diff --git a/clientv3/clientv3util/util.go b/clientv3/clientv3util/util.go new file mode 100644 index 00000000000..3afbffe5468 --- /dev/null +++ b/clientv3/clientv3util/util.go @@ -0,0 +1,32 @@ +// Copyright 2017 The etcd Authors +// +// Licensed 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 clientv3util + +import ( + "github.com/coreos/etcd/clientv3" +) + +// KeyExists returns a comparison operation that evaluates to true iff the given +// key exists. It does this by checking if the key `Version` is greater than 0. +// It is a useful guard in transaction delete operations. +func KeyExists(key string) clientv3.Cmp { + return clientv3.Compare(clientv3.Version(key), ">", 0) +} + +// KeyMissing returns a comparison operation that evaluates to true iff the +// given key does not exist. +func KeyMissing(key string) clientv3.Cmp { + return clientv3.Compare(clientv3.Version(key), "=", 0) +}