/*
* Copyright 2012 NGDATA nv
*
* 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 org.lilyproject.indexer.derefmap;
import java.io.IOException;
import org.lilyproject.hbaseindex.QueryResult;
import org.lilyproject.repository.api.AbsoluteRecordId;
/**
* Implementation of {@link org.lilyproject.indexer.derefmap.DependantRecordIdsIterator}.
*
*
*/
final class DependantRecordIdsIteratorImpl implements DependantRecordIdsIterator {
private final QueryResult queryResult;
private final DerefMapSerializationUtil serializationUtil;
DependantRecordIdsIteratorImpl(QueryResult queryResult, DerefMapSerializationUtil serializationUtil) {
this.queryResult = queryResult;
this.serializationUtil = serializationUtil;
}
@Override
public void close() throws IOException {
queryResult.close();
}
AbsoluteRecordId next = null;
private AbsoluteRecordId getNextFromQueryResult() throws IOException {
// the identifier is the record id of the record that depends on the queried record
final byte[] nextIdentifier = queryResult.next();
if (nextIdentifier == null) {
return null;
} else {
return serializationUtil.deserializeDependantRecordId(nextIdentifier);
}
}
@Override
public boolean hasNext() throws IOException {
synchronized (this) { // to protect setting/resetting the next value from race conditions
if (next != null) {
// the next was already set, but not yet used
return true;
} else {
// try setting a next value
next = getNextFromQueryResult();
return next != null;
}
}
}
@Override
public AbsoluteRecordId next() throws IOException {
synchronized (this) { // to protect setting/resetting the next value from race conditions
if (next != null) {
// the next was already set, but not yet used
AbsoluteRecordId nextToReturn = next;
next = null;
return nextToReturn;
} else {
// try setting a next value
next = getNextFromQueryResult();
return next;
}
}
}
}