/*
    * Copyright 2006-2013 the original author or authors.
    *
    * Licensed 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.springframework.batch.core.partition.support;
  
  import java.util.Collection;
  
  import org.springframework.batch.core.BatchStatus;
  import org.springframework.batch.core.ExitStatus;
  import org.springframework.batch.core.StepExecution;
  import org.springframework.util.Assert;
  
  /**
   * Convenience class for aggregating a set of {@link StepExecution} instances
   * into a single result.
   *
   * @author Dave Syer
   * @since 2.1
   */
  public class DefaultStepExecutionAggregator implements StepExecutionAggregator {
  
  	/**
  	 * Aggregates the input executions into the result {@link StepExecution}.
  	 * The aggregated fields are
  	 * <ul>
  	 * <li>status - choosing the highest value using
  	 * {@link BatchStatus#max(BatchStatus, BatchStatus)}</li>
  	 * <li>exitStatus - using {@link ExitStatus#and(ExitStatus)}</li>
  	 * <li>commitCount, rollbackCount, etc. - by arithmetic sum</li>
  	 * </ul>
  	 * @see StepExecutionAggregator #aggregate(StepExecution, Collection)
  	 */
  	@Override
  	public void aggregate(StepExecution result, Collection<StepExecution> executions) {
  		Assert.notNull(result, "To aggregate into a result it must be non-null.");
  		if (executions == null) {
  			return;
  		}
  		for (StepExecution stepExecution : executions) {
  			BatchStatus status = stepExecution.getStatus();
  			result.setStatus(BatchStatus.max(result.getStatus(), status));
  			result.setExitStatus(result.getExitStatus().and(stepExecution.getExitStatus()));
  			result.setCommitCount(result.getCommitCount() + stepExecution.getCommitCount());
  			result.setRollbackCount(result.getRollbackCount() + stepExecution.getRollbackCount());
  			result.setReadCount(result.getReadCount() + stepExecution.getReadCount());
  			result.setReadSkipCount(result.getReadSkipCount() + stepExecution.getReadSkipCount());
  			result.setWriteCount(result.getWriteCount() + stepExecution.getWriteCount());
  			result.setWriteSkipCount(result.getWriteSkipCount() + stepExecution.getWriteSkipCount());
  		}
  	}
  
  }