| // 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 ordering is a clientv3 wrapper that caches response header revisions |
| // to detect ordering violations from stale responses. Users may define a |
| // policy on how to handle the ordering violation, but typically the client |
| // should connect to another endpoint and reissue the request. |
| // |
| // The most common situation where an ordering violation happens is a client |
| // reconnects to a partitioned member and issues a serializable read. Since the |
| // partitioned member is likely behind the last member, it may return a Get |
| // response based on a store revision older than the store revision used to |
| // service a prior Get on the former endpoint. |
| // |
| // First, create a client: |
| // |
| // cli, err := clientv3.New(clientv3.Config{Endpoints: []string{"localhost:2379"}}) |
| // if err != nil { |
| // // handle error! |
| // } |
| // |
| // Next, override the client interface with the ordering wrapper: |
| // |
| // vf := func(op clientv3.Op, resp clientv3.OpResponse, prevRev int64) error { |
| // return fmt.Errorf("ordering: issued %+v, got %+v, expected rev=%v", op, resp, prevRev) |
| // } |
| // cli.KV = ordering.NewKV(cli.KV, vf) |
| // |
| // Now calls using 'cli' will reject order violations with an error. |
| // |
| package ordering |