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Commit 1e4b1f93 authored by Rob Pike's avatar Rob Pike
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netchan: handle closing of channels. 

This also silences some misleading logging.
Also improve logging.

R=rsc
CC=golang-dev
https://golang.org/cl/2245041
parent 63623ba2
Hide whitespace changes
Inline Side-by-side
Showing with 117 additions and 45 deletions
src/pkg/netchan/common.go
View file @ 1e4b1f93
......@@ -37,6 +37,7 @@ const (
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
......
src/pkg/netchan/export.go
View file @ 1e4b1f93
......@@ -31,6 +31,12 @@ import (
// 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.
......@@ -60,7 +66,7 @@ func newClient(exp *Exporter, conn net.Conn) *expClient {
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
......@@ -96,13 +102,13 @@ func (client *expClient) run() {
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 {
......@@ -114,12 +120,14 @@ func (client *expClient) run() {
// 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 {
......@@ -127,12 +135,14 @@ func (client *expClient) run() {
// 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)
......@@ -148,7 +158,9 @@ func (client *expClient) serveRecv(hdr header, count int64) {
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
......@@ -161,7 +173,7 @@ func (client *expClient) serveRecv(hdr header, count int64) {
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
}
......@@ -184,11 +196,20 @@ func (client *expClient) serveSend(hdr header) {
// 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 {
......@@ -217,7 +238,7 @@ func (exp *Exporter) listen() {
for {
conn, err := exp.listener.Accept()
if err != nil {
log.Stderr("exporter.listen:", err)
expLog("listen:", err)
break
}
client := exp.addClient(conn)
......
src/pkg/netchan/import.go
View file @ 1e4b1f93
......@@ -14,6 +14,12 @@ import (
// 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.
......@@ -66,7 +72,7 @@ func (imp *Importer) run() {
for {
*hdr = header{}
if e := imp.decode(hdrValue); e != nil {
log.Stderr("importer header:", e)
impLog("header:", e)
imp.shutdown()
return
}
......@@ -75,27 +81,30 @@ func (imp *Importer) run() {
// 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
......@@ -105,13 +114,24 @@ func (imp *Importer) run() {
// 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 {
......@@ -145,18 +165,24 @@ func (imp *Importer) ImportNValues(name string, chT interface{}, dir Dir, n int)
}
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
}
}
......
src/pkg/netchan/netchan_test.go
View file @ 1e4b1f93
......@@ -9,6 +9,8 @@ import "testing"
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)
......@@ -17,7 +19,7 @@ func exportSend(exp *Exporter, n int, t *testing.T) {
}
go func() {
for i := 0; i < n; i++ {
ch <- 23+i
ch <- base+i
}
close(ch)
}()
......@@ -31,12 +33,32 @@ func exportReceive(exp *Exporter, t *testing.T) {
}
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)
......@@ -47,12 +69,12 @@ func importReceive(imp *Importer, t *testing.T, done chan bool) {
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 {
......@@ -60,17 +82,6 @@ func importReceive(imp *Importer, t *testing.T, done chan bool) {
}
}
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 {
......@@ -93,7 +104,7 @@ func TestExportReceiveImportSend(t *testing.T) {
if err != nil {
t.Fatal("new importer:", err)
}
go importSend(imp, t)
importSend(imp, count, t)
exportReceive(exp, t)
}
......@@ -110,6 +121,19 @@ func TestClosingExportSendImportReceive(t *testing.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")
......
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