When a network is deleted, only one Placement call per segment
is done to remove the associated (if existing) resource provider.
Before this patch, each time a subnet was deleted, the segment
resource provider was updated. When no subnets were present in the
related segment, the associated resource provider was deleted.
This optimization improves the network deletion time (see Launchpad
bug). E.g.: a network with two segments and ten subnets, the Neutron
server processing time dropped from 8.2 seconds to 4.4 seconds (note
that the poor performance was due to the modest testing environment).
Along with the segment RP optimization during the network deletion,
this patch also skips the router subnet update. Because all subnets
in the network are going to be deleted, there is no need to update
them during the network deletion process.
Change-Id: Ifd50027911a9ca3508e80e0de9a6cc45b67006cf
Closes-Bug: #1878916
7f40e626d6