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/*
* Copyright 2020 Yelp 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.yelp.nrtsearch.server.luceneserver.search;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.CollectionTerminatedException;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.CollectorManager;
import org.apache.lucene.search.LeafCollector;
import org.apache.lucene.search.Scorable;
import org.apache.lucene.search.ScoreMode;
/**
* {@link CollectorManager} that wraps another manager to provide support for cutting short a search
* operation under certain conditions, such as a timeout.
*
* The timeout value is checked before processing each segment. If partial results are allowed, a
* {@link CollectionTerminatedException} is thrown so the searcher moves to the next segment. If
* partial results are not allowed, a {@link CollectionTimeoutException} is thrown. The timer starts
* on the first call to {@link #newCollector()}.
*
* @param collector type of wrapped manager
*/
public class SearchCutoffWrapper
implements CollectorManager.TimeoutCollectorWrapper, SearcherResult> {
private final CollectorManager in;
private final boolean noPartialResults;
private final double timeoutSec;
private final int checkEvery;
private final Runnable onTimeout;
private long maxTime = -1;
/**
* Constructor
*
* @param in manager to wrap
* @param timeoutSec timeout for collecting
* @param noPartialResults if a cutoff should be an exception, instead of using partial results
* @param onTimeout an action to do if there was a timeout (done in reduce call)
*/
public SearchCutoffWrapper(
CollectorManager in,
double timeoutSec,
boolean noPartialResults,
Runnable onTimeout) {
this(in, timeoutSec, 0, noPartialResults, onTimeout);
}
/**
* Constructor
*
* @param in manager to wrap
* @param timeoutSec timeout for collecting
* @param checkEvery check timeout condition after each collection of this many document in a
* segment, 0 to only check on the segment boundary
* @param noPartialResults if a cutoff should be an exception, instead of using partial results
* @param onTimeout an action to do if there was a timeout (done in reduce call)
*/
public SearchCutoffWrapper(
CollectorManager in,
double timeoutSec,
int checkEvery,
boolean noPartialResults,
Runnable onTimeout) {
this.in = in;
this.noPartialResults = noPartialResults;
this.timeoutSec = timeoutSec;
this.checkEvery = checkEvery;
this.onTimeout = onTimeout;
}
// make this overridable for testing
protected long getTimeMs() {
return System.currentTimeMillis();
}
/** Get timeout for search phase. */
public double getTimeoutSec() {
return timeoutSec;
}
/** Check timeout every time this many docs are collected, or 0 for only at segment boundaries. */
public int getCheckEvery() {
return checkEvery;
}
@Override
public TimeoutCollectorWrapper newCollector() throws IOException {
// start timer when first collector is created
if (maxTime < 0) {
maxTime = getTimeMs() + (long) (timeoutSec * 1000);
}
return new TimeoutCollectorWrapper(in.newCollector());
}
@Override
public SearcherResult reduce(
Collection.TimeoutCollectorWrapper> collectors) throws IOException {
List innerCollectors = new ArrayList<>(collectors.size());
boolean hadTimeout = false;
for (TimeoutCollectorWrapper collector : collectors) {
innerCollectors.add(collector.collector);
if (collector.hadTimeout) {
hadTimeout = true;
}
}
if (hadTimeout) {
onTimeout.run();
}
return in.reduce(innerCollectors);
}
/** Get the collector manager being wrapped. */
public CollectorManager getWrapped() {
return in;
}
/**
* {@link Collector} implementation that wraps another collector and checks if the operation has
* timed out before providing each segment collector.
*/
class TimeoutCollectorWrapper implements Collector {
private final C collector;
private boolean hadTimeout = false;
public TimeoutCollectorWrapper(C collector) {
this.collector = collector;
}
@Override
public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException {
checkTimeout();
if (checkEvery > 0) {
return new TimeoutLeafCollectorWrapper(collector.getLeafCollector(context));
} else {
return collector.getLeafCollector(context);
}
}
@Override
public ScoreMode scoreMode() {
return collector.scoreMode();
}
private void checkTimeout() {
if (getTimeMs() > maxTime) {
hadTimeout = true;
if (noPartialResults) {
throw new CollectionTimeoutException(
"Search collection exceeded timeout of " + timeoutSec + "s");
} else {
throw new CollectionTerminatedException();
}
}
}
/**
* {@link LeafCollector} implementation that wraps another leaf collector and checks if the
* operations has timed out during document collection. The timeout condition is checked every
* time the configured number of documents are collected.
*/
class TimeoutLeafCollectorWrapper implements LeafCollector {
private final LeafCollector leafCollector;
private int collectionCount = 0;
public TimeoutLeafCollectorWrapper(LeafCollector leafCollector) {
this.leafCollector = leafCollector;
}
@Override
public void setScorer(Scorable scorer) throws IOException {
leafCollector.setScorer(scorer);
}
@Override
public void collect(int doc) throws IOException {
if (collectionCount == checkEvery) {
collectionCount = 0;
checkTimeout();
}
leafCollector.collect(doc);
collectionCount++;
}
}
}
/** Exception to indicate collection during a search operation timed out. */
public static class CollectionTimeoutException extends RuntimeException {
public CollectionTimeoutException(String message) {
super(message);
}
public CollectionTimeoutException(String message, Throwable cause) {
super(message, cause);
}
}
}