On 01/05/2011 03:40 AM, Osier Yang wrote:
>> Then maybe the patch should be altered to output both name and UUID
>> (probably by introducing a helper function, which when given a
>> virDomainPtr outputs all three pieces of debug information rather than
>> the current %p). I like the idea behind the patch, but only if we can
>> come up with the correct way of getting the extra information when
>> debugging is enabled, and without adding extra time when debugging is
>> off. I'm not even sure what the right internal APIs for the job would
>> be, or if they even exist yet.
>>
>
> Hi, Eric,
>
> I implemented a helper function like so in src/libvirt.c:
>
> static const char *
> virDomainNameUUID(virDomainPtr domain) {
> char *entry = NULL;
> const char *name = NULL;
> char uuidstr[VIR_UUID_STRING_BUFLEN];
>
> if (!VIR_IS_DOMAIN(domain)) {
> entry = strdup("(VM: invalid domain)");
malloc'd return...
> return entry;
> }
>
> name = domain->name;
> virUUIDFormat(domain->uuid, uuidstr);
>
> if(virAsprintf(&entry, "(VM: name=%s, uuid=%s)", name,
> uuidstr) < 0)
> virReportOOMError();
>
> return NULLSTR(entry);
and static return. Ouch - that means the caller doesn't know whether to
call free or not. You have to be consistent (the result is either NULL
or malloc'd; or the result is always static).
> }
>
> But how to avoid extra time when debugging is off? Following
> is not correct way definitely, as malloc'ed "entry" need to be
> freed.
>
> virConnectPtr
> virDomainGetConnect (virDomainPtr dom)
> {
> DEBUG("dom=%p, %s", dom, virDomainNameUUID(dom));
When I envisioned a helper function, I'm thinking more like callers
using a simpler:
DEBUG_DOMAIN(dom)
and a helper like:
void
DEBUG_DOMAIN (virDomainPtr dom)
{
if !DEBUG then early exit
gather data
DEBUG("dom=%p, %s", dom, virDomainNameUUID(dom));
free any gathered data if needed
}
That would mean that your new helper function would need to look at the
guts of DEBUG to mirror the same decision of whether DEBUG will result
in any output.
--
Eric Blake eblake@xxxxxxxxxx +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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