| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package lb |
| |
| import "sync/atomic" |
| |
| type RoundRobinLB struct { |
| Endpoints []string |
| index int32 |
| } |
| |
| func (lb *RoundRobinLB) Next() string { |
| l := len(lb.Endpoints) |
| if l == 0 { |
| return "" |
| } |
| c := atomic.LoadInt32(&lb.index) |
| if c >= int32(l)-1 { |
| atomic.StoreInt32(&lb.index, 0) |
| return lb.Endpoints[0] |
| } else if atomic.CompareAndSwapInt32(&lb.index, c, c+1) { |
| return lb.Endpoints[c+1] |
| } |
| return lb.Endpoints[atomic.LoadInt32(&lb.index)] |
| } |
| |
| func NewRoundRobinLB(endpoints []string) *RoundRobinLB { |
| lb := &RoundRobinLB{ |
| Endpoints: make([]string, len(endpoints)), |
| index: -1, |
| } |
| copy(lb.Endpoints, endpoints) |
| return lb |
| } |