From f7aeaa61291dd75f92901bcbeecc7fce07a28dec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Thu, 8 Nov 2018 10:24:13 +0100
Subject: [PATCH] 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
---
 cache/filecache/filecache.go       | 442 +++++++++++++++++++++++++++++
 cache/filecache/filecache_test.go  | 306 ++++++++++++++++++++
 commands/commandeer.go             |  17 +-
 common/hugio/writers.go            |  33 +++
 deps/deps.go                       |  16 +-
 go.mod                             |   2 +-
 go.sum                             |   2 +
 helpers/path.go                    |  55 ++++
 hugolib/filesystems/basefs.go      |   8 -
 hugolib/filesystems/basefs_test.go |   3 -
 hugolib/prune_resources.go         |  33 +--
 resource/bundler/bundler.go        |   2 +-
 resource/create/create.go          |   2 +-
 resource/image.go                  | 107 ++-----
 resource/image_cache.go            |  88 +++---
 resource/image_test.go             |  19 +-
 resource/resource.go               |  26 +-
 resource/resource_cache.go         |  61 ++--
 resource/testhelpers_test.go       |  17 +-
 resource/transform.go              |  19 +-
 tpl/data/cache.go                  |  85 ------
 tpl/data/cache_test.go             |  63 ----
 tpl/data/data.go                   | 108 ++++---
 tpl/data/init_test.go              |   7 +-
 tpl/data/resources.go              | 151 +++++-----
 tpl/data/resources_test.go         |  63 ++--
 26 files changed, 1192 insertions(+), 543 deletions(-)
 create mode 100644 cache/filecache/filecache.go
 create mode 100644 cache/filecache/filecache_test.go
 delete mode 100644 tpl/data/cache.go
 delete mode 100644 tpl/data/cache_test.go

