package org.apache.lucene.search;
/**
* 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.
*/
import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Callable;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.NamedThreadFactory;
import org.apache.lucene.util.ThreadInterruptedException;
/** Implements parallel search over a set of <code>Searchables</code>.
*
* <p>Applications usually need only call the inherited {@link #search(Query,int)}
* or {@link #search(Query,Filter,int)} methods.
*/
public class ParallelMultiSearcher extends MultiSearcher {
private final ExecutorService executor;
private final Searchable[] searchables;
private final int[] starts;
/** Creates a {@link Searchable} which searches <i>searchables</i>. */
public ParallelMultiSearcher(Searchable... searchables) throws IOException {
super(searchables);
this.searchables = searchables;
this.starts = getStarts();
executor = Executors.newCachedThreadPool(new NamedThreadFactory(this.getClass().getSimpleName()));
}
/**
* Executes each {@link Searchable}'s docFreq() in its own thread and waits for each search to complete and merge
* the results back together.
*/
@Override
public int docFreq(final Term term) throws IOException {
final ExecutionHelper<Integer> runner = new ExecutionHelper<Integer>(executor);
for(int i = 0; i < searchables.length; i++) {
final Searchable searchable = searchables[i];
runner.submit(new Callable<Integer>() {
public Integer call() throws IOException {
return Integer.valueOf(searchable.docFreq(term));
}
});
}
int docFreq = 0;
for (Integer num : runner) {
docFreq += num.intValue();
}
return docFreq;
}
/**
* A search implementation which executes each
* {@link Searchable} in its own thread and waits for each search to complete and merge
* the results back together.
*/
@Override
public TopDocs search(Weight weight, Filter filter, int nDocs) throws IOException {
final HitQueue hq = new HitQueue(nDocs, false);
final Lock lock = new ReentrantLock();
final ExecutionHelper<TopDocs> runner = new ExecutionHelper<TopDocs>(executor);
for (int i = 0; i < searchables.length; i++) { // search each searchable
runner.submit(
new MultiSearcherCallableNoSort(lock, searchables[i], weight, filter, nDocs, hq, i, starts));
}
int totalHits = 0;
float maxScore = Float.NEGATIVE_INFINITY;
for (final TopDocs topDocs : runner) {
totalHits += topDocs.totalHits;
maxScore = Math.max(maxScore, topDocs.getMaxScore());
}
final ScoreDoc[] scoreDocs = new ScoreDoc[hq.size()];
for (int i = hq.size() - 1; i >= 0; i--) // put docs in array
scoreDocs[i] = hq.pop();
return new TopDocs(totalHits, scoreDocs, maxScore);
}
/**
* A search implementation allowing sorting which spans a new thread for each
* Searchable, waits for each search to complete and merges
* the results back together.
*/
@Override
public TopFieldDocs search(Weight weight, Filter filter, int nDocs, Sort sort) throws IOException {
if (sort == null) throw new NullPointerException();
final FieldDocSortedHitQueue hq = new FieldDocSortedHitQueue(nDocs);
final Lock lock = new ReentrantLock();
final ExecutionHelper<TopFieldDocs> runner = new ExecutionHelper<TopFieldDocs>(executor);
for (int i = 0; i < searchables.length; i++) { // search each searchable
runner.submit(
new MultiSearcherCallableWithSort(lock, searchables[i], weight, filter, nDocs, hq, sort, i, starts));
}
int totalHits = 0;
float maxScore = Float.NEGATIVE_INFINITY;
for (final TopFieldDocs topFieldDocs : runner) {
totalHits += topFieldDocs.totalHits;
maxScore = Math.max(maxScore, topFieldDocs.getMaxScore());
}
final ScoreDoc[] scoreDocs = new ScoreDoc[hq.size()];
for (int i = hq.size() - 1; i >= 0; i--) // put docs in array
scoreDocs[i] = hq.pop();
return new TopFieldDocs(totalHits, scoreDocs, hq.getFields(), maxScore);
}
/** Lower-level search API.
*
* <p>{@link Collector#collect(int)} is called for every matching document.
*
* <p>Applications should only use this if they need <i>all</i> of the
* matching documents. The high-level search API ({@link
* Searcher#search(Query,int)}) is usually more efficient, as it skips
* non-high-scoring hits.
*
* <p>This method cannot be parallelized, because {@link Collector}
* supports no concurrent access.
*
* @param weight to match documents
* @param filter if non-null, a bitset used to eliminate some documents
* @param collector to receive hits
*/
@Override
public void search(final Weight weight, final Filter filter, final Collector collector)
throws IOException {
for (int i = 0; i < searchables.length; i++) {
final int start = starts[i];
final Collector hc = new Collector() {
@Override
public void setScorer(final Scorer scorer) throws IOException {
collector.setScorer(scorer);
}
@Override
public void collect(final int doc) throws IOException {
collector.collect(doc);
}
@Override
public void setNextReader(final IndexReader reader, final int docBase) throws IOException {
collector.setNextReader(reader, start + docBase);
}
@Override
public boolean acceptsDocsOutOfOrder() {
return collector.acceptsDocsOutOfOrder();
}
};
searchables[i].search(weight, filter, hc);
}
}
@Override
public void close() throws IOException {
executor.shutdown();
super.close();
}
/**
* A helper class that wraps a {@link CompletionService} and provides an
* iterable interface to the completed {@link Callable} instances.
*
* @param <T>
* the type of the {@link Callable} return value
*/
private static final class ExecutionHelper<T> implements Iterator<T>, Iterable<T> {
private final CompletionService<T> service;
private int numTasks;
ExecutionHelper(final Executor executor) {
this.service = new ExecutorCompletionService<T>(executor);
}
public boolean hasNext() {
return numTasks > 0;
}
public void submit(Callable<T> task) {
this.service.submit(task);
++numTasks;
}
public T next() {
if(!this.hasNext())
throw new NoSuchElementException();
try {
return service.take().get();
} catch (InterruptedException e) {
throw new ThreadInterruptedException(e);
} catch (ExecutionException e) {
throw new RuntimeException(e);
} finally {
--numTasks;
}
}
public void remove() {
throw new UnsupportedOperationException();
}
public Iterator<T> iterator() {
// use the shortcut here - this is only used in a privat context
return this;
}
}
}