聊聊dubbogo的EchoFilter

序

本文次要钻研一下 dubbo-go 的 EchoFilter

EchoFilter

dubbo-go-v1.4.2/filter/filter_impl/echo_filter.go

const (
    // ECHO echo module name
    ECHO = "echo"
)

func init() {extension.SetFilter(ECHO, GetFilter)
}

// EchoFilter
// RPCService need a Echo method in consumer, if you want to use EchoFilter
// eg:
//        Echo func(ctx context.Context, arg interface{}, rsp *Xxx) error
type EchoFilter struct{}

• EchoFilter 没有定义属性

Invoke

dubbo-go-v1.4.2/filter/filter_impl/echo_filter.go

// Invoke ...
func (ef *EchoFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {logger.Infof("invoking echo filter.")
    logger.Debugf("%v,%v", invocation.MethodName(), len(invocation.Arguments()))
    if invocation.MethodName() == constant.ECHO && len(invocation.Arguments()) == 1 {
        return &protocol.RPCResult{Rest:  invocation.Arguments()[0],
            Attrs: invocation.Attachments(),}
    }

    return invoker.Invoke(ctx, invocation)
}

• Invoke 办法判断 invocation.MethodName 是否是 echo，且有一个参数，是的话则返回 protocol.RPCResult

OnResponse

dubbo-go-v1.4.2/filter/filter_impl/echo_filter.go

// OnResponse ...
func (ef *EchoFilter) OnResponse(_ context.Context, result protocol.Result, _ protocol.Invoker,
    _ protocol.Invocation) protocol.Result {return result}

• OnResponse 办法间接返回 result

GetFilter

dubbo-go-v1.4.2/filter/filter_impl/echo_filter.go

// GetFilter ...
func GetFilter() filter.Filter {return &EchoFilter{}
}

• GetFilter 办法创立 EchoFilter

小结

EchoFilter 的 Invoke 办法判断 invocation.MethodName 是否是 echo，且有一个参数，是的话则返回 protocol.RPCResult

doc

• echo_filter