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/*
* Copyright (c) 2024 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Runtime
* File: RuntimePluginLoader.cs
*
* RuntimePluginLoader.cs is part of VNLib.Plugins.Runtime which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Runtime 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.Runtime 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.Runtime. If not, see http://www.gnu.org/licenses/.
*/
using System;
using System.IO;
using System.Reflection;
using VNLib.Utils;
using VNLib.Utils.IO;
using VNLib.Utils.Logging;
namespace VNLib.Plugins.Runtime
{
/// <summary>
/// A runtime .NET assembly loader specialized to load
/// assemblies that export <see cref="IPlugin"/> types.
/// </summary>
public sealed class RuntimePluginLoader : VnDisposeable, IPluginReloadEventHandler
{
private static readonly IPluginAssemblyWatcher Watcher = new AssemblyWatcher();
private readonly IPluginAssemblyLoader Loader;
private readonly ILogProvider? Log;
/// <summary>
/// Gets the plugin assembly loader configuration information
/// </summary>
public IPluginAssemblyLoadConfig Config => Loader.Config;
/// <summary>
/// Gets the plugin lifecycle controller
/// </summary>
public PluginController Controller { get; }
/// <summary>
/// Creates a new <see cref="RuntimePluginLoader"/> with the specified config and host config dom.
/// </summary>
/// <param name="loader">The plugin's assembly loader</param>
/// <param name="log">A log provider to write plugin unload log events to</param>
/// <exception cref="ArgumentNullException"></exception>
public RuntimePluginLoader(IPluginAssemblyLoader loader, ILogProvider? log)
{
Log = log;
Loader = loader ?? throw new ArgumentNullException(nameof(loader));
//Configure watcher if requested
if (loader.Config.WatchForReload)
{
Watcher.WatchAssembly(this, loader);
}
//Init container
Controller = new();
}
/// <summary>
/// Initializes the plugin loader, and populates the <see cref="Controller"/>
/// with initialized plugins.
/// </summary>
/// <returns>A task that represents the initialization</returns>
/// <exception cref="IOException"></exception>
/// <exception cref="FileNotFoundException"></exception>
public void InitializeController()
{
//Prep the assembly loader
Loader.Load();
//Load the main assembly
Assembly PluginAsm = Loader.GetAssembly();
//Init container from the assembly
Controller.InitializePlugins(PluginAsm);
string[] cliArgs = Environment.GetCommandLineArgs();
//Write the config to binary to pass it to the plugin
using VnMemoryStream vms = new();
//Read config data
Loader.Config.ReadConfigurationData(vms);
//Reset memstream
vms.Seek(0, SeekOrigin.Begin);
//Configure log/doms
Controller.ConfigurePlugins(vms, cliArgs);
}
/// <summary>
/// Loads all configured plugins by calling <see cref="IPlugin.Load"/>
/// event hook on the current thread. Loading exceptions are aggregated so not
/// to block individual loading.
/// </summary>
/// <exception cref="AggregateException"></exception>
public void LoadPlugins() => Controller.LoadPlugins();
/// <summary>
/// Manually reload the internal <see cref="IPluginAssemblyLoader"/>
/// which will reload the assembly and re-initialize the controller
/// </summary>
/// <param name="forceGc">A value that indicates if the current unload should cause a manual garbage collection</param>
/// <exception cref="AggregateException"></exception>
/// <exception cref="NotSupportedException"></exception>
public void ReloadPlugins(bool forceGc)
{
//Not unloadable
if (!Config.Unloadable)
{
throw new NotSupportedException("The loading context is not unloadable, you may not dynamically reload plugins");
}
//All plugins must be unloaded first
UnloadAll(forceGc);
//Reload the assembly and
InitializeController();
//Load plugins
LoadPlugins();
}
/// <summary>
/// Calls the <see cref="IPlugin.Unload"/> method for all plugins within the lifecycle controller
/// and invokes the <see cref="IPluginEventListener.OnPluginUnloaded(PluginController, object?)"/>
/// for all listeners.
/// </summary>
/// <exception cref="AggregateException"></exception>
public void UnloadPlugins() => Controller.UnloadPlugins();
/// <summary>
/// Attempts to unload all plugins within the lifecycle controller, all event handlers
/// then attempts to unload the <see cref="IPluginAssemblyLoader"/> if dynamic unloading
/// is enabled, otherwise does nothing.
/// </summary>
/// <param name="forceGc">A value that indicates if the current unload should cause a manual garbage collection</param>
/// <exception cref="AggregateException"></exception>
public void UnloadAll(bool forceGc)
{
UnloadPlugins();
//If the assembly loader is unloadable calls its unload method
if (Config.Unloadable)
{
Loader.Unload();
}
//Optionally wait for GC to finish
if (forceGc)
{
GC.Collect();
GC.WaitForPendingFinalizers();
}
}
//Process unload events
void IPluginReloadEventHandler.OnPluginUnloaded(IPluginAssemblyLoader loader)
{
try
{
//All plugins must be unloaded before the assembly loader
UnloadPlugins();
//Unload the loader before initializing
loader.Unload();
//Reload the assembly and controller
InitializeController();
//Load plugins
LoadPlugins();
}
catch (Exception ex)
{
Log?.Error("Failed reload plugins for {loader}\n{ex}", Config.AssemblyFile, ex);
}
}
///<inheritdoc/>
protected override void Free()
{
//Stop watching for events
Watcher.StopWatching(this);
//Cleanup
Controller.Dispose();
Loader.Dispose();
}
}
}
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