gamerwalt

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

gamerwalt

GROKKING NOTES

I liked the way Grokking the coding interview organized problems into learnable patterns. However, the course is expensive and the majority of the time the problems are copy-pasted from leetcode. As the explanations on leetcode are usually just as good, the course really boils down to being a glorified curated list of leetcode problems.

So below I made a list of leetcode problems that are as close to grokking problems as possible.

Pattern: Sliding Window

• https://leetcode.com/problems/maximum-subarray/ # Close enough
• https://leetcode.com/problems/minimum-size-subarray-sum/

gamerwalt

#Steps to install latest Laravel, LEMP on AWS Ubuntu 16.4 version. This tutorial is the improvised verision of this tutorial on Digitalocean based on my experience.

Install PHP 7 on Ubuntu

Run the following commands in sequence.

sudo apt-get install -y language-pack-en-base
sudo LC_ALL=en_US.UTF-8 add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get install zip unzip

gamerwalt

class User extends BaseModel implements Authenticatable, CanResetPassword, IAggregateRoot
{
  use DomainEvents;

  protected $connection = 'benta';
  
  protected $table = 'users';
  
  protected $primaryKey = 'user_id';
  

gamerwalt

<?php

class StatusGroup extends BaseModel
{
    protected $connection = 'benta_tenant';
    
    protected $table = 'db_status_groups';
    
    protected $primaryKey = 'status_group_id';
    

gamerwalt

abstract class TenantBaseController extends Controller
{
    /**
     * @var CommandBus
     */
    public $commandBus;

	/**
	 * @param \BentaCore\Infrastructure\Common\Commanding\CommandBus $commandBus
	 */

gamerwalt

if ($this->auth->guest()) {
    if ($request->ajax()) {
        return response('Unauthorized.', 401);
    } else {
        return redirect()->guest('signin');
    }
}

//get the current user
$this->user = $this->auth->user();

gamerwalt

private function createUser($host, $databaseName, $username, $password)
{
    $createUserQuery = "CREATE USER '$username'@'$host' IDENTIFIED BY '$password'";

    $this->runStatement($createUserQuery);

    $grantUserQuery = "GRANT SELECT, INSERT, UPDATE, EXECUTE, DELETE ON $databaseName.* TO '$username'@'$host' IDENTIFIED BY '$password'";

    $this->runStatement($grantUserQuery);
}

gamerwalt

<?php

namespace BentaCore\Services\Provisioners;

use BentaCore\Services\Provisioners\IDatabaseProvisioner;
use Carbon\Carbon;
use DB;
use Exception;
use Illuminate\Contracts\Console\Kernel;
use PDO;

gamerwalt

/**
     * Handle the event.
     *
     * @param  TenantRegisteredEvent  $event
     * @return void
     */
    public function handle(TenantRegisteredEvent $event)
    {
        $migrate = '1';