/usr/share/gocode/src/github.com/hanwen/go-fuse/unionfs/dircache.go is in golang-github-hanwen-go-fuse-dev 0.0~git20171124.0.14c3015-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 | // Copyright 2016 the Go-FUSE Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package unionfs
import (
"sync"
"time"
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/pathfs"
)
// newDirnameMap reads the contents of the given directory. On error,
// returns a nil map. This forces reloads in the dirCache until we
// succeed.
func newDirnameMap(fs pathfs.FileSystem, dir string) map[string]bool {
stream, code := fs.OpenDir(dir, nil)
if code == fuse.ENOENT {
// The directory not existing is not an error.
return map[string]bool{}
}
if !code.Ok() {
return nil
}
result := make(map[string]bool)
for _, e := range stream {
if e.Mode&fuse.S_IFREG != 0 {
result[e.Name] = true
}
}
return result
}
// dirCache caches names in a directory for some time.
//
// If called when the cache is expired, the filenames are read afresh in
// the background.
type dirCache struct {
dir string
ttl time.Duration
fs pathfs.FileSystem
// Protects data below.
lock sync.RWMutex
// If nil, you may call refresh() to schedule a new one.
names map[string]bool
updateRunning bool
}
func (c *dirCache) setMap(newMap map[string]bool) {
c.lock.Lock()
defer c.lock.Unlock()
c.names = newMap
c.updateRunning = false
_ = time.AfterFunc(c.ttl,
func() { c.DropCache() })
}
func (c *dirCache) DropCache() {
c.lock.Lock()
defer c.lock.Unlock()
c.names = nil
}
// Try to refresh: if another update is already running, do nothing,
// otherwise, read the directory and set it.
func (c *dirCache) maybeRefresh() {
c.lock.Lock()
defer c.lock.Unlock()
if c.updateRunning {
return
}
c.updateRunning = true
go func() {
newmap := newDirnameMap(c.fs, c.dir)
c.setMap(newmap)
}()
}
func (c *dirCache) RemoveEntry(name string) {
c.lock.Lock()
defer c.lock.Unlock()
if c.names == nil {
go c.maybeRefresh()
return
}
delete(c.names, name)
}
func (c *dirCache) AddEntry(name string) {
c.lock.Lock()
defer c.lock.Unlock()
if c.names == nil {
go c.maybeRefresh()
return
}
c.names[name] = true
}
func newDirCache(fs pathfs.FileSystem, dir string, ttl time.Duration) *dirCache {
dc := new(dirCache)
dc.dir = dir
dc.fs = fs
dc.ttl = ttl
return dc
}
func (c *dirCache) HasEntry(name string) (mapPresent bool, found bool) {
c.lock.RLock()
defer c.lock.RUnlock()
if c.names == nil {
go c.maybeRefresh()
return false, false
}
return true, c.names[name]
}
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