1 /*
2 * Grapht, an open source dependency injector.
3 * Copyright 2014-2015 various contributors (see CONTRIBUTORS.txt)
4 * Copyright 2010-2014 Regents of the University of Minnesota
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as
8 * published by the Free Software Foundation; either version 2.1 of the
9 * License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
14 * details.
15 *
16 * You should have received a copy of the GNU General Public License along with
17 * this program; if not, write to the Free Software Foundation, Inc., 51
18 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
19 */
20 package org.grouplens.grapht.util;
21
22 import java.util.Collections;
23 import java.util.Map;
24 import org.slf4j.MDC;
25
26 /**
27 * Utility class to manage log data with {@link MDC}. This class allows MDC parameters
28 * to be set, and popped back off when the context is finished.
29 */
30
31 public class LogContext {
32 @SuppressWarnings("rawtypes")
33
34 private final Map memory = MDC.getCopyOfContextMap();
35
36 private LogContext() {}
37
38 /**
39 * Method creates a new log context,
40 * capturing the MDC's current data to be
41 * restored when finish() is called.
42 */
43 static public LogContext create() {
44 return new LogContext();
45 }
46
47 /**
48 * Set a key in the MDC environment.
49 * @param key The key to set.
50 * @param value The key's value.
51 * @see MDC#put(String, String)
52 */
53 public void put(String key, String value) {
54 MDC.put(key, value);
55 }
56
57 /**
58 * Finish the context. This restores the MDC context map to the value it had when the
59 * log context was created.
60 */
61 public void finish() {
62 MDC.setContextMap(memory == null ? Collections.EMPTY_MAP : memory);
63 }
64 }
65