rpmalloc zig port

This project is an attempt to make a fast general-purpose allocator for zig. It is mostly derived from rpmalloc, using the same general structure and mostly retaining the essential strategies that make it fast, though with many options and facets stripped down or modified to suit Zig.

WIP

This project is under development, does not guarantee a stable API and lacks documentation and tests. Contributions, in the form of PRs and relevant resources, are greatly appreciated.

Usage

If you cloned the repository, or vendor it as a git submodule or similar, you can just add the main source file as a module like so:

exe.addAnonymousModule("rpmalloc", .{ .source_file = .{ .path = "<path to repo>/src/rpmalloc.zig" } });

However, if you want to use the zig package manager, the recommended process (at the time of writing) is as follows:

1. Get the SHA of the commit you want to depend on.
2. Make sure you have something akin to the following in your build.zig.zon file:

   .dependencies = .{
       // -- snip --
       .@"rpmalloc-zig-port" = .{
           .url = "https://github.com/InKryption/rpmalloc-zig-port/archive/<commit SHA>.tar.gz",
           .hash = <hash>, // you can get the expected value by running `zig build` while omitting this field.
       },
   },

3. Add something akin to the following to your build.zig file:

   const rpmalloc_dep = b.dependency("rpmalloc-zig-port", .{});
   const rpmalloc_module = rpmalloc_dep.module("rpmalloc");
   exe.addModule("rpmalloc", rpmalloc_module);

and then import and use it:

const rpmalloc = @import("rpmalloc");
const Rp = rpmalloc.RPMalloc(.{});

pub fn main() !void {
    try Rp.init(null, .{});
    defer Rp.deinit();

    const allocator = Rp.allocator();
    // -- snip --
}

It should be noted that this allocator is indeed a singleton, much like in the original C source, with an important distinction being that you can concurrently have different permutations based on the configuration.

Notes

• There are a good few TODO comments in the code, comprised mostly of uncertanties on as to the benefits or semantics of certain parts of the code.
• At the time of writing, the port runs marginally slower than the original C source in the benchmark when linked statically, and notably slower when linked dynamically.
• I've opted to remove most code related to partial unmapping, as it's not a pattern that is well-suited to Zig (or at least that I couldn't figure out how to map to Zig's prototypical allocator patterns).