hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/Namesystem.java

/**
 * 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.hadoop.hdfs.server.namenode;

import java.io.IOException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockCollection;
import org.apache.hadoop.hdfs.server.namenode.ha.HAContext;
import org.apache.hadoop.hdfs.util.RwLock;

/** Namesystem operations. */
@InterfaceAudience.Private
public interface Namesystem extends RwLock, SafeMode {
  /** Is this name system running? */
  boolean isRunning();

  BlockCollection getBlockCollection(long id);

  FSDirectory getFSDirectory();

  void startSecretManagerIfNecessary();

  boolean isInSnapshot(long blockCollectionID);

  CacheManager getCacheManager();

  HAContext getHAContext();

  /**
   * @return Whether the namenode is transitioning to active state and is in the
   *         middle of the starting active services.
   */
  boolean inTransitionToActive();

  /**
   * Check if file is been opened for write purpose.
   * @param filePath
   * @return true if valid write lease exists, otherwise return false.
   */
  boolean isFileOpenedForWrite(String filePath);

  /**
   * Remove xAttr from the inode.
   * @param id
   * @param xattrName
   * @throws IOException
   */
  void removeXattr(long id, String xattrName) throws IOException;

  /**
   * Gets the fileInfo of the given file path.
   *
   * @param filePath string representation of the path to the file
   * @param resolveLink whether to throw UnresolvedLinkException
   *        if src refers to a symlink
   * @param needLocation if blockLocations need to be returned
   *
   * @return hdfs file status details
   * @throws IOException
   */
  HdfsFileStatus getFileInfo(String filePath, boolean resolveLink,
      boolean needLocation) throws IOException;
}