Re: code cleanup

В Срд, 28.04.2004, в 22:41, John Baldwin пишет:
> On Wednesday 28 April 2004 02:26 pm, Julian Elischer wrote:
> > On Wed, 28 Apr 2004, John Baldwin wrote:
> > > On Wednesday 28 April 2004 02:26 am, Alex Lyashkov wrote:
> > > > Hi All
> > > >
> > > > how i see many points at kernel work with allproc list direct, but
> > > > proc.h introduce macros FOREACH_PROC_IN_SYSTEM.
> > > > This patch clean this places.
> > >
> > > I'd actually rather see the FOREACH_PROC macro removed, I don't think
> > > hiding the fact that it's a TAILQ is all that useful.
> >
> > it makes it possible (well, easier) to do:
> >
> > FOREACH_PROC_IN_SYSTEM(p) {
> > 	FOREACH_KSEGROUP_IN_PROC(p, kg) {
> > 		FOREACH_THREAD_IN_GROUP(kg.td) {
> > 			something(td, kg);
> > 		}
> > 	}
> > }
> >
> > Which is a lot easier to read and understand
> > than the expanded version. You don't kave to remember the linkage
> > pointer's names and you can add debugging  to it
> > and check that the correct loks are held etc.
> > (the latter being a major reason I did it).
> 
> Note that the allproc_lock protects the allproc list.  W/o the FOREACH_PROC 
> macro, I can grep for 'allproc' in the source tree to find all users to 
> verify locking, etc.  With the extra macro, I now have to do multiple greps. 
two greps is multiple ? first of FOREACH_PROC, second allproc or combine
at one grep with two -e parameters.

> When you multiple the effect with several wrapper macros, it now becomes much 
> more work to work on locking the lists of structures since you have to do 
> multiple greps to find the places to look at.  I think remembering the 
> linkages for lists is actually quite important to avoid using the same 
> linkage for multiple lists incorrectly.
you wrong.
it`s code from linux kernel, but illustrate who create more readable
code with macros same as FORAEACH_PROC_IN_SYSTEM.
==========================
        read_lock(&in_dev->lock);
        for_primary_ifa(in_dev) {
                if (inet_ifa_match(a, ifa)) {
                        if (!b || inet_ifa_match(b, ifa)) {
                                read_unlock(&in_dev->lock);
                                return 1;
                        }
                }
        } endfor_ifa(in_dev);
        read_unlock(&in_dev->lock);
==========================
where difficult for find locking problem? but using macro allow write
more readable code.

Other argument for this patch - FreeBSD already have this macro and src
need change to even code.

-- 
Alex Lyashkov <shadow_at_psoft.net>
PSoft