Refactor Java agent to let applications manage the log handlers

[lttng-ust.git] / liblttng-ust-java-agent / java / lttng-ust-agent-jul / org / lttng / ust / agent / jul / LttngLogHandler.java

diff --git a/liblttng-ust-java-agent/java/lttng-ust-agent-jul/org/lttng/ust/agent/jul/LttngLogHandler.java b/liblttng-ust-java-agent/java/lttng-ust-agent-jul/org/lttng/ust/agent/jul/LttngLogHandler.java
new file mode 100644 (file)
index 0000000..d8e0cb8
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+++ b/liblttng-ust-java-agent/java/lttng-ust-agent-jul/org/lttng/ust/agent/jul/LttngLogHandler.java
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
+ * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License, version 2.1 only,
+ * as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+package org.lttng.ust.agent.jul;
+
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.logging.Handler;
+import java.util.logging.LogRecord;
+
+import org.lttng.ust.agent.ILttngAgent;
+import org.lttng.ust.agent.ILttngHandler;
+
+/**
+ * LTTng-UST JUL log handler.
+ *
+ * Applications can attach this handler to their
+ * {@link java.util.logging.Logger} to have it generate UST events from logging
+ * events received through the logger.
+ *
+ * It sends its events to UST via the JNI library "liblttng-ust-jul-jni.so".
+ * Make sure this library is available before using this handler.
+ *
+ * @author Alexandre Montplaisir
+ * @author David Goulet
+ */
+public class LttngLogHandler extends Handler implements ILttngHandler {
+
+       private static final String SHARED_OBJECT_NAME = "lttng-ust-jul-jni";
+
+       private final ILttngAgent<LttngLogHandler> agent;
+
+       /** Number of events logged (really sent through JNI) by this handler */
+       private final AtomicLong eventCount = new AtomicLong(0);
+
+       /**
+        * Constructor
+        *
+        * @throws IOException
+        *             This handler requires the lttng-ust-jul-jni.so native
+        *             library, through which it will send the trace events. This
+        *             exception is throw is this library cannot be found.
+        * @throws SecurityException
+        *             We will forward any SecurityExcepion that may be thrown when
+        *             trying to load the JNI library.
+        */
+       public LttngLogHandler() throws IOException, SecurityException {
+               super();
+               /* Initialize LTTng UST tracer. */
+               try {
+                       System.loadLibrary(SHARED_OBJECT_NAME); //$NON-NLS-1$
+               } catch (UnsatisfiedLinkError e) {
+                       throw new IOException(e);
+               }
+
+               /** Register to the relevant agent */
+               agent = LttngJulAgent.getInstance();
+               agent.registerHandler(this);
+       }
+
+       @Override
+       public synchronized void close() {
+               agent.unregisterHandler(this);
+       }
+
+       /**
+        * Get the number of events logged by this handler so far. This means the
+        * number of events actually sent through JNI to UST.
+        *
+        * @return The number of events logged so far
+        */
+       @Override
+       public long getEventCount() {
+               return eventCount.get();
+       }
+
+       @Override
+       public void flush() {
+       }
+
+       @Override
+       public void publish(LogRecord record) {
+               /*
+                * Check if the current message should be logged, according to the UST
+                * session settings.
+                */
+               if (!agent.isEventEnabled(record.getLoggerName())) {
+                       return;
+               }
+
+               eventCount.incrementAndGet();
+               /*
+                * Specific tracepoint designed for JUL events. The source class of the
+                * caller is used for the event name, the raw message is taken, the
+                * loglevel of the record and the thread ID.
+                */
+               tracepoint(record.getMessage(),
+                               record.getLoggerName(),
+                               record.getSourceClassName(),
+                               record.getSourceMethodName(),
+                               record.getMillis(),
+                               record.getLevel().intValue(),
+                               record.getThreadID());
+       }
+
+       /* Send tracepoint information to the JNI library */
+       private native void tracepoint(String msg,
+                       String logger_name,
+                       String class_name,
+                       String method_name,
+                       long millis,
+                       int log_level,
+                       int thread_id);
+}