/*
* 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.tigon.internal.app.queue;
import co.cask.tigon.app.queue.InputDatum;
import co.cask.tigon.data.queue.QueueConsumer;
import com.google.common.base.Function;
import com.google.common.base.Supplier;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.concurrent.TimeUnit;
/**
* A {@link co.cask.tigon.app.queue.QueueReader} for reading from {@link QueueConsumer}.
*
* @param <T> Type of input dequeued from this reader.
*/
public final class SingleQueue2Reader<T> extends TimeTrackingQueueReader<T> {
private final Supplier<QueueConsumer> consumerSupplier;
private final int batchSize;
private final Function<byte[], T> decoder;
SingleQueue2Reader(Supplier<QueueConsumer> consumerSupplier, int batchSize, final Function<ByteBuffer, T> decoder) {
this.consumerSupplier = consumerSupplier;
this.batchSize = batchSize;
this.decoder = new Function<byte[], T>() {
@Override
public T apply(byte[] input) {
return decoder.apply(ByteBuffer.wrap(input));
}
};
}
@Override
public InputDatum<T> tryDequeue(long timeout, TimeUnit timeoutUnit) throws IOException {
QueueConsumer consumer = consumerSupplier.get();
return new BasicInputDatum<byte[], T>(consumer.getQueueName(), consumer.dequeue(batchSize), decoder);
}
}