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/*
 * 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.fs;

import org.apache.hadoop.classification.InterfaceStability;

/**
 * Common path capabilities.
 */
public final class CommonPathCapabilities {

  private CommonPathCapabilities() {
  }

  /**
   * Does the store support
   * {@code FileSystem.setAcl(Path, List)},
   * {@code FileSystem.getAclStatus(Path)}
   * and related methods?
   * Value: {@value}.
   */
  public static final String FS_ACLS = "fs.capability.paths.acls";

  /**
   * Does the store support {@code FileSystem.append(Path)}?
   * Value: {@value}.
   */
  public static final String FS_APPEND = "fs.capability.paths.append";

  /**
   * Does the store support {@code FileSystem.getFileChecksum(Path)}?
   * Value: {@value}.
   */
  public static final String FS_CHECKSUMS = "fs.capability.paths.checksums";

  /**
   * Does the store support {@code FileSystem.concat(Path, Path[])}?
   * Value: {@value}.
   */
  public static final String FS_CONCAT = "fs.capability.paths.concat";

  /**
   * Does the store support {@code FileSystem.listCorruptFileBlocks(Path)} ()}?
   * Value: {@value}.
   */
  public static final String FS_LIST_CORRUPT_FILE_BLOCKS =
      "fs.capability.paths.list-corrupt-file-blocks";

  /**
   * Does the store support
   * {@code FileSystem.createPathHandle(FileStatus, Options.HandleOpt...)}
   * and related methods?
   * Value: {@value}.
   */
  public static final String FS_PATHHANDLES = "fs.capability.paths.pathhandles";

  /**
   * Does the store support {@code FileSystem.setPermission(Path, FsPermission)}
   * and related methods?
   * Value: {@value}.
   */
  public static final String FS_PERMISSIONS = "fs.capability.paths.permissions";

  /**
   * Does this filesystem connector only support filesystem read operations?
   * For example, the {@code HttpFileSystem} is always read-only.
   * This is different from "is the specific instance and path read only?",
   * which must be determined by checking permissions (where supported), or
   * attempting write operations under a path.
   * Value: {@value}.
   */
  public static final String FS_READ_ONLY_CONNECTOR =
      "fs.capability.paths.read-only-connector";

  /**
   * Does the store support snapshots through
   * {@code FileSystem.createSnapshot(Path)} and related methods??
   * Value: {@value}.
   */
  public static final String FS_SNAPSHOTS = "fs.capability.paths.snapshots";

  /**
   * Does the store support {@code FileSystem.setStoragePolicy(Path, String)}
   * and related methods?
   * Value: {@value}.
   */
  public static final String FS_STORAGEPOLICY =
      "fs.capability.paths.storagepolicy";

  /**
   * Does the store support symlinks through
   * {@code FileSystem.createSymlink(Path, Path, boolean)} and related methods?
   * Value: {@value}.
   */
  public static final String FS_SYMLINKS =
      "fs.capability.paths.symlinks";

  /**
   * Does the store support {@code FileSystem#truncate(Path, long)} ?
   * Value: {@value}.
   */
  public static final String FS_TRUNCATE =
      "fs.capability.paths.truncate";

  /**
   * Does the store support XAttributes through
   * {@code FileSystem#.setXAttr()} and related methods?
   * Value: {@value}.
   */
  public static final String FS_XATTRS = "fs.capability.paths.xattrs";

  /**
   * Probe for support for {@link BatchListingOperations}.
   */
  @InterfaceStability.Unstable
  public static final String FS_EXPERIMENTAL_BATCH_LISTING =
      "fs.capability.batch.listing";

  /**
   * Does the store support multipart uploading?
   * Value: {@value}.
   */
  public static final String FS_MULTIPART_UPLOADER =
      "fs.capability.multipart.uploader";


  /**
   * Stream abort() capability implemented by {@link Abortable#abort()}.
   * Value: {@value}.
   */
  public static final String ABORTABLE_STREAM =
      "fs.capability.outputstream.abortable";

  /**
   * Does this FS support etags?
   * That is: will FileStatus entries from listing/getFileStatus
   * probes support EtagSource and return real values.
   */
  public static final String ETAGS_AVAILABLE =
      "fs.capability.etags.available";

  /**
   * Are etags guaranteed to be preserved across rename() operations..
   * FileSystems MUST NOT declare support for this feature
   * unless this holds.
   */
  public static final String ETAGS_PRESERVED_IN_RENAME =
      "fs.capability.etags.preserved.in.rename";

  /**
   * Does this Filesystem support lease recovery operations such as
   * {@link LeaseRecoverable#recoverLease(Path)} and {@link LeaseRecoverable#isFileClosed(Path)}}?
   * Value: {@value}.
   */
  public static final String LEASE_RECOVERABLE = "fs.capability.lease.recoverable";

  /**
   * Is this a store where parent directory listings are potentially inconsistent with
   * direct list/getFileStatus calls?
   * This can happen with Amazon S3 Express One Zone Storage when there are pending
   * uploads under a path.
   * Application code can use this flag to decide whether or not to treat
   * FileNotFoundExceptions on treewalk as errors or something to downgrade.
   * Value: {@value}.
   */
  public static final String DIRECTORY_LISTING_INCONSISTENT =
      "fs.capability.directory.listing.inconsistent";

  /**
   * Capability string to probe for bulk delete: {@value}.
   */
  public static final String BULK_DELETE = "fs.capability.bulk.delete";

  /**
   * Capability string to probe for block locations returned in {@code LocatedFileStatus}
   * instances from calls such as {@code getBlockLocations()} and {@code listStatus()}l
   * to be 'virtual' rather than actual values resolved against a Distributed Filesystem including
   * HDFS: {@value}.
   * 
   * Key implications from this path capability being true:
   * 

   *   Work can be scheduled anywhere
   *   Creation of the location list is a low cost-client side operation
   * 
   * Implication #2 means there is no performance penalty from use of FileSystem operations which
   * return lists or iterators of {@code LocatedFileStatus}.
   */
  public static final String VIRTUAL_BLOCK_LOCATIONS = "fs.capability.virtual.block.locations";

}