On Fri, Dec 12, 2008 at 12:05:21PM -0800, Brett Monroe wrote:
> Happy Friday,
>
> I'm having a hard time wrapping my head around the proper way to use
> conditional expressions in DTrace.
>
> The following line seems to not want to compile:
>
> args[0]->b_flags & B_READ ? (
> @dev_r[args[1]->dev_statname,args[1]->dev_pathname]=sum(args[0]->b_bcount)
> ) : ( @dev_w[args[1]->dev_statname]=sum(args[0]->b_bcount) );
You cannot use conditional expressions to do different actions; they can
only be used in expressions. You need to use predicates:
io:::start
/ args[0]->b_flags & B_READ /
{
@dev_r[args[1]->dev_statname,args[1]->dev_pathname] =
sum(args[0]->b_bcount);
}
io:::start
/ !(args[0]->b_flags & B_READ) /
{
@dev_w[args[1]->dev_statname] = sum(args[0]->b_bcount);
}
Cheers,
- jonathan
> I get the following error:
>
> dtrace: failed to compile script ./script.d: line 6: operator ?:
> operands cannot be of dynamic type
>
> My general (and apparently wrong) understanding is that all three
> expressions should evaluate to either true or false so (B_READ bit is
> set or not, @dev_r aggregate gets populated or not, or the @dev_w
> aggregate gets populated or not). It seems on the surface to be
> pretty strait forward....but of course I am missing something.
>
> Any help would be appreciated.
> --Brett
> _______________________________________________
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> dtrace-discuss@opensolaris.org
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