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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.
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  1 d3df3087 2003-12-06 devnull /* Copyright (C) 2003 Russ Cox, Massachusetts Institute of Technology */

  2 d3df3087 2003-12-06 devnull /* See COPYRIGHT */

  3 d3df3087 2003-12-06 devnull 

  4 d3df3087 2003-12-06 devnull #include <u.h>

  5 d3df3087 2003-12-06 devnull #include <libc.h>

  6 d3df3087 2003-12-06 devnull #include <mux.h>

  7 d3df3087 2003-12-06 devnull 

  8 d3df3087 2003-12-06 devnull /*

  9 d3df3087 2003-12-06 devnull  * If you fork off two procs running muxrecvproc and muxsendproc,

 10 d3df3087 2003-12-06 devnull  * then muxrecv/muxsend (and thus muxrpc) will never block except on 

 11 d3df3087 2003-12-06 devnull  * rendevouses, which is nice when it's running in one thread of many.

 12 d3df3087 2003-12-06 devnull  */

 13 d3df3087 2003-12-06 devnull void

 14 d3df3087 2003-12-06 devnull _muxrecvproc(void *v)

 15 d3df3087 2003-12-06 devnull {

 16 d3df3087 2003-12-06 devnull 	void *p;

 17 d3df3087 2003-12-06 devnull 	Mux *mux;

 18 d3df3087 2003-12-06 devnull 	Muxqueue *q;

 19 d3df3087 2003-12-06 devnull 

 20 d3df3087 2003-12-06 devnull 	mux = v;

 21 d3df3087 2003-12-06 devnull 	q = _muxqalloc();

 22 d3df3087 2003-12-06 devnull 

 23 d3df3087 2003-12-06 devnull 	qlock(&mux->lk);

 24 d3df3087 2003-12-06 devnull 	mux->readq = q;

 25 d3df3087 2003-12-06 devnull 	qlock(&mux->inlk);

 26 d3df3087 2003-12-06 devnull 	rwakeup(&mux->rpcfork);

 27 d3df3087 2003-12-06 devnull 	qunlock(&mux->lk);

 28 d3df3087 2003-12-06 devnull 

 29 d3df3087 2003-12-06 devnull 	while((p = mux->recv(mux)) != nil)

 30 d3df3087 2003-12-06 devnull 		if(_muxqsend(q, p) < 0){

 31 d3df3087 2003-12-06 devnull 			free(p);

 32 d3df3087 2003-12-06 devnull 			break;

 33 d3df3087 2003-12-06 devnull 		}

 34 d3df3087 2003-12-06 devnull 	qunlock(&mux->inlk);

 35 d3df3087 2003-12-06 devnull 	qlock(&mux->lk);

 36 d3df3087 2003-12-06 devnull 	_muxqhangup(q);

 37 3a194702 2006-11-04 devnull 	while(_muxnbqrecv(q, &p))

 38 d3df3087 2003-12-06 devnull 		free(p);

 39 d3df3087 2003-12-06 devnull 	free(q);

 40 d3df3087 2003-12-06 devnull 	mux->readq = nil;

 41 d3df3087 2003-12-06 devnull 	rwakeup(&mux->rpcfork);

 42 d3df3087 2003-12-06 devnull 	qunlock(&mux->lk);

 43 d3df3087 2003-12-06 devnull }

 44 d3df3087 2003-12-06 devnull 

 45 d3df3087 2003-12-06 devnull void

 46 d3df3087 2003-12-06 devnull _muxsendproc(void *v)

 47 d3df3087 2003-12-06 devnull {

 48 d3df3087 2003-12-06 devnull 	Muxqueue *q;

 49 d3df3087 2003-12-06 devnull 	void *p;

 50 d3df3087 2003-12-06 devnull 	Mux *mux;

 51 d3df3087 2003-12-06 devnull 

 52 d3df3087 2003-12-06 devnull 	mux = v;

 53 d3df3087 2003-12-06 devnull 	q = _muxqalloc();

 54 d3df3087 2003-12-06 devnull 

 55 d3df3087 2003-12-06 devnull 	qlock(&mux->lk);

 56 d3df3087 2003-12-06 devnull 	mux->writeq = q;

 57 d3df3087 2003-12-06 devnull 	qlock(&mux->outlk);

 58 d3df3087 2003-12-06 devnull 	rwakeup(&mux->rpcfork);

 59 d3df3087 2003-12-06 devnull 	qunlock(&mux->lk);

 60 d3df3087 2003-12-06 devnull 

 61 d3df3087 2003-12-06 devnull 	while((p = _muxqrecv(q)) != nil)

 62 d3df3087 2003-12-06 devnull 		if(mux->send(mux, p) < 0)

 63 d3df3087 2003-12-06 devnull 			break;

 64 d3df3087 2003-12-06 devnull 	qunlock(&mux->outlk);

 65 d3df3087 2003-12-06 devnull 	qlock(&mux->lk);

 66 d3df3087 2003-12-06 devnull 	_muxqhangup(q);

 67 3a194702 2006-11-04 devnull 	while(_muxnbqrecv(q, &p))

 68 d3df3087 2003-12-06 devnull 		free(p);

 69 d3df3087 2003-12-06 devnull 	free(q);

 70 d3df3087 2003-12-06 devnull 	mux->writeq = nil;

 71 d3df3087 2003-12-06 devnull 	rwakeup(&mux->rpcfork);

 72 d3df3087 2003-12-06 devnull 	qunlock(&mux->lk);

 73 d3df3087 2003-12-06 devnull 	return;

 74 d3df3087 2003-12-06 devnull }

 75 d3df3087 2003-12-06 devnull 

 76 3a194702 2006-11-04 devnull int

 77 3a194702 2006-11-04 devnull _muxrecv(Mux *mux, int canblock, void **vp)

 78 d3df3087 2003-12-06 devnull {

 79 d3df3087 2003-12-06 devnull 	void *p;

 80 3a194702 2006-11-04 devnull 	int ret;

 81 d3df3087 2003-12-06 devnull 

 82 d3df3087 2003-12-06 devnull 	qlock(&mux->lk);

 83 d3df3087 2003-12-06 devnull 	if(mux->readq){

 84 d3df3087 2003-12-06 devnull 		qunlock(&mux->lk);

 85 3a194702 2006-11-04 devnull 		if(canblock){

 86 3a194702 2006-11-04 devnull 			*vp = _muxqrecv(mux->readq);

 87 3a194702 2006-11-04 devnull 			return 1;

 88 3a194702 2006-11-04 devnull 		}

 89 3a194702 2006-11-04 devnull 		return _muxnbqrecv(mux->readq, vp);

 90 d3df3087 2003-12-06 devnull 	}

 91 d3df3087 2003-12-06 devnull 

 92 d3df3087 2003-12-06 devnull 	qlock(&mux->inlk);

 93 d3df3087 2003-12-06 devnull 	qunlock(&mux->lk);

 94 3a194702 2006-11-04 devnull 	if(canblock){

 95 2d2e5c71 2006-06-25 devnull 		p = mux->recv(mux);

 96 3a194702 2006-11-04 devnull 		ret = 1;

 97 3a194702 2006-11-04 devnull 	}else{

 98 2d2e5c71 2006-06-25 devnull 		if(mux->nbrecv)

 99 3a194702 2006-11-04 devnull 			ret = mux->nbrecv(mux, &p);

100 3a194702 2006-11-04 devnull 		else{

101 3a194702 2006-11-04 devnull 			/* send eof, not "no packet ready" */

102 2d2e5c71 2006-06-25 devnull 			p = nil;

103 3a194702 2006-11-04 devnull 			ret = 1;

104 3a194702 2006-11-04 devnull 		}

105 2d2e5c71 2006-06-25 devnull 	}

106 d3df3087 2003-12-06 devnull 	qunlock(&mux->inlk);

107 3a194702 2006-11-04 devnull 	*vp = p;

108 3a194702 2006-11-04 devnull 	return ret;

109 d3df3087 2003-12-06 devnull }

110 d3df3087 2003-12-06 devnull 

111 d3df3087 2003-12-06 devnull int

112 d3df3087 2003-12-06 devnull _muxsend(Mux *mux, void *p)

113 d3df3087 2003-12-06 devnull {

114 d3df3087 2003-12-06 devnull 	qlock(&mux->lk);

115 d3df3087 2003-12-06 devnull /*

116 d3df3087 2003-12-06 devnull 	if(mux->state != VtStateConnected){

117 d3df3087 2003-12-06 devnull 		packetfree(p);

118 d3df3087 2003-12-06 devnull 		werrstr("not connected");

119 d3df3087 2003-12-06 devnull 		qunlock(&mux->lk);

120 d3df3087 2003-12-06 devnull 		return -1;

121 d3df3087 2003-12-06 devnull 	}

122 d3df3087 2003-12-06 devnull */

123 d3df3087 2003-12-06 devnull 	if(mux->writeq){

124 d3df3087 2003-12-06 devnull 		qunlock(&mux->lk);

125 d3df3087 2003-12-06 devnull 		if(_muxqsend(mux->writeq, p) < 0){

126 d3df3087 2003-12-06 devnull 			free(p);

127 d3df3087 2003-12-06 devnull 			return -1;

128 d3df3087 2003-12-06 devnull 		}

129 d3df3087 2003-12-06 devnull 		return 0;

130 d3df3087 2003-12-06 devnull 	}

131 d3df3087 2003-12-06 devnull 

132 d3df3087 2003-12-06 devnull 	qlock(&mux->outlk);

133 d3df3087 2003-12-06 devnull 	qunlock(&mux->lk);

134 d3df3087 2003-12-06 devnull 	if(mux->send(mux, p) < 0){

135 d3df3087 2003-12-06 devnull 		qunlock(&mux->outlk);

136 d3df3087 2003-12-06 devnull 		/* vthangup(mux); */

137 d3df3087 2003-12-06 devnull 		return -1;	

138 d3df3087 2003-12-06 devnull 	}

139 d3df3087 2003-12-06 devnull 	qunlock(&mux->outlk);

140 d3df3087 2003-12-06 devnull 	return 0;

141 d3df3087 2003-12-06 devnull }

142 d3df3087 2003-12-06 devnull