/* 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.activiti.spring;

import java.util.concurrent.RejectedExecutionException;

import org.activiti.engine.impl.asyncexecutor.DefaultAsyncJobExecutor;
import org.activiti.engine.impl.asyncexecutor.ExecuteAsyncRunnable;
import org.activiti.engine.impl.jobexecutor.JobExecutor;
import org.activiti.engine.impl.jobexecutor.RejectedJobsHandler;
import org.activiti.engine.impl.persistence.entity.JobEntity;
import org.springframework.core.task.TaskExecutor;

/**
 * <p>
 * This is a spring based implementation of the {@link JobExecutor} using spring
 * abstraction {@link TaskExecutor} for performing background task execution.
 * </p>
 * <p>
 * The idea behind this implementation is to externalize the configuration of
 * the task executor, so it can leverage to Application servers controller
 * thread pools, for example using the commonj API. The use of unmanaged thread
 * in application servers is discouraged by the Java EE spec.
 * </p>
 *
 * @author Pablo Ganga
 */
public class SpringAsyncExecutor extends DefaultAsyncJobExecutor {

  protected TaskExecutor taskExecutor;
  protected SpringRejectedJobsHandler rejectedJobsHandler;

  public SpringAsyncExecutor() {
  }

  public SpringAsyncExecutor(TaskExecutor taskExecutor, SpringRejectedJobsHandler rejectedJobsHandler) {
    this.taskExecutor = taskExecutor;
    this.rejectedJobsHandler = rejectedJobsHandler;
  }

  public TaskExecutor getTaskExecutor() {
    return taskExecutor;
  }

  /**
   * Required spring injected {@link TaskExecutor} implementation that will be
   * used to execute runnable jobs.
   *
   * @param taskExecutor
   */
  public void setTaskExecutor(TaskExecutor taskExecutor) {
    this.taskExecutor = taskExecutor;
  }
  
  public SpringRejectedJobsHandler getRejectedJobsHandler() {
    return rejectedJobsHandler;
  }

  /**
   * Required spring injected {@link RejectedJobsHandler} implementation that will be
   * used when jobs were rejected by the task executor.
   *
   * @param taskExecutor
   */
  public void setRejectedJobsHandler(SpringRejectedJobsHandler rejectedJobsHandler) {
    this.rejectedJobsHandler = rejectedJobsHandler;
  }

	@Override
  public boolean executeAsyncJob(JobEntity job) {
	  try {
      taskExecutor.execute(new ExecuteAsyncRunnable(job, commandExecutor));
    } catch (RejectedExecutionException e) {
      rejectedJobsHandler.jobRejected(this, job);
      return false;
    }
	  return true;
  }

  @Override
  protected void startExecutingAsyncJobs() {
    startJobAcquisitionThread();
  }

  @Override
  protected void stopExecutingAsyncJobs() {
    stopJobAcquisitionThread();
  }
}