org.apache.hadoop.io.PositionInputStream.java Source code

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Here is the source code for org.apache.hadoop.io.PositionInputStream.java

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/**
 * 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.io;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * An input stream which supports {@link #position()}. 
 */
public class PositionInputStream extends FilterInputStream {
    public static final Log LOG = LogFactory.getLog(PositionInputStream.class);

    private long currPos = 0;
    private long markPos = -1;

    public PositionInputStream(InputStream in) {
        super(in);
    }

    /**
     * @return the current position
     */
    public long position() {
        return currPos;
    }

    @Override
    public int read() throws IOException {
        final int b = super.read();
        if (b != -1) {
            currPos++;
        }
        return b;
    }

    @Override
    public int read(byte[] buffer) throws IOException {
        return read(buffer, 0, buffer.length);
    }

    @Override
    public int read(byte[] buffer, int offset, int length) throws IOException {
        final int n = super.read(buffer, offset, length);
        if (n > 0) {
            currPos += n;
        }
        return n;
    }

    @Override
    public long skip(long length) throws IOException {
        final long n = super.skip(length);
        if (n > 0) {
            currPos += n;
        }
        return n;
    }

    @Override
    public void mark(int readlimit) {
        super.mark(readlimit);
        markPos = currPos;

        if (LOG.isDebugEnabled()) {
            LOG.debug("mark: markPos=" + markPos + ", readlimit=" + readlimit);
        }
    }

    @Override
    public void reset() throws IOException {
        if (markPos == -1) {
            throw new IOException("Not marked!");
        }
        super.reset();
        currPos = markPos;
        markPos = -1;

        if (LOG.isDebugEnabled()) {
            LOG.debug("reset: currPos=" + currPos);
        }
    }
}