/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.
*/
package org.apache.zookeeper.server;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Iterator;
import org.apache.jute.BinaryOutputArchive;
import org.apache.jute.Record;
import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator;
import org.apache.zookeeper.server.quorum.Leader;
import org.apache.zookeeper.server.quorum.Leader.Proposal;
import org.apache.zookeeper.server.quorum.QuorumPacket;
import org.apache.zookeeper.txn.TxnHeader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This class provides an iterator interface to access Proposal deserialized
* from on-disk txnlog. The iterator deserializes one proposal at a time
* to reduce memory footprint. Note that the request part of the proposal
* is not initialized and set to null since we don't need it during
* follower sync-up.
*
*/
public class TxnLogProposalIterator implements Iterator<Proposal> {
private static final Logger LOG = LoggerFactory
.getLogger(TxnLogProposalIterator.class);
public static final TxnLogProposalIterator EMPTY_ITERATOR = new TxnLogProposalIterator();
private boolean hasNext = false;
private TxnIterator itr;
@Override
public boolean hasNext() {
return hasNext;
}
/**
* Proposal returned by this iterator has request part set to null, since
* it is not used for follower sync-up.
*/
@Override
public Proposal next() {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BinaryOutputArchive boa = BinaryOutputArchive.getArchive(baos);
Proposal p = new Proposal();
try {
TxnHeader hdr = itr.getHeader();
Record txn = itr.getTxn();
hdr.serialize(boa, "hdr");
if (txn != null) {
txn.serialize(boa, "txn");
}
baos.close();
QuorumPacket pp = new QuorumPacket(Leader.PROPOSAL, itr.getHeader()
.getZxid(), baos.toByteArray(), null);
p.packet = pp;
p.request = null;
// This is the only place that can throw IO exception
hasNext = itr.next();
} catch (IOException e) {
LOG.error("Unable to read txnlog from disk", e);
hasNext = false;
}
return p;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
/**
* Close the files and release the resources which are used for iterating
* transaction records
*/
public void close() {
if(itr != null){
try {
itr.close();
} catch (IOException ioe) {
LOG.warn("Error closing file iterator", ioe);
}
}
}
private TxnLogProposalIterator() {
}
public TxnLogProposalIterator(TxnIterator itr) {
if (itr != null) {
this.itr = itr;
hasNext = (itr.getHeader() != null);
}
}
}