/* | |
* Licensed to the Apache Software Foundation (ASF) under one | |
* or more contributor license agreements. See the NOTICE file | |
* distributed with this work for additional information | |
* regarding copyright ownership. The ASF licenses this file | |
* to you 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 org.apache.pig.backend.datastorage; | |
import java.util.Properties; | |
import java.util.Map; | |
import java.io.IOException; | |
/** | |
* DataStorage provides an abstraction of a generic container. | |
* Special instances of it can be a file system. | |
* | |
*/ | |
public interface DataStorage { | |
public static final String USED_BYTES_KEY = "pig.used.bytes"; | |
public static final String RAW_CAPACITY_KEY = "pig.raw.capacity.bytes"; // replication is disregarded | |
public static final String RAW_USED_KEY = "pig.raw.used.capacity.bytes"; // replication is disregarded | |
// | |
// TODO: more keys | |
// | |
/** | |
* Place holder for possible initialization activities. | |
*/ | |
public void init(); | |
/** | |
* Clean-up and releasing of resources. | |
*/ | |
public void close() throws IOException; | |
/** | |
* Provides configuration information about the storage itself. | |
* For instance global data-replication policies if any, default | |
* values, ... Some of such values could be overridden at a finer | |
* granularity (e.g. on a specific object in the Data Storage) | |
* | |
* @return - configuration information | |
*/ | |
public Properties getConfiguration(); | |
/** | |
* Provides a way to change configuration parameters | |
* at the Data Storage level. For instance, change the | |
* data replication policy. | |
* | |
* @param newConfiguration - the new configuration settings | |
* @throws when configuration conflicts are detected | |
* | |
*/ | |
public void updateConfiguration(Properties newConfiguration) | |
throws DataStorageException; | |
/** | |
* Provides statistics on the Storage: capacity values, how much | |
* storage is in use... | |
* @return statistics on the Data Storage | |
*/ | |
public Map<String, Object> getStatistics() throws IOException; | |
/** | |
* Creates an entity handle for an object (no containment | |
* relation) from a String | |
* | |
* @param name of the object | |
* @return an object descriptor | |
* @throws DataStorageException if name does not conform to naming | |
* convention enforced by the Data Storage. | |
*/ | |
public ElementDescriptor asElement(String name) | |
throws DataStorageException; | |
public ElementDescriptor asElement(ElementDescriptor element) | |
throws DataStorageException; | |
public ElementDescriptor asElement(String parent, | |
String child) | |
throws DataStorageException; | |
public ElementDescriptor asElement(ContainerDescriptor parent, | |
String child) | |
throws DataStorageException; | |
public ElementDescriptor asElement(ContainerDescriptor parent, | |
ElementDescriptor child) | |
throws DataStorageException; | |
public boolean isContainer(String name) throws DataStorageException; | |
/** | |
* Created an entity handle for a container. | |
* | |
* @param name of the container | |
* @return a container descriptor | |
* @throws DataStorageException if name does not conform to naming | |
* convention enforced by the Data Storage. | |
*/ | |
public ContainerDescriptor asContainer(String name) | |
throws DataStorageException; | |
public ContainerDescriptor asContainer(ContainerDescriptor container) | |
throws DataStorageException; | |
public ContainerDescriptor asContainer(String parent, | |
String child) | |
throws DataStorageException; | |
public ContainerDescriptor asContainer(ContainerDescriptor parent, | |
String child) | |
throws DataStorageException; | |
public ContainerDescriptor asContainer(ContainerDescriptor parent, | |
ContainerDescriptor child) | |
throws DataStorageException; | |
public ElementDescriptor[] asCollection(String pattern) | |
throws DataStorageException; | |
public void setActiveContainer(ContainerDescriptor container); | |
public ContainerDescriptor getActiveContainer(); | |
} |