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Several packages are only used while running the e2e suite. These packages are less important to update, as the they can not influence the final executable that is part of the Ceph-CSI container-image. By moving these dependencies out of the main Ceph-CSI go.mod, it is easier to identify if a reported CVE affects Ceph-CSI, or only the testing (like most of the Kubernetes CVEs). Signed-off-by: Niels de Vos <ndevos@ibm.com>
84 lines
2.2 KiB
Go
84 lines
2.2 KiB
Go
/*
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Copyright 2023 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 synctrack
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import (
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"sync"
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"sync/atomic"
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)
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// Lazy defers the computation of `Evaluate` to when it is necessary. It is
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// possible that Evaluate will be called in parallel from multiple goroutines.
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type Lazy[T any] struct {
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Evaluate func() (T, error)
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cache atomic.Pointer[cacheEntry[T]]
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}
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type cacheEntry[T any] struct {
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eval func() (T, error)
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lock sync.RWMutex
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result *T
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}
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func (e *cacheEntry[T]) get() (T, error) {
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if cur := func() *T {
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e.lock.RLock()
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defer e.lock.RUnlock()
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return e.result
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}(); cur != nil {
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return *cur, nil
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}
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e.lock.Lock()
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defer e.lock.Unlock()
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if e.result != nil {
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return *e.result, nil
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}
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r, err := e.eval()
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if err == nil {
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e.result = &r
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}
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return r, err
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}
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func (z *Lazy[T]) newCacheEntry() *cacheEntry[T] {
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return &cacheEntry[T]{eval: z.Evaluate}
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}
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// Notify should be called when something has changed necessitating a new call
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// to Evaluate.
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func (z *Lazy[T]) Notify() { z.cache.Swap(z.newCacheEntry()) }
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// Get should be called to get the current result of a call to Evaluate. If the
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// current cached value is stale (due to a call to Notify), then Evaluate will
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// be called synchronously. If subsequent calls to Get happen (without another
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// Notify), they will all wait for the same return value.
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//
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// Error returns are not cached and will cause multiple calls to evaluate!
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func (z *Lazy[T]) Get() (T, error) {
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e := z.cache.Load()
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if e == nil {
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// Since we don't force a constructor, nil is a possible value.
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// If multiple Gets race to set this, the swap makes sure only
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// one wins.
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z.cache.CompareAndSwap(nil, z.newCacheEntry())
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e = z.cache.Load()
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}
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return e.get()
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}
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