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.common.util;
  
  /**
   * A simple limiter interface which tracks acquire/release of permits, for
   * example for tracking outstanding writes.
   */
  public interface PermitLimiter {
  
      PermitLimiter NULL_PERMIT_LIMITER = new PermitLimiter() {
          @Override
          public boolean acquire() {
              return true;
          }
          @Override
          public void release(int permits) {
          }
  
          @Override
          public void close() {
  
          }
      };
  
      /**
       * Acquire a permit.
       *
       * @return true if successfully acquire a permit, otherwise false.
       */
      boolean acquire();
  
      /**
       * Release a permit.
       */
      void release(int permits);
  
      /**
       * Close the resources created by the limiter.
       */
      void close();
  }
  