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/*
* Copyright (c) 2022 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Extensions.Loading
* File: EventHandle.cs
*
* EventHandle.cs is part of VNLib.Plugins.Extensions.Loading which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Extensions.Loading 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 2 of the License,
* or (at your option) any later version.
*
* VNLib.Plugins.Extensions.Loading 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.
*
* You should have received a copy of the GNU General Public License
* along with VNLib.Plugins.Extensions.Loading. If not, see http://www.gnu.org/licenses/.
*/
using System;
using System.Threading;
using System.Threading.Tasks;
using VNLib.Utils;
using VNLib.Utils.Extensions;
using VNLib.Utils.Logging;
namespace VNLib.Plugins.Extensions.Loading.Events
{
/// <summary>
/// Represents a handle to a scheduled event interval that is managed by the plugin but may be cancled by disposing the instance
/// </summary>
public class EventHandle : VnDisposeable
{
private readonly PluginBase _pbase;
private readonly Timer _eventTimer;
private readonly TimeSpan _interval;
private readonly AsyncSchedulableCallback _callback;
internal EventHandle(AsyncSchedulableCallback callback, TimeSpan interval, PluginBase pbase)
{
_pbase = pbase;
_interval = interval;
_callback = callback;
//Init new timer
_eventTimer = new(OnTimerElapsed, this, interval, interval);
//Register dispose to unload token
_ = pbase.UnloadToken.RegisterUnobserved(Dispose);
}
private void OnTimerElapsed(object? state)
{
//Run on task scheuler
_ = Task.Run(RunInterval)
.ConfigureAwait(false);
}
private async Task RunInterval()
{
try
{
await _callback(_pbase.Log, _pbase.UnloadToken);
}
catch (OperationCanceledException)
{
//unloaded
_pbase.Log.Verbose("Interval callback canceled due to plugin unload or other event cancellation");
}
catch (Exception ex)
{
_pbase.Log.Error(ex, "Unhandled exception raised during timer callback");
}
}
/// <summary>
/// Invokes the event handler manually and observes the result.
/// This method writes execptions to the plugin's default log provider.
/// </summary>
/// <returns></returns>
/// <exception cref="ObjectDisposedException"></exception>
public Task ManualInvoke()
{
Check();
return Task.Run(RunInterval);
}
/// <summary>
/// Pauses the event timer until the <see cref="OpenHandle"/> is released or disposed
/// then resumes to the inital interval period
/// </summary>
/// <returns>A <see cref="OpenHandle"/> that restores the timer to its initial state when disposed</returns>
/// <exception cref="ObjectDisposedException"></exception>
public OpenHandle Pause()
{
Check();
return _eventTimer.Stop(_interval);
}
///<inheritdoc/>
protected override void Free()
{
_eventTimer.Dispose();
}
}
}
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