diff --git a/cache/filecache/filecache.go b/cache/filecache/filecache.go
new file mode 100644
index 000000000..45359f574
--- /dev/null
+++ b/cache/filecache/filecache.go
@@ -0,0 +1,442 @@
+// Copyright 2018 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 filecache
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"path"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/gohugoio/hugo/common/hugio"
+
+	"github.com/gohugoio/hugo/helpers"
+
+	"github.com/gohugoio/hugo/hugolib/paths"
+
+	"github.com/pkg/errors"
+
+	"github.com/BurntSushi/locker"
+	"github.com/bep/mapstructure"
+	"github.com/spf13/afero"
+)
+
+const (
+	cachesConfigKey = "caches"
+
+	resourcesGenDir = ":resourceDir/_gen"
+)
+
+var defaultCacheConfig = cacheConfig{
+	MaxAge: -1, // Never expire
+	Dir:    ":cacheDir",
+}
+
+const (
+	cacheKeyGetJSON = "getjson"
+	cacheKeyGetCSV  = "getcsv"
+	cacheKeyImages  = "images"
+	cacheKeyAssets  = "assets"
+)
+
+var defaultCacheConfigs = map[string]cacheConfig{
+	cacheKeyGetJSON: defaultCacheConfig,
+	cacheKeyGetCSV:  defaultCacheConfig,
+	cacheKeyImages: cacheConfig{
+		MaxAge: -1,
+		Dir:    resourcesGenDir,
+	},
+	cacheKeyAssets: cacheConfig{
+		MaxAge: -1,
+		Dir:    resourcesGenDir,
+	},
+}
+
+type cachesConfig map[string]cacheConfig
+
+type cacheConfig struct {
+	// Maxe age of ache entries in this cache. Any items older than this will
+	// be removed and not returned from the cache.
+	// -1 means forever, 0 means cache is disabled.
+	MaxAge int
+
+	// The directory where files are stored.
+	Dir string
+}
+
+// Cache caches a set of files in a directory. This is usually a file on
+// disk, but since this is backed by an Afero file system, it can be anything.
+type Cache struct {
+	Fs afero.Fs
+
+	// Max age in seconds.
+	maxAge int
+
+	nlocker *locker.Locker
+}
+
+// ItemInfo contains info about a cached file.
+type ItemInfo struct {
+	// This is the file's name relative to the cache's filesystem.
+	Name string
+}
+
+// NewCache creates a new file cache with the given filesystem and max age.
+func NewCache(fs afero.Fs, maxAge int) *Cache {
+	return &Cache{
+		Fs:      fs,
+		nlocker: locker.NewLocker(),
+		maxAge:  maxAge,
+	}
+}
+
+// lockedFile is a file with a lock that is released on Close.
+type lockedFile struct {
+	afero.File
+	unlock func()
+}
+
+func (l *lockedFile) Close() error {
+	defer l.unlock()
+	return l.File.Close()
+}
+
+// GetWriteCloser returns a transactional writer into the cache.
+// It's important that it's closed when done.
+func (c *Cache) WriteCloser(id string) (ItemInfo, io.WriteCloser, error) {
+	id = cleanID(id)
+	c.nlocker.Lock(id)
+
+	info := ItemInfo{Name: id}
+
+	f, err := helpers.OpenFileForWriting(c.Fs, id)
+	if err != nil {
+		c.nlocker.Unlock(id)
+		return info, nil, err
+	}
+
+	return info, &lockedFile{
+		File:   f,
+		unlock: func() { c.nlocker.Unlock(id) },
+	}, nil
+}
+
+// ReadOrCreate tries to lookup the file in cache.
+// If found, it is passed to read and then closed.
+// If not found a new file is created and passed to create, which should close
+// it when done.
+func (c *Cache) ReadOrCreate(id string,
+	read func(info ItemInfo, r io.Reader) error,
+	create func(info ItemInfo, w io.WriteCloser) error) (info ItemInfo, err error) {
+	id = cleanID(id)
+
+	c.nlocker.Lock(id)
+	defer c.nlocker.Unlock(id)
+
+	info = ItemInfo{Name: id}
+
+	if r := c.getOrRemove(id); r != nil {
+		err = read(info, r)
+		defer r.Close()
+		return
+	}
+
+	f, err := helpers.OpenFileForWriting(c.Fs, id)
+	if err != nil {
+		return
+	}
+
+	err = create(info, f)
+
+	return
+
+}
+
+// GetOrCreate tries to get the file with the given id from cache. If not found or expired, create will
+// be invoked and the result cached.
+// This method is protected by a named lock using the given id as identifier.
+func (c *Cache) GetOrCreate(id string, create func() (io.ReadCloser, error)) (ItemInfo, io.ReadCloser, error) {
+	id = cleanID(id)
+
+	c.nlocker.Lock(id)
+	defer c.nlocker.Unlock(id)
+
+	info := ItemInfo{Name: id}
+
+	if r := c.getOrRemove(id); r != nil {
+		return info, r, nil
+	}
+
+	r, err := create()
+	if err != nil {
+		return info, nil, err
+	}
+
+	if c.maxAge == 0 {
+		// No caching.
+		return info, hugio.ToReadCloser(r), nil
+	}
+
+	var buff bytes.Buffer
+	return info,
+		hugio.ToReadCloser(&buff),
+		afero.WriteReader(c.Fs, id, io.TeeReader(r, &buff))
+}
+
+// GetOrCreateBytes is the same as GetOrCreate, but produces a byte slice.
+func (c *Cache) GetOrCreateBytes(id string, create func() ([]byte, error)) (ItemInfo, []byte, error) {
+	id = cleanID(id)
+
+	c.nlocker.Lock(id)
+	defer c.nlocker.Unlock(id)
+
+	info := ItemInfo{Name: id}
+
+	if r := c.getOrRemove(id); r != nil {
+		defer r.Close()
+		b, err := ioutil.ReadAll(r)
+		return info, b, err
+	}
+
+	b, err := create()
+	if err != nil {
+		return info, nil, err
+	}
+
+	if c.maxAge == 0 {
+		return info, b, nil
+	}
+
+	if err := afero.WriteReader(c.Fs, id, bytes.NewReader(b)); err != nil {
+		return info, nil, err
+	}
+	return info, b, nil
+
+}
+
+// GetBytes gets the file content with the given id from the cahce, nil if none found.
+func (c *Cache) GetBytes(id string) (ItemInfo, []byte, error) {
+	id = cleanID(id)
+
+	c.nlocker.Lock(id)
+	defer c.nlocker.Unlock(id)
+
+	info := ItemInfo{Name: id}
+
+	if r := c.getOrRemove(id); r != nil {
+		defer r.Close()
+		b, err := ioutil.ReadAll(r)
+		return info, b, err
+	}
+
+	return info, nil, nil
+}
+
+// Get gets the file with the given id from the cahce, nil if none found.
+func (c *Cache) Get(id string) (ItemInfo, io.ReadCloser, error) {
+	id = cleanID(id)
+
+	c.nlocker.Lock(id)
+	defer c.nlocker.Unlock(id)
+
+	info := ItemInfo{Name: id}
+
+	r := c.getOrRemove(id)
+
+	return info, r, nil
+}
+
+// get gets the file with the given id. If it's expired, it will
+// be removed.
+func (c *Cache) getOrRemove(id string) hugio.ReadSeekCloser {
+	if c.maxAge == 0 {
+		// No caching.
+		return nil
+	}
+
+	if c.maxAge > 0 {
+		fi, err := c.Fs.Stat(id)
+		if err != nil {
+			return nil
+		}
+
+		expiry := time.Now().Add(-time.Duration(c.maxAge) * time.Second)
+		expired := fi.ModTime().Before(expiry)
+		if expired {
+			c.Fs.Remove(id)
+			return nil
+		}
+	}
+
+	f, err := c.Fs.Open(id)
+
+	if err != nil {
+		return nil
+	}
+
+	return f
+}
+
+// For testing
+func (c *Cache) getString(id string) string {
+	id = cleanID(id)
+
+	c.nlocker.Lock(id)
+	defer c.nlocker.Unlock(id)
+
+	if r := c.getOrRemove(id); r != nil {
+		defer r.Close()
+		b, _ := ioutil.ReadAll(r)
+		return string(b)
+	}
+
+	return ""
+
+}
+
+// Caches is a named set of caches.
+type Caches map[string]*Cache
+
+// Get gets a named cache, nil if none found.
+func (f Caches) Get(name string) *Cache {
+	return f[strings.ToLower(name)]
+}
+
+// GetJSOnCache gets the file cache for getJSON.
+func (f Caches) GetJSONCache() *Cache {
+	return f[cacheKeyGetJSON]
+}
+
+// GetCSVCache gets the file cache for getCSV.
+func (f Caches) GetCSVCache() *Cache {
+	return f[cacheKeyGetCSV]
+}
+
+// ImageCache gets the file cache for processed images.
+func (f Caches) ImageCache() *Cache {
+	return f[cacheKeyImages]
+}
+
+// AssetsCache gets the file cache for assets (processed resources, SCSS etc.).
+func (f Caches) AssetsCache() *Cache {
+	return f[cacheKeyAssets]
+}
+
+// NewCachesFromPaths creates a new set of file caches from the given
+// configuration.
+func NewCachesFromPaths(p *paths.Paths) (Caches, error) {
+	dcfg, err := decodeConfig(p)
+	if err != nil {
+		return nil, err
+	}
+
+	fs := p.Fs.Source
+
+	m := make(Caches)
+	for k, v := range dcfg {
+		baseDir := filepath.Join(v.Dir, k)
+		if err = fs.MkdirAll(baseDir, 0777); err != nil {
+			return nil, err
+		}
+		bfs := afero.NewBasePathFs(fs, baseDir)
+		m[k] = NewCache(bfs, v.MaxAge)
+	}
+
+	return m, nil
+}
+
+func decodeConfig(p *paths.Paths) (cachesConfig, error) {
+	c := make(cachesConfig)
+	valid := make(map[string]bool)
+	// Add defaults
+	for k, v := range defaultCacheConfigs {
+		c[k] = v
+		valid[k] = true
+	}
+
+	cfg := p.Cfg
+
+	m := cfg.GetStringMap(cachesConfigKey)
+
+	_, isOsFs := p.Fs.Source.(*afero.OsFs)
+
+	for k, v := range m {
+		cc := defaultCacheConfig
+
+		if err := mapstructure.WeakDecode(v, &cc); err != nil {
+			return nil, err
+		}
+
+		if cc.Dir == "" {
+			return c, errors.New("must provide cache Dir")
+		}
+
+		name := strings.ToLower(k)
+		if !valid[name] {
+			return nil, errors.Errorf("%q is not a valid cache name", name)
+		}
+
+		c[name] = cc
+	}
+
+	// This is a very old flag in Hugo, but we need to respect it.
+	disabled := cfg.GetBool("ignoreCache")
+
+	for k, v := range c {
+		v.Dir = filepath.Clean(v.Dir)
+		dir := filepath.ToSlash(v.Dir)
+		parts := strings.Split(dir, "/")
+		first := parts[0]
+
+		if strings.HasPrefix(first, ":") {
+			resolved, err := resolveDirPlaceholder(p, first)
+			if err != nil {
+				return c, err
+			}
+			resolved = filepath.ToSlash(resolved)
+
+			v.Dir = filepath.FromSlash(path.Join((append([]string{resolved}, parts[1:]...))...))
+
+		} else if isOsFs && !path.IsAbs(dir) {
+			return c, errors.Errorf("%q must either start with a placeholder (e.g. :cacheDir, :resourceDir) or be absolute", v.Dir)
+		}
+
+		if disabled {
+			v.MaxAge = 0
+		}
+
+		c[k] = v
+	}
+
+	return c, nil
+}
+
+// Resolves :resourceDir => /myproject/resources etc., :cacheDir => ...
+func resolveDirPlaceholder(p *paths.Paths, placeholder string) (string, error) {
+	switch strings.ToLower(placeholder) {
+	case ":resourcedir":
+		return p.AbsResourcesDir, nil
+	case ":cachedir":
+		return helpers.GetCacheDir(p.Fs.Source, p.Cfg)
+	}
+
+	return "", errors.Errorf("%q is not a valid placeholder (valid values are :cacheDir or :resourceDir)", placeholder)
+}
+
+func cleanID(name string) string {
+	return filepath.Clean(name)
+}
diff --git a/cache/filecache/filecache_test.go b/cache/filecache/filecache_test.go
new file mode 100644
index 000000000..d483fc1a7
--- /dev/null
+++ b/cache/filecache/filecache_test.go
@@ -0,0 +1,306 @@
+// Copyright 2018 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 filecache
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/gohugoio/hugo/common/hugio"
+
+	"github.com/gohugoio/hugo/config"
+	"github.com/gohugoio/hugo/hugofs"
+	"github.com/gohugoio/hugo/hugolib/paths"
+	"github.com/spf13/afero"
+	"github.com/spf13/viper"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFileCache(t *testing.T) {
+	t.Parallel()
+	assert := require.New(t)
+
+	for _, cacheDir := range []string{"mycache", ""} {
+
+		configStr := `
+cacheDir = "CACHEDIR"
+[caches]
+[caches.getJSON]
+maxAge = 111
+dir = ":cacheDir/c"
+
+`
+		configStr = strings.Replace(configStr, "CACHEDIR", cacheDir, 1)
+
+		cfg, err := config.FromConfigString(configStr, "toml")
+		assert.NoError(err)
+
+		fs := hugofs.NewMem(cfg)
+		p, err := paths.New(fs, cfg)
+		assert.NoError(err)
+
+		caches, err := NewCachesFromPaths(p)
+		assert.NoError(err)
+
+		c := caches.Get("GetJSON")
+		assert.NotNil(c)
+		assert.Equal(111, c.maxAge)
+
+		bfs, ok := c.Fs.(*afero.BasePathFs)
+		assert.True(ok)
+		filename, err := bfs.RealPath("key")
+		assert.NoError(err)
+		if cacheDir != "" {
+			assert.Equal(filepath.FromSlash(cacheDir+"/c/getjson/key"), filename)
+		} else {
+			// Temp dir.
+			assert.Regexp(regexp.MustCompile("hugo_cache.*key"), filename)
+		}
+
+		rf := func(s string) func() (io.ReadCloser, error) {
+			return func() (io.ReadCloser, error) {
+				return struct {
+					io.ReadSeeker
+					io.Closer
+				}{
+					strings.NewReader(s),
+					ioutil.NopCloser(nil),
+				}, nil
+			}
+		}
+
+		bf := func() ([]byte, error) {
+			return []byte("bcd"), nil
+		}
+
+		for i := 0; i < 2; i++ {
+			info, r, err := c.GetOrCreate("a", rf("abc"))
+			assert.NoError(err)
+			assert.NotNil(r)
+			assert.Equal("a", info.Name)
+			b, _ := ioutil.ReadAll(r)
+			r.Close()
+			assert.Equal("abc", string(b))
+
+			info, b, err = c.GetOrCreateBytes("b", bf)
+			assert.NoError(err)
+			assert.NotNil(r)
+			assert.Equal("b", info.Name)
+			assert.Equal("bcd", string(b))
+
+			_, b, err = c.GetOrCreateBytes("a", bf)
+			assert.NoError(err)
+			assert.Equal("abc", string(b))
+
+			_, r, err = c.GetOrCreate("a", rf("bcd"))
+			assert.NoError(err)
+			b, _ = ioutil.ReadAll(r)
+			r.Close()
+			assert.Equal("abc", string(b))
+		}
+
+		assert.NotNil(caches.Get("getJSON"))
+
+		info, w, err := caches.ImageCache().WriteCloser("mykey")
+		assert.NoError(err)
+		assert.Equal("mykey", info.Name)
+		io.WriteString(w, "Hugo is great!")
+		w.Close()
+		assert.Equal("Hugo is great!", caches.ImageCache().getString("mykey"))
+
+		info, r, err := caches.ImageCache().Get("mykey")
+		assert.NoError(err)
+		assert.NotNil(r)
+		assert.Equal("mykey", info.Name)
+		b, _ := ioutil.ReadAll(r)
+		r.Close()
+		assert.Equal("Hugo is great!", string(b))
+
+		info, b, err = caches.ImageCache().GetBytes("mykey")
+		assert.NoError(err)
+		assert.Equal("mykey", info.Name)
+		assert.Equal("Hugo is great!", string(b))
+
+	}
+
+}
+
+func TestFileCacheConcurrent(t *testing.T) {
+	t.Parallel()
+
+	assert := require.New(t)
+
+	configStr := `
+[caches]
+[caches.getjson]
+maxAge = 1
+dir = "/cache/c"
+
+`
+
+	cfg, err := config.FromConfigString(configStr, "toml")
+	assert.NoError(err)
+	fs := hugofs.NewMem(cfg)
+	p, err := paths.New(fs, cfg)
+	assert.NoError(err)
+
+	caches, err := NewCachesFromPaths(p)
+	assert.NoError(err)
+
+	const cacheName = "getjson"
+
+	filenameData := func(i int) (string, string) {
+		data := fmt.Sprintf("data: %d", i)
+		filename := fmt.Sprintf("file%d", i)
+		return filename, data
+	}
+
+	var wg sync.WaitGroup
+
+	for i := 0; i < 50; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := 0; j < 20; j++ {
+				c := caches.Get(cacheName)
+				assert.NotNil(c)
+				filename, data := filenameData(i)
+				_, r, err := c.GetOrCreate(filename, func() (io.ReadCloser, error) {
+					return hugio.ToReadCloser(strings.NewReader(data)), nil
+				})
+				assert.NoError(err)
+				b, _ := ioutil.ReadAll(r)
+				r.Close()
+				assert.Equal(data, string(b))
+				// Trigger some expiration.
+				time.Sleep(50 * time.Millisecond)
+			}
+		}(i)
+
+	}
+	wg.Wait()
+}
+
+func TestDecodeConfig(t *testing.T) {
+	t.Parallel()
+
+	assert := require.New(t)
+
+	configStr := `
+[caches]
+[caches.getJSON]
+maxAge = 1234
+dir = "/path/to/c1"
+[caches.getCSV]
+maxAge = 3456
+dir = "/path/to/c2"
+[caches.images]
+dir = "/path/to/c3"
+
+`
+
+	cfg, err := config.FromConfigString(configStr, "toml")
+	assert.NoError(err)
+	fs := hugofs.NewMem(cfg)
+	p, err := paths.New(fs, cfg)
+	assert.NoError(err)
+
+	decoded, err := decodeConfig(p)
+	assert.NoError(err)
+
+	assert.Equal(4, len(decoded))
+
+	c2 := decoded["getcsv"]
+	assert.Equal(3456, c2.MaxAge)
+	assert.Equal(filepath.FromSlash("/path/to/c2"), c2.Dir)
+
+	c3 := decoded["images"]
+	assert.Equal(-1, c3.MaxAge)
+	assert.Equal(filepath.FromSlash("/path/to/c3"), c3.Dir)
+
+}
+
+func TestDecodeConfigIgnoreCache(t *testing.T) {
+	t.Parallel()
+
+	assert := require.New(t)
+
+	configStr := `
+ignoreCache = true
+[caches]
+[caches.getJSON]
+maxAge = 1234
+dir = "/path/to/c1"
+[caches.getCSV]
+maxAge = 3456
+dir = "/path/to/c2"
+[caches.images]
+dir = "/path/to/c3"
+
+`
+
+	cfg, err := config.FromConfigString(configStr, "toml")
+	assert.NoError(err)
+	fs := hugofs.NewMem(cfg)
+	p, err := paths.New(fs, cfg)
+	assert.NoError(err)
+
+	decoded, err := decodeConfig(p)
+	assert.NoError(err)
+
+	assert.Equal(4, len(decoded))
+
+	for _, v := range decoded {
+		assert.Equal(0, v.MaxAge)
+	}
+
+}
+
+func TestDecodeConfigDefault(t *testing.T) {
+	assert := require.New(t)
+	cfg := viper.New()
+	if runtime.GOOS == "windows" {
+		cfg.Set("resourceDir", "c:\\cache\\resources")
+		cfg.Set("cacheDir", "c:\\cache\\thecache")
+
+	} else {
+		cfg.Set("resourceDir", "/cache/resources")
+		cfg.Set("cacheDir", "/cache/thecache")
+	}
+
+	fs := hugofs.NewMem(cfg)
+	p, err := paths.New(fs, cfg)
+	assert.NoError(err)
+
+	decoded, err := decodeConfig(p)
+
+	assert.NoError(err)
+
+	assert.Equal(4, len(decoded))
+
+	if runtime.GOOS == "windows" {
+		assert.Equal("c:\\cache\\resources\\_gen", decoded[cacheKeyImages].Dir)
+	} else {
+		assert.Equal("/cache/resources/_gen", decoded[cacheKeyImages].Dir)
+	}
+}
diff --git a/commands/commandeer.go b/commands/commandeer.go
index 545191cfe..cd2866a27 100644
--- a/commands/commandeer.go
+++ b/commands/commandeer.go
@@ -359,20 +359,11 @@ func (c *commandeer) loadConfig(mustHaveConfigFile, running bool) error {
 		return err
 	}
 
