326 lines
10 KiB
C#
326 lines
10 KiB
C#
#region Disclaimer / License
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// Copyright (C) 2010, Kenneth Skovhede
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// http://www.hexad.dk, opensource@hexad.dk
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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//
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#endregion
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using System;
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using System.Collections.Generic;
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using System.Text;
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using System.Threading;
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namespace Duplicati.Library.Utility
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{
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/// <summary>
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/// Class to encapsulate a thread that runs a list of queued operations
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/// </summary>
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/// <typeparam name="Tx">The type to operate on</typeparam>
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public class WorkerThread<Tx> where Tx : class
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{
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/// <summary>
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/// Locking object for shared data
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/// </summary>
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private object m_lock = new object();
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/// <summary>
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/// The wait event
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/// </summary>
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private AutoResetEvent m_event;
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/// <summary>
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/// The internal list of tasks to perform
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/// </summary>
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private Queue<Tx> m_tasks;
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/// <summary>
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/// A flag used to terminate the thread
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/// </summary>
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private volatile bool m_terminate;
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/// <summary>
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/// The coordinating thread
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/// </summary>
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private Thread m_thread;
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/// <summary>
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/// A value indicating if the coordinating thread is running
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/// </summary>
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private volatile bool m_active;
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/// <summary>
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/// The current task being processed
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/// </summary>
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private Tx m_currentTask;
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/// <summary>
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/// A callback that performs the actual work on the item
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/// </summary>
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private Action<Tx> m_delegate;
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/// <summary>
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/// An event that is raised when the runner state changes
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/// </summary>
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public event Action<WorkerThread<Tx>, RunState> WorkerStateChanged;
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/// <summary>
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/// Event that occurs when a new operation is being processed
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/// </summary>
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public event EventHandler StartingWork;
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/// <summary>
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/// Event that occurs when an operation has completed
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/// </summary>
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public event EventHandler CompletedWork;
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/// <summary>
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/// An evnet that occurs when a new task is added to the queue or an existing one is removed
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/// </summary>
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public event EventHandler WorkQueueChanged;
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/// <summary>
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/// The internal state
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/// </summary>
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private volatile RunState m_state;
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/// <summary>
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/// The states the scheduler can take
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/// </summary>
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public enum RunState
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{
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/// <summary>
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/// The program is running as normal
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/// </summary>
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Run,
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/// <summary>
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/// The program is suspended by the user
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/// </summary>
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Paused
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}
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/// <summary>
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/// Constructs a new WorkerThread
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/// </summary>
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/// <param name="item">The callback that performs the work</param>
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public WorkerThread(Action<Tx> item, bool paused)
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{
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m_delegate = item;
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m_event = new AutoResetEvent(paused);
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m_terminate = false;
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m_tasks = new Queue<Tx>();
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m_state = paused ? WorkerThread<Tx>.RunState.Paused : WorkerThread<Tx>.RunState.Run;
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m_thread = new Thread(new ThreadStart(Runner));
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m_thread.IsBackground = true;
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m_thread.Start();
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}
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/// <summary>
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/// Gets a copy of the current queue
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/// </summary>
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public List<Tx> CurrentTasks
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{
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get
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{
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lock(m_lock)
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return new List<Tx>(m_tasks);
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}
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}
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/// <summary>
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/// Gets a value indicating if the worker is running
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/// </summary>
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public bool Active
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{
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get { return m_active; }
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}
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/// <summary>
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/// Adds a task to the queue
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/// </summary>
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/// <param name="task">The task to add</param>
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public void AddTask(Tx task)
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{
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lock (m_lock)
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{
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m_tasks.Enqueue(task);
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m_event.Set();
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}
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if (WorkQueueChanged != null)
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WorkQueueChanged(this, null);
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}
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/// <summary>
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/// Removes a task from the queue, does not remove the task if it is currently running
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/// </summary>
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/// <param name="task">The task to remove</param>
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public void RemoveTask(Tx task)
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{
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lock (m_lock)
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{
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Queue<Tx> tmp = new Queue<Tx>();
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while (m_tasks.Count > 0)
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{
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Tx n = m_tasks.Dequeue();
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if (n != task)
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tmp.Enqueue(n);
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}
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m_tasks = tmp;
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}
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if (WorkQueueChanged != null)
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WorkQueueChanged(this, null);
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}
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/// <summary>
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/// This will clear the pending queue
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/// <param name="abortThread">True if the current running thread should be aborted</param>
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/// </summary>
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public void ClearQueue(bool abortThread)
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{
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lock (m_lock)
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m_tasks.Clear();
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if (abortThread)
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{
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try
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{
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m_thread.Abort();
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m_thread.Join(500);
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}
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catch
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{
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}
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m_thread = new Thread(new ThreadStart(Runner));
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m_thread.Start();
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}
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}
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/// <summary>
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/// Gets a reference to the currently executing task.
