payError // error structure follows
payData // user payload follows
payAck // acknowledgement; no payload
+ payClosed // channel is now closed
)
// A header is sent as a prefix to every transmission. It will be followed by
// Export
+// expLog is a logging convenience function. The first argument must be a string.
+func expLog(args ...interface{}) {
+ args[0] = "netchan export: " + args[0].(string)
+ log.Stderr(args)
+}
+
// An Exporter allows a set of channels to be published on a single
// network port. A single machine may have multiple Exporters
// but they must use different ports.
func (client *expClient) sendError(hdr *header, err string) {
error := &error{err}
- log.Stderr("export:", error.error)
+ expLog("sending error to client", error.error)
client.encode(hdr, payError, error) // ignore any encode error, hope client gets it
client.mu.Lock()
client.errored = true
for {
*hdr = header{}
if err := client.decode(hdrValue); err != nil {
- log.Stderr("error decoding client header:", err)
+ expLog("error decoding client header:", err)
break
}
switch hdr.payloadType {
case payRequest:
if err := client.decode(reqValue); err != nil {
- log.Stderr("error decoding client request:", err)
+ expLog("error decoding client request:", err)
break
}
switch req.dir {
// The actual sends will have payload type payData.
// TODO: manage the count?
default:
- error.error = "export request: can't handle channel direction"
- log.Stderr(error.error, req.dir)
+ error.error = "request: can't handle channel direction"
+ expLog(error.error, req.dir)
client.encode(hdr, payError, error)
}
case payData:
client.serveSend(*hdr)
+ case payClosed:
+ client.serveClosed(*hdr)
case payAck:
client.mu.Lock()
if client.ackNum != hdr.seqNum-1 {
// in a single instance of locking client.mu, the messages are guaranteed
// to be sent in order. Therefore receipt of acknowledgement N means
// all messages <=N have been seen by the recipient. We check anyway.
- log.Stderr("netchan export: sequence out of order:", client.ackNum, hdr.seqNum)
+ expLog("sequence out of order:", client.ackNum, hdr.seqNum)
}
if client.ackNum < hdr.seqNum { // If there has been an error, don't back up the count.
client.ackNum = hdr.seqNum
}
client.mu.Unlock()
+ default:
+ log.Exit("netchan export: unknown payload type", hdr.payloadType)
}
}
client.exp.delClient(client)
for {
val := ech.ch.Recv()
if ech.ch.Closed() {
- client.sendError(&hdr, os.EOF.String())
+ if err := client.encode(&hdr, payClosed, nil); err != nil {
+ expLog("error encoding server closed message:", err)
+ }
break
}
// We hold the lock during transmission to guarantee messages are
err := client.encode(&hdr, payData, val.Interface())
client.mu.Unlock()
if err != nil {
- log.Stderr("error encoding client response:", err)
+ expLog("error encoding client response:", err)
client.sendError(&hdr, err.String())
break
}
// Create a new value for each received item.
val := reflect.MakeZero(ech.ch.Type().(*reflect.ChanType).Elem())
if err := client.decode(val); err != nil {
- log.Stderr("exporter value decode:", err)
+ expLog("value decode:", err)
return
}
ech.ch.Send(val)
- // TODO count
+}
+
+// Report that client has closed the channel that is sending to us.
+// The header is passed by value to avoid issues of overwriting.
+func (client *expClient) serveClosed(hdr header) {
+ ech := client.getChan(&hdr, Recv)
+ if ech == nil {
+ return
+ }
+ ech.ch.Close()
}
func (client *expClient) unackedCount() int64 {
for {
conn, err := exp.listener.Accept()
if err != nil {
- log.Stderr("exporter.listen:", err)
+ expLog("listen:", err)
break
}
client := exp.addClient(conn)
// Import
+// impLog is a logging convenience function. The first argument must be a string.
+func impLog(args ...interface{}) {
+ args[0] = "netchan import: " + args[0].(string)
+ log.Stderr(args)
+}
+
// An Importer allows a set of channels to be imported from a single
// remote machine/network port. A machine may have multiple
// importers, even from the same machine/network port.
for {
*hdr = header{}
if e := imp.decode(hdrValue); e != nil {
- log.Stderr("importer header:", e)
+ impLog("header:", e)
imp.shutdown()
return
}
// done lower in loop
case payError:
if e := imp.decode(errValue); e != nil {
- log.Stderr("importer error:", e)
+ impLog("error:", e)
return
}
if err.error != "" {
- log.Stderr("importer response error:", err.error)
+ impLog("response error:", err.error)
imp.shutdown()
return
}
+ case payClosed:
+ ich := imp.getChan(hdr.name)
+ if ich != nil {
+ ich.ch.Close()
+ }
+ continue
default:
- log.Stderr("unexpected payload type:", hdr.payloadType)
+ impLog("unexpected payload type:", hdr.payloadType)
return
}
- imp.chanLock.Lock()
- ich, ok := imp.chans[hdr.name]
- imp.chanLock.Unlock()
- if !ok {
- log.Stderr("unknown name in request:", hdr.name)
- return
+ ich := imp.getChan(hdr.name)
+ if ich == nil {
+ continue
}
if ich.dir != Recv {
- log.Stderr("cannot happen: receive from non-Recv channel")
+ impLog("cannot happen: receive from non-Recv channel")
return
}
// Acknowledge receipt
// Create a new value for each received item.
