1   /*
2    * Copyright (c) 2004-2009 QOS.ch
3    * All rights reserved.
4    * 
5    * Permission is hereby granted, free  of charge, to any person obtaining
6    * a  copy  of this  software  and  associated  documentation files  (the
7    * "Software"), to  deal in  the Software without  restriction, including
8    * without limitation  the rights to  use, copy, modify,  merge, publish,
9    * distribute,  sublicense, and/or sell  copies of  the Software,  and to
10   * permit persons to whom the Software  is furnished to do so, subject to
11   * the following conditions:
12   * 
13   * The  above  copyright  notice  and  this permission  notice  shall  be
14   * included in all copies or substantial portions of the Software.
15   * 
16   * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
17   * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
18   * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
19   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21   * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
22   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23   */
24  package org.slf4j;
25  
26  import org.slf4j.MDC;
27  
28  public class NDC {
29    public final static String PREFIX = "NDC";
30  
31    private static int size() {
32      int i = 0;
33      while (true) {
34        String val = MDC.get(PREFIX + i);
35        if (val != null) {
36          i++;
37        } else {
38          break;
39        }
40      }
41      return i;
42    }
43  
44    public static void push(String val) {
45      int next = size();
46      MDC.put(PREFIX + next, val);
47    }
48  
49    public static String pop() {
50      int next = size();
51      if(next == 0) {
52        return "";
53      }
54      int last = next-1; 
55      String key = PREFIX+last;
56      String val = MDC.get(key);
57      MDC.remove(key);
58      return val;
59    }
60  
61  }