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

It's quite trivial to use, just add some code along the lines of

exe.addPackagePath("rpmalloc", "path/to/rpmalloc/src/rpmalloc.zig");

to your build.zig, and then import it and use like so:

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

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

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

Although it should be clear from the example, I'll note 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).