com.moz.fiji.schema.util.SplitKeyFile.java Source code

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Here is the source code for com.moz.fiji.schema.util.SplitKeyFile.java

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/**
 * (c) Copyright 2012 WibiData, Inc.
 *
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * 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 com.moz.fiji.schema.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.hbase.util.Bytes;

import com.moz.fiji.annotations.ApiAudience;

/**
 * Parses region boundaries split files.
 *
 * <ul>
 * <li> The file contains one row key per line.</li>
 * <li> Row keys are encoded in ASCII.</li>
 * <li> Non printable characters must be escaped in hexadecimal "\x??".</li>
 * <li> Backslash must be escaped (doubled) "\\"</li>
 * </ul>
 *
 * <p>
 * If a file contains N split keys, N+1 regions will be created, since the first region will contain
 * everything before the first split key, and the last region will contain everything after the last
 * split key.
 * </p>
 */
@ApiAudience.Private
public final class SplitKeyFile {
    /** Utility class. */
    private SplitKeyFile() {
    }

    /**
     * Constructs a split key file from an input stream.  This object will take ownership of
     * the inputStream, which you should clean up by calling close().
     *
     * @param inputStream The file contents.
     * @return the region boundaries, as a list of row keys.
     * @throws IOException on I/O error.
     */
    public static List<byte[]> decodeRegionSplitList(InputStream inputStream) throws IOException {
        try {
            final String content = Bytes.toString(IOUtils.toByteArray(Preconditions.checkNotNull(inputStream)));
            final String[] encodedKeys = content.split("\n");
            final List<byte[]> keys = Lists.newArrayListWithCapacity(encodedKeys.length);
            for (String encodedKey : encodedKeys) {
                keys.add(decodeRowKey(encodedKey));
            }
            return keys;
        } finally {
            ResourceUtils.closeOrLog(inputStream);
        }
    }

    /**
     * Decodes a string encoded row key.
     *
     * @param encoded Encoded row key.
     * @return the row key, as a byte array.
     * @throws IOException on I/O error.
     */
    public static byte[] decodeRowKey(String encoded) throws IOException {
        final ByteArrayOutputStream os = new ByteArrayOutputStream();
        int index = 0;
        final byte[] bytes = Bytes.toBytes(encoded);
        while (index < bytes.length) {
            final byte data = bytes[index++];

            if (data != '\\') {
                os.write(data);
            } else {
                if (index == bytes.length) {
                    throw new IOException(
                            String.format("Invalid trailing escape in encoded row key: '%s'.", encoded));
                }
                final byte escaped = bytes[index++];

                switch (escaped) {
                case '\\': {
                    // Escaped backslash:
                    os.write('\\');
                    break;
                }
                case 'x': {
                    // Escaped byte in hexadecimal:
                    if (index + 1 >= bytes.length) {
                        throw new IOException(
                                String.format("Invalid hexadecimal escape in encoded row key: '%s'.", encoded));
                    }
                    final String hex = Bytes.toString(Arrays.copyOfRange(bytes, index, index + 2));
                    try {
                        final int decodedByte = Integer.parseInt(hex, 16);
                        if ((decodedByte < 0) || (decodedByte > 255)) {
                            throw new IOException(
                                    String.format("Invalid hexadecimal escape in encoded row key: '%s'.", encoded));
                        }
                        os.write(decodedByte);
                    } catch (NumberFormatException nfe) {
                        throw new IOException(
                                String.format("Invalid hexadecimal escape in encoded row key: '%s'.", encoded));
                    }
                    index += 2;
                    break;
                }
                default:
                    throw new IOException(String.format("Invalid escape in encoded row key: '%s'.", encoded));
                }
            }
        }
        return os.toByteArray();
    }
}