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.causeway.commons.internal.base;
  
  import java.io.Serializable;
  
  /**
   * <h1>- internal use only -</h1>
   * <p>
   * One-shot utility, thread-safe and serializable
   * <p>
   * <b>WARNING</b>: Do <b>NOT</b> use any of the classes provided by this package! <br/>
   * These may be changed or removed without notice!
   * @since 2.0
   */
  public final class _Oneshot implements Serializable {
  
      private static final long serialVersionUID = 1L;
  
      private final Object $lock = new Object[0]; // serializable lock
  
      private volatile int triggerCount = 0;
  
      /**
       * Returns whether the trigger was accepted.
       */
      public boolean trigger() {
          synchronized ($lock) {
              if(triggerCount==0) {
                  ++ triggerCount;
                  return true;
              }
              return false;
          }
      }
  
      /**
       * Returns whether the {@link Runnable} was actually executed
       * (indifferent to whether completing with or without success).
       * If the {@link Runnable} throws an {@link Exception}, this one-shot will be exhausted regardless.
       */
      public boolean trigger(final Runnable runnable) {
          synchronized ($lock) {
              if(triggerCount==0) {
                  ++ triggerCount;
                  runnable.run();
              }
              return false;
          }
      }
  
      /**
       * resets to initial condition, that is it allows one more trigger
       */
      public void reset() {
          synchronized ($lock) {
              triggerCount = 0;
          }
      }
  
  }
  