added cephfs/volumecache - stores volume info in json files

pkg/cephfs/volumecache.go

@@ -0,0 +1,131 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+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 cephfs
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strings"
+	"sync"
+
+	"github.com/golang/glog"
+)
+
+const (
+	volumeCacheRoot = PluginFolder + "/controller/volume-cache"
+)
+
+type volumeCacheEntry struct {
+	VolOptions volumeOptions
+	Identifier volumeIdentifier
+}
+
+type volumeCache struct {
+	entries map[string]*volumeCacheEntry
+}
+
+var (
+	volCache    volumeCache
+	volCacheMtx sync.RWMutex
+)
+
+// Loads all .json files from volumeCacheRoot into volCache
+// Called from driver.go's Run()
+func loadVolumeCache() error {
+	cacheDir, err := ioutil.ReadDir(volumeCacheRoot)
+	if err != nil {
+		return fmt.Errorf("cannot read volume cache: %v", err)
+	}
+
+	volCacheMtx.Lock()
+	defer volCacheMtx.Unlock()
+
+	volCache.entries = make(map[string]*volumeCacheEntry)
+
+	for _, fi := range cacheDir {
+		if !strings.HasSuffix(fi.Name(), ".json") || !fi.Mode().IsRegular() {
+			continue
+		}
+
+		f, err := os.Open(path.Join(volumeCacheRoot, fi.Name()))
+		if err != nil {
+			glog.Errorf("cephfs: couldn't read '%s' from volume cache: %v", fi.Name(), err)
+			continue
+		}
+
+		d := json.NewDecoder(f)
+		ent := &volumeCacheEntry{}
+
+		if err = d.Decode(ent); err != nil {
+			glog.Errorf("cephfs: failed to parse '%s': %v", fi.Name(), err)
+		} else {
+			volCache.entries[ent.Identifier.uuid] = ent
+		}
+
+		f.Close()
+	}
+
+	return nil
+}
+
+func getVolumeCacheEntryPath(volUuid string) string {
+	return path.Join(volumeCacheRoot, fmt.Sprintf("vol-%s.json", volUuid))
+}
+
+func (vc *volumeCache) insert(ent *volumeCacheEntry) error {
+	filePath := getVolumeCacheEntryPath(ent.Identifier.uuid)
+
+	volCacheMtx.Lock()
+	defer volCacheMtx.Unlock()
+
+	f, err := os.Create(filePath)
+	if err != nil {
+		return fmt.Errorf("couldn't create cache entry file %s: %v", filePath, err)
+	}
+	defer f.Close()
+
+	e := json.NewEncoder(f)
+	if err = e.Encode(ent); err != nil {
+		return fmt.Errorf("failed to encode cache entry for volume %s: %v", ent.Identifier.id)
+	}
+
+	vc.entries[ent.Identifier.uuid] = ent
+
+	return nil
+}
+
+func (vc *volumeCache) erase(volUuid string) error {
+	volCacheMtx.Lock()
+	delete(vc.entries, volUuid)
+	volCacheMtx.Unlock()
+
+	return os.Remove(getVolumeCacheEntryPath(volUuid))
+}
+
+func (vc *volumeCache) get(volUuid string) (volumeCacheEntry, bool) {
+	volCacheMtx.RLock()
+	defer volCacheMtx.RUnlock()
+
+	if ent, ok := vc.entries[volUuid]; ok {
+		return *ent, true
+	} else {
+		return volumeCacheEntry{}, false
+	}
+}