cache/filecache: Add a cache prune func

Fixes #5439

cache/filecache/filecache_pruner_test.go

@@ -0,0 +1,100 @@
+// 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"
+	"testing"
+	"time"
+
+	"github.com/gohugoio/hugo/config"
+	"github.com/gohugoio/hugo/hugofs"
+	"github.com/gohugoio/hugo/hugolib/paths"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPrune(t *testing.T) {
+	t.Parallel()
+
+	assert := require.New(t)
+
+	configStr := `
+resourceDir = "myresources"
+[caches]
+[caches.getjson]
+maxAge = "200ms"
+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)
+
+	jsonCache := caches.GetJSONCache()
+	for i := 0; i < 10; i++ {
+		id := fmt.Sprintf("i%d", i)
+		jsonCache.GetOrCreateBytes(id, func() ([]byte, error) {
+			return []byte("abc"), nil
+		})
+		if i == 4 {
+			// This will expire the first 5
+			time.Sleep(201 * time.Millisecond)
+		}
+	}
+
+	count, err := caches.Prune()
+	assert.NoError(err)
+	assert.Equal(5, count)
+
+	for i := 0; i < 10; i++ {
+		id := fmt.Sprintf("i%d", i)
+		v := jsonCache.getString(id)
+		if i < 5 {
+			assert.Equal("", v, id)
+		} else {
+			assert.Equal("abc", v, id)
+		}
+	}
+
+	caches, err = NewCachesFromPaths(p)
+	assert.NoError(err)
+	jsonCache = caches.GetJSONCache()
+	// Touch one and then prune.
+	jsonCache.GetOrCreateBytes("i5", func() ([]byte, error) {
+		return []byte("abc"), nil
+	})
+
+	count, err = caches.Prune()
+	assert.NoError(err)
+	assert.Equal(4, count)
+
+	// Now only the i5 should be left.
+	for i := 0; i < 10; i++ {
+		id := fmt.Sprintf("i%d", i)
+		v := jsonCache.getString(id)
+		if i != 5 {
+			assert.Equal("", v, id)
+		} else {
+			assert.Equal("abc", v, id)
+		}
+	}
+
+}