On 07/15/2011 05:20 PM, Eric Blake wrote:
Right now, 'virsh vcpucount' understands --current differently than all
other commands that understand --current. That is, --current is not a
synonym for whichever of --live or --config matches the current domain
state, but a counterpart of --maximum.
I'm about to teach VIR_AFFECT_CURRENT to the virDomainGetVcpusFlags
command. Do we fix 'virsh vcpucount --current' to map to this new flag
and come up with a new option that means the opposite of --maximum, or
do we just leave the virsh interface stuck the way it is?
I thought some more about this. What if we introduce a new flag while
providing backwards compatibility with the old usage?
For a refresher, the old usage is:
vcpucount (no flags) - okay, prints all possible counts
vcpucount --maximum --live - okay, prints maximum vcpus for running domain
vcpucount --maximum --config - okay, prints maximum vcpus for inactive xml
vcpucount --current --live - okay, prints active vcpus for running domain
vcpucount --current --config - okay, prints active vcpus for inactive xml
vcpucount --maximum - error, missing --config or --live
vcpucount --current - error, missing --config or --live
vcpucount --live - error, missing --maximum or --current
vcpucount --config - error, missing --maximum or --current
vcpucount --maximum --current - error, can't combine --maximum and --current
vcpucount --live --config - error, can't combine --live and --config
The proposed new usage would be documented:
vcpucount <domain> [{--maximum | --active} {--current | --config | --live}]
that is, if any flags are present, then either --maximum or --active
must be specified (to list the max vcpu or the active vcpu count), and
either --current, --config, or --live must be specified (with --current
gaining its traditional semantics as used in other virsh commands).
We can always tell the two cases apart. '--maximum --current' would no
longer be an error, but be the new syntax. '--current --live' and
'--current --config' would continue to work as the old syntax, but the
new preferred spelling for the same command would be '--active --live'
and '--active --config'. Any use of exactly 1 or more than 2 flags
continues to be an error.
Any problems with this approach?
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Eric Blake eblake@xxxxxxxxxx +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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