content: /*
   * 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.cassandra.utils;
  
  import java.nio.ByteBuffer;
  import java.security.SecureRandom;
  import java.util.Random;
  
  import static org.apache.cassandra.config.CassandraRelevantProperties.JAVA_SECURITY_EGD;
  import static org.apache.cassandra.utils.Clock.Global.currentTimeMillis;
  import static org.apache.cassandra.utils.LocalizeString.toUpperCaseLocalized;
  
  public class GuidGenerator
  {
      private static final Random myRand;
      private static final SecureRandom mySecureRand;
      private static final String s_id;
  
      static
      {
          if (!JAVA_SECURITY_EGD.isPresent())
          {
              JAVA_SECURITY_EGD.setString("file:/dev/urandom");
          }
          mySecureRand = new SecureRandom();
          long secureInitializer = mySecureRand.nextLong();
          myRand = new Random(secureInitializer);
          try {
              s_id = FBUtilities.getLocalAddressAndPort().toString();
          }
          catch (RuntimeException e) {
              throw new AssertionError(e);
          }
      }
  
      public static String guid()
      {
          ByteBuffer array = guidAsBytes();
  
          StringBuilder sb = new StringBuilder();
          for (int j = array.position(); j < array.limit(); ++j)
          {
              int b = array.get(j) & 0xFF;
              if (b < 0x10) sb.append('0');
              sb.append(Integer.toHexString(b));
          }
  
          return convertToStandardFormat( sb.toString() );
      }
  
      public static String guidToString(byte[] bytes)
      {
          StringBuilder sb = new StringBuilder();
          for (int j = 0; j < bytes.length; ++j)
          {
              int b = bytes[j] & 0xFF;
              if (b < 0x10) sb.append('0');
              sb.append(Integer.toHexString(b));
          }
  
          return convertToStandardFormat( sb.toString() );
      }
  
      public static ByteBuffer guidAsBytes(Random random, String hostId, long time)
      {
          StringBuilder sbValueBeforeMD5 = new StringBuilder();
          long rand = random.nextLong();
          sbValueBeforeMD5.append(hostId)
                          .append(":")
                          .append(Long.toString(time))
                          .append(":")
                          .append(Long.toString(rand));
  
          String valueBeforeMD5 = sbValueBeforeMD5.toString();
          return ByteBuffer.wrap(MD5Digest.threadLocalMD5Digest().digest(valueBeforeMD5.getBytes()));
      }
  
      public static ByteBuffer guidAsBytes()
      {
          return guidAsBytes(myRand, s_id, currentTimeMillis());
      }
  
      /*
          * Convert to the standard format for GUID
          * Example: C2FEEEAC-CFCD-11D1-8B05-00600806D9B6
      */
  
      private static String convertToStandardFormat(String valueAfterMD5)
      {
          String raw = toUpperCaseLocalized(valueAfterMD5);
          StringBuilder sb = new StringBuilder();
          sb.append(raw.substring(0, 8))
            .append("-")
            .append(raw.substring(8, 12))
            .append("-")
            .append(raw.substring(12, 16))
            .append("-")
            .append(raw.substring(16, 20))
            .append("-")
            .append(raw.substring(20));
          return sb.toString();
      }
  }
  
  
  
  
  
  
  