I recently upgraded an install of PHP Free Chat to that latest version of 1.0 Final. However it was still lacking a feature to notify individual(s) that someone has joined the chat if they were not already in the chat application to begin with. I came across a posting explaining how to achieve this in PHP Free Chat at PHP Free Chat Forum. After a little reading and discussion I was able to implement the feature.

Here’s my modified version for the solution based on the forum posting. The pfcmail() function can be made to be way more versatile for any use, however for my use it was made to be simple and produce properly formated email messages.

Solution

1. Create a new PHP file called pfcmail.php with the following lines of code.

2. …

A high-performance application that has producers and consumers of some resource, such as a queue of messages, needs an efficient way to notify the consumers when the producer has inserted into the queue. Polling the queue for changes is not a good option. MySQL's GET_LOCK() and RELEASE_LOCK() functions can provide both mutual exclusivity and notifications.

This post was prompted by a message to the MySQL general emailing list some time ago, but I'm finally getting around to actually testing the theoretical solution I mentioned then. I can never just think my way through anything that involves locking and waiting... I have to test it.