On May 25, 4:10 pm, Erik Corry <[email protected]> wrote:
> 2009/5/25 <[email protected]>:
> > The good news is that string manipulation looked pretty fast -- 50,000
> > looped regexes in a JS function passed to the V8 wrapper ran in about
> > 0.19 seconds versus 0.14 seconds against our C++ PCRE wrapper. Not bad
> > at all, very happy with that, as PCRE is known to be a very fast
> > library with all kinds of speedup tricks.
>
> Actually I would have expected us to do better than that. Care to
> share your test?
Sure. In a slightly larger scale test I created 250,000 strings of the
form "00-00-0000", which are iterated through as dates, so I end up
with "05-03-1667" through to "22-08-2351", for example. Then the
following JS function is created and called...
function regex_test(re){
return (re.replace(/^(\d\d)(\d\d)(\d{4})$/,'$3-$2-$1'));
}
...using some code that looks quite like this (extracted/simplified
from main program):
const v8::Handle<v8::Object> exec_global = execution_context->Global
();
const v8::Handle<v8::Function> js_func = v8::Handle<v8::Function>::Cast
( exec_global->Get(func_name) );
for( int i=0; i<n_calls; i++ ){
v8::HandleScope loop_scope;
setArgvParams( i,ParamBlock );
v8::Handle<v8::Value> js_func_result = js_func->Call( exec_global,
1,argv );
// etc
}
I'm wondering if the code in setArgvParams can be improved. Everything
is passed by ref into that block to instantiate the argv for Call; the
only copy being done is to instantiate the v8::String object:
argv[j] = v8::String::New( Variant->asStr(),Variant->strLen() );
I see something about an ExternalAsciiString in the v8.h header. Would
this let me just provide a pointer to the existing string and avoid a
copy? If so I can't really see how to use it in this way from the few
fragments of code that I found. Possible? Would avoid a lot of
unnecessary copies if so.
Will try some more complex math as sugegsted, and see what happens. I
haven't used the profiler yet, will search for some docs/examples and
see what that returns.
// ---
> Erik Corry, Software Engineer
> Google Denmark ApS. CVR nr. 28 86 69 84
> c/o Philip & Partners, 7 Vognmagergade, P.O. Box 2227, DK-1018
> Copenhagen K, Denmark.
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