dubbox 增加google-gprc/protobuf支持

好久没写东西了，今年实在太忙，基本都在搞业务开发，晚上来补一篇，作为今年的收官博客。google-rpc 正式发布以来，受到了不少人的关注，这么知名的rpc框架，不集成到dubbox中有点说不过去。

但是grpc的思路与其它rpc(比如：avro/thrift)有些不一样，并非直接采用 "接口定义+服务实现"的套路，而是采用了"抽象类派生"的做法，见下面的示例：

 syntax = "proto3";

 option java_multiple_files = true;
 option java_package = "com.cnblogs.yjmyzz.demo.service.api.grpc";
 option java_outer_classname = "GrpcHelloServiceProto";

 package hello;

 service GrpcHelloService {
     rpc ping (PingRequest) returns (PingResponse) {}
 }

 message PingRequest{}

 message PingResponse {
     string message = 1;
 }

这是一段protobuf的定义文件，最终生成的java代码为：

 package com.cnblogs.yjmyzz.demo.service.api.grpc;

 import static io.grpc.stub.ClientCalls.asyncUnaryCall;
 import static io.grpc.stub.ClientCalls.asyncServerStreamingCall;
 import static io.grpc.stub.ClientCalls.asyncClientStreamingCall;
 import static io.grpc.stub.ClientCalls.asyncBidiStreamingCall;
 import static io.grpc.stub.ClientCalls.blockingUnaryCall;
 import static io.grpc.stub.ClientCalls.blockingServerStreamingCall;
 import static io.grpc.stub.ClientCalls.futureUnaryCall;
 import static io.grpc.MethodDescriptor.generateFullMethodName;
 import static io.grpc.stub.ServerCalls.asyncUnaryCall;
 import static io.grpc.stub.ServerCalls.asyncServerStreamingCall;
 import static io.grpc.stub.ServerCalls.asyncClientStreamingCall;
 import static io.grpc.stub.ServerCalls.asyncBidiStreamingCall;
 import static io.grpc.stub.ServerCalls.asyncUnimplementedUnaryCall;
 import static io.grpc.stub.ServerCalls.asyncUnimplementedStreamingCall;

 /**
  */
 @javax.annotation.Generated(
     value = "by gRPC proto compiler (version 1.0.1)",
     comments = "Source: hello.proto")
 public class GrpcHelloServiceGrpc {

   private GrpcHelloServiceGrpc() {}

   public static final String SERVICE_NAME = "hello.GrpcHelloService";

   // Static method descriptors that strictly reflect the proto.
   @io.grpc.ExperimentalApi("https://github.com/grpc/grpc-java/issues/1901")
   public static final io.grpc.MethodDescriptor<com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest,
       com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse> METHOD_PING =
       io.grpc.MethodDescriptor.create(
           io.grpc.MethodDescriptor.MethodType.UNARY,
           generateFullMethodName(
               "hello.GrpcHelloService", "ping"),
           io.grpc.protobuf.ProtoUtils.marshaller(com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest.getDefaultInstance()),
           io.grpc.protobuf.ProtoUtils.marshaller(com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse.getDefaultInstance()));

   /**
    * Creates a new async stub that supports all call types for the service
    */
   public static GrpcHelloServiceStub newStub(io.grpc.Channel channel) {
     return new GrpcHelloServiceStub(channel);
   }

   /**
    * Creates a new blocking-style stub that supports unary and streaming output calls on the service
    */
   public static GrpcHelloServiceBlockingStub newBlockingStub(
       io.grpc.Channel channel) {
     return new GrpcHelloServiceBlockingStub(channel);
   }

   /**
    * Creates a new ListenableFuture-style stub that supports unary and streaming output calls on the service
    */
   public static GrpcHelloServiceFutureStub newFutureStub(
       io.grpc.Channel channel) {
     return new GrpcHelloServiceFutureStub(channel);
   }

