1// Copyright 2017 The etcd Authors 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15package ordering 16 17import ( 18 "errors" 19 "sync" 20 "time" 21 22 "github.com/coreos/etcd/clientv3" 23) 24 25type OrderViolationFunc func(op clientv3.Op, resp clientv3.OpResponse, prevRev int64) error 26 27var ErrNoGreaterRev = errors.New("etcdclient: no cluster members have a revision higher than the previously received revision") 28 29func NewOrderViolationSwitchEndpointClosure(c clientv3.Client) OrderViolationFunc { 30 var mu sync.Mutex 31 violationCount := 0 32 return func(op clientv3.Op, resp clientv3.OpResponse, prevRev int64) error { 33 if violationCount > len(c.Endpoints()) { 34 return ErrNoGreaterRev 35 } 36 mu.Lock() 37 defer mu.Unlock() 38 eps := c.Endpoints() 39 // force client to connect to given endpoint by limiting to a single endpoint 40 c.SetEndpoints(eps[violationCount%len(eps)]) 41 // give enough time for operation 42 time.Sleep(1 * time.Second) 43 // set available endpoints back to all endpoints in to ensure 44 // the client has access to all the endpoints. 45 c.SetEndpoints(eps...) 46 violationCount++ 47 return nil 48 } 49} 50