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 15 // Package clientv3util contains utility functions derived from clientv3. 16 package clientv3util 17 18 import ( 19 "go.etcd.io/etcd/client/v3" 20 ) 21 22 // KeyExists returns a comparison operation that evaluates to true iff the given 23 // key exists. It does this by checking if the key `Version` is greater than 0. 24 // It is a useful guard in transaction delete operations. 25 func KeyExists(key string) clientv3.Cmp { 26 return clientv3.Compare(clientv3.Version(key), ">", 0) 27 } 28 29 // KeyMissing returns a comparison operation that evaluates to true iff the 30 // given key does not exist. 31 func KeyMissing(key string) clientv3.Cmp { 32 return clientv3.Compare(clientv3.Version(key), "=", 0) 33 } 34