   /**
    */
   public static abstract class GrpcHelloServiceImplBase implements io.grpc.BindableService {

     /**
      */
     public void ping(com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest request,
         io.grpc.stub.StreamObserver<com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse> responseObserver) {
       asyncUnimplementedUnaryCall(METHOD_PING, responseObserver);
     }

     @java.lang.Override public io.grpc.ServerServiceDefinition bindService() {
       return io.grpc.ServerServiceDefinition.builder(getServiceDescriptor())
           .addMethod(
             METHOD_PING,
             asyncUnaryCall(
               new MethodHandlers<
                 com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest,
                 com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse>(
                   this, METHODID_PING)))
           .build();
     }
   }

   /**
    */
   public static final class GrpcHelloServiceStub extends io.grpc.stub.AbstractStub<GrpcHelloServiceStub> {
     private GrpcHelloServiceStub(io.grpc.Channel channel) {
       super(channel);
     }

     private GrpcHelloServiceStub(io.grpc.Channel channel,
         io.grpc.CallOptions callOptions) {
       super(channel, callOptions);
     }

     @java.lang.Override
     protected GrpcHelloServiceStub build(io.grpc.Channel channel,
         io.grpc.CallOptions callOptions) {
       return new GrpcHelloServiceStub(channel, callOptions);
     }

     /**
      */
     public void ping(com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest request,
         io.grpc.stub.StreamObserver<com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse> responseObserver) {
       asyncUnaryCall(
           getChannel().newCall(METHOD_PING, getCallOptions()), request, responseObserver);
     }
   }

   /**
    */
   public static final class GrpcHelloServiceBlockingStub extends io.grpc.stub.AbstractStub<GrpcHelloServiceBlockingStub> {
     private GrpcHelloServiceBlockingStub(io.grpc.Channel channel) {
       super(channel);
     }

     private GrpcHelloServiceBlockingStub(io.grpc.Channel channel,
         io.grpc.CallOptions callOptions) {
       super(channel, callOptions);
     }

     @java.lang.Override
     protected GrpcHelloServiceBlockingStub build(io.grpc.Channel channel,
         io.grpc.CallOptions callOptions) {
       return new GrpcHelloServiceBlockingStub(channel, callOptions);
     }

     /**
      */
     public com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse ping(com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest request) {
       return blockingUnaryCall(
           getChannel(), METHOD_PING, getCallOptions(), request);
     }
   }

   /**
    */
   public static final class GrpcHelloServiceFutureStub extends io.grpc.stub.AbstractStub<GrpcHelloServiceFutureStub> {
     private GrpcHelloServiceFutureStub(io.grpc.Channel channel) {
       super(channel);
     }

     private GrpcHelloServiceFutureStub(io.grpc.Channel channel,
         io.grpc.CallOptions callOptions) {
       super(channel, callOptions);
     }

     @java.lang.Override
     protected GrpcHelloServiceFutureStub build(io.grpc.Channel channel,
         io.grpc.CallOptions callOptions) {
       return new GrpcHelloServiceFutureStub(channel, callOptions);
     }

     /**
      */
     public com.google.common.util.concurrent.ListenableFuture<com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse> ping(
         com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest request) {
       return futureUnaryCall(
           getChannel().newCall(METHOD_PING, getCallOptions()), request);
     }
   }

   private static final int METHODID_PING = 0;

   private static class MethodHandlers<Req, Resp> implements
       io.grpc.stub.ServerCalls.UnaryMethod<Req, Resp>,
       io.grpc.stub.ServerCalls.ServerStreamingMethod<Req, Resp>,
       io.grpc.stub.ServerCalls.ClientStreamingMethod<Req, Resp>,
       io.grpc.stub.ServerCalls.BidiStreamingMethod<Req, Resp> {
     private final GrpcHelloServiceImplBase serviceImpl;
     private final int methodId;

     public MethodHandlers(GrpcHelloServiceImplBase serviceImpl, int methodId) {
       this.serviceImpl = serviceImpl;
       this.methodId = methodId;
     }

