alluxio-master-2.x/core/server/master/src/main/java/alluxio/master/file/meta/LockingScheme.java
/*
 * 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.conf.Configuration;
import alluxio.conf.PropertyKey;
import alluxio.exception.InvalidPathException;
import alluxio.file.options.DescendantType;
import alluxio.grpc.FileSystemMasterCommonPOptions;
import alluxio.master.file.meta.InodeTree.LockPattern;

import com.google.common.base.MoreObjects;

import javax.annotation.concurrent.ThreadSafe;

/**
 * This class represents information about how a path should be locked.
 */
@ThreadSafe
public final class LockingScheme {
  private final AlluxioURI mPath;
  private final LockPattern mDesiredLockPattern;
  private final SyncCheck mShouldSync;

  // CHECKSTYLE.OFF: LineLengthExceed - cannot break the method link
  /**
   * Constructs a {@link LockingScheme}.
   *
   * Avoid using this constructor where shouldSync is set true, if possible.
   * {@link #LockingScheme(AlluxioURI, LockPattern, FileSystemMasterCommonPOptions, UfsSyncPathCache, DescendantType)}
   * is the preferred one in such case, to make the metadata sync dedup feature work.
   *
   * @param path the path to lock
   * @param desiredLockPattern the desired lock mode
   * @param shouldSync true if the path should be synced
   */
  // CHECKSTYLE.ON: LineLengthExceed
  public LockingScheme(AlluxioURI path, LockPattern desiredLockPattern, boolean shouldSync) {
    mPath = path;
    mDesiredLockPattern = desiredLockPattern;
    mShouldSync = shouldSync ? SyncCheck.SHOULD_SYNC : SyncCheck.SHOULD_NOT_SYNC;
  }

  /**
   * Create a new {@link LockingScheme}.
   *
   * Thi constructor computes the value of {@link #mShouldSync} with the extra argument provided.
   *
   * @param path the path to lock
   * @param desiredPattern the desired lock mode
   * @param options the common options provided in an RPC
   * @param pathCache the {@link alluxio.master.file.DefaultFileSystemMaster}'s path cache
   * @param descendantType the descendant type
   */
  public LockingScheme(AlluxioURI path, LockPattern desiredPattern,
      FileSystemMasterCommonPOptions options, UfsSyncPathCache pathCache,
      DescendantType descendantType) throws InvalidPathException {
    mPath = path;
    mDesiredLockPattern = desiredPattern;
    // If client options didn't specify the interval, fallback to whatever the server has
    // configured to prevent unnecessary syncing due to the default value being 0
    long syncInterval = options.hasSyncIntervalMs() ? options.getSyncIntervalMs() :
        Configuration.getMs(PropertyKey.USER_FILE_METADATA_SYNC_INTERVAL);
    mShouldSync = pathCache.shouldSyncPath(path, syncInterval, descendantType);
  }

  /**
   * @return the desired mode for the locking
   */
  public LockPattern getDesiredPattern() {
    return mDesiredLockPattern;
  }

  /**
   * @return the mode that should be used to lock the path, considering if ufs sync should occur
   */
  public LockPattern getPattern() {
    if (mShouldSync.isShouldSync()) {
      // Syncing needs to be able to delete the inode if it was deleted in the UFS.
      return LockPattern.WRITE_EDGE;
    }
    return mDesiredLockPattern;
  }

  /**
   * @return the path for this locking scheme
   */
  public AlluxioURI getPath() {
    return mPath;
  }

  /**
   * @return true if the path should be synced with ufs
   */
  public SyncCheck shouldSync() {
    return mShouldSync;
  }

  @Override
  public String toString() {
    return MoreObjects.toStringHelper(this)
        .add("path", mPath)
        .add("desiredLockPattern", mDesiredLockPattern)
        .add("shouldSync", mShouldSync)
        .toString();
  }
}
