| // 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 leasing serves linearizable reads from a local cache by acquiring |
| // exclusive write access to keys through a client-side leasing protocol. This |
| // leasing layer can either directly wrap the etcd client or it can be exposed |
| // through the etcd grpc proxy server, granting multiple clients write access. |
| // |
| // First, create a leasing KV from a clientv3.Client 'cli': |
| // |
| // lkv, err := leasing.NewKV(cli, "leasing-prefix") |
| // if err != nil { |
| // // handle error |
| // } |
| // |
| // A range request for a key "abc" tries to acquire a leasing key so it can cache the range's |
| // key locally. On the server, the leasing key is stored to "leasing-prefix/abc": |
| // |
| // resp, err := lkv.Get(context.TODO(), "abc") |
| // |
| // Future linearized read requests using 'lkv' will be served locally for the lease's lifetime: |
| // |
| // resp, err = lkv.Get(context.TODO(), "abc") |
| // |
| // If another leasing client writes to a leased key, then the owner relinquishes its exclusive |
| // access, permitting the writer to modify the key: |
| // |
| // lkv2, err := leasing.NewKV(cli, "leasing-prefix") |
| // if err != nil { |
| // // handle error |
| // } |
| // lkv2.Put(context.TODO(), "abc", "456") |
| // resp, err = lkv.Get("abc") |
| // |
| package leasing |
