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.util.UUID;
  
  /**
   * The goods are here: www.ietf.org/rfc/rfc4122.txt.
   */
  public class UUIDGen
  {
      public static final int UUID_LEN = 16;
  
      /** creates a type 1 uuid from raw bytes. */
      public static UUID getUUID(ByteBuffer raw)
      {
          return getUUID(raw.getLong(raw.position()), raw.getLong(raw.position() + 8));
      }
  
      public static UUID getUUID(long mostSigBits, long leastSigBits)
      {
          return new UUID(mostSigBits, leastSigBits);
      }
  
      public static ByteBuffer toByteBuffer(UUID uuid)
      {
          ByteBuffer buffer = ByteBuffer.allocate(UUID_LEN);
          buffer.putLong(uuid.getMostSignificantBits());
          buffer.putLong(uuid.getLeastSignificantBits());
          buffer.flip();
          return buffer;
      }
  
      /** decomposes a uuid into raw bytes. */
      public static byte[] decompose(UUID uuid)
      {
          return decompose(uuid.getMostSignificantBits(), uuid.getLeastSignificantBits());
      }
  
      public static byte[] decompose(long msb, long lsb)
      {
          byte[] b = new byte[16];
          for (int i = 0; i < 8; i++)
          {
              b[i] = (byte)(msb >>> ((7-i) * 8));
              b[8+i] = (byte)(lsb >>> ((7-i) * 8));
          }
          return b;
      }
  
      /**
       * Returns a milliseconds-since-epoch value for a type-1 UUID.
       *
       * @param uuid a type-1 (time-based) UUID
       * @return the number of milliseconds since the unix epoch
       * @throws IllegalArgumentException if the UUID is not version 1
       */
      public static long getAdjustedTimestamp(UUID uuid)
      {
          if (uuid.version() != 1)
              throw new IllegalArgumentException("incompatible with uuid version: "+uuid.version());
          return (uuid.timestamp() / 10000) + TimeUUID.UUID_EPOCH_UNIX_MILLIS;
      }
  
  }
  
  // for the curious, here is how I generated START_EPOCH
  //        Calendar c = Calendar.getInstance(TimeZone.getTimeZone("GMT-0"));
  //        c.set(Calendar.YEAR, 1582);
  //        c.set(Calendar.MONTH, Calendar.OCTOBER);
  //        c.set(Calendar.DAY_OF_MONTH, 15);
  //        c.set(Calendar.HOUR_OF_DAY, 0);
  //        c.set(Calendar.MINUTE, 0);
  //        c.set(Calendar.SECOND, 0);
  //        c.set(Calendar.MILLISECOND, 0);
  //        long START_EPOCH = c.getTimeInMillis();
  