Automatically cache Godot Mono/C# StringName and NodePath without changing your code

(Make sure to upvote the related proposal to merge into Godot, it would help a ton !)

What?

Godot uses its own string types meant for specific uses: StringName and NodePath. StringName is optimized for fast equality comparisons and hash lookups, and NodePath is optimized for storing scene tree paths.

However, in C#, they are often implicitly converted from string, which results in performance penalties.

For example, when writing Input.IsActionPressed("my_input"), the string "my_input" is implicitly converted from string to StringName. This allocates a new StringName, which contributes to performance spikes from garbage collection.

To make it worse, these implicit conversions do expensive calculations. For StringName, a hash is computed, which is then searched in a linked list. For NodePath, the path is deconstructed to its individual parts, and a list is allocated to cache the results.

There are several proposals to circumvent this issue, but this one is "plug 'n' play" and has no extra runtime performance penalties.

Integrating

Include the package in your csproj file with

<PackageReference Include="GodotSharpStringCacher.MSBuild" PrivateAssets="all" />

That's it ! The main assembly is now automatically patched.
If you want it to affect other packages, use

<ItemGroup>
    <PackageReference Include="Foo.Bar" CacheStrings="true" />
    <Reference Include=".../Foo.Bar.dll" CacheStrings="true" />
    <ProjectReference Include=".../Foo.Bar.csproj" CacheStrings="true" />

    <!-- Or by assembly name -->
    <CacheStrings Include="Foo.Bar" />
</ItemGroup>

GodotSharpStringCacher is also available as a library. Integrate it into other builds like this:

<PackageReference Include="GodotSharpStringCacher" />

Then:

using GodotSharpStringCacher;

...

using var ctx = new Context(config: new Config(...));
// (optional) open GodotSharp manually (otherwise it will be loaded if present in the same directory as the patching dll)
ctx.OpenGodotSharp("/foo/GodotSharp.dll");
ctx.RunAndSave("input.dll", "output.dll");
ctx.RunAndSave("input2.dll", "output2.dll");

Quick Testing

If you want to test without integrating it, compile GodotSharpStringCacher.Console. The syntax is:

GodotSharpStringCacher.Console <in_file> <out_file> [--long-names] [--no-warn-non-constant-implicit-operator]

You can browse the resulting assembly and see the results for yourself.

Detailed Configuration

Warning On Implicit Operator With Non Constant

You are encouraged from using the new syntax when creating a non-constant StringName/NodePath at run-time. For example

// don't
StringName myStr = networkPacket.StringVariable;
// do
StringName myStr = new StringName(networkPacket.StringVariable);

This conveys your intentions better, and you will be warned by default if you don't do this.

To disable this warning (which is not recommended), either use WarnOnNonConstantImplicitOperator=true on a specific assembly or add a property like this for global effect:

<GDStringWarnOnNonConstantImplicitOperator>false</GDStringWarnOnNonConstantImplicitOperator>

Long Names

By default, the fields created from your constant strings in the assembly have a short numeric name. However, in niche cases, like statically reversing your own project, you may want these fields to have names that resemble their original value. For example, "my_input" would create a field called _my_input. To enable this in a specific assembly, you can add LongNames=true. To enable this globally, add

<GDStringUseLongNames>true</GDStringUseLongNames>

How It Works

It executes after your project compiles and directly modifies the resulting assembly using Mono.Cecil, a library for assembly exploring and editing.
It looks for implicit conversions, and if the string is a constant, it adds its value as a StringName/NodePath field to a static class, then replaces the conversion with a direct read to this field.

Bugs and contributing

The current release should be stable. If you find a bug please please PLEASE raise an issue.

Feel free to contribute too!

If you find this project useful, drop a ⭐ too! Thank you :>