/**
* Debug.java
* Copyright 2007 - 2008 Zach Scrivena
* zachscrivena@gmail.com
* http://zs.freeshell.org/
*
* TERMS AND CONDITIONS:
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.milipede.storage.layer.internal.common;
import java.io.Console;
import java.io.PrintWriter;
import java.util.Date;
import java.util.Locale;
/**
* Perform debugging-related operations.
*/
public final class Debug
{
/** time format string (yyyy-MM-dd HH:mm:ss.SSS) */
private static final String TIMESTAMP_FORMAT_STRING = "\n[%1$tF %1$tT.%1$tL] ";
/** standard error output stream */
private static PrintWriter err;
/**
* Static initialization block.
*/
static
{
final Console c = System.console();
if (c == null)
{
err = new PrintWriter(System.out);
}
else
{
err = c.writer();
}
}
/**
* Private constructor that should never be called.
*/
private Debug()
{}
/**
* Print to the standard error output stream immediately.
*
* @param format
* format string
* @param args
* arguments referenced by the format specifiers in the format string
*/
public static void p(
final String format,
final Object... args)
{
err.format(format, args);
err.flush();
}
/**
* Print to the standard error output stream immediately, with a timestamp.
*
* @param format
* format string
* @param args
* arguments referenced by the format specifiers in the format string
*/
public static void pt(
final String format,
final Object... args)
{
err.format(Locale.ENGLISH, TIMESTAMP_FORMAT_STRING, new Date());
err.format(format, args);
err.flush();
}
/**
* Get a string representation of the stack trace for the specified exception.
*
* @param ex
* exception
* @return
* string representation of the stack trace
*/
public static String getStackTraceString(
final Exception ex)
{
final StringBuilder sb = new StringBuilder("Exception stack trace:");
for (StackTraceElement e : ex.getStackTrace())
{
sb.append("\n ");
sb.append(e);
}
return sb.toString();
}
/**
* Get a string representation of the system information (OS, JRE, JVM).
*
* @return
* string representation of the system information
*/
public static String getSystemInformationString()
{
final StringBuilder sb = new StringBuilder();
sb.append("System Information:\n ");
sb.append(getSystemProperty("os.name"));
sb.append(" (");
sb.append(getSystemProperty("os.version"));
sb.append(", ");
sb.append(getSystemProperty("os.arch"));
sb.append(")\n JRE ");
sb.append(getSystemProperty("java.version"));
sb.append(" (");
sb.append(getSystemProperty("java.vendor"));
sb.append(")\n ");
sb.append(getSystemProperty("java.vm.name"));
sb.append(' ');
sb.append(getSystemProperty("java.vm.version"));
sb.append(" (");
sb.append(getSystemProperty("java.vm.vendor"));
sb.append(')');
return sb.toString();
}
/**
* Get the specified system property, without throwing any exceptions.
*
* @param key
* key of the system property to be obtained
* @return
* String representation of the specified system property
*/
public static String getSystemProperty(
final String key)
{
try
{
return System.getProperty(key);
}
catch (Exception e)
{
return String.format("Failed to get system property \"%s\" (%s)", key, e.toString());
}
}
/**
* Set the specified system property, without throwing any exceptions.
*
* @param key
* key of the system property to be set
* @param value
* value of the system property
*/
public static void setSystemProperty(
final String key,
final String value)
{
try
{
System.setProperty(key, value);
}
catch (Exception e)
{
/* ignore */
}
}
/**
* Sleep for the specified number of milliseconds.
* This method uses the Thread.sleep() method, but will ignore the InterruptedException
* exception if thrown.
*
* @param millis
* number of milliseconds to sleep
*/
public static void sleep(
final long millis)
{
try
{
Thread.sleep(millis);
}
catch (InterruptedException e)
{
/* ignore */
}
}
/******************
* NESTED CLASSES *
******************/
/**
* Represent a "capsule" for passing a single value in a thread-safe manner.
* The capsule value is set by calling <code>set()</code>, and read by calling <code>get()</code>.
* The <code>get()</code> method blocks until the value is set.
* The original state of the capsule can be restored by calling <code>reset()</code>.
*/
public static class ValueCapsule<T>
{
/** refresh interval in milliseconds */
private static final long REFRESH_INTERVAL_MILLISECONDS = 50L;
/** capsule value to be passed */
private T value;
/** mutex lock for <code>value</code> */
private final Object valueLock = new Object();
/** has the capsule value been set by calling the <code>set()</code> method? */
private boolean setCalled;
/**
* Constructor.
*/
public ValueCapsule()
{
reset();
}
/**
* Restore the original state of the capsule.
*/
public void reset()
{
synchronized (valueLock)
{
value = null;
setCalled = false;
}
}
/**
* Set the capsule value.
*
* @param value
* new capsule value
*/
public void set(
final T value)
{
synchronized (valueLock)
{
this.value = value;
setCalled = true;
}
}
/**
* Get the capsule value.
* This method blocks until the value is set.
*
* @return
* capsule value
*/
public T get()
{
while (true)
{
synchronized (valueLock)
{
if (setCalled)
{
return value;
}
}
Debug.sleep(REFRESH_INTERVAL_MILLISECONDS);
}
}
}
}