finish ChanValue: Len and Cap.

R=r
DELTA=45  (45 added, 0 deleted, 0 changed)
OCL=33873
CL=33881

src/pkg/reflect/all_test.go

@@ -757,6 +757,17 @@ func TestChan(t *testing.T) {
 	if cv.TryRecv() != nil {
 		t.Errorf("TryRecv on sync chan succeeded");
 	}
+
+	// len/cap
+	cv = MakeChan(Typeof(c).(*ChanType), 10);
+	c = cv.Interface().(chan int);
+	for i := 0; i < 3; i++ {
+		c <- i;
+	}
+	if l, m := cv.Len(), cv.Cap(); l != len(c) || m != cap(c) {
+		t.Errorf("Len/Cap = %d/%d want %d/%d", l, m, len(c), cap(c));
+	}
+
 }
 
 // Difficult test for function call because of

src/pkg/reflect/value.go

@@ -636,6 +636,8 @@ func chansend(ch, val *byte, pres *bool)
 func chanrecv(ch, val *byte, pres *bool)
 func chanclosed(ch *byte) bool
 func chanclose(ch *byte)
+func chanlen(ch *byte) int32
+func chancap(ch *byte) int32
 
 // Closed returns the result of closed(c) on the underlying channel.
 func (v *ChanValue) Closed() bool {
@@ -649,6 +651,16 @@ func (v *ChanValue) Close() {
 	chanclose(ch);
 }
 
+func (v *ChanValue) Len() int {
+	ch := *(**byte)(v.addr);
+	return int(chanlen(ch));
+}
+
+func (v *ChanValue) Cap() int {
+	ch := *(**byte)(v.addr);
+	return int(chancap(ch));
+}
+
 // internal send; non-blocking if b != nil
 func (v *ChanValue) send(x Value, b *bool) {
 	t := v.Type().(*ChanType);

src/pkg/runtime/chan.c

@@ -917,6 +917,18 @@ chanclosed(Hchan *c)
 	return (c->closed & Rclosed) != 0;
 }
 
+int32
+chanlen(Hchan *c)
+{
+	return c->qcount;
+}
+
+int32
+chancap(Hchan *c)
+{
+	return c->dataqsiz;
+}
+
 
 // closedchan(sel *byte) bool;
 void

src/pkg/runtime/reflect.cgo

@@ -86,6 +86,14 @@ func chanclosed(ch *byte) (r bool) {
 	r = chanclosed((Hchan*)ch);
 }
 
+func chanlen(ch *byte) (r int32) {
+	r = chanlen((Hchan*)ch);
+}
+
+func chancap(ch *byte) (r int32) {
+	r = chancap((Hchan*)ch);
+}
+
 
 /*
  * Go wrappers around the functions in iface.c

src/pkg/runtime/runtime.h

@@ -493,5 +493,7 @@ void	chansend(Hchan*, void*, bool*);
 void	chanrecv(Hchan*, void*, bool*);
 void	chanclose(Hchan*);
 bool	chanclosed(Hchan*);
+int32	chanlen(Hchan*);
+int32	chancap(Hchan*);
 
 void	ifaceE2I(struct InterfaceType*, Eface, Iface*);