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 */
017
018package org.apache.logging.log4j.core;
019
020import org.apache.logging.log4j.Level;
021import org.apache.logging.log4j.Marker;
022import org.apache.logging.log4j.message.Message;
023import org.apache.logging.log4j.util.EnglishEnums;
024
025/**
026 * Interface that must be implemented to allow custom event filtering. It is highly recommended that
027 * applications make use of the Filters provided with this implementation before creating their own.
028 *
029 * This interface supports "global" filters (i.e. - all events must pass through them first), attached to
030 * specific loggers and associated with Appenders. It is recommended that, where possible, Filter implementations
031 * create a generic filtering method that can be called from any of the filter methods.
032 */
033public interface Filter {
034
035    /**
036     * The result that can returned from a filter method call.
037     */
038     enum Result {
039        /**
040         * The event will be processed without further filtering based on the log Level.
041         */
042        ACCEPT,
043        /**
044         * No decision could be made, further filtering should occur.
045         */
046        NEUTRAL,
047        /**
048         * The event should not be processed.
049         */
050        DENY;
051
052        /**
053         * Returns the Result for the given string.
054         *
055         * @param name The Result enum name, case-insensitive. If null, returns, null
056         * @return a Result enum value or null if name is null
057         */
058        public static Result toResult(final String name) {
059            return toResult(name, null);
060        }
061
062        /**
063         * Returns the Result for the given string.
064         *
065         * @param name The Result enum name, case-insensitive. If null, returns, defaultResult
066         * @param defaultResult the Result to return if name is null
067         * @return a Result enum value or null if name is null
068         */
069        public static Result toResult(final String name, final Result defaultResult) {
070            return EnglishEnums.valueOf(Result.class, name, defaultResult);
071        }
072}
073
074    /**
075     * Returns the result that should be returned when the filter does not match the event.
076     * @return the Result that should be returned when the filter does not match the event.
077     */
078    Result getOnMismatch();
079    /**
080     * Returns the result that should be returned when the filter matches the event.
081     * @return the Result that should be returned when the filter matches the event.
082     */
083    Result getOnMatch();
084
085    /**
086     * Filter an event.
087     * @param logger The Logger.
088     * @param level The event logging Level.
089     * @param marker The Marker for the event or null.
090     * @param msg String text to filter on.
091     * @param params An array of parameters or null.
092     * @return the Result.
093     */
094    Result filter(Logger logger, Level level, Marker marker, String msg, Object... params);
095
096    /**
097     * Filter an event.
098     * @param logger The Logger.
099     * @param level The event logging Level.
100     * @param marker The Marker for the event or null.
101     * @param msg Any Object.
102     * @param t A Throwable or null.
103     * @return the Result.
104     */
105    Result filter(Logger logger, Level level, Marker marker, Object msg, Throwable t);
106
107    /**
108     * Filter an event.
109     * @param logger The Logger.
110     * @param level The event logging Level.
111     * @param marker The Marker for the event or null.
112     * @param msg The Message
113     * @param t A Throwable or null.
114     * @return the Result.
115     */
116    Result filter(Logger logger, Level level, Marker marker, Message msg, Throwable t);
117
118    /**
119     * Filter an event.
120     * @param event The Event to filter on.
121     * @return the Result.
122     */
123    Result filter(LogEvent event);
124
125}