     @java.lang.Override
     @java.lang.SuppressWarnings("unchecked")
     public void invoke(Req request, io.grpc.stub.StreamObserver<Resp> responseObserver) {
       switch (methodId) {
         case METHODID_PING:
           serviceImpl.ping((com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest) request,
               (io.grpc.stub.StreamObserver<com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse>) responseObserver);
           break;
         default:
           throw new AssertionError();
       }
     }

     @java.lang.Override
     @java.lang.SuppressWarnings("unchecked")
     public io.grpc.stub.StreamObserver<Req> invoke(
         io.grpc.stub.StreamObserver<Resp> responseObserver) {
       switch (methodId) {
         default:
           throw new AssertionError();
       }
     }
   }

   public static io.grpc.ServiceDescriptor getServiceDescriptor() {
     return new io.grpc.ServiceDescriptor(SERVICE_NAME,
         METHOD_PING);
   }

 }

其中：

  public static abstract class GrpcHelloServiceImplBase implements io.grpc.BindableService {

    /**
     */
    public void ping(com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest request,
        io.grpc.stub.StreamObserver<com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse> responseObserver) {
      asyncUnimplementedUnaryCall(METHOD_PING, responseObserver);
    }

    @java.lang.Override public io.grpc.ServerServiceDefinition bindService() {
      return io.grpc.ServerServiceDefinition.builder(getServiceDescriptor())
          .addMethod(
            METHOD_PING,
            asyncUnaryCall(
              new MethodHandlers<
                com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest,
                com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse>(
                  this, METHODID_PING)))
          .build();
    }
  }

就是一个抽象类，而且调用时要借助stub来实现，而stub的生成，又要借助channel，所以在集成到dubbox中时，要花点心思。　

先定义一个辅助接口：

package com.alibaba.dubbo.rpc.protocol.grpc;

import io.grpc.BindableService;
import io.grpc.Channel;

/**
 * Created by yangjunming on 16/10/7.
 */
public interface GrpcBindableService extends BindableService {

    Channel getChannel();

    void setChannel(Channel channel);
}

这个接口的目的，是为了最终调用时，能拿到channel，进而生成stub.

然后在实现具体gprc服务时，实现这个接口：

package com.cnblogs.yjmyzz.demo.service.impl.grpc;

import com.alibaba.dubbo.rpc.protocol.grpc.GrpcBindableService;
import com.cnblogs.yjmyzz.demo.service.api.grpc.GrpcHelloServiceGrpc;
import com.cnblogs.yjmyzz.demo.service.api.grpc.PingRequest;
import com.cnblogs.yjmyzz.demo.service.api.grpc.PingResponse;
import io.grpc.Channel;
import io.grpc.stub.StreamObserver;
import org.springframework.stereotype.Service;

/**
 * Created by yangjunming on 2016/11/3.
 */
@Service("grpcService")
public class HelloServiceImpl extends GrpcHelloServiceGrpc.GrpcHelloServiceImplBase implements GrpcBindableService {

    private Channel channel;

    public Channel getChannel() {
        return channel;
    }

    public void setChannel(Channel channel) {
        this.channel = channel;
    }

    @Override
    public void ping(PingRequest request,
                     StreamObserver<PingResponse> responseObserver) {
        PingResponse reply = PingResponse.newBuilder().setMessage("grpc is running").build();
        responseObserver.onNext(reply);
        responseObserver.onCompleted();
    }
}

这样处理后，dubbox中添加grpc的协议就方便了：

package com.alibaba.dubbo.rpc.protocol.grpc;

import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.rpc.RpcException;
import com.alibaba.dubbo.rpc.protocol.AbstractProxyProtocol;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import io.grpc.Server;
import io.grpc.ServerBuilder;

import java.io.IOException;

