multiple instances access same directory

[ala888]

Im making a webserver that for every file received,

finds a randomly generated folder name, checks if it already exists; and if it does not,

it puts the files in there.But what if multiple instances are running at the same time, and by the luck of the draw, more than one batch of files gets dumped

into the same folder since all the php instances though it didnt exist at the exact same time?Is there any way to prevent this?

[ala888]

To clarify my question, I am first checking if a file directory exists via file_exists in php, before creating and inserting uploaded files

into it. However, since the server is a multithreaded one, I am afraid that two instances of the script might somehow check the same file name at the same type, before

running into each other.

Edited July 15, 2014 by ala888

[Don Jajo]

well, in this instance i use something like uniqid() function which is generated based on microtime - http://www.w3schools.com/php/func_misc_uniqid.asp

Then do something like md5(uniqid()) or sha1

 

I don't think its gonna clash since time changes every second