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Once in a while, programmers who start getting acquainted with the PVS-Studio code analyzer ask me: «Is there a list of warnings that accurately indicate errors?» There is no such list because uninteresting (false) warnings in one project are very important and useful in another one. However, one can definitely start digging into the analyzer from the most exciting warnings. Let's take a closer look at this topic.

This article is also available in Russian / Эта статья также доступна на русском языке

The mass market of smartphones without the 3.5 mm audio jack changed headphones industry, wireless Bluetooth headphones have become the main way to listen to music and communicate in headset mode for many users.
Bluetooth device manufacturers rarely disclose detailed product specifications, and Bluetooth audio articles on the Internet are contradictory and sometimes incorrect. They do not tell about all the features, and often publish the same false information.
Let's try to understand the protocol, the capabilities of Bluetooth stacks, headphones and speakers, Bluetooth codecs for music and speech, find out what affects the quality of the transmitted audio and the delay, learn how to capture and decode information about supported codecs and other device features.

TL;DR:

• SBC codec is OK
• Headphones have their own per-codec equalizer and post processing configuration
• aptX is not as good as the advertisements say
• LDAC is a marketing fluff
• Voice audio quality is still low
• Browsers are able to execute audio encoders compiled to WebAssembly from C using emscripten, and they won't even lag.

(This is the translation of the original article performed by baragol)

We had a bunch of photographs of the main PCB, a YouTube video with drain-voltage waveforms of MOSFETs, a forum post with a breakdown of the capacitance values of LC circuit capacitors and also a number of unboxing videos showing the heating-up of the soldering tip. The only thing that really worried me was the video with the measurement of the peak power consumption during the heating-up. There is nothing in the world more helpless and irresponsible and depraved than burned cartridge newly bought for 60 bucks from Amazon. But let me start from the beginning.

It is a new selection of tips and tricks about Python and programming from my Telegram-channel @pythonetc.

Previous publications.

Sometimes people ask the question, which addresses a certain topic but is actually about another thing. As the saying goes, a competently asked question contains half the answer.

Recently I've returned from the JPoint conference, where we first presented our new PVS-Studio analyzer for Java. Interest in static analysis is growing strongly in the last few years, so the audience perceived PVS-Studio enthusiastically. In addition to the positive feedback, as it happens, we had to handle objections. The most frequent objection to the suggestion to try PVS-Studio sounds something like this: «C'mon, why do we try PVS-Studio? We use IntelliJ IDEA, ReSharper, SonarLint and SonarQube. We've run PVS-Studio recently and it found errors, already highlighted by IntelliJ IDEA!»

I just can't help but write a small reply note to this comment. I even have two responses to this objection. And yes, I intentionally stated ReSharper, as there are some questions to our C# analyzer as well. Well, here comes the answer.

Java developers have access to a number of useful tools that help to write high-quality code such as the powerful IDE IntelliJ IDEA, free analyzers SpotBugs, PMD, and the like. The developers working on CUBA Platform have already been using all of these, and this review will show how the project can benefit even more from the use of the static code analyzer PVS-Studio.

SafeHandle / CriticalHandle / SafeBuffer / derived types

I feel I’m going to open the Pandora’s box for you. Let’s talk about special types: SafeHandle, CriticalHandle and their derived types.

This is the last thing about the pattern of a type that gives access to an unmanaged resource. But first, let’s list everything we usually get from unmanaged world:

The first and obvious thing is handles. This may be an meaningless word for a .NET developer, but it is a very important component of the operating system world. A handle is a 32- or 64-bit number by nature. It designates an opened session of interaction with an operating system. For example, when you open a file you get a handle from the WinApi function. Then you can work with it and do Seek, Read or Write operations. Or, you may open a socket for network access. Again an operating system will pass you a handle. In .NET handles are stored as IntPtr type;

This chapter was translated from Russian jointly by author and by professional translators. You can help us with translation from Russian or English into any other language, primarily into Chinese or German.

Also, if you want thank us, the best way you can do that is to give us a star on github or to fork repository github/sidristij/dotnetbook.

People are resorting to blockchain for all kinds of reasons these days. Ever since I started doing smart contract security audits in mid-2017, I’ve seen it all. A special category of cases is ‘blockchain use’ that seems logical and beneficial, but actually contains a problem that then spreads from one startup to another. I am going to give some examples of such problems and ineffective solutions so that you (developer/customer/investor) know what to do when somebody offers you to use blockchain this way.

Disclaimers

• The described use cases and problems occur at the initial stage. I am not saying these problems are impossible to solve. However, it is important to understand which solutions system creators offer for particular problems.
• Even though the term ‘blockchain use’ looks strange and I am not sure that blockchain can be used for anything other than money (Bitcoin), I am going to use it without quotes.

1. Supply chain management

Let’s say you ordered some goods, and a carrier guarantees to maintain certain transportation conditions, such as keeping your goods cold. A proposed solution is to install a sensor in a truck that will monitor fridge temperature and regularly transmit the data to the blockchain. This way, you can make sure that the promised conditions are met along the entire route.