-	cacheDir := config.GetString("cacheDir")
-	if cacheDir != "" {
-		if helpers.FilePathSeparator != cacheDir[len(cacheDir)-1:] {
-			cacheDir = cacheDir + helpers.FilePathSeparator
-		}
-		isDir, err := helpers.DirExists(cacheDir, sourceFs)
-		checkErr(cfg.Logger, err)
-		if !isDir {
-			mkdir(cacheDir)
-		}
-		config.Set("cacheDir", cacheDir)
-	} else {
-		config.Set("cacheDir", helpers.GetTempDir("hugo_cache", sourceFs))
+	cacheDir, err := helpers.GetCacheDir(sourceFs, config)
+	if err != nil {
+		return err
 	}
+	config.Set("cacheDir", cacheDir)
 
 	cfg.Logger.INFO.Println("Using config file:", config.ConfigFileUsed())
 
diff --git a/common/hugio/writers.go b/common/hugio/writers.go
index 2766146e1..82c4dca52 100644
--- a/common/hugio/writers.go
+++ b/common/hugio/writers.go
@@ -15,6 +15,7 @@ package hugio
 
 import (
 	"io"
+	"io/ioutil"
 )
 
 type multiWriteCloser struct {
@@ -41,3 +42,35 @@ func NewMultiWriteCloser(writeClosers ...io.WriteCloser) io.WriteCloser {
 	}
 	return multiWriteCloser{Writer: io.MultiWriter(writers...), closers: writeClosers}
 }
+
+// ToWriteCloser creates an io.WriteCloser from the given io.Writer.
+// If it's not already, one will be created with a Close method that does nothing.
+func ToWriteCloser(w io.Writer) io.WriteCloser {
+	if rw, ok := w.(io.WriteCloser); ok {
+		return rw
+	}
+
+	return struct {
+		io.Writer
+		io.Closer
+	}{
+		w,
+		ioutil.NopCloser(nil),
+	}
+}
+
+// ToReadCloser creates an io.ReadCloser from the given io.Reader.
+// If it's not already, one will be created with a Close method that does nothing.
+func ToReadCloser(r io.Reader) io.ReadCloser {
+	if rc, ok := r.(io.ReadCloser); ok {
+		return rc
+	}
+
+	return struct {
+		io.Reader
+		io.Closer
+	}{
+		r,
+		ioutil.NopCloser(nil),
+	}
+}
diff --git a/deps/deps.go b/deps/deps.go
index db59ad212..a1b54a862 100644
--- a/deps/deps.go
+++ b/deps/deps.go
@@ -4,6 +4,9 @@ import (
 	"sync"
 	"time"
 
+	"github.com/pkg/errors"
+
+	"github.com/gohugoio/hugo/cache/filecache"
 	"github.com/gohugoio/hugo/common/loggers"
 	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/helpers"
@@ -53,6 +56,9 @@ type Deps struct {
 	// The configuration to use
 	Cfg config.Provider `json:"-"`
 
+	// The file cache to use.
+	FileCaches filecache.Caches
+
 	// The translation func to use
 	Translate func(translationID string, args ...interface{}) string `json:"-"`
 
@@ -187,7 +193,12 @@ func New(cfg DepsCfg) (*Deps, error) {
 		return nil, err
 	}
 
-	resourceSpec, err := resource.NewSpec(ps, logger, cfg.OutputFormats, cfg.MediaTypes)
+	fileCaches, err := filecache.NewCachesFromPaths(ps.Paths)
+	if err != nil {
+		return nil, errors.WithMessage(err, "failed to create file caches from configuration")
+	}
+
+	resourceSpec, err := resource.NewSpec(ps, fileCaches, logger, cfg.OutputFormats, cfg.MediaTypes)
 	if err != nil {
 		return nil, err
 	}
@@ -219,6 +230,7 @@ func New(cfg DepsCfg) (*Deps, error) {
 		ResourceSpec:        resourceSpec,
 		Cfg:                 cfg.Language,
 		Language:            cfg.Language,
+		FileCaches:          fileCaches,
 		BuildStartListeners: &Listeners{},
 		Timeout:             time.Duration(timeoutms) * time.Millisecond,
 		globalErrHandler:    &globalErrHandler{},
@@ -250,7 +262,7 @@ func (d Deps) ForLanguage(cfg DepsCfg) (*Deps, error) {
 	// The resource cache is global so reuse.
 	// TODO(bep) clean up these inits.
 	resourceCache := d.ResourceSpec.ResourceCache
-	d.ResourceSpec, err = resource.NewSpec(d.PathSpec, d.Log, cfg.OutputFormats, cfg.MediaTypes)
+	d.ResourceSpec, err = resource.NewSpec(d.PathSpec, d.ResourceSpec.FileCaches, d.Log, cfg.OutputFormats, cfg.MediaTypes)
 	if err != nil {
 		return nil, err
 	}
diff --git a/go.mod b/go.mod
index a3fa54f2a..1e0d0d6eb 100644
--- a/go.mod
+++ b/go.mod
@@ -52,7 +52,7 @@ require (
 	github.com/spf13/nitro v0.0.0-20131003134307-24d7ef30a12d
 	github.com/spf13/pflag v1.0.3
 	github.com/spf13/viper v1.2.0
-	github.com/stretchr/testify v1.2.3-0.20181002232621-f2347ac6c9c9
+	github.com/stretchr/testify v1.2.3-0.20181014000028-04af85275a5c
 	github.com/tdewolff/minify/v2 v2.3.7
 	github.com/wellington/go-libsass v0.0.0-20180624165032-615eaa47ef79 // indirect
 	github.com/yosssi/ace v0.0.5
diff --git a/go.sum b/go.sum
index 4b0ca2cea..ba3c80768 100644
--- a/go.sum
+++ b/go.sum
@@ -131,6 +131,8 @@ github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.2.3-0.20181002232621-f2347ac6c9c9 h1:kcVw9CGDqYBy0TTpIq2+BNR4W9poqiwEPBh/OYX5CaU=
 github.com/stretchr/testify v1.2.3-0.20181002232621-f2347ac6c9c9/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.2.3-0.20181014000028-04af85275a5c h1:03OmljzZYsezlgAfa+f/cY8E8XXPiFh5bgANMhUlDI4=
+github.com/stretchr/testify v1.2.3-0.20181014000028-04af85275a5c/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/tdewolff/minify/v2 v2.3.7 h1:nhk7MKYRdTDwTxqEQZKLDkLe04tDHht8mBI+VJrsYvk=
 github.com/tdewolff/minify/v2 v2.3.7/go.mod h1:DD1stRlSx6JsHfl1+E/HVMQeXiec9rD1UQ0epklIZLc=
 github.com/tdewolff/parse/v2 v2.3.5 h1:/uS8JfhwVJsNkEh769GM5ENv6L9LOh2Z9uW3tCdlhs0=
diff --git a/helpers/path.go b/helpers/path.go
index f96156dcf..f5096e62f 100644
--- a/helpers/path.go
+++ b/helpers/path.go
@@ -24,6 +24,8 @@ import (
 	"strings"
 	"unicode"
 
+	"github.com/gohugoio/hugo/config"
+
 	"github.com/gohugoio/hugo/common/hugio"
 	_errors "github.com/pkg/errors"
 	"github.com/spf13/afero"
@@ -575,6 +577,59 @@ func OpenFileForWriting(fs afero.Fs, filename string) (afero.File, error) {
 	return f, err
 }
 
+// GetCacheDir returns a cache dir from the given filesystem and config.
+// The dir will be created if it does not exist.
+func GetCacheDir(fs afero.Fs, cfg config.Provider) (string, error) {
+	cacheDir := getCacheDir(cfg)
+	if cacheDir != "" {
+		exists, err := DirExists(cacheDir, fs)
+		if err != nil {
+			return "", err
+		}
+		if !exists {
+			err := fs.MkdirAll(cacheDir, 0777) // Before umask
+			if err != nil {
+				return "", _errors.Wrap(err, "failed to create cache dir")
+			}
+		}
+		return cacheDir, nil
+	}
+
+	// Fall back to a cache in /tmp.
+	return GetTempDir("hugo_cache", fs), nil
+
+}
+
+func getCacheDir(cfg config.Provider) string {
+	// Always use the cacheDir config if set.
+	cacheDir := cfg.GetString("cacheDir")
+	if len(cacheDir) > 1 {
+		return addTrailingFileSeparator(cacheDir)
+	}
+
+	// Both of these are fairly distinctive OS env keys used by Netlify.
+	if os.Getenv("DEPLOY_PRIME_URL") != "" && os.Getenv("PULL_REQUEST") != "" {
+		// Netlify's cache behaviour is not documented, the currently best example
+		// is this project:
+		// https://github.com/philhawksworth/content-shards/blob/master/gulpfile.js
+		return "/opt/build/cache/hugo_cache/"
+
+	}
+
+	// This will fall back to an hugo_cache folder in the tmp dir, which should work fine for most CI
+	// providers. See this for a working CircleCI setup:
+	// https://github.com/bep/hugo-sass-test/blob/6c3960a8f4b90e8938228688bc49bdcdd6b2d99e/.circleci/config.yml
+	// If not, they can set the HUGO_CACHEDIR environment variable or cacheDir config key.
+	return ""
+}
+
+func addTrailingFileSeparator(s string) string {
+	if !strings.HasSuffix(s, FilePathSeparator) {
+		s = s + FilePathSeparator
+	}
+	return s
+}
+
 // GetTempDir returns a temporary directory with the given sub path.
 func GetTempDir(subPath string, fs afero.Fs) string {
 	return afero.GetTempDir(fs, subPath)
diff --git a/hugolib/filesystems/basefs.go b/hugolib/filesystems/basefs.go
index ee1c870d9..8fc1861b8 100644
--- a/hugolib/filesystems/basefs.go
+++ b/hugolib/filesystems/basefs.go
@@ -81,7 +81,6 @@ type SourceFilesystems struct {
 	Layouts    *SourceFilesystem
 	Archetypes *SourceFilesystem
 	Assets     *SourceFilesystem
-	Resources  *SourceFilesystem
 
