/*
* Copyright © 2014 Cask Data, 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 co.cask.cdap.internal.app.queue;
import co.cask.cdap.api.flow.flowlet.StreamEvent;
import co.cask.cdap.app.queue.InputDatum;
import co.cask.cdap.app.queue.QueueReader;
import co.cask.cdap.data2.transaction.stream.StreamConsumer;
import com.google.common.base.Function;
import com.google.common.base.Supplier;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
/**
* A {@link QueueReader} implementation that dequeue from stream
*
* @param <T> Target type.
*/
public final class StreamQueueReader<T> implements QueueReader<T> {
private final Supplier<StreamConsumer> consumerSupplier;
private final int batchSize;
private final Function<StreamEvent, T> eventTransform;
StreamQueueReader(Supplier<StreamConsumer> consumerSupplier, int batchSize,
Function<StreamEvent, T> eventTransform) {
this.consumerSupplier = consumerSupplier;
this.batchSize = batchSize;
this.eventTransform = eventTransform;
}
@Override
public InputDatum<T> dequeue(long timeout, TimeUnit timeoutUnit) throws IOException, InterruptedException {
StreamConsumer consumer = consumerSupplier.get();
return new BasicInputDatum<StreamEvent, T>(consumer.getStreamName(),
consumer.poll(batchSize, timeout, timeoutUnit), eventTransform);
}
}