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.beam.runners.samza.util;
  
  import java.util.HashSet;
  import java.util.Set;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This class generates hash-based unique ids from String. The id length is the hash length and the
   * suffix length combined. Ids generated are guaranteed to be unique, such that same names will be
   * hashed to different ids.
   */
  public class HashIdGenerator {
    private static final Logger LOG = LoggerFactory.getLogger(HashIdGenerator.class);
  
    private static final int DEFAULT_MAX_HASH_LENGTH = 5;
    private final int maxHashLength;
    private final Set<String> usedIds = new HashSet<>();
  
    public HashIdGenerator(int maxHashLength) {
      this.maxHashLength = maxHashLength;
    }
  
    public HashIdGenerator() {
      this(DEFAULT_MAX_HASH_LENGTH);
    }
  
    public String getId(String name) {
      // Use the id directly if it is unique and the length is less than max
      if (name.length() <= maxHashLength && usedIds.add(name)) {
        return name;
      }
  
      // Pick the last bytes of hashcode and use hex format
      final String hexString = Integer.toHexString(name.hashCode());
      final String origId =
          hexString.length() <= maxHashLength
              ? hexString
              : hexString.substring(Math.max(0, hexString.length() - maxHashLength));
      String id = origId;
      int suffixNum = 2;
      while (!usedIds.add(id)) {
        // A duplicate!  Retry.
        id = origId + "-" + suffixNum++;
      }
      LOG.info("Name {} is mapped to id {}", name, id);
      return id;
    }
  }
  