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Make synced callback and named wait group private 🕵️
These utility objects don't really make sense to expose as part of the informed watcher package and are only used by the informed watcher. Writing tests for unexported code makes me a bit :( but hopefully these will get moved to some other package one day. And there's really no reason to expose these to users of knative/pkg at the moment.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,112 @@ | ||
| /* | ||
| Copyright 2021 The Knative 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 informer | ||
|
|
||
| import ( | ||
| "sync" | ||
|
|
||
| "k8s.io/apimachinery/pkg/util/sets" | ||
| "k8s.io/apimachinery/pkg/util/wait" | ||
| ) | ||
|
|
||
| // namedWaitGroup is used to increment and decrement a WaitGroup by name | ||
| type namedWaitGroup struct { | ||
| waitGroup sync.WaitGroup | ||
| keys sets.String | ||
| mu sync.Mutex | ||
| } | ||
|
|
||
| // newNamedWaitGroup returns an instantiated namedWaitGroup. | ||
| func newNamedWaitGroup() *namedWaitGroup { | ||
| return &namedWaitGroup{ | ||
| keys: sets.NewString(), | ||
| } | ||
| } | ||
|
|
||
| // Add will add the key to the list of keys being tracked and increment the wait group. | ||
| // If the key has already been added, the wait group will not be incremented again. | ||
| func (n *namedWaitGroup) Add(key string) { | ||
| n.mu.Lock() | ||
| defer n.mu.Unlock() | ||
|
|
||
| if !n.keys.Has(key) { | ||
| n.keys.Insert(key) | ||
| n.waitGroup.Add(1) | ||
| } | ||
| } | ||
|
|
||
| // Done will decrement the counter if the key is present in the tracked keys. If it is not present | ||
| // it will be ignored. | ||
| func (n *namedWaitGroup) Done(key string) { | ||
| n.mu.Lock() | ||
| defer n.mu.Unlock() | ||
|
|
||
| if n.keys.Has(key) { | ||
| n.keys.Delete(key) | ||
| n.waitGroup.Done() | ||
| } | ||
| } | ||
|
|
||
| // Wait will wait for the underlying waitGroup to complete. | ||
| func (n *namedWaitGroup) Wait() { | ||
| n.waitGroup.Wait() | ||
| } | ||
|
|
||
| // syncedCallback can be used to wait for a callback to be called at least once for a list of keys. | ||
| type syncedCallback struct { | ||
| // namedWaitGroup will block until the callback has been called for all tracked entities | ||
| namedWaitGroup *namedWaitGroup | ||
|
|
||
| // callback is the callback that is intended to be called at least once for each key | ||
| // being tracked via WaitGroup | ||
| callback func(obj interface{}) | ||
| } | ||
|
|
||
| // newSyncedCallback will return a syncedCallback that will track the provided keys. | ||
| func newSyncedCallback(keys []string, callback func(obj interface{})) *syncedCallback { | ||
| s := &syncedCallback{ | ||
| callback: callback, | ||
| namedWaitGroup: newNamedWaitGroup(), | ||
| } | ||
| for _, key := range keys { | ||
| s.namedWaitGroup.Add(key) | ||
| } | ||
| return s | ||
| } | ||
|
|
||
| // Event is intended to be a wrapper for the actual event handler; this wrapper will signal via | ||
| // the wait group that the event handler has been called at least once for the key. | ||
| func (s *syncedCallback) Call(obj interface{}, key string) { | ||
| s.callback(obj) | ||
| s.namedWaitGroup.Done(key) | ||
| } | ||
|
|
||
| // WaitForAllKeys will block until s.Call has been called for all the keys we are tracking or the stop signal is | ||
| // received. | ||
| func (s *syncedCallback) WaitForAllKeys(stopCh <-chan struct{}) error { | ||
| c := make(chan struct{}) | ||
| go func() { | ||
| defer close(c) | ||
| s.namedWaitGroup.Wait() | ||
| }() | ||
| select { | ||
| case <-c: | ||
| return nil | ||
| case <-stopCh: | ||
| return wait.ErrWaitTimeout | ||
| } | ||
| } |
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