ref: c6b661de826f3ed8768a97a5178b4e020cb2ace1
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/helpers"
"github.com/gohugoio/hugo/hugofs/glob"
"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
// Either resource.Resource or resource.Resources.
cache map[string]interface{}
fileCache *filecache.Cache
// Provides named resource locks.
nlocker *locker.Locker
}
// ResourceCacheKey converts the filename into the format used in the resource
// cache.
func ResourceCacheKey(filename string) string {
filename = filepath.ToSlash(filename)
return path.Join(resourceKeyPartition(filename), filename)
}
func resourceKeyPartition(filename string) string {
ext := strings.TrimPrefix(path.Ext(filepath.ToSlash(filename)), ".")
if ext == "" {
ext = CACHE_OTHER
}
return ext
}
// Commonly used aliases and directory names used for some types.
var extAliasKeywords = map[string][]string{
"sass": []string{"scss"},
"scss": []string{"sass"},
}
// ResourceKeyPartitions resolves a ordered slice of partitions that is
// used to do resource cache invalidations.
//
// We use the first directory path element and the extension, so:
// a/b.json => "a", "json"
// b.json => "json"
//
// For some of the extensions we will also map to closely related types,
// e.g. "scss" will also return "sass".
//
func ResourceKeyPartitions(filename string) []string {
var partitions []string
filename = glob.NormalizePath(filename)
dir, name := path.Split(filename)
ext := strings.TrimPrefix(path.Ext(filepath.ToSlash(name)), ".")
if dir != "" {
partitions = append(partitions, strings.Split(dir, "/")[0])
}
if ext != "" {
partitions = append(partitions, ext)
}
if aliases, found := extAliasKeywords[ext]; found {
partitions = append(partitions, aliases...)
}
if len(partitions) == 0 {
partitions = []string{CACHE_OTHER}
}
return helpers.UniqueStringsSorted(partitions)
}
// ResourceKeyContainsAny returns whether the key is a member of any of the
// given partitions.
//
// This is used for resource cache invalidation.
func ResourceKeyContainsAny(key string, partitions []string) bool {
parts := strings.Split(key, "/")
for _, p1 := range partitions {
for _, p2 := range parts {
if p1 == p2 {
return true
}
}
}
return false
}
func newResourceCache(rs *Spec) *ResourceCache {
return &ResourceCache{
rs: rs,
fileCache: rs.FileCaches.AssetsCache(),
cache: make(map[string]interface{}),
nlocker: locker.NewLocker(),
}
}
func (c *ResourceCache) clear() {
c.Lock()
defer c.Unlock()
c.cache = make(map[string]interface{})
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(strings.ToLower(key)), "/")
}
func (c *ResourceCache) get(key string) (interface{}, bool) {
c.RLock()
defer c.RUnlock()
r, found := c.cache[key]
return r, found
}
func (c *ResourceCache) GetOrCreate(key string, f func() (resource.Resource, error)) (resource.Resource, error) {
r, err := c.getOrCreate(key, func() (interface{}, error) { return f() })
if r == nil || err != nil {
return nil, err
}
return r.(resource.Resource), nil
}
func (c *ResourceCache) GetOrCreateResources(key string, f func() (resource.Resources, error)) (resource.Resources, error) {
r, err := c.getOrCreate(key, func() (interface{}, error) { return f() })
if r == nil || err != nil {
return nil, err
}
return r.(resource.Resources), nil
}
func (c *ResourceCache) getOrCreate(key string, f func() (interface{}, error)) (interface{}, error) {
key = c.cleanKey(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 interface{}) {
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 any 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
for p := range partitionsSet {
if strings.Contains(k, p) {
// There will be some false positive, but that's fine.
clear = true
break
}
}
if clear {
delete(c.cache, k)
}
}
}