Pull rpcplus in local for the time being. We need to modify it for server side middleware
This commit is contained in:
Asim
490
server/rpcplus_server.go
Normal file
490
server/rpcplus_server.go
Normal file
@@ -0,0 +1,490 @@
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//
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// Meh, we need to get rid of this shit
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package server
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import (
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"errors"
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"io"
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"log"
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"reflect"
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"strings"
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"sync"
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"unicode"
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"unicode/utf8"
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"golang.org/x/net/context"
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)
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const (
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lastStreamResponseError = "EOS"
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)
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var (
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// A value sent as a placeholder for the server's response value when the server
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// receives an invalid request. It is never decoded by the client since the Response
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// contains an error when it is used.
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invalidRequest = struct{}{}
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// Precompute the reflect type for error. Can't use error directly
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// because Typeof takes an empty interface value. This is annoying.
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typeOfError = reflect.TypeOf((*error)(nil)).Elem()
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)
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type methodType struct {
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sync.Mutex // protects counters
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method reflect.Method
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ArgType reflect.Type
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ReplyType reflect.Type
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ContextType reflect.Type
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stream bool
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numCalls uint
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}
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func (m *methodType) TakesContext() bool {
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return m.ContextType != nil
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}
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func (m *methodType) NumCalls() (n uint) {
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m.Lock()
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n = m.numCalls
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m.Unlock()
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return n
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}
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type service struct {
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name string // name of service
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rcvr reflect.Value // receiver of methods for the service
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typ reflect.Type // type of the receiver
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method map[string]*methodType // registered methods
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}
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type request struct {
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ServiceMethod string // format: "Service.Method"
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Seq uint64 // sequence number chosen by client
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next *request // for free list in Server
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}
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type response struct {
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ServiceMethod string // echoes that of the Request
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Seq uint64 // echoes that of the request
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Error string // error, if any.
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next *response // for free list in Server
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}
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// server represents an RPC Server.
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type server struct {
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mu sync.Mutex // protects the serviceMap
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serviceMap map[string]*service
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reqLock sync.Mutex // protects freeReq
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freeReq *request
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respLock sync.Mutex // protects freeResp
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freeResp *response
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}
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func newServer() *server {
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return &server{serviceMap: make(map[string]*service)}
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}
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// Is this an exported - upper case - name?
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func isExported(name string) bool {
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rune, _ := utf8.DecodeRuneInString(name)
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return unicode.IsUpper(rune)
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}
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// Is this type exported or a builtin?
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func isExportedOrBuiltinType(t reflect.Type) bool {
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for t.Kind() == reflect.Ptr {
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t = t.Elem()
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}
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// PkgPath will be non-empty even for an exported type,
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// so we need to check the type name as well.
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return isExported(t.Name()) || t.PkgPath() == ""
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}
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func (server *server) Register(rcvr interface{}) error {
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return server.register(rcvr, "", false)
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}
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// prepareMethod returns a methodType for the provided method or nil
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// in case if the method was unsuitable.
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func prepareMethod(method reflect.Method) *methodType {
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mtype := method.Type
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mname := method.Name
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var replyType, argType, contextType reflect.Type
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stream := false
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// Method must be exported.
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if method.PkgPath != "" {
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return nil
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}
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switch mtype.NumIn() {
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case 3:
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// normal method
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argType = mtype.In(1)
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replyType = mtype.In(2)
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contextType = nil
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case 4:
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// method that takes a context
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argType = mtype.In(2)
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replyType = mtype.In(3)
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contextType = mtype.In(1)
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default:
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log.Println("method", mname, "of", mtype, "has wrong number of ins:", mtype.NumIn())
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return nil
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}
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// First arg need not be a pointer.
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if !isExportedOrBuiltinType(argType) {
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log.Println(mname, "argument type not exported:", argType)
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return nil
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}
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// the second argument will tell us if it's a streaming call
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// or a regular call
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if replyType.Kind() == reflect.Func {
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// this is a streaming call
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stream = true
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if replyType.NumIn() != 1 {
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log.Println("method", mname, "sendReply has wrong number of ins:", replyType.NumIn())
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return nil
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}
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if replyType.In(0).Kind() != reflect.Interface {
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log.Println("method", mname, "sendReply parameter type not an interface:", replyType.In(0))
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return nil
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}
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if replyType.NumOut() != 1 {
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log.Println("method", mname, "sendReply has wrong number of outs:", replyType.NumOut())
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return nil
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}
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if returnType := replyType.Out(0); returnType != typeOfError {
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log.Println("method", mname, "sendReply returns", returnType.String(), "not error")
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return nil
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}
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} else if replyType.Kind() != reflect.Ptr {
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log.Println("method", mname, "reply type not a pointer:", replyType)
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return nil
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}
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// Reply type must be exported.
