content: package org.apache.cassandra.triggers;
  /*
   *
   * 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.
   *
   */
  
  
  import java.util.Collection;
  
  import org.apache.cassandra.db.Mutation;
  import org.apache.cassandra.db.partitions.Partition;
  
  /**
   * Trigger interface, For every partition update received by the coordinator {@link #augment(Partition)}
   * is called.<p>
   *
   * <b> Contract:</b><br>
   * 1) Implementation of this interface should only have a constructor without parameters <br>
   * 2) ITrigger implementation can be instantiated multiple times during the server life time.
   *      (Depends on the number of times trigger folder is updated.)<br>
   * 3) ITrigger implementation should be state-less (avoid dependency on instance variables).<br>
   *
   * <br><b>The API is still beta and can change.</b>
   */
  public interface ITrigger
  {
      /**
       * Called exactly once per CF update, returned mutations are atomically updated.
       *
       * @param update - update received for the CF
       * @return additional modifications to be applied along with the supplied update
       */
      public Collection<Mutation> augment(Partition update);
  }
  