hadoop LimitInputStream 源码
haddop LimitInputStream 代码
文件路径：/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/LimitInputStream.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.util;
import static org.apache.hadoop.util.Preconditions.checkArgument;
import static org.apache.hadoop.util.Preconditions.checkNotNull;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.hadoop.classification.InterfaceStability.Unstable;
/**
* Copied from guava source code v15 (LimitedInputStream)
* Guava deprecated LimitInputStream in v14 and removed it in v15. Copying this class here
* allows to be compatible with guava 11 to 15+.
*
* Originally: org.apache.hadoop.hbase.io.LimitInputStream
*/
@Unstable
public final class LimitInputStream extends FilterInputStream {
private long left;
private long mark = -1;
public LimitInputStream(InputStream in, long limit) {
super(in);
checkNotNull(in);
checkArgument(limit >= 0, "limit must be non-negative");
left = limit;
}
@Override
public int available() throws IOException {
return (int) Math.min(in.available(), left);
}
// it's okay to mark even if mark isn't supported, as reset won't work
@Override
public synchronized void mark(int readLimit) {
in.mark(readLimit);
mark = left;
}
@Override
public int read() throws IOException {
if (left == 0) {
return -1;
}
int result = in.read();
if (result != -1) {
--left;
}
return result;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (len == 0) {
return 0;
}
if (left == 0) {
return -1;
}
len = (int) Math.min(len, left);
int result = in.read(b, off, len);
if (result != -1) {
left -= result;
}
return result;
}
@Override
public synchronized void reset() throws IOException {
if (!in.markSupported()) {
throw new IOException("Mark not supported");
}
if (mark == -1) {
throw new IOException("Mark not set");
}
in.reset();
left = mark;
}
@Override
public long skip(long n) throws IOException {
n = Math.min(n, left);
long skipped = in.skip(n);
left -= skipped;
return skipped;
}
}
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