mirror of https://github.com/kubernetes/kops.git
79 lines
1.5 KiB
Go
79 lines
1.5 KiB
Go
/*
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Copyright 2019 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 vfs
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import (
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"sync"
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"time"
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)
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// NewCache is a constructor for a Cache
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func NewCache() *Cache {
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return &Cache{
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cache: make(map[string]cacheEntry),
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}
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}
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// Cache is a simple cache for vfs files.
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//
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// Currently we never expire the cache, so this is only safe for a
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// relatively bounded set of files - but it would not be too hard to
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// fix this.
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type Cache struct {
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mutex sync.Mutex
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cache map[string]cacheEntry
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}
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type cacheEntry struct {
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Added time.Time
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Contents []byte
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}
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func (c *Cache) Read(p Path, ttl time.Duration) ([]byte, error) {
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key := p.Path()
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c.mutex.Lock()
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entry, found := c.cache[key]
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c.mutex.Unlock()
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// Treat expired as not-found
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if found {
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expiresAt := entry.Added.Add(ttl)
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if time.Now().After(expiresAt) {
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found = false
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}
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}
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if found {
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return entry.Contents, nil
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}
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b, err := p.ReadFile()
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if err != nil {
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return nil, err
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}
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entry.Contents = b
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entry.Added = time.Now()
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c.mutex.Lock()
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c.cache[key] = entry
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c.mutex.Unlock()
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return b, nil
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}
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