95 lines
2.4 KiB
Go
95 lines
2.4 KiB
Go
// Package cache implements the Fs cache
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package cache
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import (
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"sync"
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"github.com/rclone/rclone/fs"
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"github.com/rclone/rclone/lib/cache"
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)
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var (
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c = cache.New()
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mu sync.Mutex // mutex to protect remap
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remap = map[string]string{} // map user supplied names to canonical names
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)
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// Lookup fsString in the mapping from user supplied names to
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// canonical names and return the canonical form
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func canonicalize(fsString string) string {
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mu.Lock()
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canonicalName, ok := remap[fsString]
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mu.Unlock()
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if !ok {
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return fsString
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}
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fs.Debugf(nil, "fs cache: switching user supplied name %q for canonical name %q", fsString, canonicalName)
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return canonicalName
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}
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// Put in a mapping from fsString => canonicalName if they are different
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func addMapping(fsString, canonicalName string) {
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if canonicalName == fsString {
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return
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}
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mu.Lock()
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remap[fsString] = canonicalName
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mu.Unlock()
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}
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// GetFn gets an fs.Fs named fsString either from the cache or creates
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// it afresh with the create function
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func GetFn(fsString string, create func(fsString string) (fs.Fs, error)) (f fs.Fs, err error) {
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fsString = canonicalize(fsString)
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created := false
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value, err := c.Get(fsString, func(fsString string) (f interface{}, ok bool, err error) {
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f, err = create(fsString)
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ok = err == nil || err == fs.ErrorIsFile
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created = ok
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return f, ok, err
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})
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if err != nil && err != fs.ErrorIsFile {
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return nil, err
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}
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f = value.(fs.Fs)
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// Check we stored the Fs at the canonical name
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if created {
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canonicalName := fs.ConfigString(f)
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if canonicalName != fsString {
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fs.Debugf(nil, "fs cache: renaming cache item %q to be canonical %q", fsString, canonicalName)
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value, found := c.Rename(fsString, canonicalName)
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if found {
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f = value.(fs.Fs)
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}
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addMapping(fsString, canonicalName)
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}
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}
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return f, err
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}
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// Pin f into the cache until Unpin is called
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func Pin(f fs.Fs) {
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c.Pin(fs.ConfigString(f))
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}
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// Unpin f from the cache
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func Unpin(f fs.Fs) {
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c.Pin(fs.ConfigString(f))
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}
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// Get gets an fs.Fs named fsString either from the cache or creates it afresh
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func Get(fsString string) (f fs.Fs, err error) {
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return GetFn(fsString, fs.NewFs)
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}
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// Put puts an fs.Fs named fsString into the cache
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func Put(fsString string, f fs.Fs) {
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canonicalName := fs.ConfigString(f)
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c.Put(canonicalName, f)
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addMapping(fsString, canonicalName)
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}
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// Clear removes everything from the cache
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func Clear() {
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c.Clear()
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}
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