On 25/09/14 15:10, Armin Rigo wrote:
Hi,
On 25 September 2014 09:06, Elefterios Stamatogiannakis
<est...@gmail.com> wrote:
Unfortunately, the C library that i use (libsqlite3) does not provide a
function like that :( . It has a function that returns the size of the
string, but in my tests the overhead of doing another CFFI call (to find the
size) is greater than doing the 2nd copy (depending on the average string
size).
In general, if performance is an issue, particularly if you're running
CPython (as opposed to PyPy), you can try to write small helpers in C
that regroup a few operations. This can reduce the overhead of doing
two calls instead of one. In this case, you can write this in the
ffi.verify() part:
These tests i'm writting about use PyPy only. In CPython i use a native
C wrapper (APSW). I try to not use ffi.verify because i want the program
to be easily deployable. Also i want to test the maximum performance of
CFFI's API.
size_t myGetString(xxx, char **presult)
{
*presult = getString(xxx);
return strlen(*presult);
}
and then in Python you'd declare the function 'myGetString', and use
it like that:
p = ffi.new("char *[1]") # you can put this before some loop
...
size = lib.myGetString(xxx, p)
..ffi.buffer(p[0], size)..
Wouldn't an "strbuffer" that does this scan (opportunistically) be
faster for cases like above?
Thank you very much for your suggestions.
l.
_______________________________________________
pypy-dev mailing list
pypy-dev@python.org
https://mail.python.org/mailman/listinfo/pypy-dev
