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.distributedlog.limiter;
  
  import static com.google.common.base.Preconditions.checkState;
  
  /**
   * Wrap a guava limiter in a simple interface to make testing easier.
   * Notes:
   * 1. Negative limit translates into (virtually) unlimited.
   * 2. Calling acquire with permits == 0 translates into no acquire.
   */
  public class GuavaRateLimiter implements RateLimiter {
      com.google.common.util.concurrent.RateLimiter limiter;
  
      public static RateLimiter of(int limit) {
          if (limit == 0) {
              return RateLimiter.REJECT;
          } else if (limit < 0) {
              return RateLimiter.ACCEPT;
          } else {
              return new GuavaRateLimiter(limit);
          }
      }
  
      public GuavaRateLimiter(int limit) {
          double effectiveLimit = limit;
          if (limit < 0) {
              effectiveLimit = Double.POSITIVE_INFINITY;
          }
          this.limiter = com.google.common.util.concurrent.RateLimiter.create(effectiveLimit);
      }
  
      @Override
      public boolean acquire(int permits) {
          checkState(permits >= 0);
          if (permits > 0) {
              return limiter.tryAcquire(permits);
          } else {
              return true;
          }
      }
  }
  