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server.go
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server.go
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package grpc
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// Meh, we need to get rid of this shit
import (
"errors"
"reflect"
"sync"
"unicode"
"unicode/utf8"
"golang.org/x/net/context"
"github.com/micro/go-log"
"github.com/micro/go-micro/server"
)
var (
// A value sent as a placeholder for the server's response value when the server
// receives an invalid request. It is never decoded by the client since the Response
// contains an error when it is used.
invalidRequest = struct{}{}
// Precompute the reflect type for error. Can't use error directly
// because Typeof takes an empty interface value. This is annoying.
typeOfError = reflect.TypeOf((*error)(nil)).Elem()
)
type methodType struct {
method reflect.Method
ArgType reflect.Type
ReplyType reflect.Type
ContextType reflect.Type
stream bool
}
type service struct {
name string // name of service
rcvr reflect.Value // receiver of methods for the service
typ reflect.Type // type of the receiver
method map[string]*methodType // registered methods
}
// server represents an RPC Server.
type rServer struct {
mu sync.Mutex // protects the serviceMap
serviceMap map[string]*service
}
// Is this an exported - upper case - name?
func isExported(name string) bool {
rune, _ := utf8.DecodeRuneInString(name)
return unicode.IsUpper(rune)
}
// Is this type exported or a builtin?
func isExportedOrBuiltinType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
// PkgPath will be non-empty even for an exported type,
// so we need to check the type name as well.
return isExported(t.Name()) || t.PkgPath() == ""
}
// prepareMethod returns a methodType for the provided method or nil
// in case if the method was unsuitable.
func prepareMethod(method reflect.Method) *methodType {
mtype := method.Type
mname := method.Name
var replyType, argType, contextType reflect.Type
var stream bool
// Method must be exported.
if method.PkgPath != "" {
return nil
}
switch mtype.NumIn() {
case 3:
// assuming streaming
argType = mtype.In(2)
contextType = mtype.In(1)
stream = true
case 4:
// method that takes a context
argType = mtype.In(2)
replyType = mtype.In(3)
contextType = mtype.In(1)
default:
log.Log("method", mname, "of", mtype, "has wrong number of ins:", mtype.NumIn())
return nil
}
if stream {
// check stream type
streamType := reflect.TypeOf((*server.Streamer)(nil)).Elem()
if !argType.Implements(streamType) {
log.Log(mname, "argument does not implement Streamer interface:", argType)
return nil
}
} else {
// if not stream check the replyType
// First arg need not be a pointer.
if !isExportedOrBuiltinType(argType) {
log.Log(mname, "argument type not exported:", argType)
return nil
}
if replyType.Kind() != reflect.Ptr {
log.Log("method", mname, "reply type not a pointer:", replyType)
return nil
}
// Reply type must be exported.
if !isExportedOrBuiltinType(replyType) {
log.Log("method", mname, "reply type not exported:", replyType)
return nil
}
}
// Method needs one out.
if mtype.NumOut() != 1 {
log.Log("method", mname, "has wrong number of outs:", mtype.NumOut())
return nil
}
// The return type of the method must be error.
if returnType := mtype.Out(0); returnType != typeOfError {
log.Log("method", mname, "returns", returnType.String(), "not error")
return nil
}
return &methodType{method: method, ArgType: argType, ReplyType: replyType, ContextType: contextType, stream: stream}
}
func (server *rServer) register(rcvr interface{}) error {
server.mu.Lock()
defer server.mu.Unlock()
if server.serviceMap == nil {
server.serviceMap = make(map[string]*service)
}
s := new(service)
s.typ = reflect.TypeOf(rcvr)
s.rcvr = reflect.ValueOf(rcvr)
sname := reflect.Indirect(s.rcvr).Type().Name()
if sname == "" {
log.Fatal("rpc: no service name for type", s.typ.String())
}
if !isExported(sname) {
s := "rpc Register: type " + sname + " is not exported"
log.Log(s)
return errors.New(s)
}
if _, present := server.serviceMap[sname]; present {
return errors.New("rpc: service already defined: " + sname)
}
s.name = sname
s.method = make(map[string]*methodType)
// Install the methods
for m := 0; m < s.typ.NumMethod(); m++ {
method := s.typ.Method(m)
if mt := prepareMethod(method); mt != nil {
s.method[method.Name] = mt
}
}
if len(s.method) == 0 {
s := "rpc Register: type " + sname + " has no exported methods of suitable type"
log.Log(s)
return errors.New(s)
}
server.serviceMap[s.name] = s
return nil
}
func (m *methodType) prepareContext(ctx context.Context) reflect.Value {
if contextv := reflect.ValueOf(ctx); contextv.IsValid() {
return contextv
}
return reflect.Zero(m.ContextType)
}