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.bifromq.mqtt.handler;
  
  import java.util.concurrent.TimeUnit;
  
  /**
   * simple mps throttler with 'hard' maximum mps limit, mps could be reset.
   */
  public class MPSThrottler {
      private int maxMPS;
      private long lastSec = 0;
      private long count = 0;
  
      public MPSThrottler(int maxMPS) {
          reset(maxMPS);
      }
  
      public int rateLimit() {
          return maxMPS;
      }
  
      public boolean pass() {
          long currentSec = upTimeInSec();
          if (lastSec == currentSec) {
              // same second bucket
              return ++count < maxMPS;
          } else {
              // new second bucket
              count = 0;
              lastSec = currentSec;
              return true;
          }
      }
  
      public void reset(int maxMPS) {
          assert maxMPS > 0;
          this.maxMPS = maxMPS;
      }
  
      private long upTimeInSec() {
          return TimeUnit.NANOSECONDS.toSeconds(System.nanoTime());
      }
  }
  