/*
* Copyright © 2015 Cask Data, Inc.
*
* 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 co.cask.cdap.store;
import co.cask.cdap.proto.Id;
import co.cask.cdap.proto.NamespaceMeta;
import java.util.List;
import javax.annotation.Nullable;
/**
* Store for namespaces.
*/
public interface NamespaceStore {
/**
* Creates a new namespace.
*
* @param metadata {@link NamespaceMeta} representing the namespace metadata
* @return existing {@link NamespaceMeta} if a namespace with the specified name existed already, null if the
* a namespace with the specified name did not exist, and was created successfully
* These semantics of return type are borrowed from {@link java.util.concurrent.ConcurrentHashMap#putIfAbsent}
*/
@Nullable
NamespaceMeta create(NamespaceMeta metadata);
/**
* Updates the namespace meta.
*
* @param metadata {@link NamespaceMeta} representing the namespace metadata
*/
void update(NamespaceMeta metadata);
/**
* Retrieves a namespace from the namespace metadata store.
*
* @param id {@link Id.Namespace} of the requested namespace
* @return {@link NamespaceMeta} of the requested namespace
*/
@Nullable
NamespaceMeta get(Id.Namespace id);
/**
* Deletes a namespace from the namespace metadata store.
*
* @param id {@link Id.Namespace} of the namespace to delete
* @return {@link NamespaceMeta} of the namespace if it was found and deleted, null if the specified namespace did not
* exist
* These semantics of return type are borrowed from {@link java.util.concurrent.ConcurrentHashMap#remove}
*/
@Nullable
NamespaceMeta delete(Id.Namespace id);
/**
* Lists all registered namespaces.
*
* @return a list of all registered namespaces
*/
List<NamespaceMeta> list();
}