[GitHub] [dubbo-go] pantianying commented on a change in pull request #495: Imp: refactor the network transport layer

[GitBox <gi...@apache.org>]

pantianying commented on a change in pull request #495:
URL: https://github.com/apache/dubbo-go/pull/495#discussion_r428405517



##########
File path: remoting/exchange_client.go
##########
@@ -0,0 +1,189 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package remoting
+
+import (
+	"sync"
+	"time"
+
+	"github.com/apache/dubbo-go/common"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/protocol"
+)
+
+var (
+	// store requestID and response
+	pendingResponses *sync.Map = new(sync.Map)
+)
+
+type SequenceType int64
+
+// It is interface of client for network communication.
+// If you use getty as network communication, you should define GettyClient that implements this interface.
+type Client interface {
+	SetExchangeClient(client *ExchangeClient)
+	// responseHandler is used to deal with msg
+	SetResponseHandler(responseHandler ResponseHandler)
+	// connect url
+	Connect(url common.URL) error
+	// close
+	Close()
+	// send request to server.
+	Request(request *Request, timeout time.Duration, response *PendingResponse) error
+}
+
+// This is abstraction level. it is like facade.
+type ExchangeClient struct {
+	ConnectTimeout time.Duration
+	address        string
+	client         Client
+}
+
+// handle the message from server
+type ResponseHandler interface {
+	Handler(response *Response)
+}
+
+// create ExchangeClient
+func NewExchangeClient(url common.URL, client Client, connectTimeout time.Duration) *ExchangeClient {
+	exchangeClient := &ExchangeClient{
+		ConnectTimeout: connectTimeout,
+		address:        url.Location,
+		client:         client,
+	}
+	client.SetExchangeClient(exchangeClient)
+	if client.Connect(url) != nil {
+		//retry for a while
+		time.Sleep(1 * time.Second)
+		if client.Connect(url) != nil {
+			return nil
+		}
+	}
+	client.SetResponseHandler(exchangeClient)
+	return exchangeClient
+}
+
+// two way request
+func (client *ExchangeClient) Request(invocation *protocol.Invocation, url common.URL, timeout time.Duration,
+	result *protocol.RPCResult) error {
+	request := NewRequest("2.0.2")
+	request.Data = invocation
+	request.Event = false
+	request.TwoWay = true
+
+	rsp := NewPendingResponse(request.ID)
+	rsp.response = NewResponse(request.ID, "2.0.2")
+	rsp.Reply = (*invocation).Reply()
+	AddPendingResponse(rsp)
+
+	err := client.client.Request(request, timeout, rsp)
+	if err != nil {
+		result.Err = err
+		return err
+	}
+	result.Rest = rsp.response.Result
+	return nil
+}
+
+// async two way request
+func (client *ExchangeClient) AsyncRequest(invocation *protocol.Invocation, url common.URL, timeout time.Duration,
+	callback common.AsyncCallback, result *protocol.RPCResult) error {
+	request := NewRequest("2.0.2")
+	request.Data = invocation
+	request.Event = false
+	request.TwoWay = true
+
+	rsp := NewPendingResponse(request.ID)
+	rsp.response = NewResponse(request.ID, "2.0.2")
+	rsp.Callback = callback
+	rsp.Reply = (*invocation).Reply()
+	AddPendingResponse(rsp)
+
+	err := client.client.Request(request, timeout, rsp)
+	if err != nil {
+		result.Err = err
+		return err
+	}
+	result.Rest = rsp.response
+	return nil
+}
+
+// oneway request
+func (client *ExchangeClient) Send(invocation *protocol.Invocation, timeout time.Duration) error {
+	request := NewRequest("2.0.2")
+	request.Data = invocation
+	request.Event = false
+	request.TwoWay = false
+
+	rsp := NewPendingResponse(request.ID)
+	rsp.response = NewResponse(request.ID, "2.0.2")
+
+	err := client.client.Request(request, timeout, rsp)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// close client
+func (client *ExchangeClient) Close() {
+	client.client.Close()
+}
+
+// handle the response from server
+func (client *ExchangeClient) Handler(response *Response) {
+
+	pendingResponse := removePendingResponse(SequenceType(response.ID))
+	if pendingResponse == nil {
+		logger.Errorf("failed to get pending response context for response package %s", *response)
+		return
+	}
+
+	pendingResponse.response = response
+
+	if pendingResponse.Callback == nil {
+		pendingResponse.Err = pendingResponse.response.Error
+		pendingResponse.Done <- struct{}{}

Review comment:
       一般chan 作为一次性关闭使用都是close，可以让全部协程<-Done 都触发。只发送一个信号，如果该Done在多个协程使用了，只能关闭一个协程。




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