From 3a19470202c5c0f6e9375e5d57535c3d508f2edf Mon Sep 17 00:00:00 2001
From: rsc <devnull@localhost>
Date: Sat, 4 Nov 2006 18:46:00 +0000
Subject: 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.
---
 src/libdraw/drawclient.c | 34 ++++++++++++++++++++--------------
 src/libdraw/event.c      | 12 +++++++++++-
 2 files changed, 31 insertions(+), 15 deletions(-)

(limited to 'src/libdraw')

diff --git a/src/libdraw/drawclient.c b/src/libdraw/drawclient.c
index 62615942..93c56235 100644
--- a/src/libdraw/drawclient.c
+++ b/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
diff --git a/src/libdraw/event.c b/src/libdraw/event.c
index 1da3fb39..101aa374 100644
--- a/src/libdraw/event.c
+++ b/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)
-- 
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