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.util;
  
  import com.google.common.annotations.Beta;
  import java.util.concurrent.CompletableFuture;
  
  /**
   * Util class represents a transaction.
   */
  @Beta
  public interface Transaction<OpResultT> {
  
      /**
       * An operation executed in a transaction.
       */
      interface Op<OpResultT> {
  
          /**
           * Execute after the transaction succeeds.
           */
          void commit(OpResultT r);
  
          /**
           * Execute after the transaction fails.
           */
          void abort(Throwable t, OpResultT r);
  
      }
  
      /**
       * Listener on the result of an {@link Transaction.Op}.
       *
       * @param <OpResultT>
       */
      interface OpListener<OpResultT> {
  
          /**
           * Trigger on operation committed.
           *
           * @param r
           *          result to return
           */
          void onCommit(OpResultT r);
  
          /**
           * Trigger on operation aborted.
           *
           * @param t
           *          reason to abort
           */
          void onAbort(Throwable t);
      }
  
      /**
       * Add the operation to current transaction.
       *
       * @param operation
       *          operation to execute under current transaction
       */
      void addOp(Op<OpResultT> operation);
  
      /**
       * Execute the current transaction. If the transaction succeed, all operations will be
       * committed (via {@link Transaction.Op#commit(Object)}.
       * Otherwise, all operations will be aborted (via {@link Op#abort(Throwable, Object)}).
       *
       * @return future representing the result of transaction execution.
       */
      CompletableFuture<Void> execute();
  
      /**
       * Abort current transaction. If this is called and the transaction haven't been executed by
       * {@link #execute()}, it would abort all operations. If the transaction has been executed,
       * the behavior is left up to implementation - if transaction is cancellable, the {@link #abort(Throwable)}
       * could attempt to cancel it.
       *
       * @param reason reason to abort the transaction
       */
      void abort(Throwable reason);
  
  }
  