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Re: How to write a test with random usage patterns?

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I wrote:
> I want to test a database by throwing random usage patterns
> at it.  Maybe like this, but replacing rand() with something
> which exhibits random patterns in the output:
> (...)

So, I don't want to code 20 usage patterns like this:

    switch (rand() % 20) {
        case 0: Do N writes in descending order; break;
        ....
    }

when I instead can get 4*5 usage patterns like this:

    switch (anti_rand() % 4) {
        case 0: write(smaller item than last time); break;
        ....
    }

    unsigned anti_rand() {
        switch (foo % 5) { 
          case 0: return the same number N times, then change foo;
          ...
        }
    }

That's still pretty unimaginative, though.  So I wonder how to write
anti_rand() to produce different patterns - mixtures of order and
randomness - to guide the test program.  Or what to google for,
since I hope someone has done this before.

E.g. maybe instead of returning the same number N times, it'll return
different numbers but with the same bottom bits each time for a while,
and specify that usage like above should use COUNT = power of 2.

And I'll need to know how to best use it, but I expect that must wait
until I know what anti_rand() is doing.  E.g. whether to use '% COUNT'
or something else.  Or instead of a "write smaller item than last time"
case, maybe write data from another anti_rand() stream and leave it to
anti_rand() to sometimes return descending values for a while.

-- 
Hallvard

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Thread

How to write a test with random usage patterns? Hallvard Breien Furuseth <h.b.furuseth@usit.uio.no> - 2015-07-27 14:48 +0200
  Re: How to write a test with random usage patterns? Julio Di Egidio <julio@diegidio.name> - 2015-07-27 07:19 -0700
    Re: How to write a test with random usage patterns? Hallvard Breien Furuseth <h.b.furuseth@usit.uio.no> - 2015-07-27 17:00 +0200
      Re: How to write a test with random usage patterns? Julio Di Egidio <julio@diegidio.name> - 2015-07-27 08:42 -0700
        Re: How to write a test with random usage patterns? Hallvard Breien Furuseth <h.b.furuseth@usit.uio.no> - 2015-07-28 12:53 +0200
  Re: How to write a test with random usage patterns? Julio Di Egidio <julio@diegidio.name> - 2015-07-27 07:42 -0700
  Re: How to write a test with random usage patterns? Hallvard Breien Furuseth <h.b.furuseth@usit.uio.no> - 2015-07-28 12:55 +0200
  Re: How to write a test with random usage patterns? Richard Heathfield <rjh@cpax.org.uk> - 2015-07-28 12:26 +0100
    Re: How to write a test with random usage patterns? Julio Di Egidio <julio@diegidio.name> - 2015-07-28 05:20 -0700
    Re: How to write a test with random usage patterns? Hallvard Breien Furuseth <h.b.furuseth@usit.uio.no> - 2015-07-28 15:03 +0200
      Re: How to write a test with random usage patterns? Richard Heathfield <rjh@cpax.org.uk> - 2015-07-28 17:17 +0100

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