1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache license, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the license for the specific language governing permissions and
15 * limitations under the license.
16 */
17 package org.apache.log4j.spi;
18
19 import org.apache.log4j.Appender;
20 import org.apache.log4j.Logger;
21
22
23 /**
24 * Appenders may delegate their error handling to
25 * <code>ErrorHandlers</code>.
26 * <p>
27 * Error handling is a particularly tedious to get right because by
28 * definition errors are hard to predict and to reproduce.
29 * </p>
30 * <p>
31 * Please take the time to contact the author in case you discover
32 * that errors are not properly handled. You are most welcome to
33 * suggest new error handling policies or criticize existing policies.
34 * </p>
35 */
36 public interface ErrorHandler {
37
38 /**
39 * Add a reference to a logger to which the failing appender might
40 * be attached to. The failing appender will be searched and
41 * replaced only in the loggers you add through this method.
42 *
43 * @param logger One of the loggers that will be searched for the failing
44 * appender in view of replacement.
45 * @since 1.2
46 */
47 void setLogger(Logger logger);
48
49
50 /**
51 * Equivalent to the {@link #error(String, Exception, int,
52 * LoggingEvent)} with the the event parameter set to
53 * <code>null</code>.
54 *
55 * @param message The message associated with the error.
56 * @param e The Exception that was thrown when the error occurred.
57 * @param errorCode The error code associated with the error.
58 */
59 void error(String message, Exception e, int errorCode);
60
61 /**
62 * This method is normally used to just print the error message
63 * passed as a parameter.
64 *
65 * @param message The message associated with the error.
66 */
67 void error(String message);
68
69 /**
70 * This method is invoked to handle the error.
71 *
72 * @param message The message associated with the error.
73 * @param e The Exception that was thrown when the error occurred.
74 * @param errorCode The error code associated with the error.
75 * @param event The logging event that the failing appender is asked
76 * to log.
77 * @since 1.2
78 */
79 void error(String message, Exception e, int errorCode, LoggingEvent event);
80
81 /**
82 * Set the appender for which errors are handled. This method is
83 * usually called when the error handler is configured.
84 *
85 * @param appender The appender
86 * @since 1.2
87 */
88 void setAppender(Appender appender);
89
90 /**
91 * Set the appender to fallback upon in case of failure.
92 *
93 * @param appender The backup appender
94 * @since 1.2
95 */
96 void setBackupAppender(Appender appender);
97 }
98