commit 3a19470202c5c0f6e9375e5d57535c3d508f2edf
from: rsc <devnull@localhost>
date: Sat Nov 04 18:46:00 2006 UTC

In non-blocking recv functions in libmux and libdraw,
distinguish between "cannot receive without blocking"
and "EOF on connection".

In libmux, do not elect async guys muxers, so that
synchronous RPC calls run in the main event loop
(e.g., in eresized) do not get stuck.

Fixes problem reported by Lu Xuxiao, namely that
jpg etc. would spin at 100% cpu usage.

commit - d3864abaee496db2f97dff1dbf5c7766d4439c7b
commit + 3a19470202c5c0f6e9375e5d57535c3d508f2edf
blob - 53321fa5258886698e48b24b585ab427bfaf3f4b
blob + e9890fc31c8fbd67357a23e68bb855e64292095b
--- include/mux.h
+++ include/mux.h
@@ -19,6 +19,7 @@ struct Muxrpc
 	uint tag;
 	void *p;
 	int waiting;
+	int async;
 };
 
 struct Mux
@@ -27,7 +28,7 @@ struct Mux
 	uint maxtag;
 	int (*send)(Mux*, void*);
 	void *(*recv)(Mux*);
-	void *(*nbrecv)(Mux*);
+	int (*nbrecv)(Mux*, void**);
 	int (*gettag)(Mux*, void*);
 	int (*settag)(Mux*, void*, uint);
 	void *aux;	/* for private use by client */
@@ -52,18 +53,18 @@ void	muxinit(Mux*);
 void*	muxrpc(Mux*, void*);
 void	muxprocs(Mux*);
 Muxrpc*	muxrpcstart(Mux*, void*);
-void*	muxrpccanfinish(Muxrpc*);
+int	muxrpccanfinish(Muxrpc*, void**);
 
 /* private */
 int	_muxsend(Mux*, void*);
-void*	_muxrecv(Mux*, int);
+int	_muxrecv(Mux*, int, void**);
 void	_muxsendproc(void*);
 void	_muxrecvproc(void*);
 Muxqueue *_muxqalloc(void);
 int _muxqsend(Muxqueue*, void*);
 void *_muxqrecv(Muxqueue*);
 void _muxqhangup(Muxqueue*);
-void *_muxnbqrecv(Muxqueue*);
+int _muxnbqrecv(Muxqueue*, void**);
 
 #if defined(__cplusplus)
 }
blob - bf1262acb95cb08a255fd37dc71ac08e35291be8
blob + 9ad6054f06557163db683e6cf061f58c3e8339c7
--- src/cmd/devdraw/x11-init.c
+++ src/cmd/devdraw/x11-init.c
@@ -47,7 +47,8 @@ static int
 xioerror(XDisplay *d)
 {
 	/*print("X I/O error\n"); */
-	sysfatal("X I/O error\n");
+	exit(0);
+	/*sysfatal("X I/O error\n");*/
 	abort();
 	return -1;
 }
blob - 62615942c4eddc1cee2008c05b0867d11edc65b4
blob + 93c562351c7d33b2bd5e3f506a9171b82b822e3a
--- src/libdraw/drawclient.c
+++ src/libdraw/drawclient.c
@@ -13,7 +13,7 @@ int chattydrawclient;
 
 static int	drawgettag(Mux *mux, void *vmsg);
 static void*	drawrecv(Mux *mux);
-static void*	drawnbrecv(Mux *mux);
+static int	drawnbrecv(Mux *mux, void**);
 static int	drawsend(Mux *mux, void *vmsg);
 static int	drawsettag(Mux *mux, void *vmsg, uint tag);
 static int canreadfd(int);
@@ -83,40 +83,46 @@ drawsend(Mux *mux, void *vmsg)
 	return write(d->srvfd, msg, n);
 }
 
-static void*
-_drawrecv(Mux *mux, int nb)
+static int
+_drawrecv(Mux *mux, int canblock, void **vp)
 {
 	int n;
 	uchar buf[4], *p;
 	Display *d;
 
 	d = mux->aux;
-	if(nb && !canreadfd(d->srvfd))
-		return nil;
+	*vp = nil;
+	if(!canblock && !canreadfd(d->srvfd))
+		return 0;
 	if((n=readn(d->srvfd, buf, 4)) != 4)
-		return nil;
+		return 1;
 	GET(buf, n);
 	p = malloc(n);
 	if(p == nil){
 		fprint(2, "out of memory allocating %d in drawrecv\n", n);
-		return nil;
+		return 1;
 	}
 	memmove(p, buf, 4);
-	if(readn(d->srvfd, p+4, n-4) != n-4)
-		return nil;
-	return p;
+	if(readn(d->srvfd, p+4, n-4) != n-4){
+		free(p);
+		return 1;
+	}
+	*vp = p;
+	return 1;
 }
 
 static void*
 drawrecv(Mux *mux)
 {
-	return _drawrecv(mux, 0);
+	void *p;
+	_drawrecv(mux, 1, &p);
+	return p;
 }
 
