Railsmine

How to Call C Code from Ruby Using FFI

Sat, 14 Sep 2024 08:28:00 +0700

In this tutorial, we’ll create a small C library that provides a function to add two integers, and then we’ll use FFI in Ruby to call that function.

1. Create the C Library

First, we’ll write a simple C library with a function to add two integers.

// myadder.c

#include <stdio.h>

// Function to add two integers
int add(int a, int b) {
    return a + b;
}

2. Compile the C Library

Compile this code into a shared library. On Unix-based systems (Linux, macOS), you can use the following command:

gcc -shared -o libadder.so -fPIC myadder.c

On Windows, you would use:

gcc -shared -o adder.dll myadder.c

3. Use FFI in Ruby

Now, we’ll write Ruby code to use the ffi gem to call the add function from our C library. If you haven’t already installed the ffi gem, you can do so using:

gem install ffi

# caller.rb
require 'ffi'

module Adder
  extend FFI::Library

  # Load the shared library
  ffi_lib './libadder.so'  # Use 'libadder.dll' on Windows

  # Attach the add function
  # Maps the `add` function from the C library to Ruby.
  # The arguments and return type are specified in the array (`[:int, :int]`
  # for two integers and `:int` for the return type).
  attach_function :add, [:int, :int], :int
end

# Use the add function
result = Adder.add(3, 7)
puts "The result of adding 3 and 7 is: #{result}"

Running the Example

Ensure that the compiled shared library (libadder.so or adder.dll) is in the same directory as your Ruby script or in a directory included in your library path.

Run your Ruby script:

ruby caller.rb

You should see the output:

The result of adding 3 and 7 is: 10

You can explore the code by visiting my GitHub repository.

Rails - New Shortcut for Not Null Columns in Migrations

Tue, 23 Jul 2024 06:38:00 +0700

Rails is introducing a handy new feature in its migration generator: a shortcut for creating not null columns. This enhancement, submitted by David Heinemeier Hansson (DHH) himself, simplifies the process of defining required fields in your database schema.

The New Syntax

Previously, to create a not null column, you’d have to explicitly specify null: false in your migration. Now, you can use the ! symbol as a shortcut.

bin/rails generate migration CreateUsers email_address:string!:uniq password_digest:string!

This generates the following migration:

class CreateUsers < ActiveRecord::Migration[8.0]
  def change
    create_table :users do |t|
      t.string :email_address, null: false
      t.string :password_digest, null: false

      t.timestamps
    end
    add_index :users, :email_address, unique: true
  end
end

How to Install Ruby 3.4 with YJIT Enabled

Sun, 07 May 2023 21:31:00 +0700

In this blog post, I will explain how to install Ruby with YJIT enabled and chruby. If you are looking for Ruby installation without YJIT, please visit How To Install and Uninstall Ruby Using chruby post.

YJIT is a lightweight, minimalistic Ruby JIT built inside CRuby. it is a new just-in-time compiler for Ruby that was introduced in Ruby 3.0.

YJIT promises faster performance for Ruby programs by compiling them at runtime. It lazily compiles code using a Basic Block Versioning (BBV) architecture. The target use case is that of servers running Ruby on Rails.

Requirements

Ruby dependencies.
chruby - I assume chruby is already installed, I’ll skip the installation process.
The Rust compiler rustc and Cargo (if you want to build in dev/debug mode)
- The Rust version must be >= 1.58.0.

Ruby Dependencies

Install the prerequisite dependencies for building the CRuby interpreter:
- C compiler
For RubyGems, you will also need:
- OpenSSL 1.1.x or 3.0.x / LibreSSL
- libyaml 0.1.7 or later
- zlib
If you want to build from the git repository, you will also need:
- autoconf - 2.67 or later
- bison - 3.0 or later
- gperf - 3.1 or later
  - Usually unneeded; only if you edit some source files using gperf
- ruby - 2.5 or later
  - We can upgrade this version to system ruby version of the latest Ubuntu LTS.
Install optional, recommended dependencies:
- readline/editline (libedit, to build readline)
- libffi (to build fiddle)
- gmp (if you with to accelerate Bignum operations)
- libexecinfo (FreeBSD)
- rustc - 1.58.0 or later (if you wish to build YJIT)
If you installed the libraries needed for extensions (openssl, readline, libyaml, zlib) into other than the OS default place, typically using Homebrew on macOS, add --with-EXTLIB-dir options to CONFIGURE_ARGS environment variable.
```
 export CONFIGURE_ARGS=""
 for ext in openssl readline libyaml zlib; do
   CONFIGURE_ARGS="${CONFIGURE_ARGS} --with-$ext-dir=$(brew --prefix $ext)"
 done
```

For Ubuntu Linux, just copy and paste command below to install the required dependencies:

sudo apt install -y build-essential bison zlib1g-dev libyaml-dev libssl-dev libreadline-dev libffi-dev

How to Install Rust:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

MRI Ruby 3.4 Installation with YJIT Enabled for chruby

wget https://cache.ruby-lang.org/pub/ruby/3.4/ruby-3.4.2.tar.gz
tar -xvzf ruby-3.4.2.tar.gz
cd ruby-3.4.2

# Generate the configure file
./autogen.sh

# don't forget to create /opt/rubies directory
./configure --enable-yjit --prefix=/opt/rubies/ruby-3.4.2 --disable-install-doc

# If your machine have a lot of RAM, you can
# use `make -j install` to make installation faster
# `make install` compiles with a single cpu core only.
make install

You can test that YJIT works correctly by running:

# Quick tests found in /bootstraptest
make btest

# Complete set of tests
make -j test-all

If the installation is successful, upon reloading the shell, running chruby will display ruby-3.4.2:

$ chruby
   ruby-3.2.2
   ruby-3.3.1
   ruby-3.4.2

Note that there is also an environment variable RUBY_YJIT_ENABLE which can be used to enable or disable YJIT. This can be useful for some deployment scripts where specifying an extra command-line option to Ruby is not practical.

You can verify that YJIT is enabled by checking that ruby -v --yjit includes the string +YJIT:

ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +YJIT +PRISM [x86_64-linux]

Ribsum - Lightweight and Simple Lorem Ipsum Text Generator

Mon, 05 Dec 2022 23:36:00 +0700

Hi! I’ve created Ribsum Ruby gem. Ribsum is a lightweight Ruby gem that allows you to easily generate lorem ipsum text.

The reason is why create this gem is so many unmaintained Lorem Ipsum generator. Beside that I want to create simpler Lorem Ipsum generator.

Ribsum is a useful tool for anyone working on a design project or who needs placeholder text for a website or application.

To use Ribsum, simply install the gem and require it in your Ruby code:

gem install ribsum

Once you have Ribsum installed, you can use it to generate lorem ipsum text in a few different ways. You can call the Ribsum methods directly, like this:

# Paragraph
Ribsum.paragraphs # default 1 paragraph
# => Lorem ipsum dolor sit amet...laborum

Ribsum.paragraphs(2)
# => Lorem ipsum dolor sit amet...laborum.
# => Lorem ipsum dolor sit amet...laborum.

# Sentences
Ribsum.sentences # default 1 sentence
# => Lorem ipsum dolor sit amet...aliqua

Ribsum.sentences(2)
# => Lorem ipsum dolor sit amet...consequat

# Words
Ribsum.words # default 1 word
# => Lorem

Ribsum.words(2)
# => Lorem ipsum

# Characters
Ribsum.chars # default 1 character
# => L

Ribsum.chars(2)
# => Lo

Alternatively, you can include Ribsum in your own class, like this:

class MyClass
  include Ribsum
  ...
end

my_class = new MyClass

my_class.paragraphs
# => Lorem ipsum dolor sit amet...laborum

my_class.sentences
# => Lorem ipsum dolor sit amet...aliqua

my_class.words
# => Lorem

my_class.chars
# => L

Ribsum is a simple and easy-to-use gem that can save you time and effort when working on design projects or creating placeholder text. It is a valuable tool for any Ruby developer.

How Add Elements an Array and Automatically Remove Duplicates in Ruby

Sat, 03 Sep 2022 06:43:00 +0700

Operator |= is bitwise OR assignment in Ruby. While working with Array, using |= operator will automatically add elements and remove duplicates.

a = [1,2,2,3,3]
# => [1,2,2,3,3]

b = [3,4,5]
# => [3,4,5]

# a |= b is shorthand for a = a | b
a |= b
# => [1,2,3,4,5]

# Array with element of string can use |= operator too
x = ['aa', 'bb']
# => ['aa', 'bb']

y = ['b', 'cc']
# => ['b', 'cc']

x |= y
# => ['aa', 'bb', 'b', 'cc']

Access Nested Hash Value with Dig Method in Ruby

Wed, 24 Aug 2022 21:58:00 +0700

When you need to access value from nested Hash, it’s better to use dig method. Without dig you have to do nil checking to prevent error.

names = {domains: {blogs: ['kaklabs.com', 'railsmine.net'], tools: 'tools.kaklabs.com'}}
# => {:domains=>{:blogs=>["kaklabs.com", "railsmine.net"], :tools=>"tools.kaklabs.com"}}

names[:domains][:tools]
# => "tools.kaklabs.com"

ames.dig(:domains, :tools)
# => "tools.kaklabs.com"

names[:random][:tools]
# in `<main>': undefined method `[]' for nil:NilClass (NoMethodError)
# from /home/example/.rvm/rubies/ruby-3.1.1/lib/ruby/gems/3.1.0/gems/irb-1.4.1/exe/irb:11:in `<top (required)>'
# from /home/example/.rvm/rubies/ruby-3.1.1/bin/irb:25:in `load'
# from /home/example/.rvm/rubies/ruby-3.1.1/bin/irb:25:in `<main>'

names.dig(:random, :tools)
# => nil

How to Solve "Could not find MIME type database" Error on M1 MacBook

Thu, 13 Jan 2022 22:28:00 +0700

When installing ruby gems for a new project I get the following error on my M1 MacBook.

Could not find MIME type database in the following
locations: ["/usr/local/share/mime/packages/freedesktop.org.xml",
"/opt/homebrew/share/mime/packages/freedesktop.org.xml",
"/opt/local/share/mime/packages/freedesktop.org.xml", "/usr/share/mime/packages/freedesktop.org.xml"]

After some Googling, there are 2 solutions to solve this error.

Manually Copy & Paste File freedesktop.org.xml

First, create a file named freedesktop.org.xml, copy the file content found from Freedesktop and save it to freedesktop.org.xml.

Second, set the FREEDESKTOP_MIME_TYPES_PATH environment variable.

export FREEDESKTOP_MIME_TYPES_PATH=/path/to/freedesktop.org.xml

Install Dependency via Homebrew

Alternatively, if Homebrew is installed on your M1 Macbook, just run brew install shared-mime-info.

References

How To Install Old Version Ruby 2.7.1 and 2.7.2 on M1 Mac

Wed, 12 Jan 2022 09:20:00 +0700

Installing old version Ruby version 2.7.1 and 2.7.2 always raises an error on my Apple M1 Macbook. These are my steps on how to install Ruby 2.7.1 and 2.7.2 on my M1 Macbook with Homebrew and asdf. But because under the hood asdf use rbenv, I assume it should work too with rbenv.

My Macbook specifications:

MacBook Pro (13-inch, M1, 2020)
Chip Apple M1
macOS Monterey version 12.1
Memory 16GB

1. Install or Upgrade asdf and asdf-ruby

Install asdf and add Ruby plugin to asdf.

brew install asdf
asdf plugin add ruby https://github.com/asdf-vm/asdf-ruby.git

Or upgrade existing asdf and asdf-ruby plugin.

brew upgrade asdf
asdf plugin update ruby

2. Install Ruby

Version 2.7.1

Add the following ENV variable to .zshrc.

export RUBY_CFLAGS="-Wno-error=implicit-function-declaration"

And install Ruby 2.7.1 with the following command.

asdf install ruby 2.7.1

If the installation is successful, run asdf list, it will shows Ruby 2.7.1.

Version 2.7.2

If Ruby is already installed, reinstall the current versions of openssl, readline and ruby-build in order to have the latest versions and configs.

brew uninstall --ignore-dependencies readline
brew uninstall --ignore-dependencies openssl
brew uninstall --ignore-dependencies ruby-build
rm -rf /opt/homebrew/etc/openssl@1.1
brew install -s readline
brew install -s openssl
brew install -s ruby-build

add the following ENV variables to .zshrc.

export RUBY_CONFIGURE_OPTS="--with-openssl-dir=$(brew --prefix openssl@1.1)"
export LDFLAGS="-L/opt/homebrew/opt/readline/lib"
export CPPFLAGS="-I/opt/homebrew/opt/readline/include"
export PKG_CONFIG_PATH="/opt/homebrew/opt/readline/lib/pkgconfig"
export optflags="-Wno-error=implicit-function-declaration"
export LDFLAGS="-L/opt/homebrew/opt/libffi/lib"
export CPPFLAGS="-I/opt/homebrew/opt/libffi/include"
export PKG_CONFIG_PATH="/opt/homebrew/opt/libffi/lib/pkgconfig"

Install Ruby 2.7.2 with the following command.

asdf install ruby 2.7.2

If the installation is successful, run asdf list, it will shows Ruby 2.7.2.

Based on Stack Overflow, above ENV variables should work too on Ruby 2.6.x, but I’ve never tried to install Ruby 2.6.x.

References

Railsmine Newsletter #2

Sun, 06 Jun 2021 14:26:00 +0700

Ruby

The Definitive Guide to Ruby’s C API - This site is a complete, practical guide to using Ruby’s C API

Moving my serverless project to Ruby on Rails - With serverless, Author was no longer dealing with his project’s domain, he was dealing with the distributed system’s domain.

Daemonizing Ruby Processes - This old posr (2014) explains step-by-step how to daemonizing Ruby processes.

Ruby on Rails in a Week - This post explains about how author is in the situation of having to learn Ruby on Rails in 7 days for interview process. Good read for beginner.

Context on STM in Ruby - There’s a proposal to add Software Transactional Memory, or STM, to the Ruby programming language. This is part of a wider effort to add better support for concurrency and parallelism in Ruby, and in particular the idea of ractors. A concept has been proposed and implemented by Koichi Sasada.

PostgreSQL

UUID, serial or identity columns for PostgreSQL auto-generated primary keys? - Sometimes customers ask me about the best choice for auto-generated primary keys. In this article, I’ll explore the options and give recommendations

10 Things I Hate About PostgreSQL - List of PostgreSQL’s imperfections based on author perspective.

Using PostgreSQL as a Data Warehouse - With some tweaking PostgreSQL can be a great data warehouse. Here’s how to configure it.

What are PostgreSQL Templates? - In this post, author explores about template databases in PostgreSQL and make full use of their potential.

How to interpret PostgreSQL EXPLAIN ANALYZE output - EXPLAIN ANALYZE is the key to optimizing SQL statements in PostgreSQL. This post explains what to look for and show you some helpful tools to visualize the output.

Railsmine Newsletter #1

Thu, 22 Apr 2021 06:58:00 +0700

First Issue of Railsmine News. Railsmine News is a collection of Ruby and PostgreSQL news and tutorial. Hope you enjoy it.

Ruby

mb-geometry - Recreational Ruby tools for geometry. This ranges from simple functions like area calculation and line intersection, to Delaunay triangulation and Voronoi partitions.

DragonRuby - DragonRuby creates toolchains that allow developers the ability to build apps and games using a programming language called Ruby.

Ruby on Rails Controller Patterns and Anti-patterns - Previously, author covered patterns and anti-patterns in general as well as in relation to Rails Models and Views. In this post, author are going to analyze the final part of the MVC (Model-View-Controller) design pattern — the Controller.

The Ruby Unbundled Series: Release Features Faster by Slowing Down - There is a saying that in order to speed up, you need to slow down. This is true in software development in that we want to control the rate at which users receive new features.

How to Implement API Key Authentication in Rails Without Devise - When it comes to authentication, Ruby on Rails is a batteries-included framework. Devise is over-kill for an API.

PostgreSQL

TOAST - TOAST is a mechanism PostgreSQL uses to keep physical data rows from exceeding the size of a data block (typically 8KB). Postgres does not support physical rows that cross block boundaries, so the block size is a hard upper limit on row size.

Getting started with QGIS, PostgreSQL and PostGIS - In this mini-tutorial, you will learn how to quickly visualize OpenStreetMap (OSM) data with PostGIS and QGIS.

Kubegres - Kubegres is a Kubernetes operator allowing to deploy a cluster of PostgreSql instances with data replication enabled out-of-the box. It brings simplicity when using PostgreSql considering how complex managing stateful-set’s life-cycle and data replication could be with Kubernetes.

Lessons Learned From 5 Years of Scaling PostgreSQL - A must read tips.

Debugging random slow writes in PostgreSQL - Understanding & mitigating randomly slow writes in PostgreSQL.

Reindexing all tables after upgrading to PostgreSQL 13 - Author reindexed all tables after the upgrade and saw index storage savings of up to 90%.

Is Amazon RDS for PostgreSQL or Amazon Aurora PostgreSQL a better choice for me? - In this post, author explains how to determine the best option between Amazon RDS for PostgreSQL and Aurora PostgreSQL for your workloads and business requirements.