[phosphor-logging] About the "Stop emitting Entry propChanged before ifacesAdded" change reason

[Ed Tanous]

On Wed, Oct 20, 2021 at 10:18 AM Patrick Williams <patrick at stwcx.xyz> wrote:
>
> On Wed, Oct 20, 2021 at 10:13:06AM -0500, Matt Spinler wrote:
> > values, and then explicitly emits the IA signal.   Others can chime in,
> > but I didn't see it as proper D-Bus behavior to emit propertiesChanged
> > before InterfacesAdded, since in fact no property is changing after the
> > interface was added.
>
> Correct.  PropertiesChanged signals should not show up before InterfacesAdded.

But they should still show up eventually (after the InterfacesAdded),
right?  The patchset here seems to be under the impression that
PropertyChanged is never emitted when the object is added, which seems
incorrect, or at the very least is a breaking behavioral change.
https://gerrit.openbmc-project.xyz/c/openbmc/bmcweb/+/48231

>
> > It seems like every application does their own thing here, so maybe we
> > can come up with some official best practices for how to emit signals
> > for new interfaces (unless it's there and I missed it).
>
> I'll admit the sdbusplus API is not great for this and a lot of applications do
> it wrong.  There was this issue on the backlog to come up with something
> "better": https://github.com/openbmc/sdbusplus/issues/53
>
> --
> Patrick Williams