value := reflect.MakeZero(ich.ch.Type().(*reflect.ChanType).Elem())
if e := imp.decode(value); e != nil {
- log.Stderr("importer value decode:", e)
+ impLog("importer value decode:", e)
return
}
ich.ch.Send(value)
}
}
+func (imp *Importer) getChan(name string) *chanDir {
+ imp.chanLock.Lock()
+ ich := imp.chans[name]
+ imp.chanLock.Unlock()
+ if ich == nil {
+ impLog("unknown name in netchan request:", name)
+ return nil
+ }
+ return ich
+}
+
// Import imports a channel of the given type and specified direction.
// It is equivalent to ImportNValues with a count of -1, meaning unbounded.
func (imp *Importer) Import(name string, chT interface{}, dir Dir) os.Error {
}
imp.chans[name] = &chanDir{ch, dir}
// Tell the other side about this channel.
- hdr := &header{name: name, payloadType: payRequest}
+ hdr := &header{name: name}
req := &request{count: int64(n), dir: dir}
- if err := imp.encode(hdr, payRequest, req); err != nil {
- log.Stderr("importer request encode:", err)
+ if err = imp.encode(hdr, payRequest, req); err != nil {
+ impLog("request encode:", err)
return err
}
if dir == Send {
go func() {
for i := 0; n == -1 || i < n; i++ {
val := ch.Recv()
- if err := imp.encode(hdr, payData, val.Interface()); err != nil {
- log.Stderr("error encoding client response:", err)
+ if ch.Closed() {
+ if err = imp.encode(hdr, payClosed, nil); err != nil {
+ impLog("error encoding client closed message:", err)
+ }
+ return
+ }
+ if err = imp.encode(hdr, payData, val.Interface()); err != nil {
+ impLog("error encoding client send:", err)
return
}
}
const count = 10 // number of items in most tests
const closeCount = 5 // number of items when sender closes early
+const base = 23
+
func exportSend(exp *Exporter, n int, t *testing.T) {
ch := make(chan int)
err := exp.Export("exportedSend", ch, Send)
}
go func() {
for i := 0; i < n; i++ {
- ch <- 23+i
+ ch <- base+i
}
close(ch)
}()
}
for i := 0; i < count; i++ {
v := <-ch
- if v != 45+i {
- t.Errorf("export Receive: bad value: expected 4%d; got %d", 45+i, v)
+ if closed(ch) {
+ if i != closeCount {
+ t.Errorf("exportReceive expected close at %d; got one at %d\n", closeCount, i)
+ }
+ break
+ }
+ if v != base+i {
+ t.Errorf("export Receive: bad value: expected %d+%d=%d; got %d", base, i, base+i, v)
}
}
}
+func importSend(imp *Importer, n int, t *testing.T) {
+ ch := make(chan int)
+ err := imp.ImportNValues("exportedRecv", ch, Send, count)
+ if err != nil {
+ t.Fatal("importSend:", err)
+ }
+ go func() {
+ for i := 0; i < n; i++ {
+ ch <- base+i
+ }
+ close(ch)
+ }()
+}
+
func importReceive(imp *Importer, t *testing.T, done chan bool) {
ch := make(chan int)
err := imp.ImportNValues("exportedSend", ch, Recv, count)
v := <-ch
if closed(ch) {
if i != closeCount {
- t.Errorf("expected close at %d; got one at %d\n", closeCount, i)
+ t.Errorf("importReceive expected close at %d; got one at %d\n", closeCount, i)
}
break
}
if v != 23+i {
- t.Errorf("importReceive: bad value: expected %d; got %+d", 23+i, v)
+ t.Errorf("importReceive: bad value: expected %%d+%d=%d; got %+d", base, i, base+i, v)
}
}
if done != nil {
}
}
-func importSend(imp *Importer, t *testing.T) {
- ch := make(chan int)
- err := imp.ImportNValues("exportedRecv", ch, Send, count)
- if err != nil {
- t.Fatal("importSend:", err)
- }
- for i := 0; i < count; i++ {
- ch <- 45+i
- }
-}
-
func TestExportSendImportReceive(t *testing.T) {
exp, err := NewExporter("tcp", "127.0.0.1:0")
if err != nil {
if err != nil {
t.Fatal("new importer:", err)
}
- go importSend(imp, t)
+ importSend(imp, count, t)
exportReceive(exp, t)
}
importReceive(imp, t, nil)
}
+func TestClosingImportSendExportReceive(t *testing.T) {
+ exp, err := NewExporter("tcp", "127.0.0.1:0")
+ if err != nil {
+ t.Fatal("new exporter:", err)
+ }
+ imp, err := NewImporter("tcp", exp.Addr().String())
+ if err != nil {
+ t.Fatal("new importer:", err)
+ }
+ importSend(imp, closeCount, t)
+ exportReceive(exp, t)
+}
+
// Not a great test but it does at least invoke Drain.
func TestExportDrain(t *testing.T) {
exp, err := NewExporter("tcp", "127.0.0.1:0")