strcspn(3) complexity improvement

From: Jeremie Le Hen (jeremie_at_le-hen.org)
Date: 03/30/05

  • Next message: Andrey Koklin: "ciss(4): speed degradation for Compaq Smart Array" 
    Date: Wed, 30 Mar 2005 10:34:35 +0200
To: freebsd-current@FreeBSD.org

    Hi list,

    Andreas Hauser made a patch to strcspn(3) for the DragonFly project
    which makes it faster when dealing with long strings [1] (rev 1.4).
    It basically changes the complexity of the function from
        O(strlen(str) * strlen(chars))
    to
        O(strlen(str) + strlen(chars))
    by using a charset.

    I have two questions. First, is this change worth enough to be merged
    in FreeBSD (this function is currently used in 42 binaries from
    /{,usr/}{s,}bin) ? I mean does the performance gain on large strings
    compensates the use of a large 256-bytes buffer ?

    Second, I would like to know how to deal with the copyright update.
    ATM, I changed the top of the copyright (up to Andrea's email address),
    is it acceptable ?

    The temporary patch is here [2], I didn't have time to try it yet, this
    is why it is not attached with this email.

    Best regards,

    [1] http://www.dragonflybsd.org/cvsweb/src/lib/libc/string/strcspn.c
    [2] http://jeremie.le-hen.org/~tataz/patches/FreeBSD/libc.strcspn.dfbsd.patch 

    -- 
Jeremie Le Hen
< jeremie at le-hen dot org >< ttz at chchile dot org >
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