org.apache.hadoop.fs.statistics.BufferedIOStatisticsInputStream Maven / Gradle / Ivy
/*
* 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.fs.statistics;
import java.io.BufferedInputStream;
import java.io.InputStream;
import org.apache.hadoop.fs.StreamCapabilities;
import static org.apache.hadoop.fs.statistics.IOStatisticsSupport.retrieveIOStatistics;
/**
* An extension of {@code BufferedInputStream} which implements
* {@link IOStatisticsSource} and forwards requests for the
* {@link IOStatistics} to the wrapped stream.
*
* This should be used when any input stream needs buffering while
* allowing the inner stream to be a source of statistics.
*
* It also implements {@link StreamCapabilities} and forwards the probe
* to the inner stream, if possible.
*/
public class BufferedIOStatisticsInputStream
extends BufferedInputStream
implements IOStatisticsSource, StreamCapabilities {
/**
* Buffer an input stream with the default buffer size of 8k.
* @param in input stream
*/
public BufferedIOStatisticsInputStream(final InputStream in) {
super(in);
}
/**
* Buffer an input stream with the chosen buffer size.
* @param in input stream
* @param size buffer size
*/
public BufferedIOStatisticsInputStream(final InputStream in, final int size) {
super(in, size);
}
/**
* Return any IOStatistics offered by the inner stream.
* @return inner IOStatistics or null
*/
@Override
public IOStatistics getIOStatistics() {
return retrieveIOStatistics(in);
}
/**
* If the inner stream supports {@link StreamCapabilities},
* forward the probe to it.
* Otherwise: return false.
*
* @param capability string to query the stream support for.
* @return true if a capability is known to be supported.
*/
@Override
public boolean hasCapability(final String capability) {
if (in instanceof StreamCapabilities) {
return ((StreamCapabilities) in).hasCapability(capability);
} else {
return false;
}
}
}