package org.lttng.ust.agent.log4j;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.Set;
+import java.util.TreeSet;
+
+import org.apache.log4j.Appender;
+import org.apache.log4j.Category;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
import org.lttng.ust.agent.AbstractLttngAgent;
/**
return instance;
}
+ @Override
+ public Collection<String> listAvailableEvents() {
+ Set<String> ret = new TreeSet<String>();
+
+ @SuppressWarnings("unchecked")
+ List<Logger> loggers = Collections.list(LogManager.getCurrentLoggers());
+ for (Logger logger : loggers) {
+ if (logger == null) {
+ continue;
+ }
+
+ /*
+ * Check if that logger has at least one LTTng log4j appender
+ * attached.
+ */
+ if (hasLttngAppenderAttached(logger)) {
+ ret.add(logger.getName());
+ }
+ }
+
+ return ret;
+ }
+
+ private static boolean hasLttngAppenderAttached(Category logger) {
+ @SuppressWarnings("unchecked")
+ Enumeration<Appender> appenders = logger.getAllAppenders();
+ if (appenders != null) {
+ for (Appender appender : Collections.list(appenders)) {
+ if (appender instanceof LttngLogAppender) {
+ return true;
+ }
+ }
+ }
+
+ /*
+ * A parent logger, if any, may be connected to an LTTng handler. In
+ * this case, we will want to include this child logger in the output,
+ * since it will be accessible by LTTng.
+ */
+ Category parent = logger.getParent();
+ if (parent != null) {
+ return hasLttngAppenderAttached(parent);
+ }
+
+ /*
+ * We have reached the root logger and have not found any LTTng handler,
+ * this event will not be accessible.
+ */
+ return false;
+ }
+
}