cleanup: move pkg/ to internal/

The internal/ directory in Go has a special meaning, and indicates that
those packages are not meant for external consumption. Ceph-CSI does
provide public APIs for other projects to consume. There is no plan to
keep the API of the internally used packages stable.

Closes: #903
Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/util/cachepersister.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2018 The Ceph-CSI 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 util
+
+import (
+	"errors"
+
+	"k8s.io/klog"
+)
+
+// ForAllFunc is a unary predicate for visiting all cache entries
+// matching the `pattern' in CachePersister's ForAll function.
+type ForAllFunc func(identifier string) error
+
+// CacheEntryNotFound is an error type for "Not Found" cache errors
+type CacheEntryNotFound struct {
+	error
+}
+
+// CachePersister interface implemented for store
+type CachePersister interface {
+	Create(identifier string, data interface{}) error
+	Get(identifier string, data interface{}) error
+	ForAll(pattern string, destObj interface{}, f ForAllFunc) error
+	Delete(identifier string) error
+}
+
+// NewCachePersister returns CachePersister based on store
+func NewCachePersister(metadataStore, pluginPath string) (CachePersister, error) {
+	if metadataStore == "k8s_configmap" {
+		klog.V(4).Infof("cache-perister: using kubernetes configmap as metadata cache persister")
+		k8scm := &K8sCMCache{}
+		k8scm.Client = NewK8sClient()
+		k8scm.Namespace = GetK8sNamespace()
+		return k8scm, nil
+	} else if metadataStore == "node" {
+		klog.V(4).Infof("cache-persister: using node as metadata cache persister")
+		nc := &NodeCache{}
+		nc.BasePath = pluginPath
+		nc.CacheDir = "controller"
+		return nc, nil
+	}
+	return nil, errors.New("cache-persister: couldn't parse metadatastorage flag")
+}