 	// This is a unified read-only view of the project's and themes' workdir.
 	Work *SourceFilesystem
@@ -376,13 +375,6 @@ func (b *sourceFilesystemsBuilder) Build() (*SourceFilesystems, error) {
 	}
 	b.result.Assets = sfs
 
-	sfs, err = b.createFs(true, false, "resourceDir", "resources")
-	if err != nil {
-		return nil, err
-	}
-
-	b.result.Resources = sfs
-
 	sfs, err = b.createFs(false, true, "", "")
 	if err != nil {
 		return nil, err
diff --git a/hugolib/filesystems/basefs_test.go b/hugolib/filesystems/basefs_test.go
index ec6ccb30c..8e9b7235c 100644
--- a/hugolib/filesystems/basefs_test.go
+++ b/hugolib/filesystems/basefs_test.go
@@ -108,7 +108,6 @@ theme = ["atheme"]
 	checkFileCount(bfs.Data.Fs, "", assert, 9)        // 7 + 2 themes
 	checkFileCount(bfs.Archetypes.Fs, "", assert, 10) // 8 + 2 themes
 	checkFileCount(bfs.Assets.Fs, "", assert, 9)
-	checkFileCount(bfs.Resources.Fs, "", assert, 10)
 	checkFileCount(bfs.Work.Fs, "", assert, 78)
 
 	assert.Equal([]string{filepath.FromSlash("/my/work/mydata"), filepath.FromSlash("/my/work/themes/btheme/data"), filepath.FromSlash("/my/work/themes/atheme/data")}, bfs.Data.Dirnames)
@@ -229,8 +228,6 @@ func TestRealDirs(t *testing.T) {
 	assert.Equal(filepath.Join(root, "myassets/scss"), realDirs[0])
 	assert.Equal(filepath.Join(themesDir, "mytheme/assets/scss"), realDirs[len(realDirs)-1])
 
-	checkFileCount(bfs.Resources.Fs, "", assert, 3)
-
 	assert.NotNil(bfs.themeFs)
 	fi, b, err := bfs.themeFs.(afero.Lstater).LstatIfPossible(filepath.Join("resources", "t1.txt"))
 	assert.NoError(err)
diff --git a/hugolib/prune_resources.go b/hugolib/prune_resources.go
index 28802c6f2..63623d75d 100644
--- a/hugolib/prune_resources.go
+++ b/hugolib/prune_resources.go
@@ -14,7 +14,6 @@
 package hugolib
 
 import (
-	"fmt"
 	"io"
 	"os"
 	"strings"
@@ -27,21 +26,12 @@ import (
 // GC requires a build first.
 func (h *HugoSites) GC() (int, error) {
 	s := h.Sites[0]
-	fs := h.PathSpec.BaseFs.Resources.Fs
+	assetsCacheFs := h.Deps.FileCaches.AssetsCache().Fs
+	imageCacheFs := h.Deps.FileCaches.ImageCache().Fs
 
-	imageCacheDir := s.ResourceSpec.GenImagePath
-	if len(imageCacheDir) < 10 {
-		panic("invalid image cache")
-	}
-	assetsCacheDir := s.ResourceSpec.GenAssetsPath
-	if len(assetsCacheDir) < 10 {
-		panic("invalid assets cache")
-	}
-
-	isImageInUse := func(filename string) bool {
-		key := strings.TrimPrefix(filename, imageCacheDir)
+	isImageInUse := func(name string) bool {
 		for _, site := range h.Sites {
-			if site.ResourceSpec.IsInImageCache(key) {
+			if site.ResourceSpec.IsInImageCache(name) {
 				return true
 			}
 		}
@@ -49,10 +39,9 @@ func (h *HugoSites) GC() (int, error) {
 		return false
 	}
 
-	isAssetInUse := func(filename string) bool {
-		key := strings.TrimPrefix(filename, assetsCacheDir)
+	isAssetInUse := func(name string) bool {
 		// These assets are stored in tuplets with an added extension to the key.
-		key = strings.TrimSuffix(key, helpers.Ext(key))
+		key := strings.TrimSuffix(name, helpers.Ext(name))
 		for _, site := range h.Sites {
 			if site.ResourceSpec.ResourceCache.Contains(key) {
 				return true
@@ -62,17 +51,13 @@ func (h *HugoSites) GC() (int, error) {
 		return false
 	}
 
-	walker := func(dirname string, inUse func(filename string) bool) (int, error) {
+	walker := func(fs afero.Fs, dirname string, inUse func(filename string) bool) (int, error) {
 		counter := 0
 		err := afero.Walk(fs, dirname, func(path string, info os.FileInfo, err error) error {
 			if info == nil {
 				return nil
 			}
 
-			if !strings.HasPrefix(path, dirname) {
-				return fmt.Errorf("Invalid state, walk outside of resource dir: %q", path)
-			}
-
 			if info.IsDir() {
 				f, err := fs.Open(path)
 				if err != nil {
@@ -103,8 +88,8 @@ func (h *HugoSites) GC() (int, error) {
 		return counter, err
 	}
 
-	imageCounter, err1 := walker(imageCacheDir, isImageInUse)
-	assetsCounter, err2 := walker(assetsCacheDir, isAssetInUse)
+	imageCounter, err1 := walker(imageCacheFs, "", isImageInUse)
+	assetsCounter, err2 := walker(assetsCacheFs, "", isAssetInUse)
 	totalCount := imageCounter + assetsCounter
 
 	if err1 != nil {
diff --git a/resource/bundler/bundler.go b/resource/bundler/bundler.go
index 39ce9b521..70b8ee536 100644
--- a/resource/bundler/bundler.go
+++ b/resource/bundler/bundler.go
@@ -105,7 +105,7 @@ func (c *Client) Concat(targetPath string, resources resource.Resources) (resour
 		}
 
 		composite, err := c.rs.NewForFs(
-			c.rs.BaseFs.Resources.Fs,
+			c.rs.FileCaches.AssetsCache().Fs,
 			resource.ResourceSourceDescriptor{
 				LazyPublish:        true,
 				OpenReadSeekCloser: concatr,
diff --git a/resource/create/create.go b/resource/create/create.go
index 0f909a36d..db23930e4 100644
--- a/resource/create/create.go
+++ b/resource/create/create.go
@@ -51,7 +51,7 @@ func (c *Client) Get(fs afero.Fs, filename string) (resource.Resource, error) {
 func (c *Client) FromString(targetPath, content string) (resource.Resource, error) {
 	return c.rs.ResourceCache.GetOrCreate(resource.CACHE_OTHER, targetPath, func() (resource.Resource, error) {
 		return c.rs.NewForFs(
-			c.rs.BaseFs.Resources.Fs,
+			c.rs.FileCaches.AssetsCache().Fs,
 			resource.ResourceSourceDescriptor{
 				LazyPublish: true,
 				OpenReadSeekCloser: func() (hugio.ReadSeekCloser, error) {
diff --git a/resource/image.go b/resource/image.go
index fc79cbef5..0fdabf788 100644
--- a/resource/image.go
+++ b/resource/image.go
@@ -21,6 +21,7 @@ import (
 	"image/draw"
 	"image/jpeg"
 	"io"
+	"io/ioutil"
 	"os"
 	"strconv"
 	"strings"
@@ -125,9 +126,6 @@ type Image struct {
 
 	copyToDestinationInit sync.Once
 
-	// Lock used when creating alternate versions of this image.
-	createMu sync.Mutex
-
 	imaging *Imaging
 
 	format imaging.Format
@@ -245,7 +243,7 @@ func (i *Image) doWithImageConfig(action, spec string, f func(src image.Image, c
 		}
 	}
 
-	return i.spec.imageCache.getOrCreate(i, conf, func(resourceCacheFilename string) (*Image, error) {
+	return i.spec.imageCache.getOrCreate(i, conf, func() (*Image, image.Image, error) {
 		imageProcSem <- true
 		defer func() {
 			<-imageProcSem
@@ -260,7 +258,7 @@ func (i *Image) doWithImageConfig(action, spec string, f func(src image.Image, c
 
 		src, err := i.decodeSource()
 		if err != nil {
-			return nil, &os.PathError{Op: errOp, Path: errPath, Err: err}
+			return nil, nil, &os.PathError{Op: errOp, Path: errPath, Err: err}
 		}
 
 		if conf.Rotate != 0 {
@@ -270,7 +268,7 @@ func (i *Image) doWithImageConfig(action, spec string, f func(src image.Image, c
 
 		converted, err := f(src, conf)
 		if err != nil {
-			return ci, &os.PathError{Op: errOp, Path: errPath, Err: err}
+			return ci, nil, &os.PathError{Op: errOp, Path: errPath, Err: err}
 		}
 
 		if i.format == imaging.PNG {
@@ -286,7 +284,7 @@ func (i *Image) doWithImageConfig(action, spec string, f func(src image.Image, c
 		ci.config = image.Config{Width: b.Max.X, Height: b.Max.Y}
 		ci.configLoaded = true
 
-		return ci, i.encodeToDestinations(converted, conf, resourceCacheFilename, ci.targetFilenames()...)
+		return ci, converted, nil
 	})
 
 }
@@ -462,79 +460,37 @@ func (i *Image) decodeSource() (image.Image, error) {
 	return img, err
 }
 
-func (i *Image) copyToDestination(src string) error {
-	var res error
-	i.copyToDestinationInit.Do(func() {
-		targetFilenames := i.targetFilenames()
-		var changedFilenames []string
+func (i *Image) openDestinationsForWriting() (io.WriteCloser, error) {
+	targetFilenames := i.targetFilenames()
+	var changedFilenames []string
 
