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     * This method is called if the tailed file is not found.
028     * <p>
029     * <b>Note:</b> this is called from the tailer thread.
030     * </p>
031     */
032    void fileNotFound();
033
034    /**
035     * Called if a file rotation is detected.
036     *
037     * This method is called before the file is reopened, and fileNotFound may
038     * be called if the new file has not yet been created.
039     * <p>
040     * <b>Note:</b> this is called from the tailer thread.
041     * </p>
042     */
043    void fileRotated();
044
045    /**
046     * Handles an Exception.
047     * <p>
048     * <b>Note:</b> this is called from the tailer thread.
049     * </p>
050     * @param ex the exception.
051     */
052    void handle(Exception ex);
053
054    /**
055     * Handles a line from a Tailer.
056     * <p>
057     * <b>Note:</b> this is called from the tailer thread.
058     * </p>
059     * @param line the line.
060     */
061    void handle(String line);
062
063    /**
064     * The tailer will call this method during construction,
065     * giving the listener a method of stopping the tailer.
066     * @param tailer the tailer.
067     */
068    void init(Tailer tailer);
069
070}