spark LevelDBIterator 源码
spark LevelDBIterator 代码
文件路径：/common/network-common/src/main/java/org/apache/spark/network/shuffledb/LevelDBIterator.java
/*
* 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.spark.network.shuffledb;
import com.google.common.base.Throwables;
import java.io.IOException;
import java.util.Map;
import java.util.NoSuchElementException;
public class LevelDBIterator implements DBIterator {
private final org.iq80.leveldb.DBIterator it;
private boolean checkedNext;
private boolean closed;
private Map.Entry<byte[], byte[]> next;
public LevelDBIterator(org.iq80.leveldb.DBIterator it) {
this.it = it;
}
@Override
public boolean hasNext() {
if (!checkedNext && !closed) {
next = loadNext();
checkedNext = true;
}
if (!closed && next == null) {
try {
close();
} catch (IOException ioe) {
throw Throwables.propagate(ioe);
}
}
return next != null;
}
@Override
public Map.Entry<byte[], byte[]> next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
checkedNext = false;
Map.Entry<byte[], byte[]> ret = next;
next = null;
return ret;
}
@Override
public void close() throws IOException {
if (!closed) {
it.close();
closed = true;
next = null;
}
}
@Override
public void seek(byte[] key) {
it.seek(key);
}
private Map.Entry<byte[], byte[]> loadNext() {
boolean hasNext = it.hasNext();
if (!hasNext) {
return null;
}
return it.next();
}
}
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