90 lines
3.3 KiB
Go
90 lines
3.3 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package cache
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// UndeltaStore listens to incremental updates and sends complete state on every change.
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// It implements the Store interface so that it can receive a stream of mirrored objects
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// from Reflector. Whenever it receives any complete (Store.Replace) or incremental change
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// (Store.Add, Store.Update, Store.Delete), it sends the complete state by calling PushFunc.
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// It is thread-safe. It guarantees that every change (Add, Update, Replace, Delete) results
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// in one call to PushFunc, but sometimes PushFunc may be called twice with the same values.
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// PushFunc should be thread safe.
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type UndeltaStore struct {
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Store
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PushFunc func([]interface{})
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}
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// Assert that it implements the Store interface.
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var _ Store = &UndeltaStore{}
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// Add inserts an object into the store and sends complete state by calling PushFunc.
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// Note about thread safety. The Store implementation (cache.cache) uses a lock for all methods.
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// In the functions below, the lock gets released and reacquired betweend the {Add,Delete,etc}
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// and the List. So, the following can happen, resulting in two identical calls to PushFunc.
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// time thread 1 thread 2
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// 0 UndeltaStore.Add(a)
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// 1 UndeltaStore.Add(b)
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// 2 Store.Add(a)
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// 3 Store.Add(b)
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// 4 Store.List() -> [a,b]
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// 5 Store.List() -> [a,b]
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func (u *UndeltaStore) Add(obj interface{}) error {
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if err := u.Store.Add(obj); err != nil {
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return err
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}
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u.PushFunc(u.Store.List())
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return nil
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}
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// Update sets an item in the cache to its updated state and sends complete state by calling PushFunc.
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func (u *UndeltaStore) Update(obj interface{}) error {
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if err := u.Store.Update(obj); err != nil {
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return err
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}
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u.PushFunc(u.Store.List())
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return nil
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}
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// Delete removes an item from the cache and sends complete state by calling PushFunc.
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func (u *UndeltaStore) Delete(obj interface{}) error {
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if err := u.Store.Delete(obj); err != nil {
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return err
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}
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u.PushFunc(u.Store.List())
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return nil
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}
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// Replace will delete the contents of current store, using instead the given list.
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// 'u' takes ownership of the list, you should not reference the list again
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// after calling this function.
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// The new contents complete state will be sent by calling PushFunc after replacement.
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func (u *UndeltaStore) Replace(list []interface{}, resourceVersion string) error {
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if err := u.Store.Replace(list, resourceVersion); err != nil {
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return err
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}
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u.PushFunc(u.Store.List())
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return nil
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}
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// NewUndeltaStore returns an UndeltaStore implemented with a Store.
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func NewUndeltaStore(pushFunc func([]interface{}), keyFunc KeyFunc) *UndeltaStore {
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return &UndeltaStore{
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Store: NewStore(keyFunc),
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PushFunc: pushFunc,
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}
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}
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