Re: GNAT: Performance of String functions

[stt@houdini.camb.inmet.com (Tucker Taft)]

Robert Dewar (dewar@merv.cs.nyu.edu) wrote:
: Tarjei said

: <<As unbounded strings are allocated on the heap there is a potential
: serious overhead in allocating and deallocating space for these strings
: as they change size. The serious overhead can include system calls to
: allocate or free space. I expect that it also include wholesale copying
: of the contents of the strings.
: >>

: Right, that is generally true, we have considered, but not yet implemented,
: a version of unbounded strings that would allocate a little growth space
: in each string value so that, for example, if you are adding one character
: at a time, you do not copy on every addition. I think this would be a
: valuable improvement.

For what it is worth, our latest AdaMagic runtime provides for
this growth, and it also avoids the heap completely for "short"
unbounded strings.

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA