Development

In the PHP ecosystem, there are currently two connectors for the Tarantool server: the official PECL extension tarantool/tarantool-php written in C, and tarantool-php/client written in PHP. I am the author of the latter one.

In this article I would like to share the results of performance testing of both these libraries and show how you can achieve 3x-5x performance improvement (on synthetic tests!) with minimal changes in code.

Tips and tricks from my Telegram-channel @pythonetc, November 2019

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

← Previous publications.



PATH is an environment variable that stores paths where executables are looked for. When you ask your shell to run ls, the shell looks for the ls executable file across all paths that are presented in PATH.

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.

tl;dr

github.com/QratorLabs/fastenum

pip install fast-enum

What are enums

(If you think you know that — scroll down to the “Enums in Standard Library” section).

Imagine that you need to describe a set of all possible states for the entities in your database model. You'll probably use a bunch of constants defined as module-level attributes:

# /path/to/package/static.py:
INITIAL = 0
PROCESSING = 1
PROCESSED = 2
DECLINED = 3
RETURNED = 4
...

...or as class-level attributes defined in their own class:

class MyModelStates:
  INITIAL = 0
  PROCESSING = 1
  PROCESSED = 2
  DECLINED = 3
  RETURNED = 4

That helps you refer to those states by their mnemonic names, while they persist in your storage as simple integers. By this, you get rid of magic numbers scattered through your code and make it more readable and self-descriptive.

But, both the module-level constant and the class with the static attributes suffer from the inherent nature of python objects: they are all mutable. You may accidentally assign a value to your constant at runtime, and that is a mess to debug and rollback your broken entities. So, you might want to make your set of constants immutable, which means both the number of constants declared and the values they are mapped to must not be modified at runtime.

We have already presented Tarantool Cartridge that allows you to develop and pack distributed applications. Now let's learn how to deploy and control these applications. No panic, it's all under control! We have brought together all the best practices of working with Tarantool Cartridge and wrote an Ansible role, which will deploy the package to servers, start and join instances into replica sets, configure authorization, bootstrap vshard, enable automatic failover and patch cluster configuration.

Interesting, huh? Dive in, check details under the cut.

The goal of this quick reference is to collect in one place and organize information about value categories in C++, assignment, parameter passing and returning from functions. I tried to make this quick reference convenient to quickly compare and select one of solutions possible, this is why I made several tables here.

For introduction to the topic, please use the following links:

C++ rvalue references and move semantics for beginners
Rvalues redefined
C++ moves for people who don’t know or care what rvalues are
Scott Meyers. Effective Modern C++. 2015
Understanding Move Semantics and Perfect Forwarding: Part 1
Understanding Move Semantics and Perfect Forwarding: Part 2
Understanding Move Semantics and Perfect Forwarding: Part 3
Do we need move and copy assignment

The AI Cup community and Mail.ru Group in collaboration with Codeforces.com invite you to the real battle! Get ready for the sleepless nights and calloused hands — take part in Russian AI Cup, which is one of the most challenging and vivid artificial intelligence programming competitions in the world. Believe us, managers of this madness did their best to create the game you'd want to play.

To become part of the competition, you need Internet access, computer, creativity, and enthusiasm for being a part of this extraordinary Cup. By the way, you might need some coffee. Welcome!

During the summer of 2019, Huawei gave a series of presentations announcing the Ark Compiler technology. The company claims that this open-source project will help developers make the Android system and third-party software much more fluent and responsive. By tradition, every new promising open-source project goes through PVS-Studio for us to evaluate the quality of its code.

Introduction

The Ark Compiler was first announced by Huawei at the launch of the new smartphone models P30 and P30 Pro. It is claimed that the Ark Compiler will improve the fluency of the Android system by 24% and response speed by 44%. Third-party Android applications will also gain a 60% speed-up after recompilation with the Ark Compiler. The open-source version of the project is called OpenArkCompiler; its source code is available on Gitee, a Chinese fork of GitHub.

Nowadays everyone knows about cloud services. Many companies have cracked this market segment and created their own cloud services of various purposes. Recently our team has also been interested in these services in terms of integrating the PVS-Studio code analyzer into them. Chances are, our regular readers have already guessed what type of project we will check this time. The choice fell on the code of Huawei cloud services.

This article continues the series of publications on usage of PVS-Studio in cloud systems. This time we'll look at the way the analyzer works along with GitLab CI, which is a product made by GitLab Inc. Static analyzer integration in a CI system allows detecting bugs right after the project build and is a highly effective way to reduce the cost of finding bugs.

Hi! Though the 2019 conference season is not over yet, we'd like to talk about the bug-finding challenges we offered to visitors at our booth during the past conferences. Starting with the fall of 2019, we've been bringing a new set of challenges, so we can now reveal the solutions to the previous tasks of 2018 and the first half of 2019 – after all, many of them came from previously posted articles, and we had a link or QR code with information about the respective articles printed on our challenge leaflets.

An online chatbot is a recent trend on the market. But how to interact with the clients that are offline? A significant percentage of people prefer to interact over the phone. And the business needs either a large staff of operators or a voice communication automating solution. We are offering a solution to reduce workload and costs (and will barely affect your developers’ busyness).

This is a guest post from the Orleans team. Orleans is a cross-platform framework for building distributed applications with .NET. For more information, see https://github.com/dotnet/orleans.

We are excited to announce the Orleans 3.0 release. A great number of improvements and fixes went in, as well as several new features, since Orleans 2.0. These changes were driven by the experience of many people running Orleans-based applications in production in a wide range of scenarios and environments, and by the ingenuity and passion of the global Orleans community that always strives to make the codebase better, faster, and more flexible. A BIG Thank You to all who contributed to this release in various ways!

A couple of reader alerts:

In order to (somewhat) simplify the description process and tighten the volume of the article we are going to write, it is essential to make a significant remark and state the primary constraint right away — everything we are going to tell you today on the practical side of the problematics is viable only in terms of TLS 1.3. Meaning that while your ECDSA certificate would still work in TLS 1.2 if you wish it worked, providing backwards compatibility, the description of the actual handshake process, cipher suits and client-server benchmarks covers TLS 1.3 only. Of course, this does not relate to the mathematical description of algorithms behind modern encryption systems.

This article was written by neither a mathematician nor an engineer — although those helped to find a way around scary math and reviewed this article. Many thanks to Qrator Labs employees.

(Elliptic Curve) Diffie-Hellman (Ephemeral)

The Diffie–Hellman legacy in the 21 century

Of course, this has started with neither Diffie nor Hellman. But to provide a correct timeline, we need to point out main dates and events.

There were several major personas in the development of modern cryptography. Most notably, Alan Turing and Claud Shannon both laid an incredible amount of work over the field of theory of computation and information theory as well as general cryptanalysis, and both Diffie and Hellman, are officially credited for coming up with the idea of public-key (or so-called asymmetric) cryptography (although it is known that in the UK there were made serious advances in cryptography that stayed under secrecy for a very long time), making those two gentlemen pioneers.

In what exactly?

Anyone who programs microcontrollers probably knows about FreeRTOS, or at least heard of this operating system. Amazon developers decided to enhance the abilities of this operating system to work with AWS Internet of Things services. This is how Amazon FreeRTOS appeared. We, developers of the PVS-Studio static code analyzer, were asked by mail and in comments to check these projects. Well, now get what you asked for. Keep reading to find out what came out of it.

Chapter 2.
(the link to Chapter 1)

The Art of Designing Road Networks

Transport problems of a city through the eyes of a Computer Scientist

If I were recommended an article with the title “The Art of Designing Road Networks,” I would immediately ask how many road networks were built with the participation of its author. I must admit, my professional activity was far from road construction and was recently associated with the design of microprocessors where I, among other responsibilities, was engaged in the resource consumption of data switching. At that time my table stood just opposite the panoramic window which opened up a beautiful view of the long section of the Volgograd Highway and part of the Third Transport Ring with their endless traffic jams from morning to evening, from horizon to horizon. One day, I had a sudden shock of recognition: “The complexities of the data switching process that I struggle with on a chip may be similar to the difficulties the cars face as they flow through the labyrinth of road network”.
Probably, this view from the outside and the application of methods that were not traditional for the area in question gave me a chance to understand the cause of traffic jams and make recommendations on how to overcome the problem in practice.

Most likely you've already heard about the famous exploit checkm8, which uses an unfixable vulnerability in the BootROM of most iDevices, including iPhone X. In this article, we'll provide a technical analysis of this exploit and figure out what causes the vulnerability.

Since we began work on the next version of Microsoft Edge based on Chromium, we’ve been investigating ways to modernize form controls to provide a modern appearance as well as the touch friendliness and accessibility that our users expect from Microsoft Edge today.

Over the past few months, we’ve been collaborating closely with the Google Chrome team on this project, and are excited to share the refreshed controls that will be coming to Microsoft Edge Insider builds, or other Chromium browsers near you.

While Stockholm was holding the 118th Nobel Week, I was sitting in our office, where we develop the PVS-Studio static analyzer, working on an analysis review of the ROOT project, a big-data processing framework used in scientific research. This code wouldn't win a prize, of course, but the authors can definitely count on a detailed review of the most interesting defects plus a free license to thoroughly check the project on their own.

Introduction

ROOT is a modular scientific software toolkit. It provides all the functionalities needed to deal with big data processing, statistical analysis, visualisation and storage. It is mainly written in C++. ROOT was born at CERN, at the heart of the research on high-energy physics. Every day, thousands of physicists use ROOT applications to analyze their data or to perform simulations.

Kubernetes has already become a de-facto standard for running stateless applications, mainly because it can reduce time-to-market for new features. Launching stateful applications, such as databases or stateful microservices, is still a complex task, but companies have to meet the competition and maintain a high delivery rate. So they create a demand for such solutions.

We want to introduce our solution for launching stateful Tarantool Cartridge clusters: Tarantool Kubernetes Operator, more under the cut.