Matthias Andreas Benkard | 832a54e | 2019-01-29 09:27:38 +0100 | [diff] [blame] | 1 | /* |
| 2 | Copyright 2015 The Kubernetes Authors. |
| 3 | |
| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | you may not use this file except in compliance with the License. |
| 6 | You may obtain a copy of the License at |
| 7 | |
| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | Unless required by applicable law or agreed to in writing, software |
| 11 | distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | See the License for the specific language governing permissions and |
| 14 | limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package cache |
| 18 | |
| 19 | // UndeltaStore listens to incremental updates and sends complete state on every change. |
| 20 | // It implements the Store interface so that it can receive a stream of mirrored objects |
| 21 | // from Reflector. Whenever it receives any complete (Store.Replace) or incremental change |
| 22 | // (Store.Add, Store.Update, Store.Delete), it sends the complete state by calling PushFunc. |
| 23 | // It is thread-safe. It guarantees that every change (Add, Update, Replace, Delete) results |
| 24 | // in one call to PushFunc, but sometimes PushFunc may be called twice with the same values. |
| 25 | // PushFunc should be thread safe. |
| 26 | type UndeltaStore struct { |
| 27 | Store |
| 28 | PushFunc func([]interface{}) |
| 29 | } |
| 30 | |
| 31 | // Assert that it implements the Store interface. |
| 32 | var _ Store = &UndeltaStore{} |
| 33 | |
| 34 | // Note about thread safety. The Store implementation (cache.cache) uses a lock for all methods. |
| 35 | // In the functions below, the lock gets released and reacquired betweend the {Add,Delete,etc} |
| 36 | // and the List. So, the following can happen, resulting in two identical calls to PushFunc. |
| 37 | // time thread 1 thread 2 |
| 38 | // 0 UndeltaStore.Add(a) |
| 39 | // 1 UndeltaStore.Add(b) |
| 40 | // 2 Store.Add(a) |
| 41 | // 3 Store.Add(b) |
| 42 | // 4 Store.List() -> [a,b] |
| 43 | // 5 Store.List() -> [a,b] |
| 44 | |
| 45 | func (u *UndeltaStore) Add(obj interface{}) error { |
| 46 | if err := u.Store.Add(obj); err != nil { |
| 47 | return err |
| 48 | } |
| 49 | u.PushFunc(u.Store.List()) |
| 50 | return nil |
| 51 | } |
| 52 | |
| 53 | func (u *UndeltaStore) Update(obj interface{}) error { |
| 54 | if err := u.Store.Update(obj); err != nil { |
| 55 | return err |
| 56 | } |
| 57 | u.PushFunc(u.Store.List()) |
| 58 | return nil |
| 59 | } |
| 60 | |
| 61 | func (u *UndeltaStore) Delete(obj interface{}) error { |
| 62 | if err := u.Store.Delete(obj); err != nil { |
| 63 | return err |
| 64 | } |
| 65 | u.PushFunc(u.Store.List()) |
| 66 | return nil |
| 67 | } |
| 68 | |
| 69 | func (u *UndeltaStore) Replace(list []interface{}, resourceVersion string) error { |
| 70 | if err := u.Store.Replace(list, resourceVersion); err != nil { |
| 71 | return err |
| 72 | } |
| 73 | u.PushFunc(u.Store.List()) |
| 74 | return nil |
| 75 | } |
| 76 | |
| 77 | // NewUndeltaStore returns an UndeltaStore implemented with a Store. |
| 78 | func NewUndeltaStore(pushFunc func([]interface{}), keyFunc KeyFunc) *UndeltaStore { |
| 79 | return &UndeltaStore{ |
| 80 | Store: NewStore(keyFunc), |
| 81 | PushFunc: pushFunc, |
| 82 | } |
| 83 | } |