In a new post to his blog Abhinav Singh shows you how to create a simple application that uses the memcached atomic increment command to help prevent concurrency issues.
Memcached provide atomic increment and decrement commands to manipulate integer (key,value) pairs. However special care should be taken to ensure application performance and possible race conditions while using memcached. In this blog post, I will first build a facebook style "like" application using atomic increment command of memcached. Also, I will discuss various technical difficulty one would face while ensuring atomicity in this application. Finally, I will demo how to ensure atomicity over a requested process using custom locks in memcached.
Example code is included to show how you can take a normal "store to memcached" example and modify it with the increment method to resolve issues that might come up from one or more scripts trying to get at the same values. He also includes an example of using locking to provide a similar effect.