Re: [libvirt] [PATCH] conf: rewrite filtering for capabilities lookup

The virCapabilitiesDomainDataLookupInternal() is given a list of parameters representing the desired domain characteristics. It then has to look throught the capabilities to identify an acceptable match. The virCapsDomainDataCompare() method is used for filtering out candidates which don't match the desired criteria. It is called primarily from the innermost loops and as such is doing many repeated checks. For example if architcture and os type were checked at the top level loop the two inner loops could be avoided entirely. If emulator and domain type were checked in the 2nd level loop the 3rd level loop can be avoided too. This change thus removes the virCapsDomainDataCompare() method and puts suitable checks at the start of each loop to ensure it executes the minimal number of loop iterations possible. The code becomes clearer to understand as a nice side-effect.

Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- src/conf/capabilities.c | 100 ++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 55 deletions(-)

@@ -731,6 +720,7 @@ virCapabilitiesDomainDataLookupInternal(virCapsPtr caps, goto error; } + VIR_DEBUG("No match %s", virBufferCurrentContent(&buf)); virReportError(VIR_ERR_INVALID_ARG, _("could not find capabilities for %s"), virBufferCurrentContent(&buf));