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FAST Protocol
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Re: Improving FAST
Rolf Andersson / Pantor Engineering
25 Feb 2010 12:03PM ET Dale,
the extensibility mechanism in FAST 1.1 can be used to specify maximum lengths etc. Please refer to section 9.
/Rolf
> Continuing my suggestions for improving FAST...
>
> Dynamic memory allocation can be a real performance killer. In C++
> there are a number of techniques that can be used to avoid dynamic
> memory allocation or minimize its impact including keeping thread-
> specific memory pools and caching objects for re-use rather than
> deleteing/newing them, etc.
>
> The one technique I would like to use, however, eliminates dynamic
> memory allocation altogether. That is preallocating space for the
> largest possible message. I have been able to use this with data
> feeds from particular sources to achieve some dramatic results.
> However, given the current definition of FAST templates there is no
> way to achieve these results in the general case, because there is
> no way to determine what "the largest possible message" is.
>
> So my suggestion is add upper-bound information to field instructions
> that produce variable sized objects. In particular, the sequence,
> string, and byte vector instructions could have a bound="n" attribute
> that would be a commitment by the data source/template author that
> field being transmitted would never exceed 'n' elements. This
> information is often available to the data source/encoder. Making it
> available in the template would give the decoder the information it
> needs to avoid dynamic allocation in the general case.
>
> Of course this would be an optional attribute with the default being
> that the number of elements is unbounded (or at least indeterminate.)
>
> Dale
> --
> Principal Software Engineer Object Computing, Inc (www.ociweb.com)
> Lead Developer of the QuickFAST Open Source C++ implementation of
> the FAST protocol. (www.quickfast.org)
Improving FAST Dale Wilson / Object Computing, Inc 29 Jan 2010 11:09AM ET Re: Improving FAST
Rolf Andersson / Pantor Engineering 25 Feb 2010 12:03PM ET
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