Add a consolidated file cache

This commits reworks how file caching is performed in Hugo. Now there is only one way, and it can be configured.

This is the default configuration:

```toml
[caches]
[caches.getjson]
dir = ":cacheDir"
maxAge = -1
[caches.getcsv]
dir = ":cacheDir"
maxAge = -1
[caches.images]
dir = ":resourceDir/_gen"
maxAge = -1
[caches.assets]
dir = ":resourceDir/_gen"
maxAge = -1
```

You can override any of these cache setting in your own `config.toml`.

The placeholders explained:

`:cacheDir`: This is the value of the `cacheDir` config option if set (can also be set via OS env variable `HUGO_CACHEDIR`). It will fall back to `/opt/build/cache/hugo_cache/` on Netlify, or a `hugo_cache` directory below the OS temp dir for the others.
`:resourceDir`: This is the value of the `resourceDir` config option.

`maxAge` is the time in seconds before a cache entry will be evicted, -1 means forever and 0 effectively turns that particular cache off.

This means that if you run your builds on Netlify, all caches configured with `:cacheDir` will be saved and restored on the next build. For other CI vendors, please read their documentation. For an CircleCI example, see https://github.com/bep/hugo-sass-test/blob/6c3960a8f4b90e8938228688bc49bdcdd6b2d99e/.circleci/config.yml

Fixes #5404

1 files changed, 0 insertions, 85 deletions

diff --git a/tpl/data/cache.go b/tpl/data/cache.go
deleted file mode 100644
index 6c4033160..000000000
--- a/tpl/data/cache.go
+++ /dev/null
@@ -1,85 +0,0 @@
-// Copyright 2017 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 data
-
-import (
-	"crypto/md5"
-	"encoding/hex"
-	"errors"
-	"sync"
-
-	"github.com/gohugoio/hugo/config"
-	"github.com/gohugoio/hugo/helpers"
-	"github.com/spf13/afero"
-)
-
-var cacheMu sync.RWMutex
-
-// getCacheFileID returns the cache ID for a string.
-func getCacheFileID(cfg config.Provider, id string) string {
-	hash := md5.Sum([]byte(id))
-	return cfg.GetString("cacheDir") + hex.EncodeToString(hash[:])
-}
-
-// getCache returns the content for an ID from the file cache or an error.
-// If the ID is not found, return nil,nil.
-func getCache(id string, fs afero.Fs, cfg config.Provider, ignoreCache bool) ([]byte, error) {
-	if ignoreCache {
-		return nil, nil
-	}
-
-	cacheMu.RLock()
-	defer cacheMu.RUnlock()
-
-	fID := getCacheFileID(cfg, id)
-	isExists, err := helpers.Exists(fID, fs)
-	if err != nil {
-		return nil, err
-	}
-	if !isExists {
-		return nil, nil
-	}
-
-	return afero.ReadFile(fs, fID)
-}
-
-// writeCache writes bytes associated with an ID into the file cache.
-func writeCache(id string, c []byte, fs afero.Fs, cfg config.Provider, ignoreCache bool) error {
-	if ignoreCache {
-		return nil
-	}
-
-	cacheMu.Lock()
-	defer cacheMu.Unlock()
-
-	fID := getCacheFileID(cfg, id)
-	f, err := fs.Create(fID)
-	if err != nil {
-		return errors.New("Error: " + err.Error() + ". Failed to create file: " + fID)
-	}
-	defer f.Close()
-
-	n, err := f.Write(c)
-	if err != nil {
-		return errors.New("Error: " + err.Error() + ". Failed to write to file: " + fID)
-	}
-	if n == 0 {
-		return errors.New("No bytes written to file: " + fID)
-	}
-	return nil
-}
-
-func deleteCache(id string, fs afero.Fs, cfg config.Provider) error {
-	return fs.Remove(getCacheFileID(cfg, id))
-}