package server // 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 ( "context" "errors" "fmt" "io" "reflect" "runtime/debug" "strings" "sync" "unicode" "unicode/utf8" "github.com/micro/go-micro/v2/codec" merrors "github.com/micro/go-micro/v2/errors" ) var ( lastStreamResponseError = errors.New("EOS") // 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 { sync.Mutex // protects counters 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 } type request struct { msg *codec.Message next *request // for free list in Server } type response struct { msg *codec.Message next *response // for free list in Server } // router represents an RPC router. type router struct { name string mu sync.Mutex // protects the serviceMap serviceMap map[string]*service reqLock sync.Mutex // protects freeReq freeReq *request respLock sync.Mutex // protects freeResp freeResp *response // handler wrappers hdlrWrappers []HandlerWrapper // subscriber wrappers subWrappers []SubscriberWrapper su sync.RWMutex subscribers map[string][]*subscriber } // rpcRouter encapsulates functions that become a server.Router type rpcRouter struct { h func(context.Context, Request, interface{}) error m func(context.Context, Message) error } func (r rpcRouter) ProcessMessage(ctx context.Context, msg Message) error { return r.m(ctx, msg) } func (r rpcRouter) ServeRequest(ctx context.Context, req Request, rsp Response) error { return r.h(ctx, req, rsp) } func newRpcRouter() *router { return &router{ serviceMap: make(map[string]*service), subscribers: make(map[string][]*subscriber), } } // 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.Error("method", mname, "of", mtype, "has wrong number of ins:", mtype.NumIn()) return nil } if stream { // check stream type streamType := reflect.TypeOf((*Stream)(nil)).Elem() if !argType.Implements(streamType) { log.Error(mname, "argument does not implement Stream interface:", argType) return nil } } else { // if not stream check the replyType // First arg need not be a pointer. if !isExportedOrBuiltinType(argType) { log.Error(mname, "argument type not exported:", argType) return nil } if replyType.Kind() != reflect.Ptr { log.Error("method", mname, "reply type not a pointer:", replyType) return nil } // Reply type must be exported. if !isExportedOrBuiltinType(replyType) { log.Error("method", mname, "reply type not exported:", replyType) return nil } } // Method needs one out. if mtype.NumOut() != 1 { log.Error("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.Error("method", mname, "returns", returnType.String(), "not error") return nil } return &methodType{method: method, ArgType: argType, ReplyType: replyType, ContextType: contextType, stream: stream} } func (router *router) sendResponse(sending sync.Locker, req *request, reply interface{}, cc codec.Writer, last bool) error { msg := new(codec.Message) msg.Type = codec.Response resp := router.getResponse() resp.msg = msg resp.msg.Id = req.msg.Id sending.Lock() err := cc.Write(resp.msg, reply) sending.Unlock() router.freeResponse(resp) return err } func (s *service) call(ctx context.Context, router *router, sending *sync.Mutex, mtype *methodType, req *request, argv, replyv reflect.Value, cc codec.Writer) error { defer router.freeRequest(req) function := mtype.method.Func var returnValues []reflect.Value r := &rpcRequest{ service: req.msg.Target, contentType: req.msg.Header["Content-Type"], method: req.msg.Method, endpoint: req.msg.Endpoint, body: req.msg.Body, } // only set if not nil if argv.IsValid() { r.rawBody = argv.Interface() } if !mtype.stream { fn := func(ctx context.Context, req Request, rsp interface{}) error { returnValues = function.Call([]reflect.Value{s.rcvr, mtype.prepareContext(ctx), reflect.ValueOf(argv.Interface()), reflect.ValueOf(rsp)}) // The return value for the method is an error. if err := returnValues[0].Interface(); err != nil { return err.(error) } return nil } // wrap the handler for i := len(router.hdlrWrappers); i > 0; i-- { fn = router.hdlrWrappers[i-1](fn) } // execute handler if err := fn(ctx, r, replyv.Interface()); err != nil { return err } // send response return router.sendResponse(sending, req, replyv.Interface(), cc, true) } // declare a local error to see if we errored out already // keep track of the type, to make sure we return // the same one consistently rawStream := &rpcStream{ context: ctx, codec: cc.