-static void*
-drawnbrecv(Mux *mux)
+static int
+drawnbrecv(Mux *mux, void **vp)
 {
-	return _drawrecv(mux, 1);
+	return _drawrecv(mux, 0, vp);
 }
 
 static int
blob - 1da3fb3987e90271dbb173b81b09e2051a462597
blob + 101aa374475de763bbbb8a886c5cd0a575569740
--- src/libdraw/event.c
+++ src/libdraw/event.c
@@ -214,10 +214,14 @@ static int
 finishrpc(Muxrpc *r, Wsysmsg *w)
 {
 	uchar *p;
+	void *v;
 	int n;
 	
-	if((p = muxrpccanfinish(r)) == nil)
+	if(!muxrpccanfinish(r, &v))
 		return 0;
+	p = v;
+	if(p == nil)	/* eof on connection */
+		exit(0);
 	GET(p, n);
 	convM2W(p, n, w);
 	free(p);
@@ -269,6 +273,9 @@ extract(int canblock)
 			if(eslave[i].rpc == nil)
 				eslave[i].rpc = startrpc(Trdmouse);
 			if(eslave[i].rpc){
+				/* if ready, don't block in select */
+				if(eslave[i].rpc->p)
+					canblock = 0;
 				FD_SET(display->srvfd, &rset);
 				FD_SET(display->srvfd, &xset);
 				if(display->srvfd > max)
@@ -278,6 +285,9 @@ extract(int canblock)
 			if(eslave[i].rpc == nil)
 				eslave[i].rpc = startrpc(Trdkbd);
 			if(eslave[i].rpc){
+				/* if ready, don't block in select */
+				if(eslave[i].rpc->p)
+					canblock = 0;
 				FD_SET(display->srvfd, &rset);
 				FD_SET(display->srvfd, &xset);
 				if(display->srvfd > max)
blob - 4a89ca22a72bd0c27c2ea207a5012e908b819fb2
blob + d9d9d8a6283ef25f6bb54deddb79886c03d1c8ba
--- src/libmux/io.c
+++ src/libmux/io.c
@@ -34,7 +34,7 @@ _muxrecvproc(void *v)
 	qunlock(&mux->inlk);
 	qlock(&mux->lk);
 	_muxqhangup(q);
-	while((p = _muxnbqrecv(q)) != nil)
+	while(_muxnbqrecv(q, &p))
 		free(p);
 	free(q);
 	mux->readq = nil;
@@ -64,7 +64,7 @@ _muxsendproc(void *v)
 	qunlock(&mux->outlk);
 	qlock(&mux->lk);
 	_muxqhangup(q);
-	while((p = _muxnbqrecv(q)) != nil)
+	while(_muxnbqrecv(q, &p))
 		free(p);
 	free(q);
 	mux->writeq = nil;
@@ -73,42 +73,39 @@ _muxsendproc(void *v)
 	return;
 }
 
-void*
-_muxrecv(Mux *mux, int canblock)
+int
+_muxrecv(Mux *mux, int canblock, void **vp)
 {
 	void *p;
+	int ret;
 
 	qlock(&mux->lk);
-/*
-	if(mux->state != VtStateConnected){
-		werrstr("not connected");
-		qunlock(&mux->lk);
-		return nil;
-	}
-*/
 	if(mux->readq){
 		qunlock(&mux->lk);
-		if(canblock)
-			return _muxqrecv(mux->readq);
-		return _muxnbqrecv(mux->readq);
+		if(canblock){
+			*vp = _muxqrecv(mux->readq);
+			return 1;
+		}
+		return _muxnbqrecv(mux->readq, vp);
 	}
 
