I think I noticed in this article that Rust Future is basically a state machine, which is propagated through its states via appropriate runtime (and parked when not ready to move to a next state). But I did not appreciate this fact fully until recently I was making a small utility (here is new version for new futures and tokio) for creating tar archive asynchronously – it should be a Stream that produces chunks of data – first file header and then pieces of it’s content. When file is done move to next file, until all required files are sent to stream, then finally send two empty blocks, each of 512 bytes of binary zeros. I needed this Stream for my audioserve project, where I wanted to download content of whole directory as a tar archive. Stream is a kind of Future (which produces many values instead of just one), so it’s also a state machine. And when I started to think about it this way, implementation was obvious. Rust algebraic type system is of great help here as we can represent state with one complex enum type ( called TarState in this case) and it’s variants represent states of this state machine and also contain necessary internal variables for each state. So lets see state diagram for our TarStream: Continue reading Future Is A State Machine
Sqlite3 is lightweight relational database, mainly focused on smaller local systems. Being used in Android it’s now probably most spread relational database in world with billions of instances running. Lite in the name means that it is not client-server architecture and it’s intended for lower data volumes – ideal usage profile is read mostly, with occasional writes. Sqlite3 is often used as an embedded data store in various applications (Firefox and Chrome are most prominent ones). Recently I’ve been playing a bit with sqlite3 interface in Rust and had run couple of simple tests especially focused on writes. So how does sqlite3 performs and how it compares with other more typical client-server RDBMS like PostgreSQL? It’s not any serious benchmark, just couple of toy tests to highlight few things. Continue reading Sqlite3 – How Slow Is Write?
Recently I’ve been reading this book: “Network Programming with Rust” by Abhishek Chanda. I found this book bit problematic. It’s just collection of many unrelated examples (often taken from crates documentation), with just little of background and concepts explanation and in some parts this book is just wrong, in other parts it’s using too much simplifications, so the result does not make much sense or worst it introduces some dangerous ideas. One of these places is part about futures and streams – let’s look at one example: Continue reading Future Never Sleeps
Although Rust is mostly noted for it’s memory safety and thus most prominent feature is borrow checker, it has also very decent type system, which was inspired by modern functional languages like OCAML or Haskel. In this article I’ll look into very simple example, which will however show some nice features of Rust type system – especially generics. Continue reading Tiny Etude in Generics
I have been playing with tokio already in couple of small projects (ptunnel-rust and indirectly (via hyper) in audioserve), but I cannot say that I’m proficient. Also tokio is very much moving target – what I used couple month ago is already bit outdated now(old version is tokio_core crate – where default executor was on current thread, now it’s work stealing thread pool). So I decided to refresh and deepen my knowledge and created a toy project – stupid jokes server – it’s a TCP sever, which sends a random joke to client after it connects and then closes connection. Jokes are stored in text file, separated by dashed lines. My main interest was to test how to use local file system I/Os, which are blocking by nature, with tokio asynchronous approach (so I initially skipped easiest and probably most efficient implementation, where all jokes would be cached in memory). Usually in a real project you’ll have some blocking code, so I need to know how to handle it. This article is history of my attempts (and failures) recorded in a hope that it might help others in learning tokio (and also writing it down helped me to absorb gained knowledge). Continue reading From Ignorance to Enlightenment – Playing with Tokio
Is thread pool worth to consider for my project? I was looking for some opinions around the net and as usual they differ and most common wisdom is it matters. Generally it’s “known” that creating and tearing down thread is “significant” overhead, so if you have a lot of small tasks thread pool is much better solution then spawning new thread for each task. But what is significant overhead? According to what I read time to create thread on Linux should be about 10μs (which does not look as too much to me) and app. 2MB of memory allocated for stack (configurable). I was considering thread pool in context of audioserve project, where I started with simplest possible solution (e.g. spawning individual threads ) and was wondering how much I’m loosing by not using thread pool. So I implemented simple thread pool (as learning exercise – long term audioserve solution should use tokio-threadpool) and add it to audioserve. In the remainder of this short article I’d like to share my findings and roughly quantify benefits of thread pool for such small project. Continue reading How much better is the thread pool?
Recently, as I’m progressing in learning of Rust, I wondered how asynchronous programing is done in Rust. I decided to remake my old project ptunnel (written in Python) into Rust – ptunnel is a program that tunnels arbitrary connection/protocol through HTTPS proxy, so it can be used to connect IMAP, SMTP or SSH through proxy. In the rest of this article I”l share my experiences from this project. Continue reading Asynchronous Again – Rewriting ptunnel in Rust
In todays digital world passwords and other types of secrets are omnipresent and they secure access to various assets dear to our hearts, some of those can have tremendous tangible or moral value. For such assets it’s worth to select really good and strong password, which basically means long and hard to remember. How to ensure ourselves in case of memory failure? We can write it down and lock in secure place, share with trusted person etc., but still there is one point of of failure – secure place can be robbed, that person can betray us. Can cryptography provide us with better options? Yes it can with help of method called Secret sharing – we can split secret into n parts – called shared secrets – and distribute them to different places/people. Later we (or someone else) need to collect k (k > 0 and k <= n) shared secret to recover original secret. k is called threshold and it is defined when generating shared secrets – so we for instance generate n=5 shared secrets, but only k=3 will be needed to recover original secret.
I believe you can easily imagine many other real life scenarios where secret sharing can be useful and for sure it’s used in many applications and systems today. Cryptography provides several algorithms for secure (by design) secret sharing. Most common is Shamir’s Secret Sharing based on linear algebra approach. There are many tools and libraries for Shamir’s scheme (and further advancements of original algorithm), you can for instance try ssss, which provides command line tool that you can easily install into your Linux and also there is an online demo. Another family of secret sharing schemes is based on Chinese Reminer Theorem, where especially Asmuth-Bloom scheme is interesting. I have not seen many implementation for Asmuth-Bloom secret sharing so I created one in Rust. Continue reading Secret Sharing Is Caring Too
Looking recently to languages and technology survey on Stackoverflow where Rust is leading the list of most “loved” languages (meaning developers who used the language like it and want to use it for their next projects) with head start on second one (SmallTalk) . This caught my attention and looking quickly at Rust site I decided to give it a try. Below are my first experiences learning this language. Continue reading In RUST We Trust