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/// BEWARE: This is not protected by a mutex, DO NOT MODIFY IT!!!!
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/// </summary>
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public Tx CurrentTask
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{
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get
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{
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return m_currentTask;
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}
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}
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/// <summary>
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/// Terminates the thread. Any items still in queue will be removed
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/// </summary>
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/// <param name="wait">True if the call should block until the thread has exited, false otherwise</param>
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public void Terminate(bool wait)
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{
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m_terminate = true;
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m_event.Set();
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if (wait)
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m_thread.Join();
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}
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/// <summary>
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/// This is the thread entry point
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/// </summary>
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private void Runner()
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{
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while (!m_terminate)
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{
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m_currentTask = null;
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lock (m_lock)
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if (m_state == WorkerThread<Tx>.RunState.Run && m_tasks.Count > 0)
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m_currentTask = m_tasks.Dequeue();
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if (m_currentTask == null && !m_terminate)
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if (m_state == WorkerThread<Tx>.RunState.Run)
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m_event.WaitOne(); //Sleep until signaled
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else
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{
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if (WorkerStateChanged != null)
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WorkerStateChanged(this, m_state);
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//Sleep for brief periods, until signaled
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while (!m_terminate && m_state != WorkerThread<Tx>.RunState.Run)
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m_event.WaitOne(1000 * 60 * 5, false);
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//If we were not terminated, we are now ready to run
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if (!m_terminate)
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{
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m_state = WorkerThread<Tx>.RunState.Run;
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if (WorkerStateChanged != null)
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WorkerStateChanged(this, m_state);
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}
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}
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if (m_terminate)
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return;
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if (m_currentTask == null && m_state == WorkerThread<Tx>.RunState.Run)
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lock (m_lock)
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if (m_tasks.Count > 0)
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m_currentTask = m_tasks.Dequeue();
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if (m_currentTask == null)
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continue;
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if (StartingWork != null)
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StartingWork(this, null);
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m_active = true;
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m_delegate(m_currentTask);
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m_active = false;
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if (CompletedWork != null)
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CompletedWork(this, null);
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}
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}
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/// <summary>
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/// Gets the current run state
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/// </summary>
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public RunState State { get { return m_state; } }
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/// <summary>
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/// Instructs Duplicati to run scheduled backups
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/// </summary>
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public void Resume()
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{
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m_state = RunState.Run;
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m_event.Set();
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}
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/// <summary>
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/// Instructs Duplicati to pause scheduled backups
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/// </summary>
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public void Pause()
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{
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m_state = RunState.Paused;
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m_event.Set();
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}
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/// <summary>
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/// Waits the specified number of milliseconds for the thread to terminate
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/// </summary>
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/// <param name="millisecondTimeout">The number of milliseconds to wait</param>
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/// <returns>True if the thread is terminated, false if a timeout occured</returns>
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public bool Join(int millisecondTimeout)
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{
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if (m_thread != null)
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return m_thread.Join(millisecondTimeout);
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return true;
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}
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}
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}
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