using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace Duplicati.Server
{
///
/// This class handles synchronized waiting for events
///
public class EventPollNotify
{
///
/// The lock that grants exclusive access to control structures
///
private readonly object m_lock = new object();
///
/// The current eventID
///
private long m_eventNo = 0;
///
/// The list of subscribed waiting threads
///
private readonly Queue m_waitQueue = new Queue();
///
/// An eventhandler for subscribing to event updates without blocking
///
public event EventHandler NewEvent;
///
/// Gets the current event ID
///
public long EventNo { get { return m_eventNo; } }
///
/// Call to wait for an event that is newer than the current known event
///
/// The last known event id
/// The number of milliseconds to block
/// The current event id
public long Wait(long eventId, int milliseconds)
{
System.Threading.ManualResetEvent mre;
lock (m_lock)
{
//If a newer event has already occured, return immediately
if (eventId != m_eventNo)
return m_eventNo;
//Otherwise register this thread as waiting
mre = new System.Threading.ManualResetEvent(false);
m_waitQueue.Enqueue(mre);
}
//Wait until we are signalled or the time has elapsed
mre.WaitOne(milliseconds, false);
return m_eventNo;
}
///
/// Signals that an event has occurred and notifies all waiting threads
///
public void SignalNewEvent()
{
lock (m_lock)
{
m_eventNo++;
while (m_waitQueue.Count > 0)
m_waitQueue.Dequeue().Set();
}
if (NewEvent != null)
NewEvent(this, null);
}
}
}