/**
* 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.mahout.clustering.spectral.common;
import java.io.IOException;
import java.net.URI;
import java.util.Arrays;
import com.google.common.io.Closeables;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Writable;
import org.apache.mahout.common.HadoopUtil;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileValueIterator;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This class handles reading and writing vectors to the Hadoop
* distributed cache. Created as a result of Eigencuts' liberal use
* of such functionality, but available to any algorithm requiring it.
*/
public final class VectorCache {
private static final Logger log = LoggerFactory.getLogger(VectorCache.class);
private VectorCache() {
}
/**
* @param key SequenceFile key
* @param vector Vector to save, to be wrapped as VectorWritable
*/
public static void save(Writable key,
Vector vector,
Path output,
Configuration conf,
boolean overwritePath,
boolean deleteOnExit) throws IOException {
FileSystem fs = FileSystem.get(output.toUri(), conf);
output = fs.makeQualified(output);
if (overwritePath) {
HadoopUtil.delete(conf, output);
}
// set the cache
DistributedCache.setCacheFiles(new URI[]{output.toUri()}, conf);
// set up the writer
SequenceFile.Writer writer = new SequenceFile.Writer(fs, conf, output,
IntWritable.class, VectorWritable.class);
try {
writer.append(key, new VectorWritable(vector));
} finally {
Closeables.close(writer, false);
}
if (deleteOnExit) {
fs.deleteOnExit(output);
}
}
/**
* Calls the save() method, setting the cache to overwrite any previous
* Path and to delete the path after exiting
*/
public static void save(Writable key, Vector vector, Path output, Configuration conf) throws IOException {
save(key, vector, output, conf, true, true);
}
/**
* Loads the vector from {@link DistributedCache}. Returns null if no vector exists.
*/
public static Vector load(Configuration conf) throws IOException {
Path[] files = HadoopUtil.getCachedFiles(conf);
if (files.length != 1) {
throw new IOException("Cannot read Frequency list from Distributed Cache (" + files.length + ')');
}
if (log.isInfoEnabled()) {
log.info("Files are: {}", Arrays.toString(files));
}
return load(conf, files[0]);
}
/**
* Loads a Vector from the specified path. Returns null if no vector exists.
*/
public static Vector load(Configuration conf, Path input) throws IOException {
log.info("Loading vector from: {}", input);
SequenceFileValueIterator<VectorWritable> iterator =
new SequenceFileValueIterator<VectorWritable>(input, true, conf);
try {
return iterator.next().get();
} finally {
Closeables.close(iterator, true);
}
}
}