This is a typical interview question which is going to ask you to implement a stack which can track the maximum or minimum value for the current stack. In this note, I want to show a solution on how to implement a Min stack. You might implement Max stack in…

Поиск жилья основная сложность с которой я столкнулся после переезда в Англию. Главной проблемой является огромный спрос и небольшое количество свободных квартир. На большинство вариантов которые я смотрел или собирался смотреть было несколько конкурирующих оферов от людей, которые также как и я искали жилье. Решил написать этот пост, так как…

In this article I’ll consider two common approaches to implementing depth-first search and breadth-first search in Ruby. Tree Ruby has no built-in class for initializing Binary Tree data structure. Tree is just a restricted form of a Graph which have a parent-child relationship. Here is the simplest definition for a binary…

In Container-based DevOps solutions like Kubernetes, ECS, Heroku an application must be able to stop accepting new client requests before termination, and, most importantly, it must successfully complete already running requests and processes. By default in most systems Graceful Shutdown implements by sending SIGTERM signal and 30 seconds delay before…

What is the difference, how and when to apply? — Stub A stub is the only defined result of the method call which doesn’t care about behavior. With RSpec, you can use stub with allow and receive methods. allow(object).to receive(:method_name) If you need to stub the result of the method then it’s possible with and_return allow(object).to receive(:method_name).and_return(example_value) Mock Mock expect methods to…

Failure Management, Fallbacks, Exponential backoff, Tools and Patterns — When designing modern applications on microservices architecture and systems based on cloud solutions such as AWS, Azure, or Google Cloud imply the need to handle expected failures. How to handle failures? Restarting the code in the current thread runtime Retry execute in background jobs Retry failed code We can represent the simplest retry in runtime as a…

How to manage encrypted keys for different environments — There are two most popular ways to manage secrets in your application. Encrypted file with secrets. Best choice for a single monolith application. There’s no need for additional software, just keep your encrypted data in the app repository and move decrypt key under git ignore. Centralized storage. For large and…

A tool for monitoring SQL queries in Rails — Get notified about slow queries In the early stages of development, it may be useful to identify slow queries in time (when you don’t have a paid APM). QueryTrack helps to get notified about slow queries with related data: duration and backtrace. https://github.com/kirillshevch/query_track Installation Add this line to your application’s Gemfile and then execute bundle install:

Publish/Subscribe Pattern with Message Brokers and usage of core concepts. Asynchronous execution of the application parts. — One of the tools that are rarely covered in the Ruby/Rails world are the message brokers (probably because they mostly written in Java). Everyone are familiar mostly with background jobs processing, but message brokers offer a more flexible approach to asynchronous execution. …