liblttng-ust-java-agent/java/org/lttng/ust/agent/log4j/LTTngLog4j.java

   1 /*
   2  * Copyright (C) 2014 - Christian Babeux <christian.babeux@efficios.com>
   3  *
   4  *
   5  * This library is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This library is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public License
  15  * along with this library; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 package org.lttng.ust.agent.log4j;
  20
  21 import java.util.Enumeration;
  22 import java.util.Iterator;
  23 import java.util.Vector;
  24
  25 import org.apache.log4j.LogManager;
  26 import org.apache.log4j.Logger;
  27
  28 import org.lttng.ust.agent.LogFrameworkSkeleton;
  29
  30 public class LTTngLog4j extends LogFrameworkSkeleton {
  31
  32         private LTTngLogAppender appender;
  33         private Boolean attached;
  34
  35         public LTTngLog4j(Boolean isRoot) {
  36                 super();
  37                 this.appender = new LTTngLogAppender(isRoot);
  38                 this.attached = false;
  39         }
  40
  41         @Override
  42         public Boolean enableLogger(String name) {
  43                 if(!super.enableLogger(name)) {
  44                         return false;
  45                 }
  46
  47                 /* The first enable of any event triggers the attachment to the root logger */
  48                 if (getEventCount() == 1 && !this.attached) {
  49                         attachToRootLogger();
  50                 }
  51
  52                 return true;
  53         }
  54
  55         @Override
  56         public Boolean disableLogger(String name) {
  57                 if(!super.disableLogger(name)) {
  58                         return false;
  59                 }
  60
  61                 /* Detach from the root logger when the event counts reach zero */
  62                 if (getEventCount() == 0 && this.attached) {
  63                         detachFromRootLogger();
  64                 }
  65
  66                 return true;
  67         }
  68
  69         @Override
  70         public Iterator<String> listLoggers() {
  71                 Vector<String> logs = new Vector<String>();
  72                 for (Enumeration loggers = LogManager.getCurrentLoggers(); loggers.hasMoreElements(); ) {
  73                         Logger logger = (Logger) loggers.nextElement();
  74                         String name = logger.getName();
  75                         logs.add(name);
  76                 }
  77
  78                 return logs.iterator();
  79         }
  80
  81         @Override
  82         public Boolean isRoot() {
  83                 return appender.isRoot();
  84         }
  85
  86         @Override
  87         public void reset() {
  88                 super.reset();
  89                 detachFromRootLogger();
  90         }
  91
  92         private void attachToRootLogger() {
  93                 if (this.attached) {
  94                         return;
  95                 }
  96
  97                 Logger logger = Logger.getRootLogger();
  98                 logger.addAppender(this.appender);
  99                 this.attached = true;
 100         }
 101
 102         private void detachFromRootLogger() {
 103                 if (!this.attached) {
 104                         return;
 105                 }
 106
 107                 Logger logger = Logger.getRootLogger();
 108                 logger.removeAppender(this.appender);
 109                 this.attached = false;
 110         }
 111 }