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tailscale/tailfs/tailfsimpl/webdavfs/stat_cache.go

72 lines
1.5 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package webdavfs
import (
"io/fs"
"path/filepath"
"sync"
"time"
"github.com/jellydator/ttlcache/v3"
)
// statCache provides a cache for file directory and file metadata. Especially
// when used from the command-line, mapped WebDAV drives can generate
// repetitive requests for the same file metadata. This cache helps reduce the
// number of round-trips to the WebDAV server for such requests.
type statCache struct {
// mu guards the below values.
mu sync.Mutex
cache *ttlcache.Cache[string, fs.FileInfo]
}
func newStatCache(ttl time.Duration) *statCache {
cache := ttlcache.New(
ttlcache.WithTTL[string, fs.FileInfo](ttl),
)
go cache.Start()
return &statCache{cache: cache}
}
func (c *statCache) getOrFetch(name string, fetch func(string) (fs.FileInfo, error)) (fs.FileInfo, error) {
c.mu.Lock()
item := c.cache.Get(name)
c.mu.Unlock()
if item != nil {
return item.Value(), nil
}
fi, err := fetch(name)
if err == nil {
c.mu.Lock()
c.cache.Set(name, fi, ttlcache.DefaultTTL)
c.mu.Unlock()
}
return fi, err
}
func (c *statCache) set(parentPath string, infos []fs.FileInfo) {
c.mu.Lock()
defer c.mu.Unlock()
for _, info := range infos {
path := filepath.Join(parentPath, filepath.Base(info.Name()))
c.cache.Set(path, info, ttlcache.DefaultTTL)
}
}
func (c *statCache) invalidate() {
c.mu.Lock()
defer c.mu.Unlock()
c.cache.DeleteAll()
}
func (c *statCache) stop() {
c.cache.Stop()
}