svn commit: r296933 - in head: share/man/man9 sys/sys

[Gleb Smirnoff]

On Thu, Mar 17, 2016 at 08:21:12AM +0100, Hans Petter Selasky wrote:
H> On 03/16/16 21:32, Gleb Smirnoff wrote:
H> > On Wed, Mar 16, 2016 at 08:37:52AM +0000, Hans Petter Selasky wrote:
H> > H> Author: hselasky
H> > H> Date: Wed Mar 16 08:37:52 2016
H> > H> New Revision: 296933
H> > H> URL: https://svnweb.freebsd.org/changeset/base/296933
H> > H>
H> > H> Log:
H> > H>   Improve the implementation and documentation of the
H> > H>   SYSCTL_COUNTER_U64_ARRAY() macro.
H> > H>
H> > H>   - Add proper asserts to the SYSCTL_COUNTER_U64_ARRAY() macro that checks
H> > H>     the size of the first element of the array.
H> > H>   - Add an example to the counter(9) manual page how to use the
H> > H>     SYSCTL_COUNTER_U64_ARRAY() macro.
H> > H>   - Add some missing symbolic links for counter(9) while at it.
H> >
H> > ...
H> >
H> > H> +.Sh EXAMPLES
H> > H> +The following example creates a static counter array exported to
H> > H> +userspace through a sysctl:
H> > H> +.Bd -literal -offset indent
H> > H> +#define MY_SIZE 8
H> > H> +static counter_u64_t array[MY_SIZE];
H> > H> +SYSCTL_COUNTER_U64_ARRAY(_debug, OID_AUTO, counter_array, CTLFLAG_RW,
H> > H> +    &array[0], MY_SIZE, "Test counter array");
H> >
H> > I always wondered what is stylistically better: array or &array[0]? I
H> > usually prefer the former.
H> >
H> 
H> A question: If you pass "array" why do you need a length argument in the 
H> SYSCTL macro. Can't you get the length of the array like 
H> sizeof(array)/sizeof((array)[0]) inside the macro?

IMHO, that's a good idea for the static sysctl declaration. I can't imagine
a good case when size in array declaration and in the SYSCTL declaration
would differ.

-- 
Totus tuus, Glebius.