tachyon.io.Utils.java Source code

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/*
 * Licensed to the University of California, Berkeley 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 tachyon.io;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.codec.binary.Base64;

import com.google.common.collect.Lists;

/**
 * Utilities to do ser/de String, and ByteBuffer
 */
public class Utils {
    /**
     * Converts a list of byte buffers to a list of base64-encoded Strings.
     */
    public static List<String> byteBufferListToBase64(List<ByteBuffer> bufs) {
        if (bufs == null) {
            return null;
        }

        List<String> bytes = Lists.newArrayListWithCapacity(bufs.size());
        for (ByteBuffer buf : bufs) {
            bytes.add(byteBufferToBase64(buf));
        }
        return bytes;
    }

    /**
     * Converts a byte buffer to a base64-encoded String. Avoids copying the array if possible.
     */
    public static String byteBufferToBase64(ByteBuffer buf) {
        if (buf == null) {
            return null;
        }

        if (buf.hasArray() && buf.position() == 0 && buf.limit() == buf.capacity()) {
            return Base64.encodeBase64String(buf.array());
        } else {
            byte[] b = new byte[buf.remaining()];
            buf.get(b);
            return Base64.encodeBase64String(b);
        }
    }

    public static ByteBuffer readByteBuffer(DataInputStream is) throws IOException {
        int len = is.readInt();
        if (len == -1) {
            return null;
        }

        byte[] arr = new byte[len];
        for (int k = 0; k < len; k++) {
            arr[k] = is.readByte();
        }

        return ByteBuffer.wrap(arr);
    }

    public static List<ByteBuffer> readByteBufferList(DataInputStream is) throws IOException {
        int size = is.readInt();
        if (size == -1) {
            return null;
        }

        List<ByteBuffer> ret = new ArrayList<ByteBuffer>(size);
        for (int k = 0; k < size; k++) {
            ret.add(readByteBuffer(is));
        }
        return ret;
    }

    public static List<Integer> readIntegerList(DataInputStream is) throws IOException {
        int size = is.readInt();
        if (size == -1) {
            return null;
        }
        List<Integer> ret = new ArrayList<Integer>(size);
        for (int k = 0; k < size; k++) {
            ret.add(is.readInt());
        }
        return ret;
    }

    public static String readString(DataInputStream is) throws IOException {
        int len = is.readInt();

        if (len == -1) {
            return null;
        } else if (len == 0) {
            return "";
        }

        char[] chars = new char[len];
        for (int k = 0; k < len; k++) {
            chars[k] = is.readChar();
        }
        return new String(chars);

    }

    public static List<String> readStringList(DataInputStream is) throws IOException {
        int size = is.readInt();

        if (size == -1) {
            return null;
        }

        List<String> ret = new ArrayList<String>(size);
        for (int k = 0; k < size; k++) {
            ret.add(readString(is));
        }
        return ret;
    }

    public static void writeByteBuffer(ByteBuffer buf, DataOutputStream os) throws IOException {
        if (buf == null) {
            os.writeInt(-1);
            return;
        }
        int len = buf.limit() - buf.position();
        os.writeInt(len);
        os.write(buf.array(), buf.position(), len);
    }

    public static void writeByteBufferList(List<ByteBuffer> list, DataOutputStream os) throws IOException {
        if (list == null) {
            os.writeInt(-1);
            return;
        }
        os.writeInt(list.size());
        for (int k = 0; k < list.size(); k++) {
            writeByteBuffer(list.get(k), os);
        }
    }

    public static void writeIntegerList(List<Integer> list, DataOutputStream os) throws IOException {
        if (list == null) {
            os.writeInt(-1);
            return;
        }

        os.writeInt(list.size());
        for (int k = 0; k < list.size(); k++) {
            os.writeInt(list.get(k));
        }
    }

    public static void writeString(String str, DataOutputStream os) throws IOException {
        if (str == null) {
            os.writeInt(-1);
        } else {
            os.writeInt(str.length());
            os.writeChars(str);
        }
    }

    public static void writeStringList(List<String> list, DataOutputStream os) throws IOException {
        if (list == null) {
            os.writeInt(-1);
            return;
        }
        os.writeInt(list.size());
        for (int k = 0; k < list.size(); k++) {
            writeString(list.get(k), os);
        }
    }
}