.NET Semaphore Slim that Supports Keys

While making a HUGE update to my CacheRepository project, I needed a way to have a dynamic number of semaphores that would lock on a specified cache key. The SemaphoreSlim is great, but I needed a wrapper around it that allowed me have one for each unique cache key being fetched.

The easiest solution was just to have a concurrent dictionary of string to semaphore, but at high load that would grow in size and I did not want to waste memory. Instead I created a class that does keep a dictionary of semaphores, but then removes them from the dictionary and stores them in a queue for reuse once there is nothing locking off on them.

Enough talking! Below is the code, and as always it comes with unit tests! :)

Obsolete Blog Posts

I was recently asked an interesting question:

"Are there any blog posts you wrote that you no longer agree with?"

Yes there are. As I have grown as a developer there are many patterns and practices that I have changed my opinions about. Also, many of my posts are related to specific technologies that have grown, changed, or become deprecated over time.

Here is a small list of posts on my blog that I now consider to be obsolete.

• Common.Logging.NLog40 - This is a very recent blog post, but the fact is that the more I work with Common.Logging the more that I absolutely despise their version specific packages.
• Serializable PagedList for .NET - This original implementation was too complicated, so I wrote another one.
• Compile TypeScript On Request with BundleTransformer - Just precompile your resources, perhaps with a build step; this solution is not worth the complexity.
• Bootstrap 3, LESS, Bundling, and ASP.NET MVC - Same comment as above.
• Sharing Generic Configuration Across Projects - In principal I still absolutely love this concept, but I now advocate for an even simpler approach: just register inject POCO entities for configuration.
• Unshelve to a Different Branch in TFS - It is about to be 2016, why would you still use TFS when there is Git? Got git it right now!
• Lazy Unity Injection - This is now supported by default by Unity. That's right, this blog post was ahead of it's time! :)
• Injectable Dataflow Blocks - This was just not a great approach to this problem, I would now recommend composition over inheritance.
• Throttling Datafow and the Task Parallel Library - A coworker showed me that a better way to throttle your Dataflow blocks, but I can't recall the details...maybe that would be a good blog post.
• Automated Testing w/ Selenium! - Oh no, my first blog post of all time is obsolete! If you find this one you should really be using Selenium 2 (WebDriver) instead.

Going back through these posts to write this post has made me notice a common theme as I grow: I continue to advocate simpler solutions to problems. I like that trend, and I can't wait to see what I am writing about in another 7 years.

Live and learn,
Tom

.NET WebSocket Libraries

WebSockets are awesome, and you should be using them. If you are working with .NET, then there are some very easy to consume libraries to help you host a WebSocket server or connect as a WebSocket client.

• WebSocket Server - Fleck
  • Source on GitHub
  • NuGet Package
• WebSocket Client - WebSocket4Net
  • Source on GitHub
  • NuGet Package

Below is a complete chat server and client made using ONLY these two libraries.