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.bookkeeper.tools.perf.table;
  
  import io.netty.buffer.ByteBuf;
  
  /**
   * Util class used for perf benchmarks.
   */
  final class KeyGenerator {
  
      private final long numKeys;
      private final long keysPerPrefix;
      private final int prefixSize;
  
      KeyGenerator(long numKeys,
                   long keysPerPrefix,
                   int prefixSize) {
          this.numKeys = numKeys;
          this.keysPerPrefix = keysPerPrefix;
          this.prefixSize = prefixSize;
      }
  
      public void generateKeyFromLong(ByteBuf slice, long n) {
          int startPos = 0;
          if (keysPerPrefix > 0) {
              long numPrefix = (numKeys + keysPerPrefix - 1) / keysPerPrefix;
              long prefix = n % numPrefix;
              int bytesToFill = Math.min(prefixSize, 8);
              for (int i = 0; i < bytesToFill; i++) {
                  slice.setByte(i,  (byte) (prefix % 256));
                  prefix /= 256;
              }
              for (int i = 8; i < bytesToFill; ++i) {
                  slice.setByte(i, '0');
              }
              startPos = bytesToFill;
          }
          for (int i = slice.writableBytes() - 1; i >= startPos; --i) {
              slice.setByte(i, (byte) ('0' + (n % 10)));
              n /= 10;
          }
      }
  
  }
  