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if !isExportedOrBuiltinType(replyType) {
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log.Println("method", mname, "reply type not exported:", replyType)
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return nil
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}
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// Method needs one out.
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if mtype.NumOut() != 1 {
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log.Println("method", mname, "has wrong number of outs:", mtype.NumOut())
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return nil
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}
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// The return type of the method must be error.
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if returnType := mtype.Out(0); returnType != typeOfError {
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log.Println("method", mname, "returns", returnType.String(), "not error")
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return nil
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}
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return &methodType{method: method, ArgType: argType, ReplyType: replyType, ContextType: contextType, stream: stream}
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}
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func (server *server) register(rcvr interface{}, name string, useName bool) error {
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server.mu.Lock()
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defer server.mu.Unlock()
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if server.serviceMap == nil {
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server.serviceMap = make(map[string]*service)
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}
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s := new(service)
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s.typ = reflect.TypeOf(rcvr)
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s.rcvr = reflect.ValueOf(rcvr)
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sname := reflect.Indirect(s.rcvr).Type().Name()
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if useName {
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sname = name
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}
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if sname == "" {
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log.Fatal("rpc: no service name for type", s.typ.String())
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}
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if !isExported(sname) && !useName {
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s := "rpc Register: type " + sname + " is not exported"
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log.Print(s)
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return errors.New(s)
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}
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if _, present := server.serviceMap[sname]; present {
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return errors.New("rpc: service already defined: " + sname)
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}
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s.name = sname
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s.method = make(map[string]*methodType)
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// Install the methods
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for m := 0; m < s.typ.NumMethod(); m++ {
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method := s.typ.Method(m)
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if mt := prepareMethod(method); mt != nil {
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s.method[method.Name] = mt
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}
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}
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if len(s.method) == 0 {
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s := "rpc Register: type " + sname + " has no exported methods of suitable type"
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log.Print(s)
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return errors.New(s)
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}
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server.serviceMap[s.name] = s
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return nil
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}
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func (server *server) sendResponse(sending *sync.Mutex, req *request, reply interface{}, codec serverCodec, errmsg string, last bool) (err error) {
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resp := server.getResponse()
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// Encode the response header
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resp.ServiceMethod = req.ServiceMethod
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if errmsg != "" {
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resp.Error = errmsg
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reply = invalidRequest
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}
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resp.Seq = req.Seq
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sending.Lock()
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err = codec.WriteResponse(resp, reply, last)
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if err != nil {
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log.Println("rpc: writing response:", err)
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}
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sending.Unlock()
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server.freeResponse(resp)
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return err
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}
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func (s *service) call(ctx context.Context, server *server, sending *sync.Mutex, mtype *methodType, req *request, argv, replyv reflect.Value, codec serverCodec) {
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mtype.Lock()
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mtype.numCalls++
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mtype.Unlock()
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function := mtype.method.Func
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var returnValues []reflect.Value
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if !mtype.stream {
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// Invoke the method, providing a new value for the reply.
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if mtype.TakesContext() {
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returnValues = function.Call([]reflect.Value{s.rcvr, mtype.prepareContext(ctx), argv, replyv})
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} else {
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returnValues = function.Call([]reflect.Value{s.rcvr, argv, replyv})
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}
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// The return value for the method is an error.
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errInter := returnValues[0].Interface()
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errmsg := ""
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if errInter != nil {
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errmsg = errInter.(error).Error()
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}
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server.sendResponse(sending, req, replyv.Interface(), codec, errmsg, true)
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server.freeRequest(req)
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return
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}
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// declare a local error to see if we errored out already
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// keep track of the type, to make sure we return
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// the same one consistently
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var lastError error
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var firstType reflect.Type
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sendReply := func(oneReply interface{}) error {
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// we already triggered an error, we're done
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if lastError != nil {
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return lastError
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}
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// check the oneReply has the right type using reflection
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typ := reflect.TypeOf(oneReply)
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if firstType == nil {
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firstType = typ
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} else {
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if firstType != typ {
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log.Println("passing wrong type to sendReply",
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firstType, "!=", typ)
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lastError = errors.New("rpc: passing wrong type to sendReply")
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return lastError
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}
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}
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lastError = server.sendResponse(sending, req, oneReply, codec, "", false)
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if lastError != nil {
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return lastError
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}
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// we manage to send, we're good
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return nil
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}
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// Invoke the method, providing a new value for the reply.