(codec.Codec), request: r, id: req.msg.Id, } // Invoke the method, providing a new value for the reply. fn := func(ctx context.Context, req Request, stream interface{}) error { returnValues = function.Call([]reflect.Value{s.rcvr, mtype.prepareContext(ctx), reflect.ValueOf(stream)}) if err := returnValues[0].Interface(); err != nil { // the function returned an error, we use that return err.(error) } else if serr := rawStream.Error(); serr == io.EOF || serr == io.ErrUnexpectedEOF { return nil } else { // no error, we send the special EOS error return lastStreamResponseError } } // wrap the handler for i := len(router.hdlrWrappers); i > 0; i-- { fn = router.hdlrWrappers[i-1](fn) } // client.Stream request r.stream = true // execute handler return fn(ctx, r, rawStream) } func (m *methodType) prepareContext(ctx context.Context) reflect.Value { if contextv := reflect.ValueOf(ctx); contextv.IsValid() { return contextv } return reflect.Zero(m.ContextType) } func (router *router) getRequest() *request { router.reqLock.Lock() req := router.freeReq if req == nil { req = new(request) } else { router.freeReq = req.next *req = request{} } router.reqLock.Unlock() return req } func (router *router) freeRequest(req *request) { router.reqLock.Lock() req.next = router.freeReq router.freeReq = req router.reqLock.Unlock() } func (router *router) getResponse() *response { router.respLock.Lock() resp := router.freeResp if resp == nil { resp = new(response) } else { router.freeResp = resp.next *resp = response{} } router.respLock.Unlock() return resp } func (router *router) freeResponse(resp *response) { router.respLock.Lock() resp.next = router.freeResp router.freeResp = resp router.respLock.Unlock() } func (router *router) readRequest(r Request) (service *service, mtype *methodType, req *request, argv, replyv reflect.Value, keepReading bool, err error) { cc := r.Codec() service, mtype, req, keepReading, err = router.readHeader(cc) if err != nil { if !keepReading { return } // discard body cc.ReadBody(nil) return } // is it a streaming request? then we don't read the body if mtype.stream { if cc.(codec.Codec).String() != "grpc" { cc.ReadBody(nil) } return } // Decode the argument value. argIsValue := false // if true, need to indirect before calling. if mtype.ArgType.Kind() == reflect.Ptr { argv = reflect.New(mtype.ArgType.Elem()) } else { argv = reflect.New(mtype.ArgType) argIsValue = true } // argv guaranteed to be a pointer now. if err = cc.ReadBody(argv.Interface()); err != nil { return } if argIsValue { argv = argv.Elem() } if !mtype.stream { replyv = reflect.New(mtype.ReplyType.Elem()) } return } func (router *router) readHeader(cc codec.Reader) (service *service, mtype *methodType, req *request, keepReading bool, err error) { // Grab the request header. msg := new(codec.Message) msg.Type = codec.Request req = router.getRequest() req.msg = msg err = cc.ReadHeader(msg, msg.Type) if err != nil { req = nil if err == io.EOF || err == io.ErrUnexpectedEOF { return } err = errors.New("rpc: router cannot decode request: " + err.Error()) return } // We read the header successfully. If we see an error now, // we can still recover and move on to the next request. keepReading = true serviceMethod := strings.Split(req.msg.Endpoint, ".") if len(serviceMethod) != 2 { err = errors.New("rpc: service/endpoint request ill-formed: " + req.msg.Endpoint) return } // Look up the request. router.mu.Lock() service = router.serviceMap[serviceMethod[0]] router.mu.Unlock() if service == nil { err = errors.New("rpc: can't find service " + serviceMethod[0]) return } mtype = service.method[serviceMethod[1]] if mtype == nil { err = errors.New("rpc: can't find method " + serviceMethod[1]) } return } func (router *router) NewHandler(h interface{}, opts ...HandlerOption) Handler { return newRpcHandler(h, opts...) } func (router *router) Handle(h Handler) error { router.mu.Lock() defer router.mu.Unlock() if router.serviceMap == nil { router.serviceMap = make(map[string]*service) } if len(h.Name()) == 0 { return errors.New("rpc.Handle: handler has no name") } if !isExported(h.Name()) { return errors.New("rpc.Handle: type " + h.Name() + " is not exported") } rcvr := h.Handler() s := new(service) s.typ = reflect.TypeOf(rcvr) s.rcvr = reflect.ValueOf(rcvr) // check name if _, present := router.serviceMap[h.Name()]; present { return errors.New("rpc.Handle: service already defined: " + h.Name()) } s.name = h.Name() 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 } } // Check there are methods if len(s.method) == 0 { return errors.New("rpc Register: type " + s.name + " has no exported methods of suitable type") } // save handler router.serviceMap[s.name] = s return nil } func (router *router) ServeRequest(ctx context.Context, r Request, rsp Response) error { sending := new(sync.Mutex) service, mtype, req, argv, replyv, keepReading, err := router.readRequest(r) if err != nil { if !keepReading { return err } // send a response if we actually managed to read a header. if req != nil { router.freeRequest(req) } return err } return service.call(ctx, router, sending, mtype, req, argv, replyv, rsp.Codec()) } func (router *router) NewSubscriber(topic string, handler interface{}, opts ...SubscriberOption) Subscriber { return newSubscriber(topic, handler, opts...) } func (router *router) Subscribe(s Subscriber) error { sub, ok := s.(*subscriber) if !ok { return fmt.Errorf("invalid subscriber: expected *subscriber") } if len(sub.handlers) == 0 { return fmt.Errorf("invalid subscriber: no handler functions") } if err := validateSubscriber(sub); err != nil { return err } router.su.Lock() defer router.su.Unlock() // append to subscribers subs := router.subscribers[sub.Topic()] subs = append(subs, sub) router.subscribers[sub.Topic()] = subs return nil } func (router *router) ProcessMessage(ctx context.Context, msg Message) (err error) { defer func() { // recover any panics if r := recover(); r != nil { log.Error("panic recovered: ", r) log.Error(string(debug.Stack())) err = merrors.InternalServerError("go.micro.server", "panic recovered: %v", r) } }() router.su.RLock() // get the subscribers by topic subs, ok := router.subscribers[msg.Topic()] // unlock since we only need to get the subs router.su.RUnlock() if !ok { return nil } var errResults []string // we may have multiple subscribers for the topic for _, sub := range subs { // we may have multiple handlers per subscriber for i := 0; i < len(sub.handlers); i++ { // get the handler handler := sub.handlers[i] var isVal bool var req reflect.Value // check whether the handler is a pointer if handler.reqType.Kind() == reflect.Ptr { req = reflect.New(handler.reqType.Elem()) } else { req = reflect.New(handler.reqType) isVal = true } // if its a value get the element if isVal { req = req.Elem() } if handler.reqType.Kind() == reflect.Ptr { req = reflect.New(handler.reqType.Elem()) } else { req = reflect.New(handler.reqType) isVal = true } // if its a value get the element if isVal { req = req.Elem() } cc := msg.Codec() // read the header. mostly a noop if err = cc.ReadHeader(&codec.Message{}, codec.Event); err != nil { return err } // read the body into the handler request value if err = cc.ReadBody(req.Interface()); err != nil { return err } // create the handler which will honour the SubscriberFunc type fn := func(ctx context.Context, msg Message) error { var vals []reflect.Value if sub.typ.Kind() != reflect.Func { vals = append(vals, sub.rcvr) } if handler.ctxType != nil { vals = append(vals, reflect.ValueOf(ctx)) } // values to pass the handler vals = append(vals, reflect.ValueOf(msg.Payload())) // execute the actuall call of the handler returnValues := handler.method.Call(vals) if rerr := returnValues[0].Interface(); rerr != nil { err = rerr.(error) } return err } // wrap with subscriber wrappers for i := len(router.subWrappers); i > 0; i-- { fn = router.subWrappers[i-1](fn) } // create new rpc message rpcMsg := &rpcMessage{ topic: msg.Topic(), contentType: msg.ContentType(), payload: req.Interface(), codec: msg.(*rpcMessage).codec, header: msg.Header(), body: msg.Body(), } // execute the message handler if err = fn(ctx, rpcMsg); err != nil { errResults = append(errResults, err.Error()) } } } // if no errors just return if len(errResults) > 0 { err = merrors.InternalServerError("go.micro.server", "subscriber error: %v", strings.Join(errResults, "\n")) } return err }