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 com.google.common.base.Preconditions;
  
  /**
   * Returned by {@link UfsSyncPathCache#shouldSyncPath} indicating whether
   * a sync is needed as well as the time of the last sync if one is not needed.
   * After the sync is performed, calling {@link SyncCheck#syncSuccess()} or
   * {@link SyncCheck#skippedSync()} will result in creating an object containing
   * information pertaining to the result of the sync.
   */
  public class SyncCheck {
    private final boolean mShouldSync;
    private final long mLastSyncTime;
  
    private static final long INVALID_SYNC_TIME = -1;
  
    /** Sync is not needed, with no last sync time. **/
    public static final SyncCheck SHOULD_NOT_SYNC = new SyncCheck(
        false, INVALID_SYNC_TIME);
    /** Sync is needed. **/
    public static final SyncCheck SHOULD_SYNC = new SyncCheck(
        true, INVALID_SYNC_TIME);
  
    /**
     * Create a SyncCheck object indicating a sync is needed, given
     * the last sync time.
     * @param lastSyncTime the time of the last sync
     * @return the result object
     */
    public static SyncCheck shouldSyncWithTime(long lastSyncTime) {
      return new SyncCheck(true, lastSyncTime);
    }
  
    /**
     * Create a SyncCheck object indicating a sync is not needed due to
     * a recent sync.
     * @param lastSyncTime the time of the last sync
     * @return the result object
     */
    public static SyncCheck shouldNotSyncWithTime(long lastSyncTime) {
      return new SyncCheck(false, lastSyncTime);
    }
  
    private SyncCheck(boolean shouldSync, long lastSyncTime) {
      mShouldSync = shouldSync;
      mLastSyncTime = lastSyncTime;
    }
  
    @Override
    public String toString() {
      return String.format("{Should sync: %b, Last sync time: %d}", mShouldSync, mLastSyncTime);
    }
  
    /**
     * @return true if a sync is necessary
     */
    public boolean isShouldSync() {
      return mShouldSync;
    }
  
    /**
     * @return the time of the last sync for the path
     */
    public long getLastSyncTime() {
      Preconditions.checkState(mLastSyncTime != INVALID_SYNC_TIME,
          "The sync time is invalid");
      return mLastSyncTime;
    }
  
    /**
     * This method should be called if the sync was performed successfully.
     * @return the {@link SyncResult} object
     */
    public SyncResult syncSuccess() {
      return SyncResult.SYNC_SUCCESS;
    }
  
    /**
     * This method should be called if the sync skipped due to the existence
     * of a recent sync.
     * @return the {@link SyncResult} object
     */
    public SyncResult skippedSync() {
      return SyncResult.skippedWithTime(mLastSyncTime);
    }
  
    /**
     * Information about the result of a synchronization, created by calling
     * {@link SyncCheck#syncSuccess()} or {@link SyncCheck#skippedSync()},
     * or using {@link SyncResult#INVALID_RESULT} if the sync failed
     * due to an external reason.
     */
    public static class SyncResult {
      private final boolean mPerformedSync;
      private final boolean mResultValid;
      private final long mLastSyncTime;
  
      public static final SyncResult INVALID_RESULT = new SyncResult(
          false, false, INVALID_SYNC_TIME);
  
      private static final SyncResult SYNC_SUCCESS = new SyncResult(
          true, true, INVALID_SYNC_TIME);
  
      private static SyncResult skippedWithTime(long lastSyncTime) {
        return new SyncResult(false, true, lastSyncTime);
      }
  
      private SyncResult(boolean syncPerformed, boolean resultValid, long lastSyncTime) {
        mPerformedSync = syncPerformed;
        mResultValid = resultValid;
        mLastSyncTime = lastSyncTime;
      }
  
      /**
       * @return true if the result was due to a valid sync (eiter a successful sync,
       * or a sync skipped due to a recent existing sync)
       */
      public boolean isResultValid() {
        return mResultValid;
      }
  
      /**
       * @return true if a synchronization was performed
       */
      public boolean wasSyncPerformed() {
        return mPerformedSync;
      }
  
      /**
       * @return the time of the last synchronization of this path
       */
      public long getLastSyncTime() {
        Preconditions.checkState(isResultValid() && !wasSyncPerformed()
            && mLastSyncTime != INVALID_SYNC_TIME,
            "last sync time is only valid if the sync result is valid and a sync was not performed");
        return mLastSyncTime;
      }
    }
  }
  