/**
    * 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.hadoop.hbase.procedure2;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.protobuf.generated.ProcedureProtos.SequentialProcedureData;
  
  /**
   * A SequentialProcedure describes one step in a procedure chain.
   *   -> Step 1 -> Step 2 -> Step 3
   *
   * The main difference from a base Procedure is that the execute() of a
   * SequentialProcedure will be called only once, there will be no second
   * execute() call once the child are finished. which means once the child
   * of a SequentialProcedure are completed the SequentialProcedure is completed too.
   */
  @InterfaceAudience.Private
  @InterfaceStability.Evolving
  public abstract class SequentialProcedure<TEnvironment> extends Procedure<TEnvironment> {
    private boolean executed = false;
  
    @Override
    protected Procedure[] doExecute(final TEnvironment env)
        throws ProcedureYieldException, InterruptedException {
      updateTimestamp();
      try {
        Procedure[] children = !executed ? execute(env) : null;
        executed = !executed;
        return children;
      } finally {
        updateTimestamp();
      }
    }
  
    @Override
    protected void doRollback(final TEnvironment env)
        throws IOException, InterruptedException {
      updateTimestamp();
      if (executed) {
        try {
          rollback(env);
          executed = !executed;
        } finally {
          updateTimestamp();
        }
      }
    }
  
    @Override
    protected void serializeStateData(final OutputStream stream) throws IOException {
      SequentialProcedureData.Builder data = SequentialProcedureData.newBuilder();
      data.setExecuted(executed);
      data.build().writeDelimitedTo(stream);
    }
  
    @Override
    protected void deserializeStateData(final InputStream stream) throws IOException {
      SequentialProcedureData data = SequentialProcedureData.parseDelimitedFrom(stream);
      executed = data.getExecuted();
    }
  }