Irostovsky

Payment Link Invoices — Old Logic to Remove

Issue: https://github.com/guestready/bnbstaff/issues/24637

Context

In #23057, payment link invoices were migrated to AccountingManager (accounting_manager/services/invoices/payment_link_invoices.py). The old logic that generated invoices outside of AccountingManager should now be removed.

Magnifinance and Hostkit webhook are out of scope for this report.

Irostovsky

Celery ack_late Idempotency Audit

Context

Celery 5.x has a known bug: without ack_late, the prefetch count is not enforced correctly. Workers grab all messages from the queue into an internal buffer, acking them immediately on receipt. RabbitMQ then shows 0 "Ready" messages, and autoscalers have nothing to trigger on.

With ack_late enabled, the prefetch limit works correctly: each worker holds at most prefetch_multiplier * concurrency (= 2 in our case) unacked messages, and the rest stay as "Ready" in the queue.

Trade-off

Irostovsky

import logging
log = logging.getLogger('django.db.backends')
log.setLevel(logging.DEBUG)
log.addHandler(logging.StreamHandler())

Irostovsky

# frozen_string_literal: true

module Utils
  class Timer
    def self.call(name)
      t = Time.zone.now
      result = yield
      time = ((Time.zone.now - t).to_d * 1000).to_i
      p "++++++++++ #{name}: #{time}ms"
      { result: result, time: time }

Irostovsky

class FooPresenter
  include Draper::Decoratable
  attr_accessor :user

  def initialize(user)
    @user = user
  end

  def name
    user.name

Irostovsky

# Let we have Post(title, body) -> Comments(body).
# Write the active record query to get all posts, where "query" is into title or body or comment.

class Post < ActiveRecord::Base
  #title, body
  has_many :comments
  
  scope :search, ->(text) {
    wildcard_search = "%#{text}%"
    joins(:comments).where("title ILIKE :search OR body ILIKE :search OR comments.body ILIKE :search", search: wildcard_search)

Irostovsky

Dir["app/assets/images/*"].each  do |image|
  name = File.basename(image)
  if Dir.glob("**/*").reject {|fn| File.directory?(fn) }.
      map{|fn| File.read(fn).include?(name) ? fn : nil }.any?
    p image
  else
    p "To delete: #{image}"
    File.delete image
  end
end

Irostovsky

module AuthenticityTokenCatcher
  extend ActiveSupport::Concern
  included do
    rescue_from ActionController::InvalidAuthenticityToken do |exception|
      if request.referrer
        flash[:error] = I18n.t :authenticit_token_error
        redirect_to request.referrer
      else
        raise exception
      end

Irostovsky

This is a demo task.

A zero-indexed array A consisting of N integers is given. An equilibrium index of this array is any integer P such that 0 ≤ P < N and the sum of elements of lower indices is equal to the sum of elements of higher indices, i.e. 
A[0] + A[1] + ... + A[P−1] = A[P+1] + ... + A[N−2] + A[N−1].
Sum of zero elements is assumed to be equal to 0. This can happen if P = 0 or if P = N−1.

For example, consider the following array A consisting of N = 8 elements:

  A[0] = -1
  A[1] =  3

Irostovsky

https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-redis-on-ubuntu-16-04

How To Install and Configure Redis on Ubuntu 16.04
PostedMay 11, 2016 51.6k views NOSQL REDIS UBUNTU UBUNTU 16.04
Introduction

Redis is an in-memory key-value store known for its flexibility, performance, and wide language support. In this guide, we will demonstrate how to install and configure Redis on an Ubuntu 16.04 server.

Prerequisites
To complete this guide, you will need access to an Ubuntu 16.04 server. You will need a non-root user with sudo privileges to perform the administrative functions required for this process. You can learn how to set up an account with these privileges by following our Ubuntu 16.04 initial server setup guide.