[Laszlo-dev] New, improved class arguments processing

[P T Withington]

Can you either explain the things you measured, or perhaps just show  
the tests?  I'd be interested to measure the case you are worrying  
about, say:

   3 instanceof Function

i.e., what is the cost of a failed instanceof, vs. a successful one?

Do you have measurements that indicate the new consolidated arglist  
processing is actually slower than the old processing of args,  
constraints, and styles?  I would have expected the simplifications in  
applyArgs et al. would more than make up for any additional overhead.

Also, it might be more profitable to work on the idea of computing a  
custom applyArgs method for each class at compile time to eliminate  
all of the remaining interpretation of the arglist.

On 2008-02-20, at 19:23 EST, Max Carlson wrote:

> Hi Tucker,
>
> I've been working a few kinks out of the runtime, and reading the docs
> on LzNode.construct(), which say:
>
> @param Object args: A dictionary of initialization arguments that  
> should
>  * be applied
>  * to the instance. This contains any arguments that are default  
> arguments
>  * written in the class definition.  Note that initial value
>  * expressions (`$once{...}`) and constraints (`${...}`), are in this
>  * list also, they can be differentiated from initial values by their
>  * type: `LzInitExpr` for the former, and `LzConstraintExpr` for the
>  * latter.  If you handle the installation of any instance attributes
>  * in your construct method, you are responsible for dealing with
>  * these "binders" as well.  Normally, they will be processed by
>  * LzNode.
>
> So, I did a little performance testing (trunk/test/performance/ 
> typeof-instance-of.lzx) and found a few potential optimizations:
>
> a) typeof func == 'function' is about 2x faster than f instanceof  
> Function.
>
> b) typeof seems to be much faster than instanceof.  Since many  
> arguments are not LzInitExpr, it might be worth doing this:
> typeof arg == 'object' && arg instanceof LzInitExpr;
>
> instead of just this:
> txt instanceof LzInitExpr;
>
> Here are my numbers for swf8:
> iterations = 200
> empty                         :     6.35us ±    2.23 [5.00..10.00]/100
> instanceof                    :    30.25us ±    2.88 [20.00..35.00]/ 
> 100
> typeof                        :    21.05us ±    2.59 [10.00..25.00]/ 
> 100
> typeof with instanceof        :    30.00us ±    2.25 [25.00..35.00]/ 
> 100
> property lookup               :    19.60us ±    2.43 [15.00..25.00]/ 
> 100
> typeof with instanceof with short circuit:    15.05us ±    0.87  
> [10.00..20.00]/100
> typeof function               :    12.90us ±    2.48 [10.00..15.00]/ 
> 100
> instanceof function           :    26.40us ±    2.26 [25.00..30.00]/ 
> 100
>
>
> And for DHTML, firefox OS x:
> iterations = 200
> empty : 5.65us ± 1.69 [5.00..10.00]/100
> instanceof : 29.90us ± 7.85 [15.00..40.00]/100
> typeof : 17.40us ± 4.23 [10.00..25.00]/100
> typeof with instanceof : 30.40us ± 3.94 [20.00..35.00]/100
> property lookup : 15.35us ± 1.78 [10.00..20.00]/100
> typeof with instanceof with short circuit: 12.75us ± 2.50  
> [10.00..15.00]/100
> typeof function : 12.40us ± 2.51 [10.00..15.00]/100
> instanceof function : 19.10us ± 2.29 [15.00..25.00]/100
>
> Let me know what you think...
>
> -- 
> Regards,
> Max Carlson
> OpenLaszlo.org
>