/*
* Copyright (C) 2014 Indeed Inc.
*
* 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 com.indeed.imhotep.service;
import com.google.common.base.Throwables;
import com.google.common.collect.Lists;
import com.indeed.util.core.io.Closeables2;
import com.indeed.imhotep.api.DocIterator;
import com.indeed.imhotep.io.CircularIOStream;
import org.apache.log4j.Logger;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
/**
* @author jplaisance
*/
public final class DocIteratorMerger implements DocIterator {
private static final Logger log = Logger.getLogger(DocIteratorMerger.class);
private final CircularIOStream circularBuffer;
private final InputStreamDocIterator iterator;
private final List<DocIterator> iterators;
private final ExecutorService executorService = Executors.newCachedThreadPool();
public DocIteratorMerger(List<DocIterator> iterators, final int numIntFields, final int numStringFields) throws IOException {
circularBuffer = new CircularIOStream(16384);
this.iterators = iterators;
final DataOutputStream dataOut = new DataOutputStream(circularBuffer.getOutputStream());
final List<Future<Void>> futures = Lists.newArrayList();
for (final DocIterator docIterator : iterators) {
futures.add(
executorService.submit(new Callable<Void>() {
public Void call() throws Exception {
DocOutputStreamWriter.writeThreadSafe(docIterator, numIntFields, numStringFields, dataOut);
return null;
}
}
));
}
final Thread monitorThread = new Thread(new Runnable() {
public void run() {
try {
for (Future<Void> future : futures) {
try {
future.get();
} catch (ExecutionException e) {
log.error("error", e.getCause());
synchronized (dataOut) {
dataOut.writeByte(0);
}
close();
}
}
dataOut.writeByte(0);
dataOut.close();
} catch (InterruptedException e) {
throw Throwables.propagate(e);
} catch (IOException e) {
throw Throwables.propagate(e);
}
}
});
monitorThread.start();
iterator = new InputStreamDocIterator(circularBuffer.getInputStream(), numIntFields, numStringFields);
}
public boolean next() {
return iterator.next();
}
public int getGroup() {
return iterator.getGroup();
}
public long getInt(final int index) {
return iterator.getInt(index);
}
public String getString(final int index) {
return iterator.getString(index);
}
public synchronized void close() {
try {
Closeables2.closeAll(log, circularBuffer.getInputStream(), circularBuffer.getOutputStream(), iterator);
} finally {
try {
executorService.shutdownNow();
executorService.awaitTermination(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
throw Throwables.propagate(e);
} finally {
Closeables2.closeAll(log, iterators);
}
}
}
}