[bitbake-devel] python function used in variable expansion called multiple times per recipe

[McClintock Matthew-B29882]

On Thu, Apr 19, 2012 at 5:28 PM, Richard Purdie
<richard.purdie at linuxfoundation.org> wrote:
> On Thu, 2012-04-19 at 21:24 +0000, Daniel Lazzari wrote:
>> >> I think immediate expansion is what I’ll need to use, thanks for the tip.
>> >> That at least brings the invocation down to once per run. Unfortunately, the
>> >> variable doesn’t seem to get filled in when I change to immediate
>> >expansion.
>> >>
>> >> def testFunc(bb, d):
>> >>                 print( bb.data.getVar("PN", d, True) )
>> >>                 return "e1"
>> >>
>> >> EXTERNPV := "${@testFunc(bb, d)}"
>> >>
>> >> Now only prints the package name once, but using –e, I don’t see the
>> >> variable EXTERNPV at all.
>> >
>> >Don't know what to tell you. It does work, so it's something wrong on
>> >your end. Either it's returning an empty string, which will result in
>> >-e only showing the commented out definition, or it's raising an
>> >exception, or something else in your setup. Aside: you don't need to
>> >pass 'bb' in. That namespace is always accessible, even from def'd
>> >python functions.
>> >--
>> >Christopher Larson
>>
>> Just thought I'd provide an update real quick on this. I discovered,
>> to my dismay, that even doing an immediate expansion still ran the
>> code before every task for that recipe. I switched to using an event
>> handler, but the RecipeParsed event occurs before every task for that
>> recipe. Eventually I discovered that the variable BB_WORKERCONTEXT is
>> set for RecipeParsed events when they are occurring before a task, but
>> not for the initial parse. Also, I discovered that setting a variable
>> in the event handler would not necessarily keep it set through
>> building the recipe. Thus I devised the below code to run the time
>> intensive code during initial parse and cache the value in a file so
>> it can be picked up again in later events. I'm leaving this here in
>> case it helps someone else.
>
> Just as a note, we have the persist_data code in bitbake which was
> written for this kind of reason in relation to SRCREV and AUTOINC which
> uses a sqlite backend as the storage. There isn't anything wrong with
> what you're doing, I just thought I'd mention it.

Richard,

I'm curious if something like an eventhandler is more suitable for me
trying to modify the PV/PR? Seems like eventhandler + BB_WORKERCONTEXT
could be what I'm looking for?

-M