geode-core/src/main/java/org/apache/geode/internal/cache/snapshot/SnapshotFileMapper.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.geode.internal.cache.snapshot;

import java.io.File;
import java.io.Serializable;

import org.apache.geode.cache.snapshot.CacheSnapshotService;
import org.apache.geode.cache.snapshot.RegionSnapshotService;
import org.apache.geode.distributed.DistributedMember;

/**
 * Defines a mapping between the snapshot path and the file(s) to be imported or exported on a
 * specific member.
 *
 * @see SnapshotOptionsImpl#setMapper(SnapshotFileMapper)
 *
 */
public interface SnapshotFileMapper extends Serializable {
  /**
   * Invoked during a parallel export to map the supplied path to a new file name. This is necessary
   * when the export file must be written to a member-specific location. The result of the mapping
   * must resolve to a valid file path.
   * <p>
   * Example:
   *
   * <pre>
   * public File mapExportFile(String regionPath, DistributedMember member, File snapshot) {
   *   return new File(snapshot.getAbsolutePath() + "-" + member.getId());
   * }
   * </pre>
   *
   * If members are writing to a shared location, the implementation <b>must</b> provide a unique
   * file path to avoid an export error.
   *
   * @param member the member performing the export
   * @param snapshot the path specified in the invocation of
   *        {@link RegionSnapshotService#save(File, org.apache.geode.cache.snapshot.SnapshotOptions.SnapshotFormat)
   *        RegionSnapshotService.load()} or
   *        {@link CacheSnapshotService#save(File, org.apache.geode.cache.snapshot.SnapshotOptions.SnapshotFormat)
   *        CacheSnapshotService.load()}
   * @return the mapped filename, or null to use the existing file
   */
  File mapExportPath(DistributedMember member, File snapshot);

  /**
   * Invoked during a parallel import to map the supplied path to one or more files. This is
   * necessary when the import files must be read from a member-specific path or when the cache
   * topology differs from the exporting system. The result of the mapping must resolve to one or
   * more valid file paths.
   * <p>
   * Example:
   *
   * <pre>
   * public File[] mapImportPath(DistributedMember member, File snapshot) {
   *   File dir = new File(snapshot, member.getHost() + ":" + member.getProcessId());
   *   return dir.listFiles();
   * }
   * </pre>
   *
   * If members are reading from a shared location, the implementation should partition the files so
   * that a snapshot file is only imported once.
   *
   * @param member the member performing the import
   * @param snapshot the path specified in the invocation of
   *        {@link RegionSnapshotService#load(File, org.apache.geode.cache.snapshot.SnapshotOptions.SnapshotFormat)
   *        RegionSnapshotService.load()} or
   *        {@link CacheSnapshotService#load(File, org.apache.geode.cache.snapshot.SnapshotOptions.SnapshotFormat)
   *        CacheSnapshotService.load()}
   * @return the list of files to import
   */
  File[] mapImportPath(DistributedMember member, File snapshot);
}