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if mtype.TakesContext() {
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returnValues = function.Call([]reflect.Value{s.rcvr, mtype.prepareContext(ctx), argv, reflect.ValueOf(sendReply)})
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} else {
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returnValues = function.Call([]reflect.Value{s.rcvr, argv, reflect.ValueOf(sendReply)})
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}
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errInter := returnValues[0].Interface()
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errmsg := ""
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if errInter != nil {
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// the function returned an error, we use that
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errmsg = errInter.(error).Error()
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} else if lastError != nil {
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// we had an error inside sendReply, we use that
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errmsg = lastError.Error()
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} else {
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// no error, we send the special EOS error
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errmsg = lastStreamResponseError
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}
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// this is the last packet, we don't do anything with
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// the error here (well sendStreamResponse will log it
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// already)
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server.sendResponse(sending, req, nil, codec, errmsg, true)
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server.freeRequest(req)
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}
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func (m *methodType) prepareContext(ctx context.Context) reflect.Value {
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if contextv := reflect.ValueOf(ctx); contextv.IsValid() {
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return contextv
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}
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return reflect.Zero(m.ContextType)
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}
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func (server *server) ServeRequestWithContext(ctx context.Context, codec serverCodec) error {
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sending := new(sync.Mutex)
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service, mtype, req, argv, replyv, keepReading, err := server.readRequest(codec)
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if err != nil {
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if !keepReading {
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return err
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}
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// send a response if we actually managed to read a header.
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if req != nil {
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server.sendResponse(sending, req, invalidRequest, codec, err.Error(), true)
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server.freeRequest(req)
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}
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return err
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}
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service.call(ctx, server, sending, mtype, req, argv, replyv, codec)
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return nil
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}
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func (server *server) getRequest() *request {
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server.reqLock.Lock()
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req := server.freeReq
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if req == nil {
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req = new(request)
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} else {
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server.freeReq = req.next
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*req = request{}
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}
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server.reqLock.Unlock()
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return req
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}
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func (server *server) freeRequest(req *request) {
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server.reqLock.Lock()
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req.next = server.freeReq
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server.freeReq = req
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server.reqLock.Unlock()
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}
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func (server *server) getResponse() *response {
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server.respLock.Lock()
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resp := server.freeResp
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if resp == nil {
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resp = new(response)
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} else {
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server.freeResp = resp.next
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*resp = response{}
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}
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server.respLock.Unlock()
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return resp
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}
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func (server *server) freeResponse(resp *response) {
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server.respLock.Lock()
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resp.next = server.freeResp
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server.freeResp = resp
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server.respLock.Unlock()
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}
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func (server *server) readRequest(codec serverCodec) (service *service, mtype *methodType, req *request, argv, replyv reflect.Value, keepReading bool, err error) {
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service, mtype, req, keepReading, err = server.readRequestHeader(codec)
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if err != nil {
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if !keepReading {
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return
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}
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// discard body
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codec.ReadRequestBody(nil)
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return
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}
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// Decode the argument value.
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argIsValue := false // if true, need to indirect before calling.
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if mtype.ArgType.Kind() == reflect.Ptr {
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argv = reflect.New(mtype.ArgType.Elem())
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} else {
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argv = reflect.New(mtype.ArgType)
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argIsValue = true
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}
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// argv guaranteed to be a pointer now.
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if err = codec.ReadRequestBody(argv.Interface()); err != nil {
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return
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}
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if argIsValue {
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argv = argv.Elem()
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}
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if !mtype.stream {
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replyv = reflect.New(mtype.ReplyType.Elem())
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}
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return
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}
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func (server *server) readRequestHeader(codec serverCodec) (service *service, mtype *methodType, req *request, keepReading bool, err error) {
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// Grab the request header.
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req = server.getRequest()
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err = codec.ReadRequestHeader(req)
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if err != nil {
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req = nil
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if err == io.EOF || err == io.ErrUnexpectedEOF {
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return
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}
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err = errors.New("rpc: server cannot decode request: " + err.Error())
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return
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}
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// We read the header successfully. If we see an error now,
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// we can still recover and move on to the next request.
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keepReading = true
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serviceMethod := strings.Split(req.ServiceMethod, ".")
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if len(serviceMethod) != 2 {
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err = errors.New("rpc: service/method request ill-formed: " + req.ServiceMethod)
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return
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}
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// Look up the request.
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server.mu.Lock()
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service = server.serviceMap[serviceMethod[0]]
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server.mu.Unlock()
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if service == nil {
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err = errors.New("rpc: can't find service " + req.ServiceMethod)
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return
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}
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mtype = service.method[serviceMethod[1]]
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if mtype == nil {
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err = errors.New("rpc: can't find method " + req.ServiceMethod)
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}
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return
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}
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// A serverCodec implements reading of RPC requests and writing of
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// RPC responses for the server side of an RPC session.
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// The server calls ReadRequestHeader and ReadRequestBody in pairs
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// to read requests from the connection, and it calls WriteResponse to
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// write a response back. The server calls Close when finished with the
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// connection. ReadRequestBody may be called with a nil
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// argument to force the body of the request to be read and discarded.
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type serverCodec interface {
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ReadRequestHeader(*request) error
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ReadRequestBody(interface{}) error
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WriteResponse(*response, interface{}, bool) error
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Close() error
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||||
}
|
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Reference in New Issue
Block a user