How to check that an auction is finished - Triggered PHP processing_问答_开发者

I have a few ideas about this but here is what I need to do and just wanted some second opinions really.

I am writing a small auction site in PHP/SQL, but I have come up against a hurdle.

When an开发者_C百科 item finishes, much like eBay, I need to be able to tell that it's finished and send out the emails to who has won it and who has sold it.

The only way I can think of is to schedule a piece of code to keep checking what auctions have ended but surely there is a better way?

The solution can be in multiple parts :

A script that is launched via Cron (every 5 minutes could be good, even less...). It detects the finished auction and put them in a queue.
A script, that pretty much runs continuously, and that processes items in the queue.

Note that :

You have to ensure that an auction is still open before displaying the page ! (a simple test) That way people can't join in after it closes.
For each script, you can use PHP, or any other language

Advantages :

The cron job is very fast, low on resources, and if there are a lot of auction to process, there is no risk it will be run in parallel (and then conflicts)
The queue system ensure that your system won't crash because there is too much going on... It will process the queue as fast as possible, but if it is not fast enough, the website will continue to run. You can however end up with emails being sent hours or days after the auction is closed. But the "limit" is way more predictible, and won't crash your system.
You can extend it in the future with multithreading processing of the queue, distributed processing... This is a scalable architecture.
This architecture is fun.

Additionnal informations :

Regarding the daemon script, I doesn't have to run continuously. What you can do is : at the end of the cron job, if there are items in the queue, then it checks if the other script (processing) is running. If yes then exit. If the other script is not running, it launches it...
The daemon script gets an item out of the queue and process it. At the end, if there are still items in the queue, it processes it, else, it exits.
With this system, everything is optimal and everyone loves each other !

To check if the other script is running, you can use a file and write in it "1" or "0" (= running / not running). The first script reads it, the second writes it... You can also use the database to do it. Or you can maybe use system tools or shell command...

Please be kind to share the SQL script that query the highest bidder based on the bidding end date (how to know the bidding is over) and award the product to the highest bidder

I would setup a cron job to run every 10-20-30-60 minutes etc to send out emails and update the auction details.

If you're script is fast, running it every minute or so may be alright.

Be aware that many shared hosting will only allow you to send out a certain number of emails per hour.

Do these emails need to be sent out instantly?,

I can see 2 possible problems and goals you are trying to achive:

Visual: You want that when a user browse your website, without updating or refreshing the page, it keeps updating the page so that if an audition ends, it appears something like "Audition ended, the item goes to...". Solution: You should use Javascript and AJAX. (I assume you are already using it for countdowns or something). Make an AJAX call every 5 seconds (could be enough) and update the content.
Pratical: You want that if an audition is ended an user cannot join it. Solution: You can do it just with PHP and mysql. You could create a fields where you store the audition start timestamp and then make a simple if (time() >= ($timestamp + $duration)) {} (where $timestamp is the start of the audition and $duration is the duration of the audition) to block possible bad users trying to do it.