-		// Fast path:
-		// This is a processed version of the original.
-		// If it exists on destination with the same filename and file size, it is
-		// the same file, so no need to transfer it again.
-		for _, targetFilename := range targetFilenames {
-			if fi, err := i.spec.BaseFs.PublishFs.Stat(targetFilename); err == nil && fi.Size() == i.osFileInfo.Size() {
-				continue
-			}
-			changedFilenames = append(changedFilenames, targetFilename)
+	// Fast path:
+	// This is a processed version of the original.
+	// If it exists on destination with the same filename and file size, it is
+	// the same file, so no need to transfer it again.
+	for _, targetFilename := range targetFilenames {
+		if fi, err := i.spec.BaseFs.PublishFs.Stat(targetFilename); err == nil && fi.Size() == i.osFileInfo.Size() {
+			continue
 		}
-
-		if len(changedFilenames) == 0 {
-			return
-		}
-
-		in, err := i.sourceFs().Open(src)
-		if err != nil {
-			res = err
-			return
-		}
-		defer in.Close()
-
-		out, err := helpers.OpenFilesForWriting(i.spec.BaseFs.PublishFs, changedFilenames...)
-
-		if err != nil {
-			res = err
-			return
-		}
-		defer out.Close()
-
-		_, err = io.Copy(out, in)
-		if err != nil {
-			res = err
-			return
-		}
-	})
-
-	if res != nil {
-		return fmt.Errorf("failed to copy image to destination: %s", res)
+		changedFilenames = append(changedFilenames, targetFilename)
 	}
-	return nil
+
+	if len(changedFilenames) == 0 {
+		return struct {
+			io.Writer
+			io.Closer
+		}{
+			ioutil.Discard,
+			ioutil.NopCloser(nil),
+		}, nil
+
+	}
+
+	return helpers.OpenFilesForWriting(i.spec.BaseFs.PublishFs, changedFilenames...)
+
 }
 
-func (i *Image) encodeToDestinations(img image.Image, conf imageConfig, resourceCacheFilename string, targetFilenames ...string) error {
-
-	file1, err := helpers.OpenFilesForWriting(i.spec.BaseFs.PublishFs, targetFilenames...)
-	if err != nil {
-		return err
-	}
-
-	defer file1.Close()
-
-	var w io.Writer
-
-	if resourceCacheFilename != "" {
-		// Also save it to the image resource cache for later reuse.
-		file2, err := helpers.OpenFileForWriting(i.spec.BaseFs.Resources.Fs, resourceCacheFilename)
-		if err != nil {
-			return err
-		}
-
-		w = io.MultiWriter(file1, file2)
-		defer file2.Close()
-	} else {
-		w = file1
-	}
-
+func (i *Image) encodeTo(conf imageConfig, img image.Image, w io.Writer) error {
 	switch i.format {
 	case imaging.JPEG:
 
@@ -557,7 +513,6 @@ func (i *Image) encodeToDestinations(img image.Image, conf imageConfig, resource
 	default:
 		return imaging.Encode(w, img, i.format)
 	}
-
 }
 
 func (i *Image) clone() *Image {
diff --git a/resource/image_cache.go b/resource/image_cache.go
index 470c24c99..22c86ea32 100644
--- a/resource/image_cache.go
+++ b/resource/image_cache.go
@@ -15,19 +15,25 @@ package resource
 
 import (
 	"fmt"
+	"image"
+	"io"
 	"path/filepath"
 	"strings"
 	"sync"
 	"time"
 
+	"github.com/gohugoio/hugo/common/hugio"
+
+	"github.com/gohugoio/hugo/cache/filecache"
 	"github.com/gohugoio/hugo/helpers"
 )
 
 type imageCache struct {
-	cacheDir string
 	pathSpec *helpers.PathSpec
-	mu       sync.RWMutex
 
+	fileCache *filecache.Cache
+
+	mu    sync.RWMutex
 	store map[string]*Image
 }
 
@@ -66,7 +72,7 @@ func (c *imageCache) clear() {
 }
 
 func (c *imageCache) getOrCreate(
-	parent *Image, conf imageConfig, create func(resourceCacheFilename string) (*Image, error)) (*Image, error) {
+	parent *Image, conf imageConfig, createImage func() (*Image, image.Image, error)) (*Image, error) {
 
 	relTarget := parent.relTargetPathFromConfig(conf)
 	key := parent.relTargetPathForRel(relTarget.path(), false, false)
@@ -80,58 +86,76 @@ func (c *imageCache) getOrCreate(
 		return img, nil
 	}
 
-	// Now look in the file cache.
-	// Multiple Go routines can invoke same operation on the same image, so
-	// we need to make sure this is serialized per source image.
-	parent.createMu.Lock()
-	defer parent.createMu.Unlock()
+	// These funcs are protected by a named lock.
+	// read clones the parent to its new name and copies
+	// the content to the destinations.
+	read := func(info filecache.ItemInfo, r io.Reader) error {
+		img = parent.clone()
+		img.relTargetDirFile.file = relTarget.file
+		img.sourceFilename = info.Name
 
-	cacheFilename := filepath.Join(c.cacheDir, key)
+		w, err := img.openDestinationsForWriting()
+		if err != nil {
+			return err
+		}
+
+		defer w.Close()
+		_, err = io.Copy(w, r)
+		return err
+	}
+
+	// create creates the image and encodes it to w (cache) and to its destinations.
+	create := func(info filecache.ItemInfo, w io.WriteCloser) (err error) {
+		var conv image.Image
+		img, conv, err = createImage()
+		if err != nil {
+			w.Close()
+			return
+		}
+		img.relTargetDirFile.file = relTarget.file
+		img.sourceFilename = info.Name
+
+		destinations, err := img.openDestinationsForWriting()
+		if err != nil {
+			w.Close()
+			return err
+		}
+
+		mw := hugio.NewMultiWriteCloser(w, destinations)
+		defer mw.Close()
+
+		return img.encodeTo(conf, conv, mw)
+	}
+
+	// Now look in the file cache.
 
 	// The definition of this counter is not that we have processed that amount
 	// (e.g. resized etc.), it can be fetched from file cache,
 	//  but the count of processed image variations for this site.
 	c.pathSpec.ProcessingStats.Incr(&c.pathSpec.ProcessingStats.ProcessedImages)
 
-	exists, err := helpers.Exists(cacheFilename, c.pathSpec.BaseFs.Resources.Fs)
+	_, err := c.fileCache.ReadOrCreate(key, read, create)
 	if err != nil {
 		return nil, err
 	}
 
-	if exists {
-		img = parent.clone()
-	} else {
-		img, err = create(cacheFilename)
-		if err != nil {
-			return nil, err
-		}
-	}
-	img.relTargetDirFile.file = relTarget.file
-	img.sourceFilename = cacheFilename
-	// We have to look in the resources file system for this.
-	img.overriddenSourceFs = img.spec.BaseFs.Resources.Fs
+	// The file is now stored in this cache.
+	img.overriddenSourceFs = c.fileCache.Fs
 
 	c.mu.Lock()
 	if img2, found := c.store[key]; found {
 		c.mu.Unlock()
 		return img2, nil
 	}
-
 	c.store[key] = img
-
 	c.mu.Unlock()
 
-	if !exists {
-		// File already written to destination
-		return img, nil
-	}
-
-	return img, img.copyToDestination(cacheFilename)
+	return img, nil
 
 }
 
-func newImageCache(ps *helpers.PathSpec, cacheDir string) *imageCache {
-	return &imageCache{pathSpec: ps, store: make(map[string]*Image), cacheDir: cacheDir}
+func newImageCache(fileCache *filecache.Cache, ps *helpers.PathSpec) *imageCache {
+	return &imageCache{fileCache: fileCache, pathSpec: ps, store: make(map[string]*Image)}
 }
 
 func timeTrack(start time.Time, name string) {
diff --git a/resource/image_test.go b/resource/image_test.go
index a9aacbdce..07eab5d56 100644
--- a/resource/image_test.go
+++ b/resource/image_test.go
@@ -62,6 +62,7 @@ func TestImageTransformBasic(t *testing.T) {
 	assert := require.New(t)
 
 	image := fetchSunset(assert)
+	fileCache := image.spec.FileCaches.ImageCache().Fs
 
 	assert.Equal("/a/sunset.jpg", image.RelPermalink())
 	assert.Equal("image", image.ResourceType())
@@ -76,19 +77,20 @@ func TestImageTransformBasic(t *testing.T) {
 	assert.NoError(err)
 	assert.Equal(320, resized0x.Width())
 	assert.Equal(200, resized0x.Height())
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, resized0x.RelPermalink(), 320, 200)
+
+	assertFileCache(assert, fileCache, resized0x.RelPermalink(), 320, 200)
 
 	resizedx0, err := image.Resize("200x")
 	assert.NoError(err)
 	assert.Equal(200, resizedx0.Width())
 	assert.Equal(125, resizedx0.Height())
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, resizedx0.RelPermalink(), 200, 125)
+	assertFileCache(assert, fileCache, resizedx0.RelPermalink(), 200, 125)
 
 	resizedAndRotated, err := image.Resize("x200 r90")
 	assert.NoError(err)
 	assert.Equal(125, resizedAndRotated.Width())
 	assert.Equal(200, resizedAndRotated.Height())
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, resizedAndRotated.RelPermalink(), 125, 200)
+	assertFileCache(assert, fileCache, resizedAndRotated.RelPermalink(), 125, 200)
 
 	assert.Equal("/a/sunset_hu59e56ffff1bc1d8d122b1403d34e039f_90587_300x200_resize_q68_linear.jpg", resized.RelPermalink())
 	assert.Equal(300, resized.Width())
@@ -113,21 +115,21 @@ func TestImageTransformBasic(t *testing.T) {
 	assert.Equal("/a/sunset_hu59e56ffff1bc1d8d122b1403d34e039f_90587_200x100_fill_q68_linear_bottomleft.jpg", filled.RelPermalink())
 	assert.Equal(200, filled.Width())
 	assert.Equal(100, filled.Height())
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, filled.RelPermalink(), 200, 100)
+	assertFileCache(assert, fileCache, filled.RelPermalink(), 200, 100)
 
 	smart, err := image.Fill("200x100 smart")
 	assert.NoError(err)
 	assert.Equal(fmt.Sprintf("/a/sunset_hu59e56ffff1bc1d8d122b1403d34e039f_90587_200x100_fill_q68_linear_smart%d.jpg", smartCropVersionNumber), smart.RelPermalink())
 	assert.Equal(200, smart.Width())
 	assert.Equal(100, smart.Height())
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, smart.RelPermalink(), 200, 100)
+	assertFileCache(assert, fileCache, smart.RelPermalink(), 200, 100)
 
 	// Check cache
 	filledAgain, err := image.Fill("200x100 bottomLeft")
 	assert.NoError(err)
 	assert.True(filled == filledAgain)
 	assert.True(filled.sourceFilename == filledAgain.sourceFilename)
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, filledAgain.RelPermalink(), 200, 100)
+	assertFileCache(assert, fileCache, filledAgain.RelPermalink(), 200, 100)
 
 }
 
@@ -286,6 +288,7 @@ func TestImageResizeInSubPath(t *testing.T) {
 	assert := require.New(t)
 
 	image := fetchImage(assert, "sub/gohugoio2.png")
+	fileCache := image.spec.FileCaches.ImageCache().Fs
 
 	assert.Equal(imaging.PNG, image.format)
 	assert.Equal("/a/sub/gohugoio2.png", image.RelPermalink())
@@ -297,7 +300,7 @@ func TestImageResizeInSubPath(t *testing.T) {
 	assert.Equal("/a/sub/gohugoio2_hu0e1b9e4a4be4d6f86c7b37b9ccce3fbc_73886_101x101_resize_linear_2.png", resized.RelPermalink())
 	assert.Equal(101, resized.Width())
 
