102 lines
1.7 KiB
Go
102 lines
1.7 KiB
Go
// Copyright (C) 2022 Marius Schellenberger
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package fs
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import (
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"errors"
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"io"
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"os"
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"sync"
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"time"
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"github.com/go-logr/logr"
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)
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var NoCacheEntry = errors.New("no cache entry")
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type DirCacheEntry struct {
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mtime time.Time
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fi []os.FileInfo
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}
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type DirCache struct {
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mu sync.RWMutex
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m map[string]*DirCacheEntry
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}
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func NewDirCache() *DirCache {
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return &DirCache{m: make(map[string]*DirCacheEntry)}
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}
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func (dc *DirCache) Get(name string) (*DirCacheEntry, error) {
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dc.mu.RLock()
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defer dc.mu.RUnlock()
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if dce, ok := dc.m[name]; ok {
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return dce, nil
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}
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return nil, NoCacheEntry
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}
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func (dc *DirCache) Set(name string, dce *DirCacheEntry) {
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dc.mu.Lock()
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defer dc.mu.Unlock()
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dc.m[name] = dce
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}
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type Dir struct {
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log logr.Logger
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f *os.File
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dc *DirCache
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}
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func (f *Dir) Read(_ []byte) (int, error) {
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return 0, io.EOF
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}
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func (f *Dir) Seek(_ int64, _ int) (int64, error) {
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return 0, io.EOF
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}
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func readDir(f *os.File) (fi []os.FileInfo, err error) {
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ent, err := f.ReadDir(0)
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if err != nil {
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return
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}
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fi = make([]os.FileInfo, len(ent))
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for j, e := range ent {
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i, _ := e.Info()
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fi[j] = i
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}
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return
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}
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func (f *Dir) Readdir(_ int) (fi []os.FileInfo, err error) {
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i, err := f.Stat()
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if err != nil {
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return
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}
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name := f.f.Name()
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dce, err := f.dc.Get(name)
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log := f.log
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if err == NoCacheEntry || i.ModTime().After(dce.mtime) {
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log.V(3).Info("cache miss")
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fi, err = readDir(f.f)
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if err != nil {
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return
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}
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dce = &DirCacheEntry{i.ModTime(), fi}
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f.dc.Set(name, dce)
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} else {
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log.V(3).Info("cache hit")
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}
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fi = dce.fi
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return
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}
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func (f *Dir) Stat() (os.FileInfo, error) {
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return f.f.Stat()
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}
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func (f *Dir) Close() error {
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return f.f.Close()
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}
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