service/exception/SuccinctStackTraceFormatter.java

	SuccinctStackTraceFormatter.java revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/* ident    "%Z%%M% %I% %E% SMI" */

package com.sun.solaris.service.exception;

import java.io.*;

/**
 * Formats a stack trace in a single line.  The format is meant to
 * convey the stack trace as a sequence of class names and line numbers,
 * with the topmost frame first, suitable for logging.  Beware, the
 * format may evolve.
 */
public class SuccinctStackTraceFormatter {
    /**
     * Formats a Throwable and adds an optional description string.
     * The string should be suitable to precede the top stack
     * element, and include any punctuation that should
     * differentiate it from the element.
     */
    public static String formatWithDescription(Throwable t,
        String description)
    {
        StringBuffer s = new StringBuffer();

        s.append("(");

        if (description != null)
            s.append(description);

        s.append(t.getClass().getName());
        s.append(", ");
        StackTraceElement[] trace = t.getStackTrace();
        for (int i = 0; i < trace.length; i++) {
            appendStackTraceElement(i > 0 ? trace[i - 1] : null,
                trace[i], s);
            if (i != trace.length - 1)
                s.append(", ");
        }
        s.append(")");

        if (t.getCause() != null) {
            s.append(" caused by ");
            s.append(format(t.getCause()));
        }

        return (s.toString());
    }

    /**
     * Formats a Throwable's stack trace.  The format is meant to be
     * a single line of output, conveying the stack trace as a
     * sequence of class names and line numbers, with the topmost
     * frame first, suitable for logging.  If two adjacent stack
     * trace elements share some portion of a class name, the
     * bottommost element may have the common part replaced with an
     * ampersand.
     */
    public static String format(Throwable t)
    {
        return (formatWithDescription(t, null));
    }

    /**
     * Formats a stack trace element as per <code>format()</code>.
     */
    private static void appendStackTraceElement(StackTraceElement last,
        StackTraceElement e, StringBuffer s)
    {
        /*
         * This could grab more of a common class name.  (See
         * SuccinctStackTraceFormatter.format())
         */
        if (last == null || !last.getClassName().equals(
            e.getClassName())) {
            s.append(e.getClassName());
            s.append(".");
        } else
            s.append("&.");

        s.append(e.getMethodName());
        if (e.getLineNumber() > 0) {
            s.append(":");
            s.append(e.getLineNumber());
        }
        if (e.isNativeMethod()) {
            s.append(":");
            s.append("native");
        }
    }

    public static void printStackTrace(Throwable t)
    {
        printStackTrace(t, System.err);
    }

    public static void printStackTrace(Throwable t, PrintStream out)
    {
        out.print(t);
        out.print(" at ");
        out.print(format(t));
    }

    public static final void main(String args[])
    {
        SuccinctStackTraceFormatter.printStackTrace(big());
    }

    public static final Throwable big() {
        return new Throwable().initCause(little());
    }

    public static final Throwable little() {
        return new Throwable();
    }

}