“Come on, baby, what’s wrong? Tell me what you need,” my uncle Nicholas was shredding up his old car’s engine, which totally refused to start. Being a schoolboy back then, I was absolutely sure that any exhortation my uncle voiced was powerless against a dumb ton of metal. Talking to a car was just a psychological trick that probably helped my uncle cope with exasperation. Moreover, neither me nor my uncle believed in a possibility to communicate with “dead metal” sometime in the near future. That was in the mid-1980s. When I reached the age of my uncle, the situation changed radically.

Like any developer, you are constantly developing. You are learning new technologies by reading books, watching online lessons, attending some courses, and so on and so forth. You know that if you stop learning, you become uncompetitive. But have you ever thought about your performance? How do you improve that? If you don't know how to answer than welcome under the cut.

I was putting things in order in a garage, when I found an arithmometer Felix M. It is old school iron gadget, there are no electronics inside.

Let me share an interesting experience in promotion of a mobile game.

1. Introduction

I am going to describe all the benefits and of course show the final results. The example will be the mobile game Quick Brain which is available for Android и iOS. Quick Brain Android was released the first that's why its possibilities differ considerably from iOS version.

I have been always kept by the thoughts that everyone's talking about high returns in contrast with Android. I just couldn't resist such attractive prospects and started more active refinement of iOS version in order to feel less embarrassed about it.

After Google play iOS has become an absolutely new field for the games for me. During my comparative experiment I've found out that iOS version can bring comparable earnings to Android with daily audience 3 to 10 times less depending on the country.

There are a lot of posts about what a typical coding interview at Google looks like. But, while not as widely described and discussed, there is also quite often a system design interview. For an SRE position it’s NALSD: non-abstract large system design. The key difference between SWE and SRE interviews consists in these two letters: NA.

So, what is the difference? How to be prepared for this interview? Let’s be non-abstract, and use an example. To be more non-abstract, let’s take something from the material world, such that you won’t be asked the exact same thing at the real interview (at least, not at the Google interview) :)

So, let’s design a public library system. For the paper books, like you have seen everywhere around. The whole text below was written all at once within around one hour, to roughly show you the areas that you should be able to cover / touch during the interview. Please excuse some disorder, that’s how I think (therefore I am).

We all hear of iconic movies, games, books or musical compositions that get vehemently praised by the community of sophisticados, professionals and critics, yet never seem to attract tangible commercial success or the attention of the wider audience. Such situations leave me deeply frustrated.

When it comes to development, good tech also sometimes never gets into the limelight. Take F# for example. All I know about it is that it is a super-cool, yet totally unpopular language which makes it hard for developers – upon getting to know it – to get back to the languages they’re used to.

I tried to find out what is the story behind this. In fact, who are the people who use it and why are they doing this if the language is out of demand in business? To find answers, I joined the Russian-speaking F# community on Telegram – our round table for the discussion.

Author of the original post in Russian: old_gamer



I'm a ragman. I have a closet full of old hardware. From Boolean logic microchips in DIP-cases to Voodoo5. Of course, there's no practical value in all of this, but some people enjoy messing with old hardware. If you are one of them, I invite you under the cut, where I will tell you how the computer based on AMD 286 processor worked with a modern network, and what came out of it.

This project is aimed at creating an experimental device for emulating RFID labels of three widely available components. I simplified the explanation of the process so that it could be easily replicated. I also developed some helpful ideas along the way, including writing a special program for converting a serial number into the transmitted data, which will definitely prove useful.

I manage a team that designs and introduces in-house Kubernetes aaS at Mail.ru Cloud Solutions. And we often see a lack of understanding as to this technology, so I’d like to talk about common strategic mistakes at Kubernetes implementation in major projects.

Most of the problems arise because the technology is quite sophisticated. There are unobvious implementation and operation challenges, as well as poorly used advantages, all of those resulting in money loss. Another issue is the global lack of knowledge and experience with Kubernetes. Learning its use by the book can be tricky, and hiring qualified staff can be challenging. All the hype complicates Kubernetes-related decision making. Curiously enough, Kubernetes is often implemented rather formally – just for it to be there and make their lives better in some way.

Hopefully, this post will help you to make a decision you will feel proud of later (and won’t regret or feel like building a time machine to undo it).

I came to Mail.ru Group in 2013, and I required a queue for one task. First of all, I decided to check what the company had already got. They told me they had this Tarantool product, and I checked how it worked and decided that adding a queue broker to it could work perfectly well.

I contacted Kostja Osipov, the senior expert in Tarantool, and the next day he gave me a 250-string script that was capable of managing almost everything I needed. Since that moment, I have been in love with Tarantool. It turned out that a small amount of code written with a quite simple script language was capable of ensuring some totally new performance for this DBMS.

Today, I’m going to tell you how to instantiate your own queue in Tarantool 2.2.

This is a transcription of a talk that was presented at CSNOG 2020 — video is at the end of the page

Greetings! My name is Alexander Zubkov. I work at Qrator Labs, where we protect our customers against DDoS attacks and provide BGP analytics.

We started using Mellanox switches around 2 or 3 years ago. At the time we got acquainted with Switchdev in Linux and today I want to share with you our experience.

2019 is coming to an end, and it's Christmas soon. It is also the time to grab all data and collect statistics and a rating of the most interesting Habr's articles for this period.



In this post the best articles and best Habr authors 2019 will be presented, I also will show some statistical graphs that I find interesting or unusual.

Let's get started.