dubbo.apache.org/dubbo-go/v3@v3.1.1/registry/servicediscovery/instance/random/random_service_instance_selector.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 random
    19  
    20  import (
    21  	"math/rand"
    22  	"time"
    23  )
    24  
    25  import (
    26  	"dubbo.apache.org/dubbo-go/v3/common"
    27  	"dubbo.apache.org/dubbo-go/v3/common/extension"
    28  	"dubbo.apache.org/dubbo-go/v3/registry"
    29  	"dubbo.apache.org/dubbo-go/v3/registry/servicediscovery/instance"
    30  )
    31  
    32  func init() {
    33  	rand.Seed(time.Now().UnixNano())
    34  	extension.SetServiceInstanceSelector("random", NewRandomServiceInstanceSelector)
    35  }
    36  
    37  // the ServiceInstanceSelector implementation based on Random algorithm
    38  type RandomServiceInstanceSelector struct{}
    39  
    40  func NewRandomServiceInstanceSelector() instance.ServiceInstanceSelector {
    41  	return &RandomServiceInstanceSelector{}
    42  }
    43  
    44  func (r *RandomServiceInstanceSelector) Select(url *common.URL, serviceInstances []registry.ServiceInstance) registry.ServiceInstance {
    45  	if len(serviceInstances) == 0 {
    46  		return nil
    47  	}
    48  	if len(serviceInstances) == 1 {
    49  		return serviceInstances[0]
    50  	}
    51  	index := rand.Intn(len(serviceInstances))
    52  	return serviceInstances[index]
    53  }