/*
* 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.data2.queue;
import co.cask.cdap.common.queue.QueueName;
import co.cask.tephra.Transaction;
import co.cask.tephra.TransactionAware;
import com.google.common.collect.ImmutableList;
import java.io.IOException;
import java.util.Collection;
/**
* A {@link TransactionAware} {@link QueueConsumer} that forwards all queue operations to another
* {@link QueueConsumer} and optionally forward transaction operations if the target {@link QueueConsumer}
* is also {@link TransactionAware}.
*/
public abstract class ForwardingQueueConsumer implements QueueConsumer, TransactionAware {
protected final QueueConsumer consumer;
protected final TransactionAware txAware;
public ForwardingQueueConsumer(QueueConsumer consumer) {
this.consumer = consumer;
if (consumer instanceof TransactionAware) {
txAware = (TransactionAware) consumer;
} else {
txAware = null;
}
}
@Override
public String getTransactionAwareName() {
return getClass().getSimpleName() + "(" + txAware.getTransactionAwareName() + ")";
}
@Override
public QueueName getQueueName() {
return consumer.getQueueName();
}
@Override
public ConsumerConfig getConfig() {
return consumer.getConfig();
}
@Override
public DequeueResult<byte[]> dequeue() throws IOException {
return consumer.dequeue();
}
@Override
public DequeueResult<byte[]> dequeue(int maxBatchSize) throws IOException {
return consumer.dequeue(maxBatchSize);
}
@Override
public void startTx(Transaction tx) {
if (txAware != null) {
txAware.startTx(tx);
}
}
@Override
public void updateTx(Transaction transaction) {
if (txAware != null) {
txAware.updateTx(transaction);
}
}
@Override
public Collection<byte[]> getTxChanges() {
return (txAware != null) ? txAware.getTxChanges() : ImmutableList.<byte[]>of();
}
@Override
public boolean commitTx() throws Exception {
return (txAware == null) || txAware.commitTx();
}
@Override
public void postTxCommit() {
if (txAware != null) {
txAware.postTxCommit();
}
}
@Override
public boolean rollbackTx() throws Exception {
return (txAware == null) || txAware.rollbackTx();
}
}