Posts

Showing posts with the label spring

This Blog Has Moved!

Right, so yes, five years ago I moved to github pages, and never bothered to redirect any of these pages there. Now I've moved on from there, and... Finally I am using my real domain, trishagee.com . My blog is now at trishagee.com/blog .  See you there!
Post a Comment
Read more

Amazing!

Today, I found my own blog useful.  I was configuring Spring validation on my new project, and had to remind myself how to do it .  We configured validation on the new project in less than an hour, which beats the two days it took me to work out how to do it the first time. And I impressed one of my new work collegues.  Apparently I am now the Spring Guru.  Oooops.
Post a Comment
Read more

AOP Caching

Today I would like to document my experiences implementing caching with Aspect Oriented Programming (AOP) and annotations.  Background context   Caching may need to be implemented in your application for a number of reasons. OK, actually usually only one: performance. I would like to add my own tuppence-worth to this though - if you can get away without caching (specifically in application that provide the ability to view and change data) then do so, unless you are using a cache implementation that will handle as much of the pain as possible for you. Implementing a home-grown cache from scratch is almost never the correct thing to do in my experience, you spend lots of time debugging and tweaking the cache when you should be working on your day-job, not re-inventing something that someone, somewhere, has already done a perfectly good job of .  The example I'm about to show you is for a web application created to let users read and edit values from a database (not an unusu...
1 comment
Read more

Validation with Spring Modules Validation

So if java generics slightly disappointed me lately , what have I found cool? I'm currently working on a web application using Spring MVC , which probably doesn't come as a big surprise, it seems to be all the rage these days. Since this is my baby, I got to call the shots as to a lot of the framework choices. When it came to looking at implementing validation, I refused to believe I'd have to go through the primitive process of looking at all the values on the request and deciding if they pass muster, with some huge if statement. Even with Spring's rather marvelous binding and validation mechanisms to take the worst of the tasks off you, it still looked like it would be a bit of a chore. Given all the cool things you can do with AOP etc I figured someone somewhere must've implemented an annotations-based validation plugin for Spring. And they have . And there's actually a reasonable amount of information about how to set it up and get it working. The pr...
2 comments
Read more

Popular posts from this blog

Dissecting the Disruptor: Writing to the ring buffer

Image
This is the missing piece in the end-to-end view of the Disruptor.  Brace yourselves, it's quite long.  But I decided to keep it in a single blog so you could have the context in one place. The important areas are: not wrapping the ring; informing the consumers; batching for producers; and how multiple producers work. ProducerBarriers The Disruptor code has interfaces and helper classes for the Consumer s, but there's no interface for your producer, the thing that writes to the ring buffer.  That's because nothing else needs to access your producer, only you need to know about it.  However, like the consuming side, a ProducerBarrier is created by the ring buffer and your producer will use this to write to it. Writing to the ring buffer involves a two-phase commit.  First, your producer has to claim the next slot on the buffer.  Then, when the producer has finished writing to the slot, it will call commit on the ProducerBarrier . So let's look at...
Read more

Dissecting the Disruptor: What's so special about a ring buffer?

Image
Recently we open sourced the LMAX Disruptor , the key to what makes our exchange so fast.  Why did we open source it?  Well, we've realised that conventional wisdom around high performance programming is... a bit wrong. We've come up with a better, faster way to share data between threads, and it would be selfish not to share it with the world.  Plus it makes us look dead clever. On the site you can download a technical article explaining what the Disruptor is and why it's so clever and fast.  I even get a writing credit on it, which is gratifying when all I really did is insert commas and re-phrase sentences I didn't understand. However I find the whole thing a bit much to digest all at once, so I'm going to explain it in smaller pieces, as suits my  NADD audience. First up - the ring buffer.  Initially I was under the impression the Disruptor was just the ring buffer.  But I've come to realise that while this data structure is at the hea...
Read more

Dissecting the Disruptor: Demystifying Memory Barriers

Image
My recent slow-down in posting is because I've been trying to write a post explaining memory barriers and their applicability in the Disruptor . The problem is, no matter how much I read and no matter how many times I ask the ever-patient Martin and Mike questions trying to clarify some point, I just don't intuitively grasp the subject. I guess I don't have the deep background knowledge required to fully understand. So, rather than make an idiot of myself trying to explain something I don't really get, I'm going to try and cover, at an abstract / massive-simplification level, what I do understand in the area.  Martin has written a post  going into memory barriers  in some detail, so hopefully I can get away with skimming the subject. Disclaimer: any errors in the explanation are completely my own, and no reflection on the implementation of the Disruptor or on the LMAX guys who actually do know about this stuff. What's the point? My main aim in this s...
Read more