/*
* sulky-modules - several general-purpose modules.
* Copyright (C) 2007-2011 Joern Huxhorn
*
* This program 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 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* Copyright 2007-2011 Joern Huxhorn
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package de.huxhorn.sulky.io;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.io.Reader;
import java.io.Writer;
/**
* As a matter of fact, catching IOException seems to be a major issue on Solaris
* since it might actually be a java.io.InterruptedIOException that extends java.io.IOException
* but must be handled like an InterruptedException, i.e. it should interrupt the current
* thread.
*
* Catching java.lang.Exception or java.lang.Throwable has the same problem
* since those could swallow either java.lang.InterruptedException
* or java.io.InterruptedIOException, too.
*
* Use the method {@link #interruptIfNecessary(Throwable)} in those cases to make sure that
* the current thread is interrupted properly. This method calls {@link java.lang.Thread#interrupt()}
* on the current thread if either exception is contained in the cause hierarchy.
*
* The methods {@link #closeQuietly(InputStream)}, {@link #closeQuietly(OutputStream)},
* {@link #closeQuietly(Reader)} and {@link #closeQuietly(Writer)} are replacements for the corresponding
* methods in org.apache.commons.io.IOUtils. In addition, this class also includes a similar
* {@link #closeQuietly(RandomAccessFile)} method for use with {@link RandomAccessFile}.
*
* This class is a direct result of http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4385444
* as well as the corresponding log4j bug report at https://issues.apache.org/bugzilla/show_bug.cgi?id=44157
*
* It was brought to my attention by the following post to the logback-user-mailinglist:
* http://www.qos.ch/pipermail/logback-user/2010-July/001644.html
*
* Thanks to Andreas Dejung for teaching me yet another piece of Java.
*
* @see InterruptedException
* @see InterruptedIOException
* @see Thread#interrupt()
*/
public final class IOUtilities
{
private IOUtilities()
{}
/**
* This method calls Thread.currentThread().interrupt() if any exception
* in the hierarchy (including all getCause()) is either InterruptedIOException
* or InterruptedException.
*
* This method should be called in every catch(IOException), catch(Exception) or
* catch(Throwable) block.
*
* @param t the Throwable to be checked for interruption. Does nothing if null.
*/
public static void interruptIfNecessary(Throwable t)
{
if(t == null)
{
return;
}
Throwable current=t;
do
{
if(current instanceof InterruptedIOException || current instanceof InterruptedException)
{
Thread.currentThread().interrupt();
break;
}
current=current.getCause();
}
while(current !=null);
}
/**
* Unconditionally close an <code>InputStream</code>.
* <p>
* Equivalent to {@link InputStream#close()}, except any exceptions will be ignored.
* {@link InterruptedIOException} is handled correctly by {@link #interruptIfNecessary(Throwable)}.
* This is typically used in finally blocks.
*
* @param x the InputStream to close, may be null or already closed
*/
public static void closeQuietly(InputStream x)
{
if(x == null)
{
return;
}
try
{
x.close();
}
catch(IOException e)
{
interruptIfNecessary(e);
}
}
/**
* Unconditionally close an <code>Reader</code>.
* <p>
* Equivalent to {@link Reader#close()}, except any exceptions will be ignored.
* {@link InterruptedIOException} is handled correctly by {@link #interruptIfNecessary(Throwable)}.
* This is typically used in finally blocks.
*
* @param x the Reader to close, may be null or already closed
*/
public static void closeQuietly(Reader x)
{
if(x == null)
{
return;
}
try
{
x.close();
}
catch(IOException e)
{
interruptIfNecessary(e);
}
}
/**
* Unconditionally close an <code>OutputStream</code>.
* <p>
* Equivalent to {@link OutputStream#close()}, except any exceptions will be ignored.
* {@link InterruptedIOException} is handled correctly by {@link #interruptIfNecessary(Throwable)}.
* This is typically used in finally blocks.
*
* @param x the OutputStream to close, may be null or already closed
*/
public static void closeQuietly(OutputStream x)
{
if(x == null)
{
return;
}
try
{
x.close();
}
catch(IOException e)
{
interruptIfNecessary(e);
}
}
/**
* Unconditionally close a <code>Writer</code>.
* <p>
* Equivalent to {@link Writer#close()}, except any exceptions will be ignored.
* {@link InterruptedIOException} is handled correctly by {@link #interruptIfNecessary(Throwable)}.
* This is typically used in finally blocks.
*
* @param x the Writer to close, may be null or already closed
*/
public static void closeQuietly(Writer x)
{
if(x == null)
{
return;
}
try
{
x.close();
}
catch(IOException e)
{
interruptIfNecessary(e);
}
}
/**
* Unconditionally close a <code>RandomAccessFile</code>.
* <p>
* Equivalent to {@link RandomAccessFile#close()}, except any exceptions will be ignored.
* {@link InterruptedIOException} is handled correctly by {@link #interruptIfNecessary(Throwable)}.
* This is typically used in finally blocks.
*
* @param x the RandomAccessFile to close, may be null or already closed
*/
public static void closeQuietly(RandomAccessFile x)
{
if(x == null)
{
return;
}
try
{
x.close();
}
catch(IOException e)
{
interruptIfNecessary(e);
}
}
}