001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.input;
018
019/**
020 * Listener for events from a {@link Tailer}.
021 *
022 * @since 2.0
023 */
024public interface TailerListener {
025
026    /**
027     * The tailer will call this method during construction,
028     * giving the listener a method of stopping the tailer.
029     * @param tailer the tailer.
030     */
031    void init(Tailer tailer);
032
033    /**
034     * This method is called if the tailed file is not found.
035     * <p>
036     * <b>Note:</b> this is called from the tailer thread.
037     */
038    void fileNotFound();
039
040    /**
041     * Called if a file rotation is detected.
042     *
043     * This method is called before the file is reopened, and fileNotFound may
044     * be called if the new file has not yet been created.
045     * <p>
046     * <b>Note:</b> this is called from the tailer thread.
047     */
048    void fileRotated();
049
050    /**
051     * Handles a line from a Tailer.
052     * <p>
053     * <b>Note:</b> this is called from the tailer thread.
054     * @param line the line.
055     */
056    void handle(String line);
057
058    /**
059     * Handles an Exception .
060     * <p>
061     * <b>Note:</b> this is called from the tailer thread.
062     * @param ex the exception.
063     */
064    void handle(Exception ex);
065
066}