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 }