// Package cache implements the Fs cachepackage cache import (	"context"	"runtime"	"sync" 	"github.com/rclone/rclone/fs"	"github.com/rclone/rclone/fs/filter"	"github.com/rclone/rclone/lib/cache") var (	once  sync.Once // creation	c     *cache.Cache	mu    sync.Mutex            // mutex to protect remap	remap = map[string]string{} // map user supplied names to canonical names) // Create the cache just oncefunc createOnFirstUse() {	once.Do(func() {		ci := fs.GetConfig(context.Background())		c = cache.New()		c.SetExpireDuration(ci.FsCacheExpireDuration)		c.SetExpireInterval(ci.FsCacheExpireInterval)	})} // Canonicalize looks up fsString in the mapping from user supplied// names to canonical names and return the canonical formfunc Canonicalize(fsString string) string {	createOnFirstUse()	mu.Lock()	canonicalName, ok := remap[fsString]	mu.Unlock()	if !ok {		return fsString	}	fs.Debugf(nil, "fs cache: switching user supplied name %q for canonical name %q", fsString, canonicalName)	return canonicalName} // Put in a mapping from fsString => canonicalName if they are differentfunc addMapping(fsString, canonicalName string) {	if canonicalName == fsString {		return	}	mu.Lock()	remap[fsString] = canonicalName	mu.Unlock()} // GetFn gets an fs.Fs named fsString either from the cache or creates// it afresh with the create functionfunc GetFn(ctx context.Context, fsString string, create func(ctx context.Context, fsString string) (fs.Fs, error)) (f fs.Fs, err error) {	createOnFirstUse()	canonicalFsString := Canonicalize(fsString)	created := false	value, err := c.Get(canonicalFsString, func(canonicalFsString string) (f interface{}, ok bool, err error) {		f, err = create(ctx, fsString) // always create the backend with the original non-canonicalised string		ok = err == nil || err == fs.ErrorIsFile		created = ok		return f, ok, err	})	if err != nil && err != fs.ErrorIsFile {		return nil, err	}	f = value.(fs.Fs)	// Check we stored the Fs at the canonical name	if created {		canonicalName := fs.ConfigString(f)		if canonicalName != canonicalFsString {			// Note that if err == fs.ErrorIsFile at this moment			// then we can't rename the remote as it will have the			// wrong error status, we need to add a new one.			if err == nil {				fs.Debugf(nil, "fs cache: renaming cache item %q to be canonical %q", canonicalFsString, canonicalName)				value, found := c.Rename(canonicalFsString, canonicalName)				if found {					f = value.(fs.Fs)				}				addMapping(canonicalFsString, canonicalName)			} else {				fs.Debugf(nil, "fs cache: adding new entry for parent of %q, %q", canonicalFsString, canonicalName)				Put(canonicalName, f)			}		}	}	return f, err} // Pin f into the cache until Unpin is calledfunc Pin(f fs.Fs) {	createOnFirstUse()	c.Pin(fs.ConfigString(f))} // PinUntilFinalized pins f into the cache until x is garbage collected//// This calls runtime.SetFinalizer on x so it shouldn't have a// finalizer already.func PinUntilFinalized(f fs.Fs, x interface{}) {	Pin(f)	runtime.SetFinalizer(x, func(_ interface{}) {		Unpin(f)	}) } // Unpin f from the cachefunc Unpin(f fs.Fs) {	createOnFirstUse()	c.Pin(fs.ConfigString(f))} // Get gets an fs.Fs named fsString either from the cache or creates it afreshfunc Get(ctx context.Context, fsString string) (f fs.Fs, err error) {	// If we are making a long lived backend which lives longer	// than this request, we want to disconnect it from the	// current context and in particular any WithCancel contexts,	// but we want to preserve the config embedded in the context.	newCtx := context.Background()	newCtx = fs.CopyConfig(newCtx, ctx)	newCtx = filter.CopyConfig(newCtx, ctx)	return GetFn(newCtx, fsString, fs.NewFs)} // GetArr gets []fs.Fs from []fsStrings either from the cache or creates it afreshfunc GetArr(ctx context.Context, fsStrings []string) (f []fs.Fs, err error) {	var fArr []fs.Fs	for _, fsString := range fsStrings {		f1, err1 := GetFn(ctx, fsString, fs.NewFs)		if err1 != nil {			return fArr, err1		}		fArr = append(fArr, f1)	}	return fArr, nil} // Put puts an fs.Fs named fsString into the cachefunc Put(fsString string, f fs.Fs) {	createOnFirstUse()	canonicalName := fs.ConfigString(f)	c.Put(canonicalName, f)	addMapping(fsString, canonicalName)} // ClearConfig deletes all entries which were based on the config name passed in//// Returns number of entries deletedfunc ClearConfig(name string) (deleted int) {	createOnFirstUse()	return c.DeletePrefix(name + ":")} // Clear removes everything from the cachefunc Clear() {	createOnFirstUse()	c.Clear()} // Entries returns the number of entries in the cachefunc Entries() int {	createOnFirstUse()	return c.Entries()}