content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.master.file.meta;
  
  import alluxio.AlluxioURI;
  import alluxio.exception.AccessControlException;
  import alluxio.exception.FileDoesNotExistException;
  import alluxio.exception.InvalidPathException;
  import alluxio.exception.status.UnavailableException;
  import alluxio.master.file.FileSystemMaster;
  import alluxio.wire.FileBlockInfo;
  import alluxio.wire.FileInfo;
  import alluxio.wire.WorkerInfo;
  
  import com.google.common.base.Preconditions;
  
  import java.util.List;
  import javax.annotation.concurrent.ThreadSafe;
  
  /**
   * This class exposes a read-only view of {@link FileSystemMaster}.
   */
  @ThreadSafe
  public final class FileSystemMasterView {
    private final FileSystemMaster mFileSystemMaster;
  
    /**
     * Constructs a view of the {@link FileSystemMaster}.
     *
     * @param fileSystemMaster the file system master
     */
    public FileSystemMasterView(FileSystemMaster fileSystemMaster) {
      mFileSystemMaster = Preconditions.checkNotNull(fileSystemMaster, "fileSystemMaster");
    }
  
    /**
     * Returns the {@link FileInfo} for a given path. Called via RPC, as well as internal masters.
     *
     * @param fileId the file id to get the {@link FileInfo} for
     * @return the {@link FileInfo} for the given file id
     * @throws FileDoesNotExistException if the file does not exist
     * @throws AccessControlException if permission denied
     */
    public synchronized FileInfo getFileInfo(long fileId)
        throws FileDoesNotExistException, AccessControlException, UnavailableException {
      return mFileSystemMaster.getFileInfo(fileId);
    }
  
    /**
     * Returns the file id for a given path. If the given path does not exist in Alluxio, the method
     * attempts to load it from UFS.
     *
     * @param path the path to get the file id for
     * @return the file id for a given path, or -1 if there is no file at that path
     * @throws AccessControlException if permission checking fails
     * @throws FileDoesNotExistException if file does not exist
     */
    public synchronized long getFileId(AlluxioURI path)
        throws AccessControlException, FileDoesNotExistException, UnavailableException {
      return mFileSystemMaster.getFileId(path);
    }
  
    /**
     * @param path the path to get the info for
     * @return a list of {@link FileBlockInfo} for all the blocks of the given file
     * @throws FileDoesNotExistException if the file does not exist
     * @throws InvalidPathException if the path of the given file is invalid
     * @throws AccessControlException if permission checking fails
     */
    public synchronized List<FileBlockInfo> getFileBlockInfoList(AlluxioURI path)
        throws FileDoesNotExistException, InvalidPathException, AccessControlException,
        UnavailableException {
      return mFileSystemMaster.getFileBlockInfoList(path);
    }
  
    /**
     * Gets the path of a file with the given id.
     *
     * @param fileId the id of the file to look up
     * @return the path of the file
     * @throws FileDoesNotExistException raise if the file does not exist
     */
    public synchronized AlluxioURI getPath(long fileId) throws FileDoesNotExistException {
      return mFileSystemMaster.getPath(fileId);
    }
  
    /**
     * @return a list of {@link WorkerInfo} objects representing the workers in Alluxio
     */
    public synchronized List<WorkerInfo> getWorkerInfoList() throws UnavailableException {
      return mFileSystemMaster.getWorkerInfoList();
    }
  }
  