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 * <p>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 * <p>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 *
35 * @author Ceki Gülcü
36 */
37 public interface ErrorHandler {
38
39 /**
40 * Add a reference to a logger to which the failing appender might
41 * be attached to. The failing appender will be searched and
42 * replaced only in the loggers you add through this method.
43 *
44 * @param logger One of the loggers that will be searched for the failing
45 * appender in view of replacement.
46 * @since 1.2
47 */
48 void setLogger(Logger logger);
49
50
51 /**
52 * Equivalent to the {@link #error(String, Exception, int,
53 * LoggingEvent)} with the the event parameter set to
54 * <code>null</code>.
55 */
56 void error(String message, Exception e, int errorCode);
57
58 /**
59 * This method is normally used to just print the error message
60 * passed as a parameter.
61 */
62 void error(String message);
63
64 /**
65 * This method is invoked to handle the error.
66 *
67 * @param message The message associated with the error.
68 * @param e The Exception that was thrown when the error occurred.
69 * @param errorCode The error code associated with the error.
70 * @param event The logging event that the failing appender is asked
71 * to log.
72 * @since 1.2
73 */
74 void error(String message, Exception e, int errorCode, LoggingEvent event);
75
76 /**
77 * Set the appender for which errors are handled. This method is
78 * usually called when the error handler is configured.
79 *
80 * @since 1.2
81 */
82 void setAppender(Appender appender);
83
84 /**
85 * Set the appender to fallback upon in case of failure.
86 *
87 * @since 1.2
88 */
89 void setBackupAppender(Appender appender);
90 }
91