movfuscator VS tokio

Everything can be reduced to assignments. https://github.com/xoreaxeaxeax/movfuscator

However, the movfuscator as implemented does still require a sigaction(2) syscall to set up a signal handler, under the justifications that "it is not actually part of the program" and that "if we were in ring 0, we wouldn't need help from the kernel" [0]. However, the latter part seems a little dubious to me: without the help of the kernel running non-MOV instructions, you'd never be able to escape from 16-bit real mode into 32-bit protected mode, since you wouldn't be able to load a valid GDT with the LGDT instruction (as far as I am aware).

[0] https://github.com/xoreaxeaxeax/movfuscator/blob/90a49f31219...

I _think_ the idea is thinking of an "interface" as "something that you use as a way to interact with something from outside an abstraction". I'd summarize their argument as reasoning that if the goal of an abstraction is to avoid having to care about the internal details of something, an interface is a way to expose a subset of ways to interact with it, and the more you expand it, the more it exposes the internals of the thing being abstracted. I don't think they necessarily mean this only in terms of programming, but you could apply this argument to a programming language interface; if you use an interface for interacting with something instead of its direct functionality, each additional method you add to the interface exposes more details of the inner value, which makes it less of an abstraction.

Assuming my interpretation is correct, I'm not sure I totally buy this argument because there doesn't seem to be an obvious way to define the "size" of an interface where it holds true. The naive way to define the size would be number of methods, but I'd argue that methods can vary so much in terms of the amount of cognitive overhead they "expose" to the user that it's not very meaningful. Consider the Movfuscator compiler[0], which compiles code into binaries only using MOV x86 instructions because it happens to be Turing complete; as complex as it might be to learn x86 assembly as a whole and start writing programs directly in it, I'm dubious that trying to do so only with MOV would somehow be easier. Put another way, an x86 instruction set that only contains the MOV instruction is not a "stronger" abstraction than the actual one because it _introduces_ complexity that doesn't exist in the original. Does adding an ADD instruction alongside MOV increase the strength of the abstraction, or weaken it? I don't think there's an answer that we'd immediately all agree on for this sort of thing.

Ultimately, I think trying to measure interfaces through the number of methods they expose is similar to trying to measure code by the number of lines in it; while there are some extreme cases where we'd likely all agree (e.g. for a fizzbuzz implementation, having 10 lines of code is probably better than thousands of lines of code[1]), we can't really come up with a good objective metric because the "target" number is based on the complexity of what you're trying to define, and we don't have a way of quantifying that complexity. I think the ideas here are still super interesting though, not because they have definitive right or wrong answers, but because thinking about stuff like this overall improves one's ability to write good software for usage by other programmers.

[0]: https://github.com/xoreaxeaxeax/movfuscator

The mov instruction in x86-64 is Turing complete. Someone even made a C compiler using only mov.

Are you sure they didn't use the MOVFUSCATOR?

Yep. In fact you can reduce everything to just one simple assembly instruction.

Being able to control nondeterminism is particularly useful for testing and debugging. This allows creating reproducible test environments, as well as discrete-event simulation for faster-than-real-time simulation of time delays. For example, Cardano uses a simulation environment for the IO monad that closely follows core Haskell packages; Sui has a simulator based on madsim that provides an API-compatible replacement for the Tokio runtime and intercepts various POSIX API calls in order to enforce determinism. Both allow running the same code in production as in the simulator for testing.

tokio / hyper / toml / serde / serde_json / json5 / console

tokio - An asynchronous runtime for Rust

3. Tokio

The AWS SDK makes use of the async capabilities in the Tokio library. So when you see async in front of a fn that function is capable of executing asynchronously.

Petar is also looking at implementing concurrency the way it is in Go to have a fully functional virtual machine as it is in the spec. This would likely attract more external contributors to developing the VM. One advantage of Rust is that, with the concurrency model, there is already an extensive library called Tokio which he can use. Petar stresses that this isn’t easy, but he believes it’s achievable, at least as a research topic around determinism and concurrency.

Another thing to point out is that async is a thing in Rust. I'm not going to begin to dive into this paradigm in this article, but know it's handled by the awesome Tokio framework.

So I started by using Tokio, a popular async runtime. The docs and samples helped me get a simple outbound TCP connection working. The Rust async book also had a lot of good explanations, both practical and digging into the details of what a runtime does.

Regarding the quote:

> The Original Sin of Rust async programming is making it multi-threaded by default. If premature optimization is the root of all evil, this is the mother of all premature optimizations, and it curses all your code with the unholy Send + 'static, or worse yet Send + Sync + 'static, which just kills all the joy of actually writing Rust.

Agree about the melodramatic tone. I also don't think removing the Send + Sync really makes that big a difference. It's the 'static that bothers me the most. I want scoped concurrency. Something like <https://github.com/tokio-rs/tokio/issues/2596>.

Another thing I really hate about Rust async right now is the poor instrumentation. I'm having a production problem at work right now in which some tasks just get stuck. I wish I could do the equivalent of `gdb; thread apply all bt`. Looking forward to <https://github.com/tokio-rs/tokio/issues/5638> landing at least. It exists right now but is experimental and in my experience sometimes panics. I'm actually writing a PR today to at least use the experimental version on SIGTERM to see what's going on, on the theory that if it crashes oh well, we're shutting down anyway.

Neither of these complaints would be addressed by taking away work stealing. In fact, I could keep doing down my list, and taking away work stealing wouldn't really help with much of anything.

The PHP <-> Rust bindings are provided by https://github.com/Nicelocal/ext-php-rs/ (our fork of https://github.com/davidcole1340/ext-php-rs with a bunch of UX improvements :).

php-tokio's integrates the https://revolt.run event loop with the https://tokio.rs event loop; async functionality is provided by the two event loops, in combination with PHP fibers through revolt's suspension API (I could've directly used the PHP Fiber API to provide coroutine suspension, but it was a tad easier with revolt's suspension API (https://revolt.run/fibers), since it also handles the base case of suspension in the main fiber).