Skip to content

Instantly share code, notes, and snippets.

@chetan
chetan / yardoc_cheatsheet.md
Last active April 13, 2025 14:08
YARD cheatsheet
@jboner
jboner / latency.txt
Last active May 17, 2025 20:12
Latency Numbers Every Programmer Should Know
Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns 14x L1 cache
Mutex lock/unlock 25 ns
Main memory reference 100 ns 20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy 3,000 ns 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD
@ikusalic
ikusalic / notes_on_testing.md
Created October 24, 2013 21:12
Exploration: how to do unit testing

Testing notes

Uncle Bob: Test First

Source: http://blog.8thlight.com/uncle-bob/2013/09/23/Test-first.html

  • tests are specs for the system and are more important than the system itself
  • (Tests should be) short, well factored, and well named. They ought to read like specifications; because they are specifications
  • (Goal:) trust your test suite to the extent that, if it passes, you know you
@brasic
brasic / clear_redis_script.rb
Last active October 13, 2020 19:52
Clear a large number of redis keys by pattern using SCAN and pipelining
#!/usr/bin/env ruby
require 'redis'
# Clear a large number of keys matching a pattern using SCAN and
# pipelining to avoid killing the server.
class ClearKeys
def initialize(pattern, host='localhost', postprocess_pattern=nil)
@redis = Redis.new(host: host)
@pattern = pattern
@joepie91
joepie91 / .md
Last active May 5, 2025 05:14
Running a Node.js application using nvm as a systemd service

Read this first!

Hi there! Since this post was originally written, nvm has gained some new tools, and some people have suggested alternative (and potentially better) approaches for modern systems. Make sure to have a look at the comments to this article, before following this guide!


The original article

Trickier than it seems.

@craigvantonder
craigvantonder / install-configure-letsencrypt.md
Last active April 26, 2022 08:58
Install and configure LetsEncrypt on Ubuntu Server 14.04 & 16.04 (Apache)
#!/bin/bash
# https://www.digitalocean.com/community/tutorials/how-to-secure-apache-with-let-s-encrypt-on-ubuntu-14-04
# Download the Let’s Encrypt Client
cd /usr/local/sbin
sudo wget https://dl.eff.org/certbot-auto
sudo chmod a+x /usr/local/sbin/certbot-auto
# Set Up the SSL Certificate
@delameko
delameko / upgrade-postgres-9.5-to-9.6.md
Last active October 24, 2024 08:55 — forked from johanndt/upgrade-postgres-9.3-to-9.5.md
Upgrading PostgreSQL from 9.5 to 9.6 on Ubuntu 16.04

TL;DR

Install Postgres 9.6, and then:

sudo pg_dropcluster 9.6 main --stop
sudo pg_upgradecluster 9.5 main
sudo pg_dropcluster 9.5 main
@phansch
phansch / yardoc_cheatsheet.md
Last active May 3, 2025 01:44 — forked from chetan/yardoc_cheatsheet.md
Improved YARD cheatsheet
@mankind
mankind / rails-jsonb-queries
Last active May 3, 2025 05:37
Ruby on Rails-5 postgresql-9.6 jsonb queries
http://stackoverflow.com/questions/22667401/postgres-json-data-type-rails-query
http://stackoverflow.com/questions/40702813/query-on-postgres-json-array-field-in-rails
#payload: [{"kind"=>"person"}]
Segment.where("payload @> ?", [{kind: "person"}].to_json)
#data: {"interest"=>["music", "movies", "programming"]}
Segment.where("data @> ?", {"interest": ["music", "movies", "programming"]}.to_json)
Segment.where("data #>> '{interest, 1}' = 'movies' ")
Segment.where("jsonb_array_length(data->'interest') > 1")
@wbotelhos
wbotelhos / clear-sidekiq-jobs.sh
Last active April 30, 2025 10:26
Clear Sidekiq Jobs
require 'sidekiq/api'
# 1. Clear retry set
Sidekiq::RetrySet.new.clear
# 2. Clear scheduled jobs
Sidekiq::ScheduledSet.new.clear