org.scijava.util.DebugUtils Maven / Gradle / Ivy
/*
* #%L
* SciJava Common shared library for SciJava software.
* %%
* Copyright (C) 2009 - 2017 Board of Regents of the University of
* Wisconsin-Madison, Broad Institute of MIT and Harvard, Max Planck
* Institute of Molecular Cell Biology and Genetics, University of
* Konstanz, and KNIME GmbH.
* %%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
package org.scijava.util;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Map;
/**
* Useful methods for debugging programs.
*
* @author Curtis Rueden
*/
public final class DebugUtils {
private static final String NL = System.getProperty("line.separator");
private DebugUtils() {
// prevent instantiation of utility class
}
/** Extracts the given exception's corresponding stack trace to a string. */
public static String getStackTrace(final Throwable t) {
try {
final ByteArrayOutputStream out = new ByteArrayOutputStream();
t.printStackTrace(new PrintStream(out, false, "UTF-8"));
return new String(out.toByteArray(), "UTF-8");
}
catch (final IOException exc) {
return null;
}
}
/**
* Provides a complete stack dump of all threads.
*
* The output is similar to a subset of that given when Ctrl+\ (or Ctrl+Pause
* on Windows) is pressed from the console.
*/
public static String getStackDump() {
final StringBuilder sb = new StringBuilder();
final Map stackTraces =
Thread.getAllStackTraces();
// sort list of threads by name
final ArrayList threads =
new ArrayList<>(stackTraces.keySet());
Collections.sort(threads, new Comparator() {
@Override
public int compare(final Thread t1, final Thread t2) {
return t1.getName().compareTo(t2.getName());
}
});
for (final Thread t : threads) {
dumpThread(t, stackTraces.get(t), sb);
}
return sb.toString();
}
/**
* This method uses reflection to scan the values of the given class's static
* fields, returning the first matching field's name.
*/
public static String getFieldName(final Class c, final int value) {
final Field[] fields = c.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
if (!Modifier.isStatic(fields[i].getModifiers())) continue;
fields[i].setAccessible(true);
try {
if (fields[i].getInt(null) == value) return fields[i].getName();
}
catch (final IllegalAccessException exc) {
// no action needed
}
catch (final IllegalArgumentException exc) {
// no action needed
}
}
return "" + value;
}
/**
* Get the class whose main method launched the application. The heuristic
* will fail if the main thread has terminated before this method is called.
*/
public static String getMainClassName() {
final Map traceMap =
Thread.getAllStackTraces();
for (final Thread thread : traceMap.keySet()) {
if (!"main".equals(thread.getName())) continue;
final StackTraceElement[] trace = traceMap.get(thread);
if (trace == null || trace.length == 0) continue;
final StackTraceElement element = trace[trace.length - 1];
return element.getClassName();
}
return null;
}
// -- Helper methods --
private static void dumpThread(final Thread t,
final StackTraceElement[] trace, final StringBuilder sb)
{
threadInfo(t, sb);
for (final StackTraceElement element : trace) {
sb.append("\tat ");
sb.append(element);
sb.append(NL);
}
sb.append(NL);
}
private static void threadInfo(final Thread t, final StringBuilder sb) {
sb.append("\"");
sb.append(t.getName());
sb.append("\"");
if (!t.isAlive()) sb.append(" DEAD");
if (t.isInterrupted()) sb.append(" INTERRUPTED");
if (t.isDaemon()) sb.append(" daemon");
sb.append(" prio=");
sb.append(t.getPriority());
sb.append(" id=");
sb.append(t.getId());
sb.append(" group=");
sb.append(t.getThreadGroup().getName());
sb.append(NL);
sb.append(" java.lang.Thread.State: ");
sb.append(t.getState());
sb.append(NL);
}
}