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rpc: make more tolerant of errors.

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Add Error type to enable clients to distinguish
between local and remote errors.
Also return "connection shut down error" after
the first error return rather than returning the
same error each time.

R=r
CC=golang-dev
https://golang.org/cl/4080058
This commit is contained in:
Roger Peppe 2011-02-09 10:57:59 -08:00 • committed by Rob Pike
parent d916cca327
commit d40ae94993
3 changed files with 131 additions and 120 deletions
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93
src/pkg/rpc/server.go
View file

@ -299,7 +299,7 @@ func (server *Server) register(rcvr interface{}, name string, useName bool) os.E
// A value sent as a placeholder for the response when the server receives an invalid request.
type InvalidRequest struct {
marker int
Marker int
}
var invalidRequest = InvalidRequest{1}
@ -316,6 +316,7 @@ func sendResponse(sending *sync.Mutex, req *Request, reply interface{}, codec Se
resp.ServiceMethod = req.ServiceMethod
if errmsg != "" {
resp.Error = errmsg
reply = invalidRequest
}
resp.Seq = req.Seq
sending.Lock()
@ -389,9 +390,28 @@ func (server *Server) ServeConn(conn io.ReadWriteCloser) {
func (server *Server) ServeCodec(codec ServerCodec) {
sending := new(sync.Mutex)
for {
// Grab the request header.
req := new(Request)
err := codec.ReadRequestHeader(req)
req, service, mtype, err := server.readRequest(codec)
if err != nil {
if err != os.EOF {
log.Println("rpc:", err)
}
if err == os.EOF || err == io.ErrUnexpectedEOF {
break
}
// discard body
codec.ReadRequestBody(new(interface{}))
// send a response if we actually managed to read a header.
if req != nil {
sendResponse(sending, req, invalidRequest, codec, err.String())
}
continue
}
// Decode the argument value.
argv := _new(mtype.ArgType)
replyv := _new(mtype.ReplyType)
err = codec.ReadRequestBody(argv.Interface())
if err != nil {
if err == os.EOF || err == io.ErrUnexpectedEOF {
if err == io.ErrUnexpectedEOF {
@ -399,44 +419,45 @@ func (server *Server) ServeCodec(codec ServerCodec) {
}
break
}
s := "rpc: server cannot decode request: " + err.String()
sendResponse(sending, req, invalidRequest, codec, s)
break
}
serviceMethod := strings.Split(req.ServiceMethod, ".", -1)
if len(serviceMethod) != 2 {
s := "rpc: service/method request ill-formed: " + req.ServiceMethod
sendResponse(sending, req, invalidRequest, codec, s)
continue
}
// Look up the request.
server.Lock()
service, ok := server.serviceMap[serviceMethod[0]]
server.Unlock()
if !ok {
s := "rpc: can't find service " + req.ServiceMethod
sendResponse(sending, req, invalidRequest, codec, s)
continue
}
mtype, ok := service.method[serviceMethod[1]]
if !ok {
s := "rpc: can't find method " + req.ServiceMethod
sendResponse(sending, req, invalidRequest, codec, s)
continue
}
// Decode the argument value.
argv := _new(mtype.ArgType)
replyv := _new(mtype.ReplyType)
err = codec.ReadRequestBody(argv.Interface())
if err != nil {
log.Println("rpc: tearing down", serviceMethod[0], "connection:", err)
sendResponse(sending, req, replyv.Interface(), codec, err.String())
break
continue
}
go service.call(sending, mtype, req, argv, replyv, codec)
}
codec.Close()
}
func (server *Server) readRequest(codec ServerCodec) (req *Request, service *service, mtype *methodType, err os.Error) {
// Grab the request header.
req = new(Request)
err = codec.ReadRequestHeader(req)
if err != nil {
req = nil
if err == os.EOF || err == io.ErrUnexpectedEOF {
return
}
err = os.ErrorString("rpc: server cannot decode request: " + err.String())
return
}
serviceMethod := strings.Split(req.ServiceMethod, ".", -1)
if len(serviceMethod) != 2 {
err = os.ErrorString("rpc: service/method request ill-formed: " + req.ServiceMethod)
return
}
// Look up the request.
server.Lock()
service = server.serviceMap[serviceMethod[0]]
server.Unlock()
if service == nil {
err = os.ErrorString("rpc: can't find service " + req.ServiceMethod)
return
}
mtype = service.method[serviceMethod[1]]
if mtype == nil {
err = os.ErrorString("rpc: can't find method " + req.ServiceMethod)
}
return
}
// Accept accepts connections on the listener and serves requests
// for each incoming connection. Accept blocks; the caller typically