hadoop StreamBackedIterator 源码
haddop StreamBackedIterator 代码
文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/join/StreamBackedIterator.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.hadoop.mapreduce.lib.join;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.Writable;
/**
* This class provides an implementation of ResetableIterator. This
* implementation uses a byte array to store elements added to it.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class StreamBackedIterator<X extends Writable>
implements ResetableIterator<X> {
private static class ReplayableByteInputStream extends ByteArrayInputStream {
public ReplayableByteInputStream(byte[] arr) {
super(arr);
}
public void resetStream() {
mark = 0;
reset();
}
}
private ByteArrayOutputStream outbuf = new ByteArrayOutputStream();
private DataOutputStream outfbuf = new DataOutputStream(outbuf);
private ReplayableByteInputStream inbuf;
private DataInputStream infbuf;
public StreamBackedIterator() { }
public boolean hasNext() {
return infbuf != null && inbuf.available() > 0;
}
public boolean next(X val) throws IOException {
if (hasNext()) {
inbuf.mark(0);
val.readFields(infbuf);
return true;
}
return false;
}
public boolean replay(X val) throws IOException {
inbuf.reset();
if (0 == inbuf.available())
return false;
val.readFields(infbuf);
return true;
}
public void reset() {
if (null != outfbuf) {
inbuf = new ReplayableByteInputStream(outbuf.toByteArray());
infbuf = new DataInputStream(inbuf);
outfbuf = null;
}
inbuf.resetStream();
}
public void add(X item) throws IOException {
item.write(outfbuf);
}
public void close() throws IOException {
if (null != infbuf)
infbuf.close();
if (null != outfbuf)
outfbuf.close();
}
public void clear() {
if (null != inbuf)
inbuf.resetStream();
outbuf.reset();
outfbuf = new DataOutputStream(outbuf);
}
}
相关信息
相关文章
hadoop ArrayListBackedIterator 源码
hadoop ComposableInputFormat 源码
hadoop ComposableRecordReader 源码
hadoop CompositeInputFormat 源码
hadoop CompositeRecordReader 源码
hadoop InnerJoinRecordReader 源码
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
8、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