Re: Cache

Evert | Rooftop wrote:

Hi, I'm developing a cache system. Which works in pseude code, like this: class Cache { function Fetchdata($id1,$id2,$id3) { $id = md5($id1 . $id2 . $id3); if ($this->DataIsExpired($id)) return false; else return unserialize(file_get_contents($id)); } function storeData($data,$id1,$id2,$id3) { $id = md5($id1 . $id2 . $id3); OpenTheFileAndWriteTheDataSerialized($data); } } $id1 $id2 and $id3 are when they are combined unique * Is there a chance of collision when MD5 is used on the id's and the ids are long strings

Yes there is a chance, but it's small enough that for practical purposes you can ignore it.

* Is file_get_contents the fastest way to open the file?

AFAIK yes it is since it takes advantage of memory mapping (where possible).

* Is serialize the fastest way to serialize ;) ?

Not sure.

* Are there any other things I should consider? (I'm aware of file-locking issues, and have taken care of that) regards, Evert

Hmmmm... well, file_get_contents() doesn't lock the file so I'm interested in how you're accomplishing this feat. Perhaps you're creating a temporary directory (atomic IIRC) for the filename and then flocking that? I dunno, I hate race conditions. You might also want to consider the security of the data that goes into your cache'd $_APP data. Because any file that is created by PHP is going to be in pretty much the same boat as the default session files and on a shared server, well...