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

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2015 EfficiOS Inc.
   5  * Copyright (C) 2015 Alexandre Montplaisir <alexmonthy@efficios.com>
   6  * Copyright (C) 2014 Christian Babeux <christian.babeux@efficios.com>
   7  */
   8
   9 package org.lttng.ust.agent.log4j;
  10
  11 import java.io.IOException;
  12 import java.util.Collection;
  13 import java.util.Map;
  14 import java.util.Map.Entry;
  15 import java.util.concurrent.atomic.AtomicLong;
  16
  17 import org.apache.log4j.AppenderSkeleton;
  18 import org.apache.log4j.spi.LoggingEvent;
  19 import org.lttng.ust.agent.ILttngAgent;
  20 import org.lttng.ust.agent.ILttngHandler;
  21 import org.lttng.ust.agent.context.ContextInfoSerializer;
  22
  23 /**
  24  * LTTng-UST Log4j 1.x log handler.
  25  *
  26  * Applications can attach this appender to their
  27  * {@link org.apache.log4j.Logger} to have it generate UST events from logging
  28  * events received through the logger.
  29  *
  30  * It sends its events to UST via the JNI library "liblttng-ust-log4j-jni.so".
  31  * Make sure this library is available before using this appender.
  32  *
  33  * @author Alexandre Montplaisir
  34  * @author Christian Babeux
  35  */
  36 public class LttngLogAppender extends AppenderSkeleton implements ILttngHandler {
  37
  38         private static final String SHARED_OBJECT_NAME = "lttng-ust-log4j-jni";
  39
  40         private final AtomicLong eventCount = new AtomicLong(0);
  41
  42         private final ILttngAgent<LttngLogAppender> agent;
  43
  44
  45         /**
  46          * Constructor
  47          *
  48          * @throws IOException
  49          *             This handler requires the lttng-ust-log4j-jni.so native
  50          *             library, through which it will send the trace events. This
  51          *             exception is throw is this library cannot be found.
  52          * @throws SecurityException
  53          *             We will forward any SecurityExcepion that may be thrown when
  54          *             trying to load the JNI library.
  55          */
  56         public LttngLogAppender() throws IOException, SecurityException {
  57                 super();
  58                 /* Initialize LTTng UST tracer. */
  59                 try {
  60                         System.loadLibrary(SHARED_OBJECT_NAME); // $NON-NLS-1$
  61                 } catch (UnsatisfiedLinkError e) {
  62                         throw new IOException(e);
  63                 }
  64
  65                 /** Register to the relevant agent */
  66                 agent = LttngLog4jAgent.getInstance();
  67                 agent.registerHandler(this);
  68         }
  69
  70         @Override
  71         public synchronized void close() {
  72                 agent.unregisterHandler(this);
  73         }
  74
  75         /**
  76          * Get the number of events logged by this handler so far. This means the
  77          * number of events actually sent through JNI to UST.
  78          *
  79          * @return The number of events logged so far
  80          */
  81         @Override
  82         public long getEventCount() {
  83                 return eventCount.get();
  84         }
  85
  86         @Override
  87         public boolean requiresLayout() {
  88                 return false;
  89         }
  90
  91         @Override
  92         protected void append(LoggingEvent event) {
  93                 /*
  94                  * Check if the current message should be logged, according to the UST
  95                  * session settings.
  96                  */
  97                 if (!agent.isEventEnabled(event.getLoggerName())) {
  98                         return;
  99                 }
 100
 101                 /*
 102                  * The line number returned from LocationInformation is a string. At
 103                  * least try to convert to a proper int.
 104                  */
 105                 int line;
 106                 try {
 107                         String lineString = event.getLocationInformation().getLineNumber();
 108                         line = Integer.parseInt(lineString);
 109                 } catch (NumberFormatException n) {
 110                         line = -1;
 111                 }
 112
 113                 /* Retrieve all the requested context information we can find */
 114                 Collection<Entry<String, Map<String, Integer>>> enabledContexts = agent.getEnabledAppContexts();
 115                 ContextInfoSerializer.SerializedContexts contextInfo = ContextInfoSerializer.queryAndSerializeRequestedContexts(enabledContexts);
 116
 117                 eventCount.incrementAndGet();
 118
 119                 LttngLog4jApi.tracepointWithContext(event.getRenderedMessage(),
 120                                 event.getLoggerName(),
 121                                 event.getLocationInformation().getClassName(),
 122                                 event.getLocationInformation().getMethodName(),
 123                                 event.getLocationInformation().getFileName(),
 124                                 line,
 125                                 event.getTimeStamp(),
 126                                 event.getLevel().toInt(),
 127                                 event.getThreadName(),
 128                                 contextInfo.getEntriesArray(),
 129                                 contextInfo.getStringsArray());
 130         }
 131
 132 }