mirror of https://github.com/k3s-io/k3s
110 lines
2.8 KiB
Go
110 lines
2.8 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors All rights reserved.
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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 watch
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import (
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"sync"
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)
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// FilterFunc should take an event, possibly modify it in some way, and return
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// the modified event. If the event should be ignored, then return keep=false.
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type FilterFunc func(in Event) (out Event, keep bool)
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// Filter passes all events through f before allowing them to pass on.
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// Putting a filter on a watch, as an unavoidable side-effect due to the way
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// go channels work, effectively causes the watch's event channel to have its
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// queue length increased by one.
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//
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// WARNING: filter has a fatal flaw, in that it can't properly update the
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// Type field (Add/Modified/Deleted) to reflect items beginning to pass the
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// filter when they previously didn't.
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//
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func Filter(w Interface, f FilterFunc) Interface {
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fw := &filteredWatch{
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incoming: w,
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result: make(chan Event),
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f: f,
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}
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go fw.loop()
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return fw
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}
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type filteredWatch struct {
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incoming Interface
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result chan Event
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f FilterFunc
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}
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// ResultChan returns a channel which will receive filtered events.
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func (fw *filteredWatch) ResultChan() <-chan Event {
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return fw.result
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}
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// Stop stops the upstream watch, which will eventually stop this watch.
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func (fw *filteredWatch) Stop() {
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fw.incoming.Stop()
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}
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// loop waits for new values, filters them, and resends them.
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func (fw *filteredWatch) loop() {
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defer close(fw.result)
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for {
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event, ok := <-fw.incoming.ResultChan()
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if !ok {
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break
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}
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filtered, keep := fw.f(event)
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if keep {
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fw.result <- filtered
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}
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}
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}
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// Recorder records all events that are sent from the watch until it is closed.
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type Recorder struct {
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Interface
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lock sync.Mutex
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events []Event
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}
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var _ Interface = &Recorder{}
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// NewRecorder wraps an Interface and records any changes sent across it.
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func NewRecorder(w Interface) *Recorder {
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r := &Recorder{}
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r.Interface = Filter(w, r.record)
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return r
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}
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// record is a FilterFunc and tracks each received event.
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func (r *Recorder) record(in Event) (Event, bool) {
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r.lock.Lock()
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defer r.lock.Unlock()
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r.events = append(r.events, in)
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return in, true
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}
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// Events returns a copy of the events sent across this recorder.
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func (r *Recorder) Events() []Event {
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r.lock.Lock()
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defer r.lock.Unlock()
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copied := make([]Event, len(r.events))
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copy(copied, r.events)
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return copied
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}
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