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 Also tokio is very much moving target – what I used couple month ago is already bit outdated now(old version is tokio_core crate – where default executor was on current thread, now it’s work stealing thread pool).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?
One may think that we have already more then enough programming languages. But community thinks differently and new languages keeps popping up and thanks for that, because some bring cool innovative features, others focus on more streamlined and effective development, but all of them contribute to the evolution of the IT industry. Because as in the nature progress comes through the variety of species and competition between them. As I have written in my past article I looked recently into Rust language – very interesting language, which comes with novel approach to memory management without garbage collection, but still assuring high security of the program. Nowadays I met another member of ever-growing happy family of programing languages – Kotlin and I’d like to share my first experiences in this article. Continue reading From Russia with Love – Kotlin Language
If you read some of my previous articles you know that I’m quite fond of audiobooks. In past I was looking for good media server, which supports audiobooks and ended with airsonic (a subsonic clone). The problem with majority of media servers is that they rely totally on audio tags, which are often messed in audiobooks. Also many of “advanced” functionalities are not applicable to audiobooks (random play, shuffle tracks, moods, etc.) I’m bit of old school so I rely more on reasonable directory structure and do not want to mess with tags for every audiobook I download. I also think that for personal collection I do not need likes, favorites, sharing and similar stuff, as I can easily remember which books are good and which I have listened or want to listen, but I do need few things, which are usually missing – like bookmarks. Interesting function is to continue listen on a device, when I left on previous device, but since I basically listen only on my mobile phone, it does not seems to be critical. So ideal audiobooks server actually requires much less functionality than today’s media servers provide. As I’m progressing with Rust language I decided two weeks ago to create simple audio streaming server adhering to KISS principle – Keep It Simple, Stupid, – Result of this exercise is an application that provides minimum viable functionalities for streaming and listening of audiobooks – it’s called Audioserve. In this article I’ll show it’s basic design and demo current application in a video. Continue reading Audioserve Audiobooks Server – Stupidly Simple or Simply Stupid?
Some time ago I’ve looked into building parser for simple logical language used by imap_detach Tool. I used there parsimonious module which uses PEG grammars. Recently I learned about another parsing technique – Parser Combinators. The idea comes from functional programming and is about combining (with help of higher order functions – so called combinators) simple parsing functions, which parse primitive tokens, into more complex parsing functions, which parse parts of text and further combine those into more complex ones, ending finally with one function, which parses all given data. I first met with parser combinators in Rust library nom. Here parsers and combinators are express as macros, which is convenient on one side (concise syntax), but can lead to pretty cryptic error messages and one cannot rely much on editor’s help with auto-completions, context help etc.. I used nom to build very simple URI parser. I was wondering also if parser combinators are available for Python and how they would compare with other approaches – like above mentioned PEG grammars. Continue reading The Different Approach to A Parser – Parser Combinators
Advantages of Continuous Integration (CI) and Continuous Delivery (CD) are obvious even for small projects with few contributors and are easily achievable with help of free cloud tools – like for instance with mighty combo of Github plus Travis. But what if we want to achieve similarly convenient environment inside of our private network, available only to our internal teams. Luckily open source is here again to help us with another great tool – GitLab – GitLab is a similar platform to GitHub, but the code is open source and we can easily install it in our environment. In this article I’ll summarize my experiences and guidelines how to build convenient environment for a small project with automatic testing and deployment. Continue reading CI/CD Environment for A Smaller Project
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
I’m big fan of audio books. During past years I’ve been using setup described in this article (libresonic server, android client, audio encoded with opus codec) for audio books listening. It works well for me , but it’s best with audio books split to chapters or to parts not longer then 1 hour. However some audio books come in one large file (m4b format, or aax proprietary file from Audible). To listen to such audio books conveniently I need to split them. Luckily with ffmpeg tool and a bit of bash scripting it is not difficult. Continue reading Splitting Large Audio Books
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
In past article I’ve written about some basic stuff we can do with Ethereum client Parity – like transfering Ethers, creating multi-signature wallet and even writing our own contracts. Now I’ll continue with writing our very own Distributed Application ( Dapp). Continue reading Writing Distributed Application for Ethereum