eu.stratosphere.nephele.util.IOUtils.java Source code

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/***********************************************************************************************************************
 * Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
 *
 * Licensed 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 eu.stratosphere.nephele.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.net.Socket;

import org.apache.commons.logging.Log;

/**
 * An utility class for I/O related functionality.
 * 
 */
public final class IOUtils {

    /**
     * The block size for byte operations in byte.
     */
    private static final int BLOCKSIZE = 4096;

    /**
     * Private constructor to overwrite the public one.
     */
    private IOUtils() {
    }

    /**
     * Copies from one stream to another.
     * 
     * @param in
     *        InputStream to read from
     * @param out
     *        OutputStream to write to
     * @param buffSize
     *        the size of the buffer
     * @param close
     *        whether or not close the InputStream and OutputStream at the end. The streams are closed in the finally
     *        clause.
     * @throws IOException
     *         thrown if an error occurred while writing to the output stream
     */
    public static void copyBytes(final InputStream in, final OutputStream out, final int buffSize,
            final boolean close) throws IOException {

        final PrintStream ps = out instanceof PrintStream ? (PrintStream) out : null;
        final byte[] buf = new byte[buffSize];
        try {
            int bytesRead = in.read(buf);
            while (bytesRead >= 0) {
                out.write(buf, 0, bytesRead);
                if ((ps != null) && ps.checkError()) {
                    throw new IOException("Unable to write to output stream.");
                }
                bytesRead = in.read(buf);
            }
        } finally {
            if (close) {
                out.close();
                in.close();
            }
        }
    }

    /**
     * Copies from one stream to another. <strong>closes the input and output
     * streams at the end</strong>.
     * 
     * @param in
     *        InputStream to read from
     * @param out
     *        OutputStream to write to
     * @throws IOException
     *         thrown if an I/O error occurs while copying
     */
    public static void copyBytes(final InputStream in, final OutputStream out) throws IOException {
        copyBytes(in, out, BLOCKSIZE, true);
    }

    /**
     * Copies from one stream to another.
     * 
     * @param in
     *        InputStream to read from
     * @param out
     *        OutputStream to write to
     * @param close
     *        whether or not close the InputStream and OutputStream at the
     *        end. The streams are closed in the finally clause.
     * @throws IOException
     *         thrown if an I/O error occurs while copying
     */
    public static void copyBytes(final InputStream in, final OutputStream out, final boolean close)
            throws IOException {
        copyBytes(in, out, BLOCKSIZE, close);
    }

    /**
     * Reads len bytes in a loop.
     * 
     * @param in
     *        The InputStream to read from
     * @param buf
     *        The buffer to fill
     * @param off
     *        offset from the buffer
     * @param len
     *        the length of bytes to read
     * @throws IOException
     *         if it could not read requested number of bytes for any reason (including EOF)
     */
    public static void readFully(final InputStream in, final byte[] buf, int off, final int len)
            throws IOException {
        int toRead = len;
        while (toRead > 0) {
            final int ret = in.read(buf, off, toRead);
            if (ret < 0) {
                throw new IOException("Premeture EOF from inputStream");
            }
            toRead -= ret;
            off += ret;
        }
    }

    /**
     * Similar to readFully(). Skips bytes in a loop.
     * 
     * @param in
     *        The InputStream to skip bytes from
     * @param len
     *        number of bytes to skip
     * @throws IOException
     *         if it could not skip requested number of bytes for any reason (including EOF)
     */
    public static void skipFully(final InputStream in, long len) throws IOException {
        while (len > 0) {
            final long ret = in.skip(len);
            if (ret < 0) {
                throw new IOException("Premeture EOF from inputStream");
            }
            len -= ret;
        }
    }

    /**
     * Close the Closeable objects and <b>ignore</b> any {@link IOException} or
     * null pointers. Must only be used for cleanup in exception handlers.
     * 
     * @param log
     *        the log to record problems to at debug level. Can be <code>null</code>.
     * @param closeables
     *        the objects to close
     */
    public static void cleanup(final Log log, final java.io.Closeable... closeables) {
        for (java.io.Closeable c : closeables) {
            if (c != null) {
                try {
                    c.close();
                } catch (IOException e) {
                    if (log != null && log.isDebugEnabled()) {
                        log.debug("Exception in closing " + c, e);
                    }
                }
            }
        }
    }

    /**
     * Closes the stream ignoring {@link IOException}. Must only be called in
     * cleaning up from exception handlers.
     * 
     * @param stream
     *        the stream to close
     */
    public static void closeStream(final java.io.Closeable stream) {
        cleanup(null, stream);
    }

    /**
     * Closes the socket ignoring {@link IOException}.
     * 
     * @param sock
     *        the socket to close
     */
    public static void closeSocket(final Socket sock) {
        // avoids try { close() } dance
        if (sock != null) {
            try {
                sock.close();
            } catch (IOException ignored) {
            }
        }
    }
}