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, resized.RelPermalink(), 101, 101)
+	assertFileCache(assert, fileCache, resized.RelPermalink(), 101, 101)
 	publishedImageFilename := filepath.Clean(resized.RelPermalink())
 	assertImageFile(assert, image.spec.BaseFs.PublishFs, publishedImageFilename, 101, 101)
 	assert.NoError(image.spec.BaseFs.PublishFs.Remove(publishedImageFilename))
@@ -309,7 +312,7 @@ func TestImageResizeInSubPath(t *testing.T) {
 	assert.NoError(err)
 	assert.Equal("/a/sub/gohugoio2_hu0e1b9e4a4be4d6f86c7b37b9ccce3fbc_73886_101x101_resize_linear_2.png", resizedAgain.RelPermalink())
 	assert.Equal(101, resizedAgain.Width())
-	assertFileCache(assert, image.spec.BaseFs.Resources.Fs, resizedAgain.RelPermalink(), 101, 101)
+	assertFileCache(assert, fileCache, resizedAgain.RelPermalink(), 101, 101)
 	assertImageFile(assert, image.spec.BaseFs.PublishFs, publishedImageFilename, 101, 101)
 
 }
diff --git a/resource/resource.go b/resource/resource.go
index be3ebdb8b..350519913 100644
--- a/resource/resource.go
+++ b/resource/resource.go
@@ -28,6 +28,7 @@ import (
 	"github.com/gohugoio/hugo/tpl"
 	"github.com/pkg/errors"
 
+	"github.com/gohugoio/hugo/cache/filecache"
 	"github.com/gohugoio/hugo/common/collections"
 	"github.com/gohugoio/hugo/common/hugio"
 	"github.com/gohugoio/hugo/common/loggers"
@@ -280,12 +281,15 @@ type Spec struct {
 
 	imageCache    *imageCache
 	ResourceCache *ResourceCache
-
-	GenImagePath  string
-	GenAssetsPath string
+	FileCaches    filecache.Caches
 }
 
-func NewSpec(s *helpers.PathSpec, logger *loggers.Logger, outputFormats output.Formats, mimeTypes media.Types) (*Spec, error) {
+func NewSpec(
+	s *helpers.PathSpec,
+	fileCaches filecache.Caches,
+	logger *loggers.Logger,
+	outputFormats output.Formats,
+	mimeTypes media.Types) (*Spec, error) {
 
 	imaging, err := decodeImaging(s.Cfg.GetStringMap("imaging"))
 	if err != nil {
@@ -296,24 +300,16 @@ func NewSpec(s *helpers.PathSpec, logger *loggers.Logger, outputFormats output.F
 		logger = loggers.NewErrorLogger()
 	}
 
-	genImagePath := filepath.FromSlash("_gen/images")
-	// The transformed assets (CSS etc.)
-	genAssetsPath := filepath.FromSlash("_gen/assets")
-
 	rs := &Spec{PathSpec: s,
 		Logger:        logger,
-		GenImagePath:  genImagePath,
-		GenAssetsPath: genAssetsPath,
 		imaging:       &imaging,
 		MediaTypes:    mimeTypes,
 		OutputFormats: outputFormats,
+		FileCaches:    fileCaches,
 		imageCache: newImageCache(
+			fileCaches.ImageCache(),
+
 			s,
-			// We're going to write a cache pruning routine later, so make it extremely
-			// unlikely that the user shoots him or herself in the foot
-			// and this is set to a value that represents data he/she
-			// cares about. This should be set in stone once released.
-			genImagePath,
 		)}
 
 	rs.ResourceCache = newResourceCache(rs)
diff --git a/resource/resource_cache.go b/resource/resource_cache.go
index e0b86ec9e..e7c6ab6d0 100644
--- a/resource/resource_cache.go
+++ b/resource/resource_cache.go
@@ -15,14 +15,13 @@ package resource
 
 import (
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"path"
 	"path/filepath"
 	"strings"
 	"sync"
 
-	"github.com/gohugoio/hugo/helpers"
-	"github.com/spf13/afero"
+	"github.com/gohugoio/hugo/cache/filecache"
 
 	"github.com/BurntSushi/locker"
 )
@@ -35,8 +34,10 @@ const (
 type ResourceCache struct {
 	rs *Spec
 
-	cache map[string]Resource
 	sync.RWMutex
+	cache map[string]Resource
+
+	fileCache *filecache.Cache
 
 	// Provides named resource locks.
 	nlocker *locker.Locker
@@ -56,9 +57,10 @@ func ResourceKeyPartition(filename string) string {
 
 func newResourceCache(rs *Spec) *ResourceCache {
 	return &ResourceCache{
-		rs:      rs,
-		cache:   make(map[string]Resource),
-		nlocker: locker.NewLocker(),
+		rs:        rs,
+		fileCache: rs.FileCaches.AssetsCache(),
+		cache:     make(map[string]Resource),
+		nlocker:   locker.NewLocker(),
 	}
 }
 
@@ -118,65 +120,56 @@ func (c *ResourceCache) GetOrCreate(partition, key string, f func() (Resource, e
 }
 
 func (c *ResourceCache) getFilenames(key string) (string, string) {
-	filenameBase := filepath.Join(c.rs.GenAssetsPath, key)
-	filenameMeta := filenameBase + ".json"
-	filenameContent := filenameBase + ".content"
+	filenameMeta := key + ".json"
+	filenameContent := key + ".content"
 
 	return filenameMeta, filenameContent
 }
 
-func (c *ResourceCache) getFromFile(key string) (afero.File, transformedResourceMetadata, bool) {
+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)
-	fMeta, err := c.rs.Resources.Fs.Open(filenameMeta)
-	if err != nil {
-		return nil, meta, false
-	}
-	defer fMeta.Close()
 
-	jsonContent, err := ioutil.ReadAll(fMeta)
-	if err != nil {
-		return nil, meta, false
+	_, jsonContent, _ := c.fileCache.GetBytes(filenameMeta)
+	if jsonContent == nil {
+		return filecache.ItemInfo{}, nil, meta, false
 	}
 
 	if err := json.Unmarshal(jsonContent, &meta); err != nil {
-		return nil, meta, false
+		return filecache.ItemInfo{}, nil, meta, false
 	}
 
-	fContent, err := c.rs.Resources.Fs.Open(filenameContent)
-	if err != nil {
-		return nil, meta, false
-	}
+	fi, rc, _ := c.fileCache.Get(filenameContent)
+
+	return fi, rc, meta, rc != nil
 
-	return fContent, meta, true
 }
 
 // writeMeta writes the metadata to file and returns a writer for the content part.
-func (c *ResourceCache) writeMeta(key string, meta transformedResourceMetadata) (afero.File, error) {
+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 nil, err
+		return filecache.ItemInfo{}, nil, err
 	}
 
-	fm, err := c.openResourceFileForWriting(filenameMeta)
+	_, fm, err := c.fileCache.WriteCloser(filenameMeta)
 	if err != nil {
-		return nil, err
+		return filecache.ItemInfo{}, nil, err
 	}
+	defer fm.Close()
 
 	if _, err := fm.Write(raw); err != nil {
-		return nil, err
+		return filecache.ItemInfo{}, nil, err
 	}
 
-	return c.openResourceFileForWriting(filenameContent)
+	fi, fc, err := c.fileCache.WriteCloser(filenameContent)
 
-}
+	return fi, fc, err
 
-func (c *ResourceCache) openResourceFileForWriting(filename string) (afero.File, error) {
-	return helpers.OpenFileForWriting(c.rs.Resources.Fs, filename)
 }
 
 func (c *ResourceCache) set(key string, r Resource) {
diff --git a/resource/testhelpers_test.go b/resource/testhelpers_test.go
index 2a5d2b3cd..05a02a6fc 100644
--- a/resource/testhelpers_test.go
+++ b/resource/testhelpers_test.go
@@ -13,6 +13,7 @@ import (
 	"runtime"
 	"strings"
 
+	"github.com/gohugoio/hugo/cache/filecache"
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/hugofs"
 	"github.com/gohugoio/hugo/media"
@@ -49,10 +50,12 @@ func newTestResourceSpecForBaseURL(assert *require.Assertions, baseURL string) *
 	fs := hugofs.NewMem(cfg)
 
 	s, err := helpers.NewPathSpec(fs, cfg)
-
 	assert.NoError(err)
 
-	spec, err := NewSpec(s, nil, output.DefaultFormats, media.DefaultTypes)
+	filecaches, err := filecache.NewCachesFromPaths(s.Paths)
+	assert.NoError(err)
+
+	spec, err := NewSpec(s, filecaches, nil, output.DefaultFormats, media.DefaultTypes)
 	assert.NoError(err)
 	return spec
 }
@@ -70,7 +73,7 @@ func newTestResourceOsFs(assert *require.Assertions) *Spec {
 	}
 
 	cfg.Set("workingDir", workDir)
-	cfg.Set("resourceDir", filepath.Join(workDir, "res"))
+	cfg.Set("resourceDir", "resources")
 	cfg.Set("contentDir", "content")
 	cfg.Set("dataDir", "data")
 	cfg.Set("i18nDir", "i18n")
@@ -83,10 +86,12 @@ func newTestResourceOsFs(assert *require.Assertions) *Spec {
 	fs.Destination = &afero.MemMapFs{}
 
 	s, err := helpers.NewPathSpec(fs, cfg)
-
 	assert.NoError(err)
 
-	spec, err := NewSpec(s, nil, output.DefaultFormats, media.DefaultTypes)
+	filecaches, err := filecache.NewCachesFromPaths(s.Paths)
+	assert.NoError(err)
+
+	spec, err := NewSpec(s, filecaches, nil, output.DefaultFormats, media.DefaultTypes)
 	assert.NoError(err)
 	return spec
 
@@ -144,7 +149,7 @@ func assertImageFile(assert *require.Assertions, fs afero.Fs, filename string, w
 }
 
 func assertFileCache(assert *require.Assertions, fs afero.Fs, filename string, width, height int) {
-	assertImageFile(assert, fs, filepath.Join("_gen/images", filename), width, height)
+	assertImageFile(assert, fs, filepath.Clean(filename), width, height)
 }
 
 func writeSource(t testing.TB, fs *hugofs.Fs, filename, content string) {
diff --git a/resource/transform.go b/resource/transform.go
index a4b1ca27c..0b5772dde 100644
--- a/resource/transform.go
+++ b/resource/transform.go
@@ -24,7 +24,6 @@ import (
 	"github.com/gohugoio/hugo/common/hugio"
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/mitchellh/hashstructure"
-	"github.com/spf13/afero"
 
