Resolved issue: NETTY-23 (Simplify an exception stack trace.)

* Added DebugUtil and StackTraceSimplifier
* DefaultExceptionEvent and InternalLoggerFactory simplifies the stack trace unless Netty debug mode is enabled.

src/main/java/org/jboss/netty/channel/DefaultExceptionEvent.java

@@ -22,6 +22,8 @@
  */
 package org.jboss.netty.channel;
 
+import org.jboss.netty.util.StackTraceSimplifier;
+
 
 public class DefaultExceptionEvent extends DefaultChannelEvent implements
         ExceptionEvent {
@@ -34,6 +36,7 @@ public class DefaultExceptionEvent extends DefaultChannelEvent implements
             throw new NullPointerException("cause");
         }
         this.cause = cause;
+        StackTraceSimplifier.simplify(cause);
     }
 
     public Throwable getCause() {

src/main/java/org/jboss/netty/logging/InternalLoggerFactory.java

@@ -22,6 +22,8 @@
  */
 package org.jboss.netty.logging;
 
+import org.jboss.netty.util.StackTraceSimplifier;
+
 /**
  * Creates an {@link InternalLogger} or changes the default factory
  * implementation.  This factory allows you to choose what logging framework
@@ -76,7 +78,61 @@ public abstract class InternalLoggerFactory {
      * Creates a new logger instance with the specified name.
      */
     public static InternalLogger getInstance(String name) {
-        return getDefaultFactory().newInstance(name);
+        final InternalLogger logger = getDefaultFactory().newInstance(name);
+        return new InternalLogger() {
+
+            public void debug(String msg) {
+                logger.debug(msg);
+            }
+
+            public void debug(String msg, Throwable cause) {
+                StackTraceSimplifier.simplify(cause);
+                logger.debug(msg, cause);
+            }
+
+            public void error(String msg) {
+                logger.error(msg);
+            }
+
+            public void error(String msg, Throwable cause) {
+                StackTraceSimplifier.simplify(cause);
+                logger.error(msg, cause);
+            }
+
+            public void info(String msg) {
+                logger.info(msg);
+            }
+
+            public void info(String msg, Throwable cause) {
+                StackTraceSimplifier.simplify(cause);
+                logger.info(msg, cause);
+            }
+
+            public boolean isDebugEnabled() {
+                return logger.isDebugEnabled();
+            }
+
+            public boolean isErrorEnabled() {
+                return logger.isErrorEnabled();
+            }
+
+            public boolean isInfoEnabled() {
+                return logger.isInfoEnabled();
+            }
+
+            public boolean isWarnEnabled() {
+                return logger.isWarnEnabled();
+            }
+
+            public void warn(String msg) {
+                logger.warn(msg);
+            }
+
+            public void warn(String msg, Throwable cause) {
+                StackTraceSimplifier.simplify(cause);
+                logger.warn(msg, cause);
+            }
+        };
     }
 
     /**

src/main/java/org/jboss/netty/util/DebugUtil.java

@@ -0,0 +1,55 @@
+/*
+ * JBoss, Home of Professional Open Source
+ *
+ * Copyright 2008, Red Hat Middleware LLC, and individual contributors
+ * by the @author tags. See the COPYRIGHT.txt in the distribution for a
+ * full listing of individual contributors.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software 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 software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.jboss.netty.util;
+
+/**
+ * Determines if Netty is running in a debug mode or not.  Please note that
+ * this is not a Java debug mode.  You can enable Netty debug mode by
+ * specifying the {@code "org.jboss.netty.debug"} system property (e.g.
+ * {@code java -Dorg.jboss.netty.debug ...})
+ *
+ * @author The Netty Project (netty-dev@lists.jboss.org)
+ * @author Trustin Lee (tlee@redhat.com)
+ *
+ * @version $Rev$, $Date$
+ */
+public class DebugUtil {
+
+    /**
+     * Returns {@code true} if and only if Netty debug mode is enabled.
+     */
+    public static boolean isDebugEnabled() {
+        String value;
+        try {
+            value = System.getProperty("org.jboss.netty.debug");
+        } catch (Exception e) {
+            value = null;
+        }
+
+        return value != null;
+    }
+
+    private DebugUtil() {
+        // Unused
+    }
+}

src/main/java/org/jboss/netty/util/StackTraceSimplifier.java

@@ -0,0 +1,80 @@
+/*
+ * JBoss, Home of Professional Open Source
+ *
+ * Copyright 2008, Red Hat Middleware LLC, and individual contributors
+ * by the @author tags. See the COPYRIGHT.txt in the distribution for a
+ * full listing of individual contributors.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software 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 software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.jboss.netty.util;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Pattern;
+
+/**
+ * @author The Netty Project (netty-dev@lists.jboss.org)
+ * @author Trustin Lee (tlee@redhat.com)
+ *
+ * @version $Rev$, $Date$
+ *
+ */
+public class StackTraceSimplifier {
+
+    private static final boolean SIMPLIFY_STACK_TRACE = !DebugUtil.isDebugEnabled();
+    private static final Pattern EXCLUDED_STACK_TRACE =
+        Pattern.compile(
+                "^org\\.jboss\\.netty\\." +
+                "(util\\.(ThreadRenamingRunnable)" +
+                "|channel\\.(SimpleChannelHandler|DefaultChannelPipeline.*))$");
+
+    public static void simplify(Throwable e) {
+        if (!SIMPLIFY_STACK_TRACE) {
+            return;
+        }
+
+        if (e.getCause() != null) {
+            simplify(e.getCause());
+        }
+
+        StackTraceElement[] trace = e.getStackTrace();
+        if (trace == null || trace.length == 0) {
+            return;
+        }
+
+        // Perhaps Netty bug.  Let's not strip things out.
+        if (EXCLUDED_STACK_TRACE.matcher(trace[0].getClassName()).matches()) {
+            return;
+        }
+
+        List<StackTraceElement> simpleTrace =
+            new ArrayList<StackTraceElement>(trace.length);
+
+        simpleTrace.add(trace[0]);
+
+        // Remove unnecessary stack trace elements.
+        for (int i = 1; i < trace.length; i ++) {
+            if (EXCLUDED_STACK_TRACE.matcher(trace[i].getClassName()).matches()) {
+                continue;
+            }
+            simpleTrace.add(trace[i]);
+        }
+
+        e.setStackTrace(
+                simpleTrace.toArray(new StackTraceElement[simpleTrace.size()]));
+    }
+}