/**
 * 为dubbo-rpc添加"google-gRPC"支持
 * by 杨俊明(http://yjmyzz.cnblogs.com/)
 */
public class GrpcProtocol extends AbstractProxyProtocol {
    public static final int DEFAULT_PORT = 50051;
    private static final Logger logger = LoggerFactory.getLogger(GrpcProtocol.class);

    public int getDefaultPort() {
        return DEFAULT_PORT;
    }

    public GrpcProtocol() {
        super(IOException.class, RpcException.class);
    }

    @Override
    protected <T> Runnable doExport(T impl, Class<T> type, URL url)
            throws RpcException {

        logger.info("impl => " + impl.getClass());
        logger.info("type => " + type.getName());
        logger.info("url => " + url);

        try {
            String clsName = url.getParameter("class");
            Class<?> cls = Class.forName(clsName);
            GrpcBindableService service = (GrpcBindableService) cls.newInstance();
            final Server grpcServer = ServerBuilder.forPort(url.getPort())
                    .addService(service)
                    .build()
                    .start();
            logger.info("grpc server started !");
            return new Runnable() {
                public void run() {
                    try {
                        logger.info("Close gRPC Server");
                        grpcServer.shutdown();
                    } catch (Throwable e) {
                        logger.warn(e.getMessage(), e);
                    }
                }
            };
        } catch (Exception e) {
            logger.error(e.getMessage(), e);
            throw new RpcException(e.getMessage(), e);
        }
    }

    @Override
    protected <T> T doRefer(Class<T> type, URL url) throws RpcException {
        logger.info("type => " + type.getName());
        logger.info("url => " + url);
        final ManagedChannel channel = ManagedChannelBuilder.forAddress(url.getHost(), url.getPort())
                .usePlaintext(true)
                .build();
        try {
            DefaultBindableService service = new DefaultBindableService();
            service.setChannel(channel);
            return (T) service;
        } catch (Exception e) {
            logger.error(e.getMessage(), e);
            throw new RpcException(e.getMessage(), e);
        }
    }

}

在doExport暴露grpc服务时，通过类型转换成我们刚才定义的接口GrpcBindableService，解决了grpc服务的启动问题。

再来看如何引用这个服务，此为还要再定义一个辅助类：

package com.alibaba.dubbo.rpc.protocol.grpc;

import io.grpc.Channel;
import io.grpc.ServerServiceDefinition;

/**
 * Created by yangjunming on 16/10/7.
 */
public class DefaultBindableService implements GrpcBindableService {

    private Channel channel;

    @Override
    public Channel getChannel() {
        return channel;
    }

    @Override
    public void setChannel(Channel channel) {
        this.channel = channel;
    }

    @Override
    public ServerServiceDefinition bindService() {
        return null;
    }
}

这个类就是刚才定义的新接口GrpcBindableService的默认实现，目的是为了能将生成的channel通过setter方法保存下来。doRefer方法利用这个类，拿到了channel，最终给到grpc服务的调用方。

客户端调用示例：

    private static void testGrpc(ConfigurableApplicationContext ctx) throws InterruptedException {
        GrpcBindableService service = ctx.getBean(GrpcBindableService.class, "grpcService");
        AbstractStub stub = GrpcHelloServiceGrpc.newBlockingStub(service.getChannel());
        PingRequest request = PingRequest.newBuilder().build();
        logger.info("\n---------gprc协议测试开始---------");
        logger.info(stub.getClass().toString());
        PingResponse response = ((GrpcHelloServiceGrpc.GrpcHelloServiceBlockingStub) stub).ping(request);
        logger.info("\tping=>" + response.getMessage());
        ((ManagedChannel) stub.getChannel()).shutdown().awaitTermination(5, TimeUnit.SECONDS);
    }

完整示例代码请参考github上我重写的dubbo-demo示例

最后：祝大家圣诞快乐！