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// Copyright (C) 2016 The Android Open Source Project
//
// 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.google.gerrit.index.query;
import com.google.common.base.MoreObjects;
import com.google.common.collect.ImmutableList;
import com.google.gerrit.exceptions.StorageException;
import com.google.gerrit.index.Index;
import com.google.gerrit.index.QueryOptions;
import java.util.Collection;
import java.util.List;
/**
* Wrapper combining an {@link IndexPredicate} together with a {@link DataSource} that returns
* matching results from the index.
*
* <p>Appropriate to return as the rootmost predicate that can be processed using the secondary
* index; such predicates must also implement {@link DataSource} to be chosen by the query
* processor.
*
* @param <I> The type of the IDs by which the entities are stored in the index.
* @param <T> The type of the entities that are stored in the index.
*/
public class IndexedQuery<I, T> extends Predicate<T> implements DataSource<T>, Paginated<T> {
protected final Index<I, T> index;
private QueryOptions opts;
private final Predicate<T> pred;
protected DataSource<T> source;
public IndexedQuery(Index<I, T> index, Predicate<T> pred, QueryOptions opts)
throws QueryParseException {
this.index = index;
this.opts = opts;
this.pred = pred;
this.source = index.getSource(pred, this.opts);
}
@Override
public int getChildCount() {
return 1;
}
@Override
public Predicate<T> getChild(int i) {
if (i == 0) {
return pred;
}
throw new ArrayIndexOutOfBoundsException(i);
}
@Override
public List<Predicate<T>> getChildren() {
return ImmutableList.of(pred);
}
@Override
public QueryOptions getOptions() {
return opts;
}
@Override
public int getCardinality() {
return source != null ? source.getCardinality() : opts.limit();
}
@Override
public ResultSet<T> read() {
return source.read();
}
@Override
public ResultSet<FieldBundle> readRaw() {
return source.readRaw();
}
@Override
public ResultSet<T> restart(int start, int pageSize) {
opts = opts.withStart(start).withPageSize(pageSize);
return search();
}
@Override
public ResultSet<T> restart(Object searchAfter, int pageSize) {
opts = opts.withSearchAfter(searchAfter).withPageSize(pageSize);
return search();
}
@Override
public Predicate<T> copy(Collection<? extends Predicate<T>> children) {
return this;
}
@Override
public int hashCode() {
return pred.hashCode();
}
@Override
public boolean equals(Object other) {
if (other == null || getClass() != other.getClass()) {
return false;
}
IndexedQuery<?, ?> o = (IndexedQuery<?, ?>) other;
return pred.equals(o.pred) && opts.equals(o.opts);
}
@Override
public String toString() {
return MoreObjects.toStringHelper("index").add("p", pred).add("opts", opts).toString();
}
private ResultSet<T> search() {
try {
source = index.getSource(pred, opts);
} catch (QueryParseException e) {
// Don't need to show this exception to the user; the only thing that
// changed about pred was its start, and any other QPEs that might happen
// should have already thrown from the constructor.
throw new StorageException(e);
}
// Don't convert start to a limit, since the caller of this method (see
// AndSource) has calculated the actual number to skip.
return read();
}
}
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