 	qlock(&mux->inlk);
 	qunlock(&mux->lk);
-	if(canblock)
+	if(canblock){
 		p = mux->recv(mux);
-	else{
+		ret = 1;
+	}else{
 		if(mux->nbrecv)
-			p = mux->nbrecv(mux);
-		else
+			ret = mux->nbrecv(mux, &p);
+		else{
+			/* send eof, not "no packet ready" */
 			p = nil;
+			ret = 1;
+		}
 	}
 	qunlock(&mux->inlk);
-/*
-	if(!p && canblock)
-		vthangup(mux);
-*/
-	return p;
+	*vp = p;
+	return ret;
 }
 
 int
blob - bfabb23890aab5bddab4123c80d2f72dd3e4009f
blob + 8257fb0e7200fc947ade5b2832f97f5b8507ad39
--- src/libmux/mux.c
+++ src/libmux/mux.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2003 Russ Cox, Massachusetts Institute of Technology */
+/* Copyright (C) 2003-2006 Russ Cox, Massachusetts Institute of Technology */
 /* See COPYRIGHT */
 
 /*
@@ -100,12 +100,17 @@ muxmsgandqlock(Mux *mux, void *p)
 void
 electmuxer(Mux *mux)
 {
+	Muxrpc *rpc;
+
 	/* if there is anyone else sleeping, wake them to mux */
-	if(mux->sleep.next != &mux->sleep){
-		mux->muxer = mux->sleep.next;
-		rwakeup(&mux->muxer->r);
-	}else
-		mux->muxer = nil;
+	for(rpc=mux->sleep.next; rpc != &mux->sleep; rpc = rpc->next){
+		if(!rpc->async){
+			mux->muxer = rpc;
+			rwakeup(&rpc->r);
+			return;
+		}
+	}
+	mux->muxer = nil;
 }
 
 void*
@@ -133,7 +138,7 @@ muxrpc(Mux *mux, void *tx)
 		mux->muxer = r;
 		while(!r->p){
 			qunlock(&mux->lk);
-			p = _muxrecv(mux, 1);
+			_muxrecv(mux, 1, &p);
 			if(p == nil){
 				/* eof -- just give up and pass the buck */
 				qlock(&mux->lk);
@@ -144,7 +149,6 @@ muxrpc(Mux *mux, void *tx)
 		}
 		electmuxer(mux);
 	}
-/*print("finished %p\n", r); */
 	p = r->p;
 	puttag(mux, r);
 	qunlock(&mux->lk);
@@ -161,24 +165,29 @@ muxrpcstart(Mux *mux, void *tx)
 
 	if((r = allocmuxrpc(mux)) == nil)
 		return nil;
+	r->async = 1;
 	if((tag = tagmuxrpc(r, tx)) < 0)
 		return nil;
 	return r;
 }
 
-void*
-muxrpccanfinish(Muxrpc *r)
+int
+muxrpccanfinish(Muxrpc *r, void **vp)
 {
-	char *p;
+	void *p;
 	Mux *mux;
-	
+	int ret;
+
 	mux = r->mux;
 	qlock(&mux->lk);
+	ret = 1;
 	if(!r->p && !mux->muxer){
 		mux->muxer = r;
 		while(!r->p){
 			qunlock(&mux->lk);
-			p = _muxrecv(mux, 0);
+			p = nil;
+			if(!_muxrecv(mux, 0, &p))
+				ret = 0;
 			if(p == nil){
 				qlock(&mux->lk);
 				break;
@@ -191,7 +200,8 @@ muxrpccanfinish(Muxrpc *r)
 	if(p)
 		puttag(mux, r);
 	qunlock(&mux->lk);
-	return p;
+	*vp = p;
+	return ret;
 }
 
 static void
blob - 1cadbe6c2c1039822f39fc9a1dbd9406295f1de5
blob + 2151c2529da550e97ca61c57c8708d7d0a400c15
--- src/libmux/queue.c
+++ src/libmux/queue.c
@@ -81,8 +81,8 @@ _muxqrecv(Muxqueue *q)
 	return p;
 }
 
-void*
-_muxnbqrecv(Muxqueue *q)
+int
+_muxnbqrecv(Muxqueue *q, void **vp)
 {
 	void *p;
 	Qel *e;
@@ -90,14 +90,16 @@ _muxnbqrecv(Muxqueue *q)
 	qlock(&q->lk);
 	if(q->head == nil){
 		qunlock(&q->lk);
-		return nil;
+		*vp = nil;
+		return q->hungup;
 	}
 	e = q->head;
 	q->head = e->next;
 	qunlock(&q->lk);
 	p = e->p;
 	free(e);
-	return p;
+	*vp = p;
+	return 1;
 }
 
 void