code: 9ferno

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first cut at devready a device to monitor pipe readers

--- a/os/port/devready.c

+++ b/os/port/devready.c

@@ -16,6 +16,8 @@

 		It belongs there..

 		instead of 2 files (watch and ready). Use 1 file (canread).

+	#r/canread

+

 up->shm = Ready*

 c->aux = 

  */

@@ -23,7 +25,7 @@

 {

 	NFD = 16,

-	Qwatch		= 0,

+	Qcanread = 0,

 	Qready

 };

@@ -45,6 +47,8 @@

 	s32 fd;

 	Queue *q;

 	s32 ready;

+	u8 stop;

+	Proc *kproc;

 };

 typedef struct Ready;

@@ -53,6 +57,7 @@

 	Qlock;

 	Readyfd *rfd[[NFD];

 	s32 nrfd;

+	Queue *commq;	/* queue for the different watcher kproc's to communicate */

 };

 static int

@@ -68,14 +73,10 @@

 		return 1;

 	}

-	if(c->qid == Qwatch){

-		mkqid(&q, Qwatch, 0, QTFILE);

-		devdir(c, q, "watch", 0, eve, 0664, dp);

+	if(c->qid == Qcanread){

+		mkqid(&q, Qcanread, 0, QTFILE);

+		devdir(c, q, "canread", 0, eve, 0664, dp);

 		return 1;

-	}else if(c->qid == Qready){

-		mkqid(&q, Qready, 0, QTFILE);

-		devdir(c, q, "ready", 0, eve, 0664, dp);

-		return 1;

 	}

 	return -1;

 }

@@ -142,11 +143,11 @@

 			error(Eperm);

 		qlock(r);

+		r->commq = qopen(1024, 0, 0, 0);

 		if(trunc) { /* shoud be Qwatch */

 			for(i = 0; i < r->nrfd; i++){

-				TODO shutdown kproc's

-				if(r->rfd[i] != nil)

-					free(r->rfd[i]);

+				r->rfd[i].stop = 1;

+				/* TODO shutdown kproc's send a note to any running kprocs */

 			}

 			r->nrfd = 0;

 		}

@@ -183,25 +184,10 @@

 	if((r = up->readyfds) == nil)

 		error(Enonexist);

-	return qread(r->q, a, n);

-

-	qlock(r);

-	should this be qbread?

-	for(i = 0; i<r->nrfd; i++){

-		if(r->rfd.ready > 0){

-			rv = snprint(a, n, "%d\n", r->rfd.fd);

-			r->rfd.ready = 0;

-			qunlock(r);

-			return rv;

-		}

-	}

-	if none of the fd's are ready, let the kproc's run and loop here until there is a ready fd

-		let the dogs go and wait for them to bring back the kill

-	this should be interruptible too. So, there can be an alarm() before.

-

-	return 0;

+	return qread(r->commq, a, n);

 }

+/* TODO close kproc by sending a note */

 static void

 stopwatchers(void)

 {

@@ -210,28 +196,29 @@

 	if((r = up->readyfds) == nil)

 		error(Enonexist);

-	if(r->q != nil)

-		qhangup(r->q, nil);

+	if(r->commq != nil)

+		qhangup(r->commq, nil);

 	for(i = 0; i < r->rnfd; i++){

-		TODO close kproc by sending a note

-		r->rfd[i].ready = 0;

+		r->rfd[i].stop = 1;

 		r->rfd[i].fd = -1;

 	}

 }

+/*

+	wrap this in an alarm() so it does not block forever?

+	should be using qread() instead? qcanread does not block(?)

+	TODO double check wv values

+ */

 static void

-startwatcher(Queue *q, Readyfd *rfd)

+startwatcher(Readyfd *rfd)

 {

 	char s[16];

 	rfd->kproc = up;

-	while(){

-		qread(rfd->readq);

-wrap this in an alarm() so it does not block forever?

-should be using qread() instead? qcanread does not block(?)

-		qcanread(rfd->q);

+	while(rfd->stop == 0 && wv != 0 && wv != -1){

+		qhasdata(rfd->q);

 		n = snprint(s, 16, "%d\n", rfd->fd);

-		qwrite(q, s, n);

+		wv = qwrite(rfd->commq, s, n);

 	}

 }

@@ -267,8 +254,9 @@

 		i = r->nrfd;

 		r->rfd[i].fd = fd;

 		r->rfd[i].ready = 0;

+		r->rfd[i].commq = r->commq;

 		snprint(name, KNAMELEN, "watch %d for %d", fd, up->pid);

-		kproc(name, startwatcher, r->q, &r->rfd[i]);

+		kproc(name, startwatcher, &r->rfd[i], 0);

 		r->nrfd++;

 	}

 	qunlock(r);

--- a/os/port/portfns.h

+++ b/os/port/portfns.h

@@ -249,6 +249,7 @@

 int		qfull(Queue*);

 Block*		qget(Queue*);

 void		qhangup(Queue*, char*);

+s32		qhasdata(Queue*);

 int		qisclosed(Queue*);

 int		qiwrite(Queue*, void*, int);

 int		qlen(Queue*);

--- a/os/port/qio.c

+++ b/os/port/qio.c

@@ -979,6 +979,20 @@

 }

 /*

+ *  same as qcanread() but blocks if there is no data, used by devready

+ */

+s32

+qhasdata(Queue *q)

+{

+	s32 rv;

+

+	ilock(q);

+	rv = qwait(q);

+	iunlock(q);

+	return rv;

+}

+

+/*

  *  read a queue.  if no data is queued, post a Block

  *  and wait on its Rendez.

  */