/*
* Licensed to Crate under one or more contributor license agreements.
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership. Crate 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.
*
* However, if you have executed another commercial license agreement
* with Crate these terms will supersede the license and you may use the
* software solely pursuant to the terms of the relevant commercial
* agreement.
*/
package io.crate.data;
import java.util.concurrent.CompletableFuture;
import java.util.function.BiConsumer;
import java.util.stream.Collector;
/**
* Visitor that iterates to the end of a BatchIterator consuming all rows.
* The returned future will complete once the end of the batchIterator has been reached.
*
* This is no proper {@link io.crate.data.BatchConsumer} and it does *NOT* close the BatchIterator.
*/
public class BatchRowVisitor {
public static <A, R> CompletableFuture<R> visitRows(BatchIterator it, Collector<Row, A, R> collector) {
return visitRows(it, collector.supplier().get(), collector, new CompletableFuture<>());
}
public static <A, R> CompletableFuture<R> visitRows(BatchIterator it,
A state,
Collector<Row, A, R> collector,
CompletableFuture<R> resultFuture) {
BiConsumer<A, Row> accumulator = collector.accumulator();
Row row = RowBridging.toRow(it.rowData());
try {
while (it.moveNext()) {
accumulator.accept(state, row);
}
} catch (Throwable t) {
resultFuture.completeExceptionally(t);
return resultFuture;
}
if (it.allLoaded()) {
resultFuture.complete(collector.finisher().apply(state));
} else {
it.loadNextBatch().whenComplete((r, t) -> {
if (t == null) {
visitRows(it, state, collector, resultFuture);
} else {
resultFuture.completeExceptionally(t);
}
});
}
return resultFuture;
}
}