package com.iluwatar.async.method.invocation;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;

/**
 * 
 * AsyncExecutor interface
 *
 */
public interface AsyncExecutor {

  /**
   * Starts processing of an async task. Returns immediately with async result.
   *
   * @param task task to be executed asynchronously
   * @return async result for the task
   */
  <T> AsyncResult<T> startProcess(Callable<T> task);

  /**
   * Starts processing of an async task. Returns immediately with async result. Executes callback
   * when the task is completed.
   *
   * @param task task to be executed asynchronously
   * @param callback callback to be executed on task completion
   * @return async result for the task
   */
  <T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback);

  /**
   * Ends processing of an async task. Blocks the current thread if necessary and returns the
   * evaluated value of the completed task.
   *
   * @param asyncResult async result of a task
   * @return evaluated value of the completed task
   * @throws ExecutionException if execution has failed, containing the root cause
   * @throws InterruptedException if the execution is interrupted
   */
  <T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException;
}
