/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.jena.atlas.data;
import java.io.BufferedInputStream ;
import java.io.BufferedOutputStream ;
import java.io.File ;
import java.io.FileInputStream ;
import java.io.FileNotFoundException ;
import java.io.FileOutputStream ;
import java.io.IOException ;
import java.io.InputStream ;
import java.io.OutputStream ;
import java.lang.ref.WeakReference ;
import java.util.ArrayList ;
import java.util.Collection ;
import java.util.Iterator ;
import java.util.List ;
import java.util.UUID ;
import org.apache.jena.atlas.lib.Closeable ;
import org.apache.jena.atlas.lib.FileOps ;
/**
* Abstract implementation of DataBag. Used as a parent for all three of the types of data bags.
*/
public abstract class AbstractDataBag<E> implements DataBag<E>
{
private final List<File> spillFiles = new ArrayList<File>();
protected Collection<E> memory = new ArrayList<E>();
private final List<WeakReference<Closeable>> closeableIterators = new ArrayList<WeakReference<Closeable>>();
// Total size, including tuples on disk.
protected long size = 0;
public boolean isEmpty()
{
return (size == 0);
}
@Override
public long size()
{
return size;
}
@Override
public void addAll(Iterable<? extends E> c)
{
addAll(c.iterator());
}
@Override
public void addAll(Iterator<? extends E> it)
{
while (it.hasNext())
{
E item = it.next();
add(item);
}
}
@Override
public void send(E item)
{
add(item);
}
/**
* Returns a handle to a temporary file. Does not actually create the file on disk.
*
* TODO Improve this by getting the directory from a config file
*/
protected File getNewTemporaryFile()
{
File sysTempDir = new File(System.getProperty("java.io.tmpdir")) ;
File tmpFile = new File(sysTempDir, "DataBag-" + UUID.randomUUID().toString() + ".tmp") ;
return tmpFile ;
}
/**
* Register the spill file handle for use later in the iterator.
*/
protected void registerSpillFile(File spillFile)
{
spillFiles.add(spillFile);
}
protected static OutputStream getOutputStream(File file) throws FileNotFoundException
{
return new BufferedOutputStream(new FileOutputStream(file));
}
protected static InputStream getInputStream(File file) throws FileNotFoundException
{
return new BufferedInputStream(new FileInputStream(file));
}
/**
* Get a stream to spill contents to. The file that backs this stream will be registered in the spillFiles array.
* @return stream to write tuples to
*/
protected OutputStream getSpillStream() throws IOException
{
File outputFile = getNewTemporaryFile();
OutputStream toReturn = getOutputStream(outputFile);
registerSpillFile(outputFile);
return toReturn;
}
/**
* Register an iterator to be closed when this data bag is closed. The iterator
* is held via a weak reference, and is meant as a backup if the user does not
* close it themselves.
* @param c the Closeable iterator to register
*/
protected void registerCloseableIterator(Closeable c)
{
closeableIterators.add(new WeakReference<Closeable>(c)) ;
}
/**
* Users should either exhaust or close any iterators they get, but if they don't we
* should forcibly close them so that we can delete any temporary files. Any further
* operations on the iterator will throw an exception.
*/
protected void closeIterators()
{
for (WeakReference<Closeable> wr : closeableIterators)
{
Closeable c = wr.get();
if (null != c)
{
c.close();
}
}
}
protected List<File> getSpillFiles()
{
return spillFiles;
}
protected void deleteSpillFiles()
{
for (File file : spillFiles)
{
FileOps.delete(file, false);
}
spillFiles.clear();
}
@Override
protected void finalize() throws Throwable
{
// Last chance to remove any files if the user forgot to call close()
try
{
close();
}
finally
{
super.finalize();
}
}
}