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package com.yahoo.search.searchers;
import com.yahoo.api.annotations.Beta;
import com.yahoo.component.chain.dependencies.After;
import com.yahoo.prelude.query.AndItem;
import com.yahoo.prelude.query.CompositeItem;
import com.yahoo.prelude.query.Item;
import com.yahoo.prelude.query.WeakAndItem;
import com.yahoo.processing.request.CompoundName;
import com.yahoo.search.Query;
import com.yahoo.search.Result;
import com.yahoo.search.Searcher;
import com.yahoo.search.querytransform.WeakAndReplacementSearcher;
import com.yahoo.search.searchchain.Execution;
import static com.yahoo.search.querytransform.WeakAndReplacementSearcher.WAND_HITS;
/**
* Will opportunistically replace the WeakAND with an AND as it is faster.
* If enough hits are returned all is good and we return. If not we fall back to the original query.
*
* @author baldersheim
*/
@Beta
@After(WeakAndReplacementSearcher.REPLACE_OR_WITH_WEAKAND)
public class OpportunisticWeakAndSearcher extends Searcher {
static final CompoundName OPPORTUNISTIC_AND = CompoundName.from("weakAnd.opportunistic.and");
@Override
public Result search(Query query, Execution execution) {
if (!query.properties().getBoolean(OPPORTUNISTIC_AND)) {
return execution.search(query);
}
Item originalRoot = query.getModel().getQueryTree().getRoot();
int targetHits = targetHits(originalRoot);
if (targetHits >= 0) {
query.getModel().getQueryTree().setRoot(weakAnd2AndRecurse(originalRoot.clone()));
query.trace("WeakAND => AND", true, 2);
Result result = execution.search(query);
if (result.getHitCount() >= query.properties().getInteger(WAND_HITS)) {
return result;
}
query.getModel().getQueryTree().setRoot(originalRoot);
return execution.search(query);
}
return execution.search(query);
}
// returns targetHits for the first WeakAndItem found, -1 if none found.
static int targetHits(Item item) {
if (!(item instanceof CompositeItem compositeItem)) return -1;
if (item instanceof WeakAndItem weakAndItem) return weakAndItem.getN();
for (int i = 0; i < compositeItem.getItemCount(); i++) {
int targetHits = targetHits(compositeItem.getItem(i));
if (targetHits >= 0) return targetHits;
}
return -1;
}
static Item weakAnd2AndRecurse(Item item) {
if (!(item instanceof CompositeItem compositeItem)) return item;
compositeItem = weakAnd2And(compositeItem);
for (int i = 0; i < compositeItem.getItemCount(); i++) {
Item subItem = compositeItem.getItem(i);
Item replacedItem = weakAnd2AndRecurse(subItem);
if (replacedItem != subItem) {
compositeItem.setItem(i, replacedItem);
}
}
return compositeItem;
}
private static CompositeItem weakAnd2And(CompositeItem item) {
if (item instanceof WeakAndItem weakAndItem) {
AndItem andItem = new AndItem();
andItem.setWeight(weakAndItem.getWeight());
item.items().forEach(andItem::addItem);
return andItem;
}
return item;
}
}
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