| khenaidoo | ffe076b | 2019-01-15 16:08:08 -0500 | [diff] [blame^] | 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 leasing serves linearizable reads from a local cache by acquiring |
| 16 | // exclusive write access to keys through a client-side leasing protocol. This |
| 17 | // leasing layer can either directly wrap the etcd client or it can be exposed |
| 18 | // through the etcd grpc proxy server, granting multiple clients write access. |
| 19 | // |
| 20 | // First, create a leasing KV from a clientv3.Client 'cli': |
| 21 | // |
| 22 | // lkv, err := leasing.NewKV(cli, "leasing-prefix") |
| 23 | // if err != nil { |
| 24 | // // handle error |
| 25 | // } |
| 26 | // |
| 27 | // A range request for a key "abc" tries to acquire a leasing key so it can cache the range's |
| 28 | // key locally. On the server, the leasing key is stored to "leasing-prefix/abc": |
| 29 | // |
| 30 | // resp, err := lkv.Get(context.TODO(), "abc") |
| 31 | // |
| 32 | // Future linearized read requests using 'lkv' will be served locally for the lease's lifetime: |
| 33 | // |
| 34 | // resp, err = lkv.Get(context.TODO(), "abc") |
| 35 | // |
| 36 | // If another leasing client writes to a leased key, then the owner relinquishes its exclusive |
| 37 | // access, permitting the writer to modify the key: |
| 38 | // |
| 39 | // lkv2, err := leasing.NewKV(cli, "leasing-prefix") |
| 40 | // if err != nil { |
| 41 | // // handle error |
| 42 | // } |
| 43 | // lkv2.Put(context.TODO(), "abc", "456") |
| 44 | // resp, err = lkv.Get("abc") |
| 45 | // |
| 46 | package leasing |