source: branches/eraser6/EraserService/Eraser.Manager/Executor.cs @ 2624

/* 
 * $Id$
 * Copyright 2008-2012 The Eraser Project
 * Original Author: Joel Low <lowjoel@users.sourceforge.net>
 * Modified By:
 * 
 * This file is part of Eraser.
 * 
 * Eraser is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * Eraser is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 * 
 * A copy of the GNU General Public License can be found at
 * <http://www.gnu.org/licenses/>.
 */

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

using System.ServiceModel;

namespace Eraser.Manager
{
    /// <summary>
    /// Executor base class. This class will manage the tasks currently scheduled
    /// to be run and will run them when they are set to be run. This class is
    /// abstract as they each will have their own ways of dealing with tasks.
    /// </summary>
    [ServiceContract(Namespace="http://eraser.sourceforge.net/", SessionMode=SessionMode.Required)]
    public interface IExecutor : IDisposable
    {
        /// <summary>
        /// Queues the task for execution.
        /// </summary>
        /// <param name="task">The task to queue.</param>
        [OperationContract]
        void QueueTask(Task task);

        /// <summary>
        /// Schedules the given task for execution.
        /// </summary>
        /// <param name="task">The task to schedule</param>
        [OperationContract]
        void ScheduleTask(Task task);

        /// <summary>
        /// Removes the given task from the execution queue.
        /// </summary>
        /// <remarks>If the task given runs a recurring schedule, the task will only
        /// remove requested tasks and not the scheduled ones</remarks>
        /// <param name="task">The task to cancel.</param>
        [OperationContract]
        void UnqueueTask(Task task);

        /// <summary>
        /// Queues all tasks in the task list which are meant for restart execution.
        /// This is a separate function rather than just running them by default on
        /// task load because creating a new instance and loading the task list
        /// may just be a program restart and may not necessarily be a system
        /// restart. Therefore this fuction has to be explicitly called by clients.
        /// </summary>
        [OperationContract]
        void QueueRestartTasks();

        /// <summary>
        /// Retrieves the current task list for the executor.
        /// </summary>
        /// <returns>A list of tasks which the executor has registered.</returns>
        [OperationContract]
        ExecutorTasksCollection GetTasks();
    }

    public abstract class Executor : IExecutor, IDisposable
    {
        #region IDisposable members
        ~Executor()
        {
            Dispose(false);
        }

        protected virtual void Dispose(bool disposing)
        {
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
        #endregion

        /// <summary>
        /// Starts the execution of tasks queued.
        /// </summary>
        public abstract void Run();

        /// <summary>
        /// Queues the task for execution.
        /// </summary>
        /// <param name="task">The task to queue.</param>
        public abstract void QueueTask(Task task);

        /// <summary>
        /// Schedules the given task for execution.
        /// </summary>
        /// <param name="task">The task to schedule</param>
        public abstract void ScheduleTask(Task task);

        /// <summary>
        /// Removes the given task from the execution queue.
        /// </summary>
        /// <remarks>If the task given runs a recurring schedule, the task will only
        /// remove requested tasks and not the scheduled ones</remarks>
        /// <param name="task">The task to cancel.</param>
        public abstract void UnqueueTask(Task task);

        /// <summary>
        /// Gets whether a task is currently queued for execution, outside of the
        /// scheduled time.
        /// </summary>
        /// <param name="task">The task to query.</param>
        /// <returns>True if the task is currently queued, false otherwise.</returns>
        internal abstract bool IsTaskQueued(Task task);

        /// <summary>
        /// Queues all tasks in the task list which are meant for restart execution.
        /// This is a separate function rather than just running them by default on
        /// task load because creating a new instance and loading the task list
        /// may just be a program restart and may not necessarily be a system
        /// restart. Therefore this fuction has to be explicitly called by clients.
        /// </summary>
        public abstract void QueueRestartTasks();

        /// <summary>
        /// Retrieves the current task list for the executor.
        /// </summary>
        /// <returns>A list of tasks which the executor has registered.</returns>
        public abstract ExecutorTasksCollection Tasks { get; }

        /// <summary>
        /// Retrieves the current task list for the executor.
        /// </summary>
        /// <returns>A list of tasks which the executor has registered.</returns>
        public ExecutorTasksCollection GetTasks()
        {
            return Tasks;
        }

        /// <summary>
        /// The task added event object.
        /// </summary>
        public EventHandler<TaskEventArgs> TaskAdded { get; set; }

        /// <summary>
        /// Helper function for the task added event.
        /// </summary>
        internal void OnTaskAdded(TaskEventArgs e)
        {
            if (TaskAdded != null)
                TaskAdded(this, e);
        }

        /// <summary>
        /// The task added event object.
        /// </summary>
        public EventHandler<TaskEventArgs> TaskDeleted { get; set; }

        /// <summary>
        /// Helper function for the task deleted event.
        /// </summary>
        internal void OnTaskDeleted(TaskEventArgs e)
        {
            if (TaskDeleted != null)
                TaskDeleted(this, e);
        }
    }

    public abstract class ExecutorTasksCollection : IList<Task>
    {
        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="executor">The <seealso cref="IExecutor"/> object owning
        /// this task list.</param>
        protected ExecutorTasksCollection(IExecutor executor)
        {
            Owner = executor;
        }

        #region IList<Task> Members
        public abstract int IndexOf(Task item);
        public abstract void Insert(int index, Task item);
        public abstract void RemoveAt(int index);
        public abstract Task this[int index] { get; set; }
        #endregion

        #region ICollection<Task> Members
        public abstract void Add(Task item);
        public abstract void Clear();
        public abstract bool Contains(Task item);
        public abstract void CopyTo(Task[] array, int arrayIndex);
        public abstract int Count { get; }
        public bool IsReadOnly { get { return false; } }
        public abstract bool Remove(Task item);
        #endregion

        #region IEnumerable<Task> Members
        public abstract IEnumerator<Task> GetEnumerator();
        #endregion

        #region IEnumerable Members
        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
        #endregion

        /// <summary>
        /// Saves a task list to the given stream.
        /// </summary>
        /// <param name="stream">The stream to save to.</param>
        public abstract void SaveToStream(Stream stream);

        /// <summary>
        /// Saves the task list to file.
        /// </summary>
        /// <param name="file">The path to the task list.</param>
        public virtual void SaveToFile(string file)
        {
            using (FileStream stream = new FileStream(file, FileMode.Create,
                FileAccess.Write, FileShare.None))
            {
                SaveToStream(stream);
            }
        }

        /// <summary>
        /// Loads the task list from the given stream.
        /// </summary>
        /// <remarks>This will append the tasks in the given stream to the current list of
        /// tasks instead of overwriting it.</remarks>
        /// <param name="stream">The stream to save to.</param>
        /// <exception cref="InvalidDataException">Thrown when the data in the stream is
        /// invalid or unrecognised.</exception>
        public abstract void LoadFromStream(Stream stream);

        /// <summary>
        /// The owner of this task list.
        /// </summary>
        protected IExecutor Owner { get; private set; }
    }
}