3 grpc的流

用来接收大量的数据，支持3中模式：服务端流，客户端流，双端流

来自书

package ecommerce;

service OrderManagement {
    rpc addOrder(Order) returns (google.protobuf.StringValue);
    rpc getOrder(google.protobuf.StringValue) returns (Order);
    rpc searchOrders(google.protobuf.StringValue) returns (stream Order);
    rpc updateOrders(stream Order) returns (google.protobuf.StringValue);
    rpc processOrders(stream google.protobuf.StringValue) returns (stream CombinedShipment);
}

message Order {
    string id = 1;
    repeated string items = 2;
    string description = 3;
    float price = 4;
    string destination = 5;
}

message CombinedShipment {
    string id = 1;
    string status = 2;
    repeated Order ordersList = 3;
}

来自鸟窝的grpc代码

syntax = "proto3";

package pb;

import "github.com/gogo/protobuf/gogoproto/gogo.proto";

option (gogoproto.gostring_all) = true;
option (gogoproto.equal_all) = true;
option (gogoproto.verbose_equal_all) = true;
option (gogoproto.goproto_stringer_all) = false;
option (gogoproto.stringer_all) =  true;
option (gogoproto.populate_all) = true;
option (gogoproto.testgen_all) = false;
option (gogoproto.benchgen_all) = false;
option (gogoproto.marshaler_all) = true;
option (gogoproto.sizer_all) = true;
option (gogoproto.unmarshaler_all) = true;


// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello1 (HelloRequest) returns (stream HelloReply) {}
  rpc SayHello2 (stream HelloRequest) returns (HelloReply) {}
  rpc SayHello3 (stream HelloRequest) returns (stream HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

流数据需要持续读取，直到遇到ioe错误

for {
		orderId, err := stream.Recv()
		log.Printf("Reading Proc order : %s", orderId)
		if err == io.EOF {
			// Client has sent all the messages
			// Send remaining shipments
			log.Printf("EOF : %s", orderId)
			for _, shipment := range combinedShipmentMap {
				if err := stream.Send(&shipment); err != nil {
					return err
				}
			}
			return nil
		}