Soroush Khanlou recently wrote The GCD Handbook, a cookbook for common Grand Central Dispatch patterns. It’s a great set of patterns, with code examples.

While a great example of semaphores, I wondered whether the code in the Limiting the number of concurrent blocks section could be improved – I’ll explain why below. Soroush and I emailed back and forth a little bit, and came up with the following.

“Less is more”. It’s a frustrating phrase. Less is not not more; by definition, it never can be. But sometimes less is better. On the other hand, sometimes more is better. Mostly, from what I can tell, there are some things where less is better and others where less is worse. Often there’s a level which is just right: more is too much, and less is too little. Salt intake falls into that bucket.

Less is more is a paraphrasing of a whole book, The Paradox of Choice, written by Barry Schwartz. It’s become a bit of a mantra, one that is deployed often without thought: “this page is cluttered, we need to remove stuff; less is more, dude”. This closes a conversation without exploring the alternatives.

It’s looking increasingly, however, like the idea is either false or, at the very least, that the book length discussion is more appropriate than the three word version.

Once you’ve learned the basics of using Lua in HAProxy, you start to see a lot of places the scripting language could be useful. At Cloudant, one of the places we saw that we could make use of Lua was when selecting from the various backends to which our frontend load balancers direct traffic. We wrote a simple proof of concept, which I wanted to document here along with some of the problems we hit along the way.

It’s a long weekend this week in the UK. I wanted to learn a bit more Ruby, so I decided to use the time to start writing a client library for CouchDB. Basically my day job at Cloudant, but in Ruby.

I first used Ruby back in about 2005, and this site was powered by a couple of Ruby incarnations: first a Ruby on Rails app for a time; then a fairly hokey static site generator. I think that lasted until around 2009 when I learned Python and switched to Google AppEngine. Even with this experience, I don’t know Ruby particularly well – I have never used it full time – but I think the library has come out okay so far.

If you use Cloudant’s dashboard to generate API keys and assign permissions, you’d be forgiven for thinking that an API key can only be used for one database. However, that’s just an unfortunate implication of the UI. In fact, you can give an API key permission to read or write any number of databases – even ones on different Cloudant accounts.

The key to doing this is to use Cloudant’s HTTP API rather than the dashboard. Here’s how.