add test for close/closed, fix a few implementation bugs.

R=ken
OCL=26664
CL=26664

src/runtime/chan.c

@@ -176,13 +176,13 @@ sendchan(Hchan *c, byte *ep, bool *pres)
 	}
 
 	lock(&chanlock);
+loop:
+	if(c->closed & Wclosed)
+		goto closed;
 
 	if(c->dataqsiz > 0)
 		goto asynch;
 
-	if(c->closed & Wclosed)
-		goto closed;
-
 	sg = dequeue(&c->recvq, c);
 	if(sg != nil) {
 		if(ep != nil)
@@ -215,6 +215,8 @@ sendchan(Hchan *c, byte *ep, bool *pres)
 
 	lock(&chanlock);
 	sg = g->param;
+	if(sg == nil)
+		goto loop;
 	freesg(c, sg);
 	unlock(&chanlock);
 	if(pres != nil)
@@ -260,7 +262,7 @@ asynch:
 closed:
 	incerr(c);
 	if(pres != nil)
-		*pres = false;
+		*pres = true;
 	unlock(&chanlock);
 }
 
@@ -277,6 +279,7 @@ chanrecv(Hchan* c, byte *ep, bool* pres)
 	}
 
 	lock(&chanlock);
+loop:
 	if(c->dataqsiz > 0)
 		goto asynch;
 
@@ -312,11 +315,8 @@ chanrecv(Hchan* c, byte *ep, bool* pres)
 
 	lock(&chanlock);
 	sg = g->param;
-
-	if(c->closed & Wclosed) {
-		freesg(c, sg);
-		goto closed;
-	}
+	if(sg == nil)
+		goto loop;
 
 	c->elemalg->copy(c->elemsize, ep, sg->elem);
 	freesg(c, sg);
@@ -368,7 +368,7 @@ closed:
 	c->closed |= Rclosed;
 	incerr(c);
 	if(pres != nil)
-		*pres = false;
+		*pres = true;
 	unlock(&chanlock);
 }
 
@@ -651,32 +651,32 @@ loop:
 		c = cas->chan;
 		if(c->dataqsiz > 0) {
 			if(cas->send) {
+				if(c->closed & Wclosed)
+					goto sclose;
 				if(c->qcount < c->dataqsiz)
 					goto asyns;
-				if(c->closed & Wclosed)
-					goto gots;
 				goto next1;
 			}
 			if(c->qcount > 0)
 				goto asynr;
 			if(c->closed & Wclosed)
-				goto gotr;
+				goto rclose;
 			goto next1;
 		}
 
 		if(cas->send) {
+			if(c->closed & Wclosed)
+				goto sclose;
 			sg = dequeue(&c->recvq, c);
 			if(sg != nil)
 				goto gots;
-			if(c->closed & Wclosed)
-				goto gots;
 			goto next1;
 		}
 		sg = dequeue(&c->sendq, c);
 		if(sg != nil)
 			goto gotr;
 		if(c->closed & Wclosed)
-			goto gotr;
+			goto rclose;
 
 	next1:
 		o += p;
@@ -823,13 +823,6 @@ gotr:
 		sys·printint(o);
 		prints("\n");
 	}
-	if(c->closed & Wclosed) {
-		if(cas->u.elemp != nil)
-			c->elemalg->copy(c->elemsize, cas->u.elemp, nil);
-		c->closed |= Rclosed;
-		incerr(c);
-		goto retc;
-	}
 	if(cas->u.elemp != nil)
 		c->elemalg->copy(c->elemsize, cas->u.elemp, sg->elem);
 	gp = sg->g;
@@ -837,6 +830,13 @@ gotr:
 	ready(gp);
 	goto retc;
 
+rclose:
+	if(cas->u.elemp != nil)
+		c->elemalg->copy(c->elemsize, cas->u.elemp, nil);
+	c->closed |= Rclosed;
+	incerr(c);
+	goto retc;
+
 gots:
 	// send path to wakeup the receiver (sg)
 	if(debug) {
@@ -848,14 +848,17 @@ gots:
 		sys·printint(o);
 		prints("\n");
 	}
-	if(c->closed & Wclosed) {
-		incerr(c);
-		goto retc;
-	}
+	if(c->closed & Wclosed)
+		goto sclose;
 	c->elemalg->copy(c->elemsize, sg->elem, cas->u.elem);
 	gp = sg->g;
 	gp->param = sg;
 	ready(gp);
+	goto retc;
+
+sclose:
+	incerr(c);
+	goto retc;
 
 retc:
 	if(sel->ncase >= 1 && sel->ncase < nelem(selfree)) {
@@ -909,7 +912,6 @@ sys·closechan(Hchan *c)
 void
 sys·closedchan(Hchan *c, bool closed)
 {
-
 	// test Rclosed
 	closed = 0;
 	if(c->closed & Rclosed)

