org.apache.drill.common.util.DataInputInputStream.java Source code

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Here is the source code for org.apache.drill.common.util.DataInputInputStream.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.drill.common.util;

import java.io.DataInput;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.lang3.exception.ExceptionUtils;

public class DataInputInputStream extends InputStream {

    private final DataInput in;
    private boolean closed = false;

    /**
     * Construct an InputStream from the given DataInput. If 'in'
     * is already an InputStream, simply returns it. Otherwise, wraps
     * it in an InputStream.
     * @param in the DataInput to wrap
     * @return an InputStream instance that inputs to 'in'
     */

    public static InputStream constructInputStream(DataInput in) {
        if (in instanceof InputStream) {
            return (InputStream) in;
        } else {
            return new DataInputInputStream(in);
        }
    }

    private DataInputInputStream(DataInput in) {
        this.in = in;
    }

    @Override
    public void close() {
        this.closed = true;
    }

    @Override
    public int available() {
        return this.closed ? 0 : 1;
    }

    @Override
    public int read() throws IOException {
        return in.readByte();
    }

    @Override
    public int read(byte[] b, int off, int len) throws IOException {
        for (int i = off; i < off + len; i++) {
            try {
                b[i] = in.readByte();
            } catch (Exception e) {
                if (ExceptionUtils.getRootCause(e) instanceof EOFException) {
                    return i - off;
                } else {
                    throw e;
                }
            }
        }
        return len;
    }

    @Override
    public int read(byte[] b) throws IOException {
        for (int i = 0; i < b.length; i++) {
            try {
                b[i] = in.readByte();
            } catch (EOFException e) {
                close();
                return i;
            }
        }
        return b.length;
    }
}