dubbo.apache.org/dubbo-go/v3@v3.1.1/filter/echo/filter.go (about)

     1  /*
     2   * Licensed to the Apache Software Foundation (ASF) under one or more
     3   * contributor license agreements.  See the NOTICE file distributed with
     4   * this work for additional information regarding copyright ownership.
     5   * The ASF licenses this file to You under the Apache License, Version 2.0
     6   * (the "License"); you may not use this file except in compliance with
     7   * the License.  You may obtain a copy of the License at
     8   *
     9   *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  
    18  // Package echo providers health check filter.
    19  // RPCService need a Echo method in consumer, if you want to use Filter
    20  // eg: Echo func(ctx context.Context, arg interface{}, rsp *Xxx) error
    21  package echo
    22  
    23  import (
    24  	"context"
    25  	"sync"
    26  )
    27  
    28  import (
    29  	"dubbo.apache.org/dubbo-go/v3/common/constant"
    30  	"dubbo.apache.org/dubbo-go/v3/common/extension"
    31  	"dubbo.apache.org/dubbo-go/v3/filter"
    32  	"dubbo.apache.org/dubbo-go/v3/protocol"
    33  )
    34  
    35  var (
    36  	once sync.Once
    37  	echo *echoFilter
    38  )
    39  
    40  func init() {
    41  	extension.SetFilter(constant.EchoFilterKey, newEchoFilter)
    42  }
    43  
    44  type echoFilter struct{}
    45  
    46  func newEchoFilter() filter.Filter {
    47  	if echo == nil {
    48  		once.Do(func() {
    49  			echo = &echoFilter{}
    50  		})
    51  	}
    52  	return echo
    53  }
    54  
    55  // Invoke response to the callers with its first argument.
    56  func (f *echoFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {
    57  	if invocation.MethodName() == constant.Echo && len(invocation.Arguments()) == 1 {
    58  		return &protocol.RPCResult{
    59  			Rest:  invocation.Arguments()[0],
    60  			Attrs: invocation.Attachments(),
    61  		}
    62  	}
    63  
    64  	return invoker.Invoke(ctx, invocation)
    65  }
    66  
    67  // OnResponse dummy process, returns the result directly
    68  func (f *echoFilter) OnResponse(_ context.Context, result protocol.Result, _ protocol.Invoker,
    69  	_ protocol.Invocation) protocol.Result {
    70  
    71  	return result
    72  }