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package de.lmu.ifi.dbs.elki.datasource.bundle;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2012
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.util.ArrayList;
import de.lmu.ifi.dbs.elki.data.type.SimpleTypeInformation;
import de.lmu.ifi.dbs.elki.data.type.TypeInformationSerializer;
import de.lmu.ifi.dbs.elki.persistent.ByteArrayUtil;
import de.lmu.ifi.dbs.elki.persistent.ByteBufferSerializer;
import de.lmu.ifi.dbs.elki.utilities.exceptions.AbortException;
/**
* Read an ELKI bundle file into a data stream.
*
* TODO: resize buffer when necessary?
*
* @author Erich Schubert
*
* @apiviz.uses FileChannel
*/
public class BundleReader implements BundleStreamSource {
/**
* Magic number, shared with {@link BundleReader}.
*/
public static final int MAGIC = BundleWriter.MAGIC;
/**
* The stream buffer.
*/
MappedByteBuffer buffer;
/**
* Bundle metadata.
*/
BundleMeta meta = null;
/**
* Input channel.
*/
FileChannel input;
/**
* Serializers to use.
*/
ArrayList<ByteBufferSerializer<?>> sers;
/**
* Current object.
*/
ArrayList<Object> data;
/**
* Constructor.
*
* @param input Input channel
*/
public BundleReader(FileChannel input) {
super();
this.input = input;
}
@Override
public BundleMeta getMeta() {
if (meta == null) {
openBuffer();
readMeta();
}
return meta;
}
/**
* Map the input file.
*/
void openBuffer() {
try {
buffer = input.map(MapMode.READ_ONLY, 0, input.size());
} catch (IOException e) {
throw new AbortException("Cannot map input bundle.", e);
}
}
/**
* Read the metadata.
*/
void readMeta() {
final int check = buffer.getInt();
if (check != MAGIC) {
throw new AbortException("File does not start with expected magic.");
}
final int nummeta = buffer.getInt();
assert (nummeta > 0);
meta = new BundleMeta(nummeta);
sers = new ArrayList<ByteBufferSerializer<?>>(nummeta);
data = new ArrayList<Object>(nummeta);
for (int i = 0; i < nummeta; i++) {
try {
@SuppressWarnings("unchecked")
SimpleTypeInformation<? extends Object> type = (SimpleTypeInformation<? extends Object>) TypeInformationSerializer.STATIC.fromByteBuffer(buffer);
meta.add(type);
sers.add(type.getSerializer());
} catch (UnsupportedOperationException e) {
throw new AbortException("Deserialization failed: "+e.getMessage(), e);
} catch (IOException e) {
throw new AbortException("IO error", e);
}
}
}
/**
* Read an object.
*/
void readObject() {
data.clear();
for (ByteBufferSerializer<?> ser : sers) {
try {
data.add(ser.fromByteBuffer(buffer));
} catch (UnsupportedOperationException e) {
throw new AbortException("Deserialization failed.", e);
} catch (IOException e) {
throw new AbortException("IO error", e);
}
}
}
@Override
public Event nextEvent() {
// Send initial meta
if (meta == null) {
return Event.META_CHANGED;
}
if (buffer.remaining() == 0) {
ByteArrayUtil.unmapByteBuffer(buffer);
return Event.END_OF_STREAM;
}
readObject();
return Event.NEXT_OBJECT;
}
@Override
public Object data(int rnum) {
return data.get(rnum);
}
}
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