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/*
* Copyright (c) 2023 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Essentials.ServiceStack
* File: ManagedPlugin.cs
*
* ManagedPlugin.cs is part of VNLib.Plugins.Essentials.ServiceStack which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Essentials.ServiceStack is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero 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.Essentials.ServiceStack 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System;
using System.IO;
using System.Linq;
using System.Threading;
using System.Reflection;
using System.ComponentModel.Design;
using VNLib.Utils;
using VNLib.Plugins.Runtime;
using VNLib.Plugins.Attributes;
namespace VNLib.Plugins.Essentials.ServiceStack
{
internal sealed class ManagedPlugin : VnDisposeable, IPluginEventListener, IManagedPlugin
{
private readonly IPluginEventListener _serviceDomainListener;
private readonly RuntimePluginLoader _plugin;
private UnloadableServiceContainer? _services;
public ManagedPlugin(RuntimePluginLoader loader, IPluginEventListener listener)
{
//configure the loader
_plugin = loader;
//Register loading event listener before loading occurs
_plugin.Controller.Register(this, this);
//Store listener to raise events
_serviceDomainListener = listener;
}
///<inheritdoc/>
public string PluginPath => _plugin.Config.AssemblyFile;
///<inheritdoc/>
public IUnloadableServiceProvider Services
{
get
{
Check();
return _services!;
}
}
///<inheritdoc/>
public PluginController Controller
{
get
{
Check();
return _plugin.Controller;
}
}
internal string PluginFileName => Path.GetFileName(PluginPath);
internal void InitializePlugins()
{
Check();
_plugin.InitializeController();
}
internal void LoadPlugins()
{
Check();
_plugin.LoadPlugins();
}
/*
* Automatically called after the plugin has successfully loaded
* by event handlers below
*/
private void ConfigureServices()
{
//If the service container is defined, dispose
_services?.Dispose();
//Init new service container
_services = new();
//Get types from plugin
foreach (LivePlugin plugin in _plugin.Controller.Plugins)
{
/*
* Get the exposed configurator method if declared,
* it may not be defined.
*/
ServiceConfigurator? callback = plugin.PluginType.GetMethods()
.Where(static m => m.GetCustomAttribute<ServiceConfiguratorAttribute>() != null && !m.IsAbstract)
.Select(m => m.CreateDelegate<ServiceConfigurator>(plugin.Plugin))
.FirstOrDefault();
//Invoke if defined to expose services
callback?.Invoke(_services);
}
}
internal void ReloadPlugins()
{
Check();
_plugin.ReloadPlugins();
}
internal void UnloadPlugins()
{
Check();
//unload plugins
_plugin.UnloadAll();
//Services will be cleaned up by the unload event
}
void IPluginEventListener.OnPluginLoaded(PluginController controller, object? state)
{
//Initialize services after load, before passing event
ConfigureServices();
//Propagate event
_serviceDomainListener.OnPluginLoaded(controller, state);
}
void IPluginEventListener.OnPluginUnloaded(PluginController controller, object? state)
{
//Cleanup services no longer in use. Plugin is still valid until this method returns
using (_services)
{
//Propagate event
_serviceDomainListener.OnPluginUnloaded(controller, state);
//signal service cancel before disposing
_services?.SignalUnload();
}
//Remove ref to services
_services = null;
}
protected override void Free()
{
//Dispose services
_services?.Dispose();
//Unregister the listener to cleanup resources
_plugin.Controller.Unregister(this);
//Dispose loader
_plugin.Dispose();
}
private sealed class UnloadableServiceContainer : ServiceContainer, IUnloadableServiceProvider
{
private readonly CancellationTokenSource _cts;
public UnloadableServiceContainer() : base()
{
_cts = new();
}
///<inheritdoc/>
CancellationToken IUnloadableServiceProvider.UnloadToken => _cts.Token;
/// <summary>
/// Signals to listensers that the service container will be unloading
/// </summary>
internal void SignalUnload() => _cts.Cancel();
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
_cts.Dispose();
}
}
}
}
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