Make plugins unloadable

This will require .NET Core 3.0 and up, which has added libraries to make assembly load contexts unloadable.

See https://github.com/dotnet/coreclr/issues/552, https://github.com/dotnet/coreclr/pull/18476, https://github.com/dotnet/corefx/issues/14724, and https://github.com/dotnet/coreclr/projects/9.

---

Update

Merged #31 which adds API when using .NET Core 3.0 to allow unloading.

Usage

Unloadable plugins is supported in .NET Core 3.0 Preview 2 and newer. To unload a plugin, make sure isUnloadable = true and dispose the loader to trigger the unload.

var loader = PluginLoader.CreateFromAssemblyFile(
                    pluginDll,
                    sharedTypes: new [] { typeof(IPlugin) },
                    isUnloadable: true);
// do stuff

loader.Dispose(); // this triggers an unload

In order for this to work, you must make sure you have not left behind any variables (static, local, etc) or manually allocated memory. Once GC has collected everything, the assembly will be unloaded. See https://github.com/dotnet/coreclr/pull/22221

[natemcmaster]

Initial implementation #31.

Usage

Unloadable plugins is supported in .NET Core 3.0 Preview 2 and newer. To unload a plugin, dispose the loader.

var loader = PluginLoader.CreateFromAssemblyFile(
                    pluginDll,
                    sharedTypes: new [] { typeof(IPlugin) });
// do stuff

loader.Dispose(); // this triggers an unload

[natemcmaster]

Merged #31 which adds API when using .NET Core 3.0 to allow unloading.

Usage

Unloadable plugins is supported in .NET Core 3.0 Preview 2 and newer. To unload a plugin, make sure isUnloadable = true and dispose the loader to trigger the unload.

var loader = PluginLoader.CreateFromAssemblyFile(
                    pluginDll,
                    sharedTypes: new [] { typeof(IPlugin) },
                    isUnloadable: true);
// do stuff

loader.Dispose(); // this triggers an unload

In order for this to work, you must make sure you have not left behind any variables (static, local, etc) or manually allocated memory. Once GC has collected everything, the assembly will be unloaded. See https://github.com/dotnet/coreclr/pull/22221