mirror of https://github.com/knative/pkg.git
102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
/*
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Copyright 2018 The Knative 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 duck
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import (
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"context"
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"sync"
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"k8s.io/apimachinery/pkg/runtime/schema"
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"k8s.io/client-go/tools/cache"
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)
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// CachedInformerFactory implements InformerFactory by delegating to another
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// InformerFactory, but memoizing the results.
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type CachedInformerFactory struct {
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Delegate InformerFactory
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m sync.Mutex
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cache map[schema.GroupVersionResource]*informerCache
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}
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// Check that CachedInformerFactory implements InformerFactory.
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var _ InformerFactory = (*CachedInformerFactory)(nil)
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// Get implements InformerFactory.
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func (cif *CachedInformerFactory) Get(ctx context.Context, gvr schema.GroupVersionResource) (cache.SharedIndexInformer, cache.GenericLister, error) {
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cif.m.Lock()
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if cif.cache == nil {
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cif.cache = make(map[schema.GroupVersionResource]*informerCache)
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}
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ic, ok := cif.cache[gvr]
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if !ok {
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ic = &informerCache{}
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ic.init = func() {
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ic.Lock()
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defer ic.Unlock()
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// double-checked lock to ensure we call the Delegate
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// only once even if multiple goroutines end up inside
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// init() simultaneously
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if ic.hasInformer() {
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return
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}
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ic.inf, ic.lister, ic.err = cif.Delegate.Get(ctx, gvr)
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}
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cif.cache[gvr] = ic
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}
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// If this were done via "defer", then TestDifferentGVRs will fail.
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cif.m.Unlock()
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// The call to the delegate could be slow because it syncs informers, so do
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// this outside of the main lock.
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return ic.Get()
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}
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type informerCache struct {
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sync.RWMutex
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init func()
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inf cache.SharedIndexInformer
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lister cache.GenericLister
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err error
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}
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// Get returns the cached informer. If it does not yet exist, we first try to
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// acquire one by executing the cache's init function.
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func (ic *informerCache) Get() (cache.SharedIndexInformer, cache.GenericLister, error) {
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if !ic.initialized() {
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ic.init()
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}
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return ic.inf, ic.lister, ic.err
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}
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func (ic *informerCache) initialized() bool {
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ic.RLock()
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defer ic.RUnlock()
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return ic.hasInformer()
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}
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func (ic *informerCache) hasInformer() bool {
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return ic.inf != nil && ic.lister != nil
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}
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