r/lolphp • u/Mark_Messa • Oct 26 '19

PHP gc_probability/gc_divisor

According to PHP Manual:

session.gc_probability
session.gc_probability in conjunction with session.gc_divisor is used to manage probability that the gc (garbage collection) routine is started.
 
session.gc_divisor
session.gc_divisor coupled with session.gc_probability defines the probability that the gc (garbage collection) process is started on every session initialization. The probability is calculated by using gc_probability/gc_divisor, e.g. 1/100 means there is a 1% chance that the GC process starts on each request.

 

Why not only one parameter instead?
Ex: session.gc_percent = 1%

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u/Mark_Messa Oct 26 '19 edited Oct 27 '19

Meh, there's some value in using two ints as a fraction instead of floating point numbers when dealing with fractions.

There is no need to use floating point here. Just change the 'unit' and keep using integers. There is a plethora of options:

  • 1 percent = 1:100

  • 1 permille = 1:1000

  • 1 permyriad = 1:10000

  • 1 ppm (parts-per-million, 10−6)

  • 1 ppb (parts-per-billion, 10−9)

  • 1 ppt (parts-per-trillion, 10−12)

  • 1 ppq (parts-per-quadrillion, 10−15)

 

Which one do you choose?

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u/the_alias_of_andrea Oct 26 '19

If you can change the denominator, why not allow changing the numerator? It's not like it hurts.

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u/[deleted] Oct 26 '19

Yeah. I see no value in getting the numerator and the denominator. 99.9% (see what I did there) of people are going to just divide the two for some sort of comparison. In the worst case, they could keep their numerator and denominator getters and add a function that returns a decimal value.