 	"fmt"
 	"io"
@@ -210,12 +209,12 @@ func (r *transformedResource) transferTransformedValues(another *transformedReso
 }
 
 func (r *transformedResource) tryTransformedFileCache(key string) io.ReadCloser {
-	f, meta, found := r.cache.getFromFile(key)
+	fi, f, meta, found := r.cache.getFromFile(key)
 	if !found {
 		return nil
 	}
 	r.transformedResourceMetadata = meta
-	r.sourceFilename = f.Name()
+	r.sourceFilename = fi.Name
 
 	return f
 }
@@ -263,7 +262,7 @@ func (r *transformedResource) initContent() error {
 	var err error
 	r.contentInit.Do(func() {
 		var b []byte
-		b, err := afero.ReadFile(r.cache.rs.Resources.Fs, r.sourceFilename)
+		_, b, err = r.cache.fileCache.GetBytes(r.sourceFilename)
 		if err != nil {
 			return
 		}
@@ -434,16 +433,15 @@ func (r *transformedResource) transform(setContent bool) (err error) {
 	}
 	defer publicw.Close()
 
-	publishwriters := []io.Writer{publicw}
+	publishwriters := []io.WriteCloser{publicw}
 
 	if transformedContentr == nil {
 		// Also write it to the cache
-		metaw, err := r.cache.writeMeta(key, r.transformedResourceMetadata)
+		fi, metaw, err := r.cache.writeMeta(key, r.transformedResourceMetadata)
 		if err != nil {
 			return err
 		}
-		r.sourceFilename = metaw.Name()
-		defer metaw.Close()
+		r.sourceFilename = fi.Name
 
 		publishwriters = append(publishwriters, metaw)
 
@@ -460,11 +458,12 @@ func (r *transformedResource) transform(setContent bool) (err error) {
 	if setContent {
 		contentmemw = bp.GetBuffer()
 		defer bp.PutBuffer(contentmemw)
-		publishwriters = append(publishwriters, contentmemw)
+		publishwriters = append(publishwriters, hugio.ToWriteCloser(contentmemw))
 	}
 
-	publishw := io.MultiWriter(publishwriters...)
+	publishw := hugio.NewMultiWriteCloser(publishwriters...)
 	_, r.transformErr = io.Copy(publishw, transformedContentr)
+	publishw.Close()
 
 	if setContent {
 		r.contentInit.Do(func() {
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))
-}
diff --git a/tpl/data/cache_test.go b/tpl/data/cache_test.go
deleted file mode 100644
index 6057f0321..000000000
--- a/tpl/data/cache_test.go
+++ /dev/null
@@ -1,63 +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 (
-	"fmt"
-	"testing"
-
-	"github.com/spf13/afero"
-	"github.com/spf13/viper"
-	"github.com/stretchr/testify/assert"
-)
-
-func TestCache(t *testing.T) {
-	t.Parallel()
-
-	fs := new(afero.MemMapFs)
-
-	for i, test := range []struct {
-		path    string
-		content []byte
-		ignore  bool
-	}{
-		{"http://Foo.Bar/foo_Bar-Foo", []byte(`T€st Content 123`), false},
-		{"fOO,bar:foo%bAR", []byte(`T€st Content 123 fOO,bar:foo%bAR`), false},
-		{"FOo/BaR.html", []byte(`FOo/BaR.html T€st Content 123`), false},
-		{"трям/трям", []byte(`T€st трям/трям Content 123`), false},
-		{"은행", []byte(`T€st C은행ontent 123`), false},
-		{"Банковский кассир", []byte(`Банковский кассир T€st Content 123`), false},
-		{"Банковский кассир", []byte(`Банковский кассир T€st Content 456`), true},
-	} {
-		msg := fmt.Sprintf("Test #%d: %v", i, test)
-
-		cfg := viper.New()
-
-		c, err := getCache(test.path, fs, cfg, test.ignore)
-		assert.NoError(t, err, msg)
-		assert.Nil(t, c, msg)
-
-		err = writeCache(test.path, test.content, fs, cfg, test.ignore)
-		assert.NoError(t, err, msg)
-
-		c, err = getCache(test.path, fs, cfg, test.ignore)
-		assert.NoError(t, err, msg)
-
-		if test.ignore {
-			assert.Nil(t, c, msg)
-		} else {
-			assert.Equal(t, string(test.content), string(c))
-		}
-	}
-}
diff --git a/tpl/data/data.go b/tpl/data/data.go
index cecce4b45..61de2f72e 100644
--- a/tpl/data/data.go
+++ b/tpl/data/data.go
@@ -20,17 +20,20 @@ import (
 	"errors"
 	"net/http"
 	"strings"
-	"time"
 
+	"github.com/gohugoio/hugo/cache/filecache"
 	"github.com/gohugoio/hugo/deps"
 	_errors "github.com/pkg/errors"
 )
 
 // New returns a new instance of the data-namespaced template functions.
 func New(deps *deps.Deps) *Namespace {
+
 	return &Namespace{
-		deps:   deps,
-		client: http.DefaultClient,
+		deps:         deps,
+		cacheGetCSV:  deps.FileCaches.GetCSVCache(),
+		cacheGetJSON: deps.FileCaches.GetJSONCache(),
+		client:       http.DefaultClient,
 	}
 }
 
@@ -38,6 +41,9 @@ func New(deps *deps.Deps) *Namespace {
 type Namespace struct {
 	deps *deps.Deps
 
+	cacheGetJSON *filecache.Cache
+	cacheGetCSV  *filecache.Cache
+
 	client *http.Client
 }
 
@@ -48,40 +54,34 @@ type Namespace struct {
 // GetCSV returns nil or a slice slice to use in a short code.
 func (ns *Namespace) GetCSV(sep string, urlParts ...string) (d [][]string, err error) {
 	url := strings.Join(urlParts, "")
+	cache := ns.cacheGetCSV
 
-	var clearCacheSleep = func(i int, u string) {
-		ns.deps.Log.INFO.Printf("Retry #%d for %s and sleeping for %s", i, url, resSleep)
-		time.Sleep(resSleep)
-		deleteCache(url, ns.deps.Fs.Source, ns.deps.Cfg)
-	}
-
-	for i := 0; i <= resRetries; i++ {
-		var req *http.Request
-		req, err = http.NewRequest("GET", url, nil)
-		if err != nil {
-			return nil, _errors.Wrapf(err, "failed to create request for getCSV for resource %s", url)
+	unmarshal := func(b []byte) (error, bool) {
+		if !bytes.Contains(b, []byte(sep)) {
+			return _errors.Errorf("cannot find separator %s in CSV for %s", sep, url), false
 		}
 
-		req.Header.Add("Accept", "text/csv")
-		req.Header.Add("Accept", "text/plain")
-
-		var c []byte
-		c, err = ns.getResource(req)
-		if err != nil {
-			return nil, _errors.Wrapf(err, "failed to read CSV resource %q", url)
-		}
-
-		if !bytes.Contains(c, []byte(sep)) {
-			return nil, _errors.Errorf("cannot find separator %s in CSV for %s", sep, url)
-		}
-
-		if d, err = parseCSV(c, sep); err != nil {
+		if d, err = parseCSV(b, sep); err != nil {
 			err = _errors.Wrapf(err, "failed to parse CSV file %s", url)
 
-			clearCacheSleep(i, url)
-			continue
+			return err, true
 		}
-		break
+
+		return nil, false
+	}
+
+	var req *http.Request
+	req, err = http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, _errors.Wrapf(err, "failed to create request for getCSV for resource %s", url)
+	}
+
+	req.Header.Add("Accept", "text/csv")
+	req.Header.Add("Accept", "text/plain")
+
+	err = ns.getResource(cache, unmarshal, req)
+	if err != nil {
+		return nil, _errors.Wrapf(err, "failed to read CSV resource %q", url)
 	}
 
 	return
@@ -90,38 +90,34 @@ func (ns *Namespace) GetCSV(sep string, urlParts ...string) (d [][]string, err e
 // GetJSON expects one or n-parts of a URL to a resource which can either be a local or a remote one.
 // If you provide multiple parts they will be joined together to the final URL.
 // GetJSON returns nil or parsed JSON to use in a short code.
-func (ns *Namespace) GetJSON(urlParts ...string) (v interface{}, err error) {
+func (ns *Namespace) GetJSON(urlParts ...string) (interface{}, error) {
+	var v interface{}
 	url := strings.Join(urlParts, "")
+	cache := ns.cacheGetJSON
 
-	for i := 0; i <= resRetries; i++ {
-		var req *http.Request
-		req, err = http.NewRequest("GET", url, nil)
-		if err != nil {
-			return nil, _errors.Wrapf(err, "Failed to create request for getJSON resource %s", url)
-		}
-
-		req.Header.Add("Accept", "application/json")
-
-		var c []byte
-		c, err = ns.getResource(req)
-		if err != nil {
-			return nil, _errors.Wrapf(err, "failed to get getJSON resource %q", url)
-		}
-		err = json.Unmarshal(c, &v)
-		if err != nil {
-			ns.deps.Log.INFO.Printf("Cannot read JSON from resource %s: %s", url, err)
-			ns.deps.Log.INFO.Printf("Retry #%d for %s and sleeping for %s", i, url, resSleep)
-			time.Sleep(resSleep)
-			deleteCache(url, ns.deps.Fs.Source, ns.deps.Cfg)
-			continue
-		}
-		break
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, _errors.Wrapf(err, "Failed to create request for getJSON resource %s", url)
 	}
 
+	unmarshal := func(b []byte) (error, bool) {
+		err := json.Unmarshal(b, &v)
+		if err != nil {
+			return err, true
+		}
+		return nil, false
+	}
+
+	req.Header.Add("Accept", "application/json")
+
+	err = ns.getResource(cache, unmarshal, req)
+
 	if err != nil {
 		return nil, _errors.Wrapf(err, "failed to get getJSON resource %q", url)
 	}
-	return
+
+	return v, nil
+
 }
 
 // parseCSV parses bytes of CSV data into a slice slice string or an error
diff --git a/tpl/data/init_test.go b/tpl/data/init_test.go
index 6bb689a95..c4751e892 100644
--- a/tpl/data/init_test.go
+++ b/tpl/data/init_test.go
@@ -16,8 +16,8 @@ package data
 import (
 	"testing"
 
-	"github.com/gohugoio/hugo/deps"
 	"github.com/gohugoio/hugo/tpl/internal"
+	"github.com/spf13/viper"
 	"github.com/stretchr/testify/require"
 )
 
@@ -25,8 +25,11 @@ func TestInit(t *testing.T) {
 	var found bool
 	var ns *internal.TemplateFuncsNamespace
 
+	v := viper.New()
+	v.Set("contentDir", "content")
+
 	for _, nsf := range internal.TemplateFuncsNamespaceRegistry {
-		ns = nsf(&deps.Deps{})
+		ns = nsf(newDeps(v))
 		if ns.Name == name {
 			found = true
 			break
diff --git a/tpl/data/resources.go b/tpl/data/resources.go
index 11c35f9d9..8b246a662 100644
--- a/tpl/data/resources.go
+++ b/tpl/data/resources.go
@@ -14,102 +14,81 @@
 package data
 
 import (
-	"fmt"
 	"io/ioutil"
 	"net/http"
 	"path/filepath"
-	"sync"
 	"time"
 