test/closedchan.go

+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test close(c), closed(c).
+//
+// TODO(rsc): Doesn't check behavior of close(c) when there
+// are blocked senders/receivers.
+
+package main
+
+type Chan interface {
+	Send(int);
+	Nbsend(int) bool;
+	Recv() int;
+	Nbrecv() (int, bool);
+	Close();
+	Closed() bool;
+	Impl() string;
+}
+
+// direct channel operations
+type XChan chan int
+func (c XChan) Send(x int) {
+	c <- x
+}
+
+func (c XChan) Nbsend(x int) bool {
+	return c <- x;
+}
+
+func (c XChan) Recv() int {
+	return <-c
+}
+
+func (c XChan) Nbrecv() (int, bool) {
+	x, ok := <-c;
+	return x, ok;
+}
+
+func (c XChan) Close() {
+	close(c)
+}
+
+func (c XChan) Closed() bool {
+	return closed(c)
+}
+
+func (c XChan) Impl() string {
+	return "(<- operator)"
+}
+
+// indirect operations via select
+type SChan chan int
+func (c SChan) Send(x int) {
+	select {
+	case c <- x:
+	}
+}
+
+func (c SChan) Nbsend(x int) bool {
+	select {
+	case c <- x:
+		return true;
+	default:
+		return false;
+	}
+	panic("nbsend");
+}
+
+func (c SChan) Recv() int {
+	select {
+	case x := <-c:
+		return x;
+	}
+	panic("recv");
+}
+
+func (c SChan) Nbrecv() (int, bool) {
+	select {
+	case x := <-c:
+		return x, true;
+	default:
+		return 0, false;
+	}
+	panic("nbrecv");
+}
+
+func (c SChan) Close() {
+	close(c)
+}
+
+func (c SChan) Closed() bool {
+	return closed(c)
+}
+
+func (c SChan) Impl() string {
+	return "(select)";
+}
+
+func test1(c Chan) {
+	// not closed until the close signal (a zero value) has been received.
+	if c.Closed() {
+		println("test1: Closed before Recv zero:", c.Impl());
+	}
+
+	for i := 0; i < 3; i++ {
+		// recv a close signal (a zero value)
+		if x := c.Recv(); x != 0 {
+			println("test1: recv on closed got non-zero:", x, c.Impl());
+		}
+
+		// should now be closed.
+		if !c.Closed() {
+			println("test1: not closed after recv zero", c.Impl());
+		}
+
+		// should work with ,ok: received a value without blocking, so ok == true.
+		x, ok := c.Nbrecv();
+		if !ok {
+			println("test1: recv on closed got not ok", c.Impl());
+		}
+		if x != 0 {
+			println("test1: recv ,ok on closed got non-zero:", x, c.Impl());
+		}
+	}
+
+	// send should work with ,ok too: sent a value without blocking, so ok == true.
+	ok := c.Nbsend(1);
+	if !ok {
+		println("test1: send on closed got not ok", c.Impl());
+	}
+
+	// but the value should have been discarded.
+	if x := c.Recv(); x != 0 {
+		println("test1: recv on closed got non-zero after send on closed:", x, c.Impl());
+	}
+
+	// similarly Send.
+	c.Send(2);
+	if x := c.Recv(); x != 0 {
+		println("test1: recv on closed got non-zero after send on closed:", x, c.Impl());
+	}
+}
+
+func testasync1(c Chan) {
+	// not closed until the close signal (a zero value) has been received.
+	if c.Closed() {
+		println("testasync1: Closed before Recv zero:", c.Impl());
+	}
+
+	// should be able to get the last value via Recv
+	if x := c.Recv(); x != 1 {
+		println("testasync1: Recv did not get 1:", x, c.Impl());
+	}
+
+	test1(c);
+}
+
+func testasync2(c Chan) {
+	// not closed until the close signal (a zero value) has been received.
+	if c.Closed() {
+		println("testasync2: Closed before Recv zero:", c.Impl());
+	}
+
+	// should be able to get the last value via Nbrecv
+	if x, ok := c.Nbrecv(); !ok || x != 1 {
+		println("testasync2: Nbrecv did not get 1, true:", x, ok, c.Impl());
+	}
+
+	test1(c);
+}
+
+func closedsync() chan int {
+	c := make(chan int);
+	close(c);
+	return c;
+}
+
+func closedasync() chan int {
+	c := make(chan int, 2);
+	c <- 1;
+	close(c);
+	return c;
+}
+
+func main() {
+	test1(XChan(closedsync()));
+	test1(SChan(closedsync()));
+
+	testasync1(XChan(closedasync()));
+	testasync1(SChan(closedasync()));
+	testasync2(XChan(closedasync()));
+	testasync2(SChan(closedasync()));
+}