[libvirt] [PATCH v2 0/9] Be consistent with vir*Obj*Remove* APIs

[Marc Hartmayer]

On Wed, Mar 28, 2018 at 11:19 PM +0200, John Ferlan <jferlan at redhat.com> wrote:
> v1: https://www.redhat.com/archives/libvir-list/2018-March/msg01295.html
>
> NB: This can wait until 4.2.0 is release, but I figured I'd post this
>     now just to put it on the radar and of course in hopes that someone
>     will look during the idle moment or two before the release.
>
> Changes since v1:
>
>  Short story: Rework the processing of the code
>
>  Longer story:
>
>  In his review Erik noted that there's a "fire dance" when processing
>  the vir*Obj*Remove APIs of requiring a locked object upon entry, then
>  adding a reference to that object, unlocking the object, locking the
>  list to which it is contained, and then relocking the object.
>
>  So it took some time to think about it and during one lengthy meeting
>  today I had the aha moment that the *Remove API's could take the same
>  key (e.g., uuid or name) used to Add or Find the object and use it for
>  the Remove API. This allows the Remove API to not require a locked (and
>  reffed) object upon entry and perform the lock dance, remove the object,
>  and return just just a reffed object forcing the caller to know to Unref
>  object.
>
>  Instead, let's simplify things. The *Remove API can take the key, Find
>  the object in the list, remove it from the hash tables, and dispose of
>  the object. In essence the antecedent to the Add or AssignDef API's
>  taking a def, creating an object, and adding it the object to the hash
>  table(s). If there are two *Remove threads competing, one will win and
>  perform the removal, while the other will call *Remove, but won't find
>  the object in the hash table, and just return none the wiser.
>
>  And yes, I think this can also work for the Domain code, but it's going
>  to take a few patch series to get there as that code is not consistent
>  between consumers.
>
> John Ferlan (9):
>   secret: Rework LoadAllConfigs
>   secret: Alter virSecretObjListRemove processing
>   interface: Alter virInterfaceObjListRemove processing
>   nodedev: Alter virNodeDeviceObjListRemove processing
>   conf: Clean up virStoragePoolObjLoad error processing
>   storage: Clean up storagePoolCreateXML error processing
>   test: Clean up testStoragePoolCreateXML error processing
>   conf: