IDisposable StopWatch to Benchmark code blocks (via Lambda or Delegate) in C#

Sometimes you need to time code execution for use *inside* your application. the StopWatch class was designed just for this purpose, but you end up with some pretty ugly code that looks like this:

Stopwatch stopwatch = new Stopwatch();
// Do something.
for (int i = 0; i < 1000; i++) { Thread.Sleep(1); }
// Stop timing.
// Write result.
Console.WriteLine("Time elapsed: {0}", stopwatch.Elapsed);

This gets really messy, especially if the code is already pretty complicated. But with very little effort you can make the .Net StopWatch just as beautiful as the Benchmark class in Ruby.

public class DisposableStopwatch: IDisposable {
  private readonly Stopwatch sw;
  private readonly Action f;

  public DisposableStopwatch(Action f) {
    this.f = f;
    sw = Stopwatch.StartNew();

  public void Dispose() {


To use the new stopwatch:

using (new DisposableStopwatch(t => Console.WriteLine("{0} elapsed", t)) {
  // do stuff that I want to measure

This is the best solution I’ve ever seen for this problem! No extension (so that it can be used on many classes) and very clean and very simple!

How to Clone or Duplicate a PostgreSQL Database

Sometimes you may find yourself needing to duplicate a postgres database – complete with schema, data; exactly. Sometimes I need to do this because I want to try out some ideas on an existing database but without the hassle of having to backup and restore or write rollbacks for the changes I want to make.

Luckily, it’s super easy to do this.  First ensure that there are not active connections to the source database; and then open the SQL Terminal of your choice and execute:


This will create a new database, by using the source database as a template.

If you get the message: “ERROR: Database being accessed by other users.” don’t worry; it just means that there are still open database connections, and these will need to be closed before it will work.

SerializationException Running Npgsql Commands on .Net Entity Framework

Recently, while working on a project for a client I was writing a .Net application using the Entity Framework backed onto a PostgreSQL database. All of a sudden I got a System.Runtime.Serialization.SerializationException when I was trying to run my app, and the stack trace (weirdly) didn’t help.

It turns out that while I had added the Npgsql dependency to the project, it wasn’t enough. Entity Framework it seems, needs to have access to Npgsql.dll assembly information.  When EntityFramework tries to use the library, it won’t find it (despite being in the project) unless it is in the Global Assembly Cache (GAC).

The Global Assembly Cache (GAC) is a folder in Windows directory to store the .NET assemblies that are specifically designated to be shared by all applications executed on a system. Assemblies can be shared among multiple applications on the machine by registering them in global Assembly cache(GAC). Source

The best way to resolve this is to use the Npgsql installer that matches the version in your project from: Those setups take care of registering Npgsql in GAC and set up the machine.config file to include the Npgsql db provider factory.

After I did this, everything worked as it should, and all was right with the world.

97 Things Every Programmer Should Know

PLEASE NOTE: This is a copy of the official list and I only copy it here for my own personal purposes (in case the list is lost), and not because I am trying to circumvent copyright or profiteer from it.

  1. Act with Prudence by Seb Rose
  2. Apply Functional Programming Principles by Edward Garson
  3. Ask “What Would the User Do?” (You Are not the User) by Giles Colborne
  4. Automate Your Coding Standard by Filip van Laenen
  5. Beauty Is in Simplicity by Jørn Ølmheim
  6. Before You Refactor by Rajith Attapattu
  7. Beware the Share by Udi Dahan
  8. The Boy Scout Rule by Uncle Bob
  9. Check Your Code First before Looking to Blame Others by Allan Kelly
  10. Choose Your Tools with Care by Giovanni Asproni
  11. Code in the Language of the Domain by Dan North
  12. Code Is Design by Ryan Brush
  13. Code Layout Matters by Steve Freeman
  14. Code Reviews by Mattias Karlsson
  15. Coding with Reason by Yechiel Kimchi
  16. A Comment on Comments by Cal Evans
  17. Comment Only What the Code Cannot Say by Kevlin Henney
  18. Continuous Learning by Clint Shank
  19. Convenience Is not an -ility by Gregor Hohpe
  20. Deploy Early and Often by Steve Berczuk
  21. Distinguish Business Exceptions from Technical by Dan Bergh Johnsson
  22. Do Lots of Deliberate Practice by Jon Jagger
  23. Domain-Specific Languages by Michael Hunger
  24. Don’t Be Afraid to Break Things by Mike Lewis
  25. Don’t Be Cute with Your Test Data by Rod Begbie
  26. Don’t Ignore that Error! by Pete Goodliffe
  27. Don’t Just Learn the Language, Understand its Culture by Anders Norås
  28. Don’t Nail Your Program into the Upright Position by Verity Stob
  29. Don’t Rely on “Magic Happens Here” by AlanGriffiths
  30. Don’t Repeat Yourself by Steve Smith
  31. Don’t Touch that Code! by Cal Evans
  32. Encapsulate Behavior, not Just State by Einar Landre
  33. Floating-point Numbers Aren’t Real by Chuck Allison
  34. Fulfill Your Ambitions with Open Source by Richard Monson-Haefel
  35. The Golden Rule of API Design by Michael Feathers
  36. The Guru Myth by Ryan Brush
  37. Hard Work Does not Pay Off by Olve Maudal
  38. How to Use a Bug Tracker by Matt Doar
  39. Improve Code by Removing It by Pete Goodliffe
  40. Install Me by Marcus Baker
  41. Inter-Process Communication Affects Application Response Time by Randy Stafford
  42. Keep the Build Clean by Johannes Brodwall
  43. Know How to Use Command-line Tools by Carroll Robinson
  44. Know Well More than Two Programming Languages by Russel Winder
  45. Know Your IDE by Heinz Kabutz
  46. Know Your Limits by Greg Colvin
  47. Know Your Next Commit by Dan Bergh Johnsson
  48. Large Interconnected Data Belongs to a Database by Diomidis Spinellis
  49. Learn Foreign Languages by Klaus Marquardt
  50. Learn to Estimate by Giovanni Asproni
  51. Learn to Say “Hello, World” by Thomas Guest
  52. Let Your Project Speak for Itself by Daniel Lindner
  53. The Linker Is not a Magical Program by Walter Bright
  54. The Longevity of Interim Solutions by Klaus Marquardt
  55. Make Interfaces Easy to Use Correctly and Hard to Use Incorrectly by Scott Meyers
  56. Make the Invisible More Visible by Jon Jagger
  57. Message Passing Leads to Better Scalability in Parallel Systems by Russel Winder
  58. A Message to the Future by Linda Rising
  59. Missing Opportunities for Polymorphism by Kirk Pepperdine
  60. News of the Weird: Testers Are Your Friends by Burk Hufnagel
  61. One Binary by Steve Freeman
  62. Only the Code Tells the Truth by Peter Sommerlad
  63. Own (and Refactor) the Build by Steve Berczuk
  64. Pair Program and Feel the Flow by Gudny Hauknes, Ann Katrin Gagnat, and Kari Røssland
  65. Prefer Domain-Specific Types to Primitive Types by Einar Landre
  66. Prevent Errors by Giles Colborne
  67. The Professional Programmer by Uncle Bob
  68. Put Everything Under Version Control by Diomidis Spinellis
  69. Put the Mouse Down and Step Away from the Keyboard by Burk Hufnagel
  70. Read Code by Karianne Berg
  71. Read the Humanities by Keith Braithwaite
  72. Reinvent the Wheel Often by Jason P Sage
  73. Resist the Temptation of the Singleton Pattern by Sam Saariste
  74. The Road to Performance Is Littered with Dirty Code Bombs by Kirk Pepperdine
  75. Simplicity Comes from Reduction by Paul W. Homer
  76. The Single Responsibility Principle by Uncle Bob
  77. Start from Yes by Alex Miller
  78. Step Back and Automate, Automate, Automate by Cay Horstmann
  79. Take Advantage of Code Analysis Tools by Sarah Mount
  80. Test for Required Behavior, not Incidental Behavior by Kevlin Henney
  81. Test Precisely and Concretely by Kevlin Henney
  82. Test While You Sleep (and over Weekends) by Rajith Attapattu
  83. Testing Is the Engineering Rigor of Software Development by Neal Ford
  84. Thinking in States by Niclas Nilsson
  85. Two Heads Are Often Better than One by Adrian Wible
  86. Two Wrongs Can Make a Right (and Are Difficult to Fix) by Allan Kelly
  87. Ubuntu Coding for Your Friends by Aslam Khan
  88. The Unix Tools Are Your Friends by Diomidis Spinellis
  89. Use the Right Algorithm and Data Structure by JC van Winkel
  90. Verbose Logging Will Disturb Your Sleep by Johannes Brodwall
  91. WET Dilutes Performance Bottlenecks by Kirk Pepperdine
  92. When Programmers and Testers Collaborate by Janet Gregory
  93. Write Code as If You Had to Support It for the Rest of Your Life by Yuriy Zubarev
  94. Write Small Functions Using Examples by Keith Braithwaite
  95. Write Tests for People by Gerard Meszaros
  96. You Gotta Care about the Code by Pete Goodliffe
  97. Your Customers Do not Mean What They Say by Nate Jackson

Tunnelling Your Way Through the Government’s Metadata Retention Laws

If you happen to be fortunate enough to have access to a Unix based web server (such as an EC2 or Linode) machine) you will surprised how easy it is to safely browse the web – circumventing the Australian government’s 2 year mandatory metadata retention laws.

t_29_0You can use an SSH tunnel to use your off-site server as SOCKS Host. A SOCKS Host (or Server) is a general purpose proxy server that establishes a TCP connection to another server on behalf of a client, then routes all the traffic back and forth between the client and the server. It works for any kind of network protocol on any port. Because the connection is secure, only the client and the host can access the the data.

This is how is circumvents Government spying. The only connection your ISP can see is the initial tunnel made to the server. All the delivery of websites etc through that connection are invisible to them (and the government).

It’s tragically easy to setup, simple initiate a SSH connection with dynamic application-level port forwarding, like this:

ssh -D 12345

And then, tell your browser that you want to use a HTTP SOCKS 5 Host for proxying (Options > Advanced > Connection Settings for Firefox):

Screen Shot 2015-11-03 at 1.52.46 PMUse manual proxy configuration; set it to SOCKS v5 on the same port you specified as forwarding.

Be warned however, while your Internet traffic will be encrypted and invisible, your DNS lookups will still be public. Firefox has a setting called ‘network.proxy.socks_remote_dns’ which you can enable by browsing to the address ‘about:config’ and searching for the string above.

Lastly, be warned that browsing this way will slightly decrease speed of your browsing – but this may be a small price to pay, and may not even be noticeable.

While this is all trivial for Linux and OSX users; Windows users will need to jump through a few more hoops. This blog post inspired and references an excellent Linode Guide which covers things in more detail, and includes instructions for Windows users using Putty.

How to Install ‘therubyracer’ or ‘libv8’ gem(s) on OSX

Recently, I need to move some Rails projects I was working on to new computer and this needs me to install all the dependencies for these projects.  While using bundler to install the gems; I encountered the following error:

extconf failed, exit code 1
Gem files will remain installed in /Users/ash/.rvm/gems/ruby-2.2.1/gems/libv8- for inspection.
Results logged to /Users/ash/.rvm/gems/ruby-2.2.1/extensions/x86_64-darwin-14/2.2.0-static/libv8-

An error occurred while installing libv8 (, and Bundler cannot continue.
Make sure that `gem install libv8 -v ''` succeeds before bundling.

Fortunately, with homebrew fixing this (on OSX 10.11, El Capitan at least) worked perfectly. Simply execute these commands:

brew install v8
gem install therubyracer
gem install libv8 -v '' -- --with-system-v8

Enable TRIM Support for 3rd Party SSDs in OSX El Capitan


There can be no doubt that the easiest way to increase the performance of an old Mac is to replace it’s hard disk with a shiny new Solid State Drive (SSD). The problem with this is that officially Apple only supports TRIM on Apple’s SSDs, effectively removing TRIM support from 3rd party SSDs. TRIM is a system-level command that allows the operating system and the drive to communicate about which areas of the drive are considered unused and thus ready to be erased and rewritten to. In the absence of TRIM, users can see significantly slower drive writes as the drive begins to fill up.

There are tolls people have written to try and get TRIM working for 3rd Party drives, but luckily, with El Capitan, Apple is relaxing the reins and allowing TRIM to be re-enabled for 3rd party SSDs.

To do this, simply open Terminal and execute the command:

sudo trimforce enable

Apple does give you a warning:

This tool force-enables TRIM for all relevant attached devices, even though they have not been validated for data integrity while using that functionality. By using this tool to enable TRIM, you agree that Apple is not liable for any consequences that may result, including but not limited to data loss or corruption.

Screen Shot 2015-10-31 at 1.21.06 AM

…but after a reboot (the utility will prompt you) TRIM should be enabled and you’ll be good to go.

As always: Proceed at your own risk. Enjoy.

Estabilishing ActiveRecord Database Connections in Ruby (But Without Rails)

Anyone who has even the smallest amount of experience developing with Ruby on Rails knows that Rails has some pretty sweet configuration conventions which make switching between environments very easy. Switching from development to production to testing is as easy as changing the RAILS_ENV variable. No doubt Rails does some dark magic behind the scenes to trivialise this. But what if you’re writing an app in Ruby, without the Rails to guide you?

ActiveRecord 101

Establishing a database connection in ActiveRecord without Rails is pretty basic:

require 'active_record'

  adapter:  'sqlite3',
  database: 'db/test.sqlite3'

It establishes a connection to the specified database with the specified connection  configuration. If you were using MySQL or PostgreSQL you would provide the relevant configuration such as username, password and host. With the connection established, we can now start consuming the connection however we like. For example, we may want to use funky Rails’ style models (so we can easily create and populate tables and reference them):

ActiveRecord::Schema.define do
  create_table :things do |t|
    t.integer :id, :null => false
    t.string  :name

class Thing < ActiveRecord::Base

  id:   0,
  name: 'Broomstick'

Care about the Environment

The other magic in Rails is the environment selection. The main benefit with this is that we can have isolated connection configurations and have our Ruby app automatically select the correct settings for us (using our environment variable ENV).

require 'active_record'

conf = case ENV['DB']
when 'conf1'
  adapter: 'sqlite3',
  database: 'db/mydb1.sqlite3'
when 'conf2'
  adapter: 'sqlite3',
  database: 'db/mydb2.sqlite3'
  raise 'export DB=conf[n]'

ActiveRecord::Base.establish_connection conf

Mind you, before this will work you first need to set the environment variable:

export DB=conf1 # or conf2

Now, depending on ENV[‘DB’], the code will open a connection to the corresponding database.

Best Practises

It’s never a good idea to store sensitive information (like database connection information and usernames and password of any kind) in your code base. Rails uses an external database configuration file called database.yml to solve this problem, so lets implement one ourselves.


  adapter: sqlite3
  database: db/mydb1.sqlite3

  adapter: sqlite3
  database: db/mydb2.sqlite3

Loading this YAML file is very simple:

require 'active_record'
conf = YAML.load_file('database.yml')
ActiveRecord::Base.establish_connection conf[ENV['DB']]

Now we can set our environment variable same as before, but our code will look in a YAML file for the proper database configuration automatically, without having to store database connection information directly inside our code.

Association Cardinality in Rails

From time to time I’ve noticed people who struggle with cardinality and associations in Ruby on Rails. So, I thought I would attempt to create a cheat sheet here to help developers understand relationship cardinality and how it maps to associations.

ActiveRecord can be used to describe relations with one-to-one, one-to-many and many-to-many cardinality; where each model defines its relation to another. Let’s cover each of the three types of associations.


Use `has_one` in the base and `belongs_to` in the association:

class Family < ActiveRecord::Base
  has_one :home
class Home < ActiveRecord::Base
  belongs_to :family

A common question about a one-to-one association is ‘how to know which direction the has_one and belongs_to go?’  The correct way to know, is that whichever model has the foreign key, gets the `belongs_to`.  In this case, Home has the foreign key `family_id`.

One-to-one relationships are a bit odd, and as a general rule, if you find yourself using a lot of them, there is probably a better solution.


Use `has_many` in the base and `belongs_to` in the association:

class Family < ActiveRecord::Base
  has_many :parents
class Parent < ActiveRecord::Base
  belongs_to :family

This will be your most common relationship. As with one-to-one’s, the table with the foreign key gets the `belongs_to` (although this is a lot more obvious with a one-to-many). In this case the foreign key is `family_id`.


These can be a lot more complicated and there is actually a couple of different ways to do it.

The first way involves a specific joining model. This results in 2 stages of has_many associations. It is referred to as `has_many :through` and is primarily used if you need to fully control the joining model/table:

class Family < ActiveRecord::Base
  belongs_to :parent
  belongs_to :kid
class Parent < ActiveRecord::Base
  has_many :kids, through: :families
class Kid < ActiveRecord::Base
  has_many :parents, through: :families

The second (and my preferred way) is to use the `has_and_belongs_to_many` method:

class Parent < ActiveRecord::Base
  has_and_belongs_to_many :kids 
class Kid < ActiveRecord::Base
  has_and_belongs_to_many :parents

The main difference (or disadvantage) with the `has_and_belongs_to_many`method is that the intermediary joining table and foreign keys need to be exactly named to match what Rails expects. Which many-to-many method you use ultimately depends on whether you need to work with the relationship model as its own entity directly.

Downloading Blackboard Unit Course Content for Offline Viewing

Blackboard is a great tool for completing college courses online, but sometimes you can get stuck without the internet making it difficult to study. There is a way however, to use a command line tool wget to download the site content for local, offline viewing.

It should be noted however, that this method is unlikely to be endorsed by your college – so use at your own risk!

To download the content for offline viewing you need two things (in FireFox):
1. Install the Firefox Cookie Exporter
2. Install wget

Use Cookie Exporter to export to cookies.txt

-the next command will download all the course material after loading the cookies.txt

wget -mk --no-check-certificate --load-cookies cookies.txt

If you use this method to download from courses with lots of content you may want to consider inserting “-w 20” into the wget command, which tells wget to wait 20secs between downloads (give the server some rest otherwise you may get booted).