Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options

Re: Custom-length random/unique string generator

by BrowserUk (Pope)
on Feb 02, 2013 at 19:33 UTC ( #1016742=note: print w/replies, xml ) Need Help??

in reply to Custom-length random/unique string generator

my $buildID = md5_base64 ( rand($$) ) . md5_base64 ( rand($$) ) . md5_base64 ( rand($$) );

Let's see. On most *nix's, max_pid is 32768. That means that at most, you have 32768**4 = 1,152,921,504,606,846,976 inputs.

But, if your process happens to get allocated pid=100; then you only have 100**4 = 100,000,000 possibles.

The random number generator is seeded elsewhere with a permutation of this child's process ID and current machine time

Again, pids ranging from ~ 2 .. 32768. Time() during the working day, say 8.00am to 6pm: 29,000 .. 64,000.

You don;t say how they are combined, but typically people use something like  srand( $$ ^ time() ), and that produces a range of number far smaller than they intuitively expect.

this is 2.4e+100 possible combinations,

I think that is way optimistic.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1016742]
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others wandering the Monastery: (3)
As of 2017-02-26 10:58 GMT
Find Nodes?
    Voting Booth?
    Before electricity was invented, what was the Electric Eel called?

    Results (372 votes). Check out past polls.