Stanislav (Stas) Katkov skatkov

Implementing Advisory Locks in SQLite3

In my Rails model, I initially had a function to handle advisory locks in PostgreSQL. Here's the code, which works as expected:

# Postgresql version
def with_advisory_lock
  self.class.connection.execute("SELECT pg_advisory_lock(#{self.id})")
  yield

In programming languages, literals are textual representations of values in the source code. This is a syntactical concept.

Some examples:

7 # integer literal

	<%= form_with model: citizen, class: "card flex flex-col gap", data: { controller: "form" } do \|form\| %>
	<div class="flex flex-col gap mb-2">
	<div class="flex flex-col gap-half">
	<% countries = Country.order(:name) %>
	<%= label_tag :country_id, "Country", class: "text-sm font-medium leading-none" %>
	<%= select_tag :country_id, options_from_collection_for_select(countries, :id, :name, citizen.country_id), include_blank: "Select one", class: "input", data: { action: "form#submit", form_submitter_param: "on_country_change" } %>
	</div>

	<div class="flex flex-col gap-half">
	<% states = State.where(country_id: citizen.country_id).order(:name) %>

	# Add these gems to your Gemfile
	gem "rails" # not strictly needed, but I use ActiveConcern, etc
	gem "raix" # helpful gem to reduce code needed for function calling etc
	gem "thor" # to make a CLI app (not needed if you make a web app)
	gem "http" # my preferred gem to make API calls

	# This is the main app (`app/models/ai_chat/cli.rb`)
	module AIChat
	class Cli
	# Thor

	-- Step 1: Create the audit logs table
	CREATE TABLE audit_logs (
	id SERIAL PRIMARY KEY,
	table_name TEXT NOT NULL,
	operation TEXT NOT NULL,
	json_diff JSONB,
	inserted_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
	);

	-- Step 2: Create the trigger function

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Fullscreen Image Viewer</title>
	<style>
	body {
	font-family: Arial, sans-serif;
	}

	#!/bin/bash

	# Create a (draft) pull request using GitHub CLI.
	# It assigns the PR to the current user, fills in the title from the first commit,
	# and uses the PR template file for the description.

	set -euo pipefail

	# Colors for output
	RED='\033[0;31m'

	frozen_string_literal: true

	# A leaky bucket rate limiter for Ruby
	#
	# @see https://www.mikeperham.com/2020/11/09/the-leaky-bucket-rate-limiter/
	# @see https://en.wikipedia.org/wiki/Leaky_bucket
	class RateLimit
	class Error < StandardError
	attr_accessor :retry_in