liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/LogFrameworkSkeleton.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;
  20
  21 import java.util.HashMap;
  22 import java.util.Iterator;
  23 import java.util.Map;
  24
  25 /**
  26  * Basic implementation of LogFramework.
  27  *
  28  * @author Christian Babeux
  29  */
  30 public abstract class LogFrameworkSkeleton implements LogFramework {
  31
  32         /* A map of event name and reference count */
  33         private final Map<String, Integer> enabledLoggers;
  34
  35         /**
  36          * Constructor
  37          */
  38         public LogFrameworkSkeleton() {
  39                 this.enabledLoggers = new HashMap<String, Integer>();
  40         }
  41
  42         @Override
  43         public Boolean enableLogger(String name) {
  44                 if (name == null) {
  45                         return false;
  46                 }
  47
  48                 if (enabledLoggers.containsKey(name)) {
  49                         /* Event is already enabled, simply increment its refcount */
  50                         Integer refcount = enabledLoggers.get(name);
  51                         refcount++;
  52                         Integer oldval = enabledLoggers.put(name, refcount);
  53                         assert (oldval != null);
  54                 } else {
  55                         /* Event was not enabled, init refcount to 1 */
  56                         Integer oldval = enabledLoggers.put(name, 1);
  57                         assert (oldval == null);
  58                 }
  59
  60                 return true;
  61         }
  62
  63         @Override
  64         public Boolean disableLogger(String name) {
  65                 if (name == null) {
  66                         return false;
  67                 }
  68
  69                 if (!enabledLoggers.containsKey(name)) {
  70                         /* Event was never enabled, abort */
  71                         return false;
  72                 }
  73
  74                 /* Event was previously enabled, simply decrement its refcount */
  75                 Integer refcount = enabledLoggers.get(name);
  76                 refcount--;
  77                 assert (refcount >= 0);
  78
  79                 if (refcount == 0) {
  80                         /* Event is not used anymore, remove it from the map */
  81                         Integer oldval = enabledLoggers.remove(name);
  82                         assert (oldval != null);
  83                 }
  84
  85                 return true;
  86         }
  87
  88         @Override
  89         public abstract Iterator<String> listLoggers();
  90
  91         @Override
  92         public abstract Boolean isRoot();
  93
  94         @Override
  95         public void reset() {
  96                 enabledLoggers.clear();
  97         }
  98
  99         /**
 100          * Get the number of enabled events.
 101          *
 102          * @return The number of enabled events
 103          */
 104         protected Integer getEventCount() {
 105                 return enabledLoggers.size();
 106         }
 107 }