+	"github.com/pkg/errors"
+
+	"github.com/gohugoio/hugo/cache/filecache"
+
 	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/spf13/afero"
-	jww "github.com/spf13/jwalterweatherman"
 )
 
 var (
-	remoteURLLock = &remoteLock{m: make(map[string]*sync.Mutex)}
-	resSleep      = time.Second * 2 // if JSON decoding failed sleep for n seconds before retrying
-	resRetries    = 1               // number of retries to load the JSON from URL or local file system
+	resSleep   = time.Second * 2 // if JSON decoding failed sleep for n seconds before retrying
+	resRetries = 1               // number of retries to load the JSON from URL
 )
 
-type remoteLock struct {
-	sync.RWMutex
-	m map[string]*sync.Mutex
-}
-
-// URLLock locks an URL during download
-func (l *remoteLock) URLLock(url string) {
-	var (
-		lock *sync.Mutex
-		ok   bool
-	)
-	l.Lock()
-	if lock, ok = l.m[url]; !ok {
-		lock = &sync.Mutex{}
-		l.m[url] = lock
-	}
-	l.Unlock()
-	lock.Lock()
-}
-
-// URLUnlock unlocks an URL when the download has been finished. Use only in defer calls.
-func (l *remoteLock) URLUnlock(url string) {
-	l.RLock()
-	defer l.RUnlock()
-	if um, ok := l.m[url]; ok {
-		um.Unlock()
-	}
-}
-
 // getRemote loads the content of a remote file. This method is thread safe.
-func getRemote(req *http.Request, fs afero.Fs, cfg config.Provider, hc *http.Client) ([]byte, error) {
+func (ns *Namespace) getRemote(cache *filecache.Cache, unmarshal func([]byte) (error, bool), req *http.Request) error {
 	url := req.URL.String()
+	id := helpers.MD5String(url)
+	var handled bool
+	var retry bool
+
+	_, b, err := cache.GetOrCreateBytes(id, func() ([]byte, error) {
+		var err error
+		handled = true
+		for i := 0; i <= resRetries; i++ {
+			ns.deps.Log.INFO.Printf("Downloading: %s ...", url)
+			var res *http.Response
+			res, err = ns.client.Do(req)
+			if err != nil {
+				return nil, err
+			}
+
+			if isHTTPError(res) {
+				return nil, errors.Errorf("Failed to retrieve remote file: %s", http.StatusText(res.StatusCode))
+			}
+
+			var b []byte
+			b, err = ioutil.ReadAll(res.Body)
+
+			if err != nil {
+				return nil, err
+			}
+			res.Body.Close()
+
+			err, retry = unmarshal(b)
+
+			if err == nil {
+				// Return it so it can be cached.
+				return b, nil
+			}
+
+			if !retry {
+				return nil, err
+			}
+
+			ns.deps.Log.INFO.Printf("Cannot read remote resource %s: %s", url, err)
+			ns.deps.Log.INFO.Printf("Retry #%d for %s and sleeping for %s", i+1, url, resSleep)
+			time.Sleep(resSleep)
+		}
 
-	c, err := getCache(url, fs, cfg, cfg.GetBool("ignoreCache"))
-	if err != nil {
 		return nil, err
-	}
-	if c != nil {
-		return c, nil
+
+	})
+
+	if !handled {
+		// This is cached content and should be correct.
+		err, _ = unmarshal(b)
 	}
 
-	// avoid race condition with locks, block other goroutines if the current url is processing
-	remoteURLLock.URLLock(url)
-	defer func() { remoteURLLock.URLUnlock(url) }()
-
-	// avoid multiple locks due to calling getCache twice
-	c, err = getCache(url, fs, cfg, cfg.GetBool("ignoreCache"))
-	if err != nil {
-		return nil, err
-	}
-	if c != nil {
-		return c, nil
-	}
-
-	jww.INFO.Printf("Downloading: %s ...", url)
-	res, err := hc.Do(req)
-	if err != nil {
-		return nil, err
-	}
-
-	if res.StatusCode < 200 || res.StatusCode > 299 {
-		return nil, fmt.Errorf("Failed to retrieve remote file: %s", http.StatusText(res.StatusCode))
-	}
-
-	c, err = ioutil.ReadAll(res.Body)
-	res.Body.Close()
-	if err != nil {
-		return nil, err
-	}
-
-	err = writeCache(url, c, fs, cfg, cfg.GetBool("ignoreCache"))
-	if err != nil {
-		return nil, err
-	}
-
-	jww.INFO.Printf("... and cached to: %s", getCacheFileID(cfg, url))
-	return c, nil
+	return err
 }
 
 // getLocal loads the content of a local file
@@ -123,12 +102,22 @@ func getLocal(url string, fs afero.Fs, cfg config.Provider) ([]byte, error) {
 
 }
 
-// getResource loads the content of a local or remote file
-func (ns *Namespace) getResource(req *http.Request) ([]byte, error) {
+// getResource loads the content of a local or remote file and returns its content and the
+// cache ID used, if relevant.
+func (ns *Namespace) getResource(cache *filecache.Cache, unmarshal func(b []byte) (error, bool), req *http.Request) error {
 	switch req.URL.Scheme {
 	case "":
-		return getLocal(req.URL.String(), ns.deps.Fs.Source, ns.deps.Cfg)
+		b, err := getLocal(req.URL.String(), ns.deps.Fs.Source, ns.deps.Cfg)
+		if err != nil {
+			return err
+		}
+		err, _ = unmarshal(b)
+		return err
 	default:
-		return getRemote(req, ns.deps.Fs.Source, ns.deps.Cfg, ns.client)
+		return ns.getRemote(cache, unmarshal, req)
 	}
 }
+
+func isHTTPError(res *http.Response) bool {
+	return res.StatusCode < 200 || res.StatusCode > 299
+}
diff --git a/tpl/data/resources_test.go b/tpl/data/resources_test.go
index c1da36d05..54eb123ee 100644
--- a/tpl/data/resources_test.go
+++ b/tpl/data/resources_test.go
@@ -23,6 +23,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/gohugoio/hugo/hugolib/paths"
+
+	"github.com/gohugoio/hugo/cache/filecache"
 	"github.com/gohugoio/hugo/common/loggers"
 	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/deps"
@@ -85,16 +88,16 @@ func getTestServer(handler func(w http.ResponseWriter, r *http.Request)) (*httpt
 func TestScpGetRemote(t *testing.T) {
 	t.Parallel()
 	fs := new(afero.MemMapFs)
+	cache := filecache.NewCache(fs, 100)
 
 	tests := []struct {
 		path    string
 		content []byte
-		ignore  bool
 	}{
-		{"http://Foo.Bar/foo_Bar-Foo", []byte(`T€st Content 123`), false},
-		{"http://Doppel.Gänger/foo_Bar-Foo", []byte(`T€st Cont€nt 123`), false},
-		{"http://Doppel.Gänger/Fizz_Bazz-Foo", []byte(`T€st Банковский кассир Cont€nt 123`), false},
-		{"http://Doppel.Gänger/Fizz_Bazz-Bar", []byte(`T€st Банковский кассир Cont€nt 456`), true},
+		{"http://Foo.Bar/foo_Bar-Foo", []byte(`T€st Content 123`)},
+		{"http://Doppel.Gänger/foo_Bar-Foo", []byte(`T€st Cont€nt 123`)},
+		{"http://Doppel.Gänger/Fizz_Bazz-Foo", []byte(`T€st Банковский кассир Cont€nt 123`)},
+		{"http://Doppel.Gänger/Fizz_Bazz-Bar", []byte(`T€st Банковский кассир Cont€nt 456`)},
 	}
 
 	for _, test := range tests {
@@ -108,53 +111,64 @@ func TestScpGetRemote(t *testing.T) {
 		})
 		defer func() { srv.Close() }()
 
-		cfg := viper.New()
+		ns := newTestNs()
+		ns.client = cl
 
-		c, err := getRemote(req, fs, cfg, cl)
+		var c []byte
+		f := func(b []byte) (error, bool) {
+			c = b
+			return nil, false
+		}
+
+		err = ns.getRemote(cache, f, req)
 		require.NoError(t, err, msg)
 		assert.Equal(t, string(test.content), string(c))
 
-		c, err = getCache(req.URL.String(), fs, cfg, test.ignore)
-		require.NoError(t, err, msg)
+		assert.Equal(t, string(test.content), string(c))
 
-		if test.ignore {
-			assert.Empty(t, c, msg)
-		} else {
-			assert.Equal(t, string(test.content), string(c))
-
-		}
 	}
 }
 
 func TestScpGetRemoteParallel(t *testing.T) {
 	t.Parallel()
 
-	ns := newTestNs()
-
 	content := []byte(`T€st Content 123`)
 	srv, cl := getTestServer(func(w http.ResponseWriter, r *http.Request) {
 		w.Write(content)
 	})
+
 	defer func() { srv.Close() }()
 
 	url := "http://Foo.Bar/foo_Bar-Foo"
 	req, err := http.NewRequest("GET", url, nil)
 	require.NoError(t, err)
 
-	for _, ignoreCache := range []bool{false, true} {
+	for _, ignoreCache := range []bool{false} {
 		cfg := viper.New()
 		cfg.Set("ignoreCache", ignoreCache)
+		cfg.Set("contentDir", "content")
+
+		ns := New(newDeps(cfg))
+		ns.client = cl
 
 		var wg sync.WaitGroup
 
-		for i := 0; i < 50; i++ {
+		for i := 0; i < 1; i++ {
 			wg.Add(1)
 			go func(gor int) {
 				defer wg.Done()
 				for j := 0; j < 10; j++ {
-					c, err := getRemote(req, ns.deps.Fs.Source, ns.deps.Cfg, cl)
+					var c []byte
+					f := func(b []byte) (error, bool) {
+						c = b
+						return nil, false
+					}
+					err := ns.getRemote(ns.cacheGetJSON, f, req)
+
 					assert.NoError(t, err)
-					assert.Equal(t, string(content), string(c))
+					if string(content) != string(c) {
+						t.Fatalf("expected\n%q\ngot\n%q", content, c)
+					}
 
 					time.Sleep(23 * time.Millisecond)
 				}
@@ -173,11 +187,16 @@ func newDeps(cfg config.Provider) *deps.Deps {
 		panic(err)
 	}
 
+	fs := hugofs.NewMem(l)
 	logger := loggers.NewErrorLogger()
+	p, _ := paths.New(fs, cfg)
+
+	fileCaches, _ := filecache.NewCachesFromPaths(p)
 
 	return &deps.Deps{
 		Cfg:              cfg,
-		Fs:               hugofs.NewMem(l),
+		Fs:               fs,
+		FileCaches:       fileCaches,
 		ContentSpec:      cs,
 		Log:              logger,
 		DistinctErrorLog: helpers.NewDistinctLogger(logger.ERROR),