Benchmark: Behavior script access performance

Richard Gaskin ambassador at fourthworld.com
Wed Mar 11 20:14:41 CDT 2009


Benchmarking fiend that I am, I was curious about the overhead of 
calling a hander in a behavior script in v3.5 as opposed to the closest 
approximation in 3.0 and earlier, a backScript which differentiates 
which objects it works on based on a custom property value.

For those unaware that v3.5 is in beta testing, Kevin introduced it in a 
recent newsletter:
<http://runrev.com/newsletter/february/issue65/newsletter1.php>

Trevor goes into detail here:
<http://runrev.com/newsletter/february/issue65/newsletter2.php>

In brief, in v3.5 you can use the script of any button to define 
behavior for any other object, enhancing the message path like this:

    <control>
        <behavior>
    <card>
    <stack>

Messages sent to an object go first to that object, and then to whatever
button script is assigned as that object's behavior.  After the behavior 
script they resume the normal message path.

In v3.0 and earlier the closest thing we had was using a backScript and 
then differentiating whether a handler should run or not based on the 
value of a custom property.  That was reasonably fast enough, but I 
wondered if behaviors would be any faster.

So in v3.5b I made a stack with three buttons:

button 1 has a uClass property set to "b", with this benchmarking script:

on mouseUp
   put 10000 into n
   -- Behavior:
   put the millisecs into t
   repeat n
     put foob() into r1
   end repeat
   put the millisecs - t into t1
   -- Backscript:
   put the millisecs into t
   repeat n
     put foobs() into r2
   end repeat
   put the millisecs - t into t2
   -- Result:
   put t1 && t2
end mouseUp


Button "b1" is inserted into the backScripts, with his handler:

function foobs
   if the uClass of the target = "b" then
     return 1+1
   end if
end foobs


Button "c1" is assigned as the behavior of button 1, with this script:

function foob
   return 1+1
end foob

True, the backScript is being asked to do more work, but it's the 
fairest comparison that way because behavior scripts only apply to 
buttons with a property assigned to them (the behavior property), and do 
not affect others.

So here's the result:

9 30

Behaviors average roughly three times faster to access than functionally 
equivalent backScripts.

And FWIW, if I take out the property check in the backScript (which 
gives the backScript method an unfair advantage), the result is:

9 16

So behaviors still win.  Not surprising, since messages have a shorter 
path to travel to them.

If you're not currently participating in the beta testing for v3.5 just 
sit tight a while longer, it's coming.  And when it's here, the new 
behaviors feature will not only change the way you script, but in some 
cases may boost performance along the way.

It's a mighty fine implementation.  Thanks, RunRev!

--
  Richard Gaskin
  Fourth World
  Revolution training and consulting: http://www.fourthworld.com
  Webzine for Rev developers: http://www.revjournal.com



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