[libvirt] [PATCH] qemu: Exit on first error in qemuDomainGetMemoryParameters

[Daniel Veillard]

On Wed, Oct 20, 2010 at 02:37:53PM +0200, Matthias Bolte wrote:
> There is no point in trying to fill params beyond the first error,
> because when qemuDomainGetMemoryParameters returns -1 then the caller
> cannot detect which values in params are valid.
> ---

  Okay ACK

> There is a similar pattern in qemuDomainSetMemoryParameters that tries
> to apply all given params even if one already failed. From a user's
> POV it's probably better to apply all params without an error or to
> apply non at all when one fails. But this is harder to implemeneted
> and requires a rollback mechanism.

  Well I don't think we can implement transactions there, so there will
always a case for uncertainties. Still since the client may want to tune
his guest domain, maybe some of the tuning will fail (and with the
current API, only retrying with one setting at a time can allow to
isolate the problem), but after the call we get closer to the expected
setup. It's still possible to see what was done with the Get API though.
  The simplest way from a client perspective is probably to change
only one setting at a time, it's also likely to match the UI offered
to the end user.

Daniel

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