hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALActionsListener.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.hadoop.hbase.regionserver.wal;

import java.io.IOException;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.wal.WALEdit;
import org.apache.hadoop.hbase.wal.WALKey;
import org.apache.yetus.audience.InterfaceAudience;

/**
 * Get notification of WAL events. The invocations are inline
 * so make sure your implementation is fast else you'll slow hbase.
 */
@InterfaceAudience.Private
public interface WALActionsListener {

  /** The reason for the log roll request. */
  static enum RollRequestReason {
    /** The length of the log exceeds the roll size threshold. */
    SIZE,
    /** Too few replicas in the writer pipeline. */
    LOW_REPLICATION,
    /** Too much time spent waiting for sync. */
    SLOW_SYNC,
    /** I/O or other error. */
    ERROR
  };

  /**
   * The WAL is going to be rolled. The oldPath can be null if this is
   * the first log file from the regionserver.
   * @param oldPath the path to the old wal
   * @param newPath the path to the new wal
   */
  default void preLogRoll(Path oldPath, Path newPath) throws IOException {}

  /**
   * The WAL has been rolled. The oldPath can be null if this is
   * the first log file from the regionserver.
   * @param oldPath the path to the old wal
   * @param newPath the path to the new wal
   */
  default void postLogRoll(Path oldPath, Path newPath) throws IOException {}

  /**
   * The WAL is going to be archived.
   * @param oldPath the path to the old wal
   * @param newPath the path to the new wal
   */
  default void preLogArchive(Path oldPath, Path newPath) throws IOException {}

  /**
   * The WAL has been archived.
   * @param oldPath the path to the old wal
   * @param newPath the path to the new wal
   */
  default void postLogArchive(Path oldPath, Path newPath) throws IOException {}

  /**
   * A request was made that the WAL be rolled.
   */
  default void logRollRequested(RollRequestReason reason) {}

  /**
   * The WAL is about to close.
   */
  default void logCloseRequested() {}

  /**
  * Called before each write.
  */
  default void visitLogEntryBeforeWrite(RegionInfo info, WALKey logKey, WALEdit logEdit) {}

  /**
   * @param logKey
   * @param logEdit TODO: Retire this in favor of
   *          {@link #visitLogEntryBeforeWrite(RegionInfo, WALKey, WALEdit)} It only exists to get
   *          scope when replicating. Scope should be in the WALKey and not need us passing in a
   *          <code>htd</code>.
   * @throws IOException If failed to parse the WALEdit
   */
  default void visitLogEntryBeforeWrite(WALKey logKey, WALEdit logEdit) throws IOException {}

  /**
   * For notification post append to the writer.  Used by metrics system at least.
   * TODO: Combine this with above.
   * @param entryLen approx length of cells in this append.
   * @param elapsedTimeMillis elapsed time in milliseconds.
   * @param logKey A WAL key
   * @param logEdit A WAL edit containing list of cells.
   * @throws IOException if any network or I/O error occurred
   */
  default void postAppend(final long entryLen, final long elapsedTimeMillis, final WALKey logKey,
      final WALEdit logEdit) throws IOException {}

  /**
   * For notification post writer sync.  Used by metrics system at least.
   * @param timeInNanos How long the filesystem sync took in nanoseconds.
   * @param handlerSyncs How many sync handler calls were released by this call to filesystem
   * sync.
   */
  default void postSync(final long timeInNanos, final int handlerSyncs) {}
}