (Channel**)&c);
161 76193d7c 2003-09-30 devnull 		}
162 76193d7c 2003-09-30 devnull 
163 76193d7c 2003-09-30 devnull 		/*
164 76193d7c 2003-09-30 devnull 		 * wait for successful rendezvous.
165 76193d7c 2003-09-30 devnull 		 * we can't just give up if the rendezvous
166 76193d7c 2003-09-30 devnull 		 * is interrupted -- someone else might come
167 76193d7c 2003-09-30 devnull 		 * along and try to rendezvous with us, so
168 76193d7c 2003-09-30 devnull 		 * we need to be here.
169 76193d7c 2003-09-30 devnull 		 */
170 76193d7c 2003-09-30 devnull 	    Again:
171 5a8e63b2 2004-02-29 devnull 		t->alt = alts;
172 5a8e63b2 2004-02-29 devnull 		t->chan = Chanalt;
173 5a8e63b2 2004-02-29 devnull 
174 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
175 76193d7c 2003-09-30 devnull 		_procsplx(s);
176 76193d7c 2003-09-30 devnull 		r = _threadrendezvous((ulong)&c, 0);
177 76193d7c 2003-09-30 devnull 		s = _procsplhi();
178 76193d7c 2003-09-30 devnull 		lock(&chanlock);
179 76193d7c 2003-09-30 devnull 
180 76193d7c 2003-09-30 devnull 		if(r==~0){		/* interrupted */
181 76193d7c 2003-09-30 devnull 			if(c!=nil)		/* someone will meet us; go back */
182 76193d7c 2003-09-30 devnull 				goto Again;
183 76193d7c 2003-09-30 devnull 			c = (Channel*)~0;	/* so no one tries to meet us */
184 76193d7c 2003-09-30 devnull 		}
185 76193d7c 2003-09-30 devnull 
186 76193d7c 2003-09-30 devnull 		/* dequeue from channels, find selected one */
187 76193d7c 2003-09-30 devnull 		a = nil;
188 76193d7c 2003-09-30 devnull 		for(xa=alts; xa->op!=CHANEND; xa++){
189 76193d7c 2003-09-30 devnull 			if(xa->op==CHANNOP)
190 76193d7c 2003-09-30 devnull 				continue;
191 76193d7c 2003-09-30 devnull 			if(xa->c == c)
192 76193d7c 2003-09-30 devnull 				a = xa;
193 76193d7c 2003-09-30 devnull 			dequeue(xa);
194 76193d7c 2003-09-30 devnull 		}
195 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
196 76193d7c 2003-09-30 devnull 		_procsplx(s);
197 76193d7c 2003-09-30 devnull 		if(a == nil){	/* we were interrupted */
198 76193d7c 2003-09-30 devnull 			assert(c==(Channel*)~0);
199 76193d7c 2003-09-30 devnull 			return -1;
200 76193d7c 2003-09-30 devnull 		}
201 76193d7c 2003-09-30 devnull 	}else{
202 76193d7c 2003-09-30 devnull 		altexec(a, s);	/* unlocks chanlock, does splx */
203 76193d7c 2003-09-30 devnull 	}
204 8c6f0e8a 2004-03-05 devnull 	if(t)
205 8c6f0e8a 2004-03-05 devnull 		t->chan = Channone;
206 76193d7c 2003-09-30 devnull 	return a - alts;
207 76193d7c 2003-09-30 devnull }
208 76193d7c 2003-09-30 devnull 
209 02a1a5c1 2004-03-05 devnull int
210 02a1a5c1 2004-03-05 devnull alt(Alt *alts)
211 02a1a5c1 2004-03-05 devnull {
212 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&alts));
213 02a1a5c1 2004-03-05 devnull 	return _alt(alts);
214 02a1a5c1 2004-03-05 devnull }
215 02a1a5c1 2004-03-05 devnull 
216 76193d7c 2003-09-30 devnull static int
217 76193d7c 2003-09-30 devnull runop(int op, Channel *c, void *v, int nb)
218 76193d7c 2003-09-30 devnull {
219 76193d7c 2003-09-30 devnull 	int r;
220 76193d7c 2003-09-30 devnull 	Alt a[2];
221 76193d7c 2003-09-30 devnull 
222 76193d7c 2003-09-30 devnull 	/*
223 76193d7c 2003-09-30 devnull 	 * we could do this without calling alt,
224 76193d7c 2003-09-30 devnull 	 * but the only reason would be performance,
225 76193d7c 2003-09-30 devnull 	 * and i'm not convinced it matters.
226 76193d7c 2003-09-30 devnull 	 */
227 76193d7c 2003-09-30 devnull 	a[0].op = op;
228 76193d7c 2003-09-30 devnull 	a[0].c = c;
229 76193d7c 2003-09-30 devnull 	a[0].v = v;
230 76193d7c 2003-09-30 devnull 	a[1].op = CHANEND;
231 76193d7c 2003-09-30 devnull 	if(nb)
232 76193d7c 2003-09-30 devnull 		a[1].op = CHANNOBLK;
233 02a1a5c1 2004-03-05 devnull 	switch(r=_alt(a)){
234 76193d7c 2003-09-30 devnull 	case -1:	/* interrupted */
235 76193d7c 2003-09-30 devnull 		return -1;
236 76193d7c 2003-09-30 devnull 	case 1:	/* nonblocking, didn't accomplish anything */
237 76193d7c 2003-09-30 devnull 		assert(nb);
238 76193d7c 2003-09-30 devnull 		return 0;
239 76193d7c 2003-09-30 devnull 	case 0:
240 76193d7c 2003-09-30 devnull 		return 1;
241 76193d7c 2003-09-30 devnull 	default:
242 76193d7c 2003-09-30 devnull 		fprint(2, "ERROR: channel alt returned %d\n", r);
243 76193d7c 2003-09-30 devnull 		abort();
244 76193d7c 2003-09-30 devnull 		return -1;
245 76193d7c 2003-09-30 devnull 	}
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 recv(Channel *c, void *v)
250 76193d7c 2003-09-30 devnull {
251 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
252 76193d7c 2003-09-30 devnull 	return runop(CHANRCV, c, v, 0);
253 76193d7c 2003-09-30 devnull }
254 76193d7c 2003-09-30 devnull 
255 76193d7c 2003-09-30 devnull int
256 76193d7c 2003-09-30 devnull nbrecv(Channel *c, void *v)
257 76193d7c 2003-09-30 devnull {
258 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
259 76193d7c 2003-09-30 devnull 	return runop(CHANRCV, c, v, 1);
260 76193d7c 2003-09-30 devnull }
261 76193d7c 2003-09-30 devnull 
262 76193d7c 2003-09-30 devnull int
263 76193d7c 2003-09-30 devnull send(Channel *c, void *v)
264 76193d7c 2003-09-30 devnull {
265 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
266 76193d7c 2003-09-30 devnull 	return runop(CHANSND, c, v, 0);
267 76193d7c 2003-09-30 devnull }
268 76193d7c 2003-09-30 devnull 
269 76193d7c 2003-09-30 devnull int
270 76193d7c 2003-09-30 devnull nbsend(Channel *c, void *v)
271 76193d7c 2003-09-30 devnull {
272 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
273 76193d7c 2003-09-30 devnull 	return runop(CHANSND, c, v, 1);
274 76193d7c 2003-09-30 devnull }
275 76193d7c 2003-09-30 devnull 
276 76193d7c 2003-09-30 devnull static void
277 76193d7c 2003-09-30 devnull channelsize(Channel *c, int sz)
278 76193d7c 2003-09-30 devnull {
279 76193d7c 2003-09-30 devnull 	if(c->e != sz){
280 76193d7c 2003-09-30 devnull 		fprint(2, "expected channel with elements of size %d, got size %d",
281 76193d7c 2003-09-30 devnull 			sz, c->e);
282 76193d7c 2003-09-30 devnull 		abort();
283 76193d7c 2003-09-30 devnull 	}
284 76193d7c 2003-09-30 devnull }
285 76193d7c 2003-09-30 devnull 
286 76193d7c 2003-09-30 devnull int
287 76193d7c 2003-09-30 devnull sendul(Channel *c, ulong v)
288 76193d7c 2003-09-30 devnull {
289 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
290 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
291 76193d7c 2003-09-30 devnull 	return send(c, &v);
292 76193d7c 2003-09-30 devnull }
293 76193d7c 2003-09-30 devnull 
294 76193d7c 2003-09-30 devnull ulong
295 76193d7c 2003-09-30 devnull recvul(Channel *c)
296 76193d7c 2003-09-30 devnull {
297 76193d7c 2003-09-30 devnull 	ulong v;
298 76193d7c 2003-09-30 devnull 
299 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
300 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
301 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 0) < 0)
302 76193d7c 2003-09-30 devnull 		return ~0;
303 76193d7c 2003-09-30 devnull 	return v;
304 76193d7c 2003-09-30 devnull }
305 76193d7c 2003-09-30 devnull 
306 76193d7c 2003-09-30 devnull int
307 76193d7c 2003-09-30 devnull sendp(Channel *c, void *v)
308 76193d7c 2003-09-30 devnull {
309 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
310 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
311 02a1a5c1 2004-03-05 devnull 	return runop(CHANSND, c, &v, 0);
312 76193d7c 2003-09-30 devnull }
313 76193d7c 2003-09-30 devnull 
314 76193d7c 2003-09-30 devnull void*
315 76193d7c 2003-09-30 devnull recvp(Channel *c)
316 76193d7c 2003-09-30 devnull {
317 76193d7c 2003-09-30 devnull 	void *v;
318 76193d7c 2003-09-30 devnull 
319 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
320 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
321 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 0) < 0)
322 76193d7c 2003-09-30 devnull 		return nil;
323 76193d7c 2003-09-30 devnull 	return v;
324 76193d7c 2003-09-30 devnull }
325 76193d7c 2003-09-30 devnull 
326 76193d7c 2003-09-30 devnull int
327 76193d7c 2003-09-30 devnull nbsendul(Channel *c, ulong v)
328 76193d7c 2003-09-30 devnull {
329 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
330 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
331 02a1a5c1 2004-03-05 devnull 	return runop(CHANSND, c, &v, 1);
332 76193d7c 2003-09-30 devnull }
333 76193d7c 2003-09-30 devnull 
334 76193d7c 2003-09-30 devnull ulong
335 76193d7c 2003-09-30 devnull nbrecvul(Channel *c)
336 76193d7c 2003-09-30 devnull {
337 76193d7c 2003-09-30 devnull 	ulong v;
338 76193d7c 2003-09-30 devnull 
339 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
340 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
341 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 1) == 0)
342 76193d7c 2003-09-30 devnull 		return 0;
343 76193d7c 2003-09-30 devnull 	return v;
344 76193d7c 2003-09-30 devnull }
345 76193d7c 2003-09-30 devnull 
346 76193d7c 2003-09-30 devnull int
347 76193d7c 2003-09-30 devnull nbsendp(Channel *c, void *v)
348 76193d7c 2003-09-30 devnull {
349 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
350 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
351 02a1a5c1 2004-03-05 devnull 	return runop(CHANSND, c, &v, 1);
352 76193d7c 2003-09-30 devnull }
353 76193d7c 2003-09-30 devnull 
354 76193d7c 2003-09-30 devnull void*
355 76193d7c 2003-09-30 devnull nbrecvp(Channel *c)
356 76193d7c 2003-09-30 devnull {
357 76193d7c 2003-09-30 devnull 	void *v;
358 76193d7c 2003-09-30 devnull 
359 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
360 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
361 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 1) == 0)
362 76193d7c 2003-09-30 devnull 		return nil;
363 76193d7c 2003-09-30 devnull 	return v;
364 76193d7c 2003-09-30 devnull }
365 76193d7c 2003-09-30 devnull 
366 76193d7c 2003-09-30 devnull static int
367 76193d7c 2003-09-30 devnull emptyentry(Channel *c)
368 76193d7c 2003-09-30 devnull {
369 76193d7c 2003-09-30 devnull 	int i, extra;
370 76193d7c 2003-09-30 devnull 
371 76193d7c 2003-09-30 devnull 	assert((c->nentry==0 && c->qentry==nil) || (c->nentry && c->qentry));
372 76193d7c 2003-09-30 devnull 
373 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
374 76193d7c 2003-09-30 devnull 		if(c->qentry[i]==nil)
375 76193d7c 2003-09-30 devnull 			return i;
376 76193d7c 2003-09-30 devnull 
377 76193d7c 2003-09-30 devnull 	extra = 16;
378 76193d7c 2003-09-30 devnull 	c->nentry += extra;
379 76193d7c 2003-09-30 devnull if(c->nentry > _threadhighnentry) _threadhighnentry = c->nentry;
380 76193d7c 2003-09-30 devnull 	c->qentry = realloc((void*)c->qentry, c->nentry*sizeof(c->qentry[0]));
381 76193d7c 2003-09-30 devnull 	if(c->qentry == nil)
382 76193d7c 2003-09-30 devnull 		sysfatal("realloc channel entries: %r");
383 76193d7c 2003-09-30 devnull 	_threadmemset(&c->qentry[i], 0, extra*sizeof(c->qentry[0]));
384 76193d7c 2003-09-30 devnull 	return i;
385 76193d7c 2003-09-30 devnull }
386 76193d7c 2003-09-30 devnull 
387 76193d7c 2003-09-30 devnull static void
388 76193d7c 2003-09-30 devnull enqueue(Alt *a, Channel **c)
389 76193d7c 2003-09-30 devnull {
390 76193d7c 2003-09-30 devnull 	int i;
391 76193d7c 2003-09-30 devnull 
392 912fba95 2003-11-24 devnull 	_threaddebug(DBGCHAN, "Queueing alt %p on channel %p", a, a->c);
393 76193d7c 2003-09-30 devnull 	a->tag = c;
394 76193d7c 2003-09-30 devnull 	i = emptyentry(a->c);
395 76193d7c 2003-09-30 devnull 	a->c->qentry[i] = a;
396 76193d7c 2003-09-30 devnull }
397 76193d7c 2003-09-30 devnull 
398 76193d7c 2003-09-30 devnull static void
399 76193d7c 2003-09-30 devnull dequeue(Alt *a)
400 76193d7c 2003-09-30 devnull {
401 76193d7c 2003-09-30 devnull 	int i;
402 76193d7c 2003-09-30 devnull 	Channel *c;
403 76193d7c 2003-09-30 devnull 
404 76193d7c 2003-09-30 devnull 	c = a->c;
405 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
406 76193d7c 2003-09-30 devnull 		if(c->qentry[i]==a){
407 76193d7c 2003-09-30 devnull 			_threaddebug(DBGCHAN, "Dequeuing alt %p from channel %p", a, a->c);
408 76193d7c 2003-09-30 devnull 			c->qentry[i] = nil;
409 76193d7c 2003-09-30 devnull 			if(c->freed)
410 76193d7c 2003-09-30 devnull 				_chanfree(c);
411 76193d7c 2003-09-30 devnull 			return;
412 76193d7c 2003-09-30 devnull 		}
413 76193d7c 2003-09-30 devnull }
414 76193d7c 2003-09-30 devnull 
415 76193d7c 2003-09-30 devnull static void*
416 76193d7c 2003-09-30 devnull altexecbuffered(Alt *a, int willreplace)
417 76193d7c 2003-09-30 devnull {
418 76193d7c 2003-09-30 devnull 	uchar *v;
419 76193d7c 2003-09-30 devnull 	Channel *c;
420 76193d7c 2003-09-30 devnull 
421 76193d7c 2003-09-30 devnull 	c = a->c;
422 76193d7c 2003-09-30 devnull 	/* use buffered channel queue */
423 76193d7c 2003-09-30 devnull 	if(a->op==CHANRCV && c->n > 0){
424 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "buffer recv alt %p chan %p", a, c);
425 76193d7c 2003-09-30 devnull 		v = c->v + c->e*(c->f%c->s);
426 76193d7c 2003-09-30 devnull 		if(!willreplace)
427 76193d7c 2003-09-30 devnull 			c->n--;
428 76193d7c 2003-09-30 devnull 		c->f++;
429 76193d7c 2003-09-30 devnull 		return v;
430 76193d7c 2003-09-30 devnull 	}
431 76193d7c 2003-09-30 devnull 	if(a->op==CHANSND && c->n < c->s){
432 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "buffer send alt %p chan %p", a, c);
433 76193d7c 2003-09-30 devnull 		v = c->v + c->e*((c->f+c->n)%c->s);
434 76193d7c 2003-09-30 devnull 		if(!willreplace)
435 76193d7c 2003-09-30 devnull 			c->n++;
436 76193d7c 2003-09-30 devnull 		return v;
437 76193d7c 2003-09-30 devnull 	}
438 76193d7c 2003-09-30 devnull 	abort();
439 76193d7c 2003-09-30 devnull 	return nil;
440 76193d7c 2003-09-30 devnull }
441 76193d7c 2003-09-30 devnull 
442 76193d7c 2003-09-30 devnull static void
443 76193d7c 2003-09-30 devnull altcopy(void *dst, void *src, int sz)
444 76193d7c 2003-09-30 devnull {
445 76193d7c 2003-09-30 devnull 	if(dst){
446 76193d7c 2003-09-30 devnull 		if(src)
447 76193d7c 2003-09-30 devnull 			memmove(dst, src, sz);
448 76193d7c 2003-09-30 devnull 		else
449 76193d7c 2003-09-30 devnull 			_threadmemset(dst, 0, sz);
450 76193d7c 2003-09-30 devnull 	}
451 76193d7c 2003-09-30 devnull }
452 76193d7c 2003-09-30 devnull 
453 76193d7c 2003-09-30 devnull static int
454 76193d7c 2003-09-30 devnull altexec(Alt *a, int spl)
455 76193d7c 2003-09-30 devnull {
456 76193d7c 2003-09-30 devnull 	volatile Alt *b;
457 76193d7c 2003-09-30 devnull 	int i, n, otherop;
458 76193d7c 2003-09-30 devnull 	Channel *c;
459 76193d7c 2003-09-30 devnull 	void *me, *waiter, *buf;
460 76193d7c 2003-09-30 devnull 
461 76193d7c 2003-09-30 devnull 	c = a->c;
462 76193d7c 2003-09-30 devnull 
463 76193d7c 2003-09-30 devnull 	/* rendezvous with others */
464 76193d7c 2003-09-30 devnull 	otherop = (CHANSND+CHANRCV) - a->op;
465 76193d7c 2003-09-30 devnull 	n = 0;
466 76193d7c 2003-09-30 devnull 	b = nil;
467 76193d7c 2003-09-30 devnull 	me = a->v;
468 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
469 76193d7c 2003-09-30 devnull 		if(c->qentry[i] && c->qentry[i]->op==otherop && *c->qentry[i]->tag==nil)
470 76193d7c 2003-09-30 devnull 			if(nrand(++n) == 0)
471 76193d7c 2003-09-30 devnull 				b = c->qentry[i];
472 76193d7c 2003-09-30 devnull 	if(b != nil){
473 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "rendez %s alt %p chan %p alt %p", a->op==CHANRCV?"recv":"send", a, c, b);
474 76193d7c 2003-09-30 devnull 		waiter = b->v;
475 76193d7c 2003-09-30 devnull 		if(c->s && c->n){
476 76193d7c 2003-09-30 devnull 			/*
477 76193d7c 2003-09-30 devnull 			 * if buffer is full and there are waiters
478 76193d7c 2003-09-30 devnull 			 * and we're meeting a waiter,
479 76193d7c 2003-09-30 devnull 			 * we must be receiving.
480 76193d7c 2003-09-30 devnull 			 *
481 76193d7c 2003-09-30 devnull 			 * we use the value in the channel buffer,
482 76193d7c 2003-09-30 devnull 			 * copy the waiter's value into the channel buffer
483 76193d7c 2003-09-30 devnull 			 * on behalf of the waiter, and then wake the waiter.
484 76193d7c 2003-09-30 devnull 			 */
485 76193d7c 2003-09-30 devnull 			if(a->op!=CHANRCV)
486 76193d7c 2003-09-30 devnull 				abort();
487 76193d7c 2003-09-30 devnull 			buf = altexecbuffered(a, 1);
488 76193d7c 2003-09-30 devnull 			altcopy(me, buf, c->e);
489 76193d7c 2003-09-30 devnull 			altcopy(buf, waiter, c->e);
490 76193d7c 2003-09-30 devnull 		}else{
491 76193d7c 2003-09-30 devnull 			if(a->op==CHANRCV)
492 76193d7c 2003-09-30 devnull 				altcopy(me, waiter, c->e);
493 76193d7c 2003-09-30 devnull 			else
494 76193d7c 2003-09-30 devnull 				altcopy(waiter, me, c->e);
495 76193d7c 2003-09-30 devnull 		}
496 76193d7c 2003-09-30 devnull 		*b->tag = c;	/* commits us to rendezvous */
497 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "unlocking the chanlock");
498 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
499 76193d7c 2003-09-30 devnull 		_procsplx(spl);
500 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "chanlock is %lud", *(ulong*)&chanlock);
501 76193d7c 2003-09-30 devnull 		while(_threadrendezvous((ulong)b->tag, 0) == ~0)
502 76193d7c 2003-09-30 devnull 			;
503 76193d7c 2003-09-30 devnull 		return 1;
504 76193d7c 2003-09-30 devnull 	}
505 76193d7c 2003-09-30 devnull 
506 76193d7c 2003-09-30 devnull 	buf = altexecbuffered(a, 0);
507 76193d7c 2003-09-30 devnull 	if(a->op==CHANRCV)
508 76193d7c 2003-09-30 devnull 		altcopy(me, buf, c->e);
509 76193d7c 2003-09-30 devnull 	else
510 76193d7c 2003-09-30 devnull 		altcopy(buf, me, c->e);
511 76193d7c 2003-09-30 devnull 
512 76193d7c 2003-09-30 devnull 	unlock(&chanlock);
513 76193d7c 2003-09-30 devnull 	_procsplx(spl);
514 76193d7c 2003-09-30 devnull 	return 1;
515 76193d7c 2003-09-30 devnull }