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/*
* Copyright (c) 2023 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.Text.Json;
using System.Reflection;
using System.Runtime.Loader;
using System.Threading.Tasks;
using McMaster.NETCore.Plugins;
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
{
private readonly PluginLoader Loader;
private readonly string PluginPath;
private readonly JsonDocument HostConfig;
private readonly ILogProvider? Log;
/// <summary>
/// Gets the plugin lifetime manager.
/// </summary>
public PluginController Controller { get; }
/// <summary>
/// The path of the plugin's configuration file. (Default = pluginPath.json)
/// </summary>
public string PluginConfigPath { get; }
/// <summary>
/// Creates a new <see cref="RuntimePluginLoader"/> with the specified
/// assembly location and host config.
/// </summary>
/// <param name="pluginPath"></param>
/// <param name="log">A nullable log provider</param>
/// <param name="hostConfig">The configuration DOM to merge with plugin config DOM and pass to enabled plugins</param>
/// <param name="unloadable">A value that specifies if the assembly can be unloaded</param>
/// <param name="hotReload">A value that spcifies if the loader will listen for changes to the assembly file and reload the plugins</param>
/// <remarks>
/// The <paramref name="log"/> argument may be null if <paramref name="unloadable"/> is false
/// </remarks>
/// <exception cref="ArgumentNullException"></exception>
public RuntimePluginLoader(string pluginPath, JsonDocument? hostConfig = null, ILogProvider? log = null, bool unloadable = false, bool hotReload = false)
:this(
new PluginConfig(pluginPath)
{
IsUnloadable = unloadable || hotReload,
EnableHotReload = hotReload,
ReloadDelay = TimeSpan.FromSeconds(1),
PreferSharedTypes = true,
DefaultContext = AssemblyLoadContext.Default
},
hostConfig, log)
{
}
/// <summary>
/// Creates a new <see cref="RuntimePluginLoader"/> with the specified config and host config dom.
/// </summary>
/// <param name="config">The plugin's loader configuration </param>
/// <param name="hostConfig">The host/process configuration DOM</param>
/// <param name="log">A log provider to write plugin unload log events to</param>
/// <exception cref="ArgumentNullException"></exception>
public RuntimePluginLoader(PluginConfig config, JsonDocument? hostConfig, ILogProvider? log)
{
//Shared types is required so the default load context shares types
config.PreferSharedTypes = true;
//Default to empty config if null
HostConfig = hostConfig ?? JsonDocument.Parse("{}");
Loader = new(config);
PluginPath = config.MainAssemblyPath;
Log = log;
//Only regiser reload handler if the load context is unloadable
if (config.IsUnloadable)
{
//Init reloaded event handler
Loader.Reloaded += Loader_Reloaded;
}
//Set the config path default
PluginConfigPath = Path.ChangeExtension(PluginPath, ".json");
//Init container
Controller = new();
}
private async void Loader_Reloaded(object sender, PluginReloadedEventArgs eventArgs)
{
try
{
//All plugins must be unloaded forst
UnloadAll();
//Reload the assembly and
await InitializeController();
//Load plugins
LoadPlugins();
}
catch (Exception ex)
{
Log?.Error("Failed reload plugins for {loader}\n{ex}", PluginPath, ex);
}
}
/// <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 async Task InitializeController()
{
JsonDocument? pluginConfig = null;
try
{
//Get the plugin's configuration file
if (FileOperations.FileExists(PluginConfigPath))
{
pluginConfig = await this.GetPluginConfigAsync();
}
else
{
//Set plugin config dom to an empty object if the file does not exist
pluginConfig = JsonDocument.Parse("{}");
}
//Load the main assembly
Assembly PluginAsm = Loader.LoadDefaultAssembly();
//Init container from the assembly
Controller.InitializePlugins(PluginAsm);
string[] cliArgs = Environment.GetCommandLineArgs();
//Configure log/doms
Controller.ConfigurePlugins(HostConfig, pluginConfig, cliArgs);
}
finally
{
pluginConfig?.Dispose();
}
}
/// <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="PluginLoader"/>
/// which will reload the assembly and its plugins
/// </summary>
public void ReloadPlugins() => Loader.Reload();
/// <summary>
/// Attempts to unload all plugins.
/// </summary>
/// <exception cref="AggregateException"></exception>
public void UnloadAll() => Controller.UnloadPlugins();
///<inheritdoc/>
protected override void Free()
{
Controller.Dispose();
Loader.Dispose();
}
}
}
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