1 // Copyright (C) The Arvados Authors. All rights reserved.
3 // SPDX-License-Identifier: Apache-2.0
13 // lookupnode is a caching tree node that is initially empty and calls
14 // loadOne and loadAll to load/update child nodes as needed.
16 // See (*customFileSystem)MountUsers for example usage.
17 type lookupnode struct {
19 loadOne func(parent inode, name string) (inode, error)
20 loadAll func(parent inode) ([]inode, error)
21 stale func(time.Time) bool
26 staleOne map[string]time.Time
29 // Sync flushes pending writes for loaded children and, if successful,
30 // triggers a reload on next lookup.
31 func (ln *lookupnode) Sync() error {
32 err := ln.treenode.Sync()
37 ln.staleAll = time.Time{}
43 func (ln *lookupnode) Readdir() ([]os.FileInfo, error) {
45 defer ln.staleLock.Unlock()
46 checkTime := time.Now()
47 if ln.stale(ln.staleAll) {
48 all, err := ln.loadAll(ln)
52 for _, child := range all {
53 _, err = ln.treenode.Child(child.FileInfo().Name(), func(inode) (inode, error) {
60 ln.staleAll = checkTime
61 // No value in ln.staleOne can make a difference to an
62 // "entry is stale?" test now, because no value is
63 // newer than ln.staleAll. Reclaim memory.
66 return ln.treenode.Readdir()
69 func (ln *lookupnode) Child(name string, replace func(inode) (inode, error)) (inode, error) {
71 defer ln.staleLock.Unlock()
72 checkTime := time.Now()
73 if ln.stale(ln.staleAll) && ln.stale(ln.staleOne[name]) {
74 _, err := ln.treenode.Child(name, func(inode) (inode, error) {
75 return ln.loadOne(ln, name)
80 if ln.staleOne == nil {
81 ln.staleOne = map[string]time.Time{name: checkTime}
83 ln.staleOne[name] = checkTime
86 return ln.treenode.Child(name, replace)