ref: 88c8a15be18a0bd1bd9b9cb175f7a68f2b9cd355
dir: /resources/resource_cache.go/
// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package resources
import (
"encoding/json"
"io"
"path"
"path/filepath"
"strings"
"sync"
"github.com/gohugoio/hugo/resources/resource"
"github.com/gohugoio/hugo/cache/filecache"
"github.com/BurntSushi/locker"
)
const (
CACHE_CLEAR_ALL = "clear_all"
CACHE_OTHER = "other"
)
type ResourceCache struct {
rs *Spec
sync.RWMutex
cache map[string]resource.Resource
fileCache *filecache.Cache
// Provides named resource locks.
nlocker *locker.Locker
}
// ResourceKeyPartition returns a partition name
// to allow for more fine grained cache flushes.
// It will return the file extension without the leading ".". If no
// extension, it will return "other".
func ResourceKeyPartition(filename string) string {
ext := strings.TrimPrefix(path.Ext(filepath.ToSlash(filename)), ".")
if ext == "" {
ext = CACHE_OTHER
}
return ext
}
func newResourceCache(rs *Spec) *ResourceCache {
return &ResourceCache{
rs: rs,
fileCache: rs.FileCaches.AssetsCache(),
cache: make(map[string]resource.Resource),
nlocker: locker.NewLocker(),
}
}
func (c *ResourceCache) clear() {
c.Lock()
defer c.Unlock()
c.cache = make(map[string]resource.Resource)
c.nlocker = locker.NewLocker()
}
func (c *ResourceCache) Contains(key string) bool {
key = c.cleanKey(filepath.ToSlash(key))
_, found := c.get(key)
return found
}
func (c *ResourceCache) cleanKey(key string) string {
return strings.TrimPrefix(path.Clean(key), "/")
}
func (c *ResourceCache) get(key string) (resource.Resource, bool) {
c.RLock()
defer c.RUnlock()
r, found := c.cache[key]
return r, found
}
func (c *ResourceCache) GetOrCreate(partition, key string, f func() (resource.Resource, error)) (resource.Resource, error) {
key = c.cleanKey(path.Join(partition, key))
// First check in-memory cache.
r, found := c.get(key)
if found {
return r, nil
}
// This is a potentially long running operation, so get a named lock.
c.nlocker.Lock(key)
// Double check in-memory cache.
r, found = c.get(key)
if found {
c.nlocker.Unlock(key)
return r, nil
}
defer c.nlocker.Unlock(key)
r, err := f()
if err != nil {
return nil, err
}
c.set(key, r)
return r, nil
}
func (c *ResourceCache) getFilenames(key string) (string, string) {
filenameMeta := key + ".json"
filenameContent := key + ".content"
return filenameMeta, filenameContent
}
func (c *ResourceCache) getFromFile(key string) (filecache.ItemInfo, io.ReadCloser, transformedResourceMetadata, bool) {
c.RLock()
defer c.RUnlock()
var meta transformedResourceMetadata
filenameMeta, filenameContent := c.getFilenames(key)
_, jsonContent, _ := c.fileCache.GetBytes(filenameMeta)
if jsonContent == nil {
return filecache.ItemInfo{}, nil, meta, false
}
if err := json.Unmarshal(jsonContent, &meta); err != nil {
return filecache.ItemInfo{}, nil, meta, false
}
fi, rc, _ := c.fileCache.Get(filenameContent)
return fi, rc, meta, rc != nil
}
// writeMeta writes the metadata to file and returns a writer for the content part.
func (c *ResourceCache) writeMeta(key string, meta transformedResourceMetadata) (filecache.ItemInfo, io.WriteCloser, error) {
filenameMeta, filenameContent := c.getFilenames(key)
raw, err := json.Marshal(meta)
if err != nil {
return filecache.ItemInfo{}, nil, err
}
_, fm, err := c.fileCache.WriteCloser(filenameMeta)
if err != nil {
return filecache.ItemInfo{}, nil, err
}
defer fm.Close()
if _, err := fm.Write(raw); err != nil {
return filecache.ItemInfo{}, nil, err
}
fi, fc, err := c.fileCache.WriteCloser(filenameContent)
return fi, fc, err
}
func (c *ResourceCache) set(key string, r resource.Resource) {
c.Lock()
defer c.Unlock()
c.cache[key] = r
}
func (c *ResourceCache) DeletePartitions(partitions ...string) {
partitionsSet := map[string]bool{
// Always clear out the resources not matching the partition.
"other": true,
}
for _, p := range partitions {
partitionsSet[p] = true
}
if partitionsSet[CACHE_CLEAR_ALL] {
c.clear()
return
}
c.Lock()
defer c.Unlock()
for k := range c.cache {
clear := false
partIdx := strings.Index(k, "/")
if partIdx == -1 {
clear = true
} else {
partition := k[:partIdx]
if partitionsSet[partition] {
clear = true
}
}
if clear {
delete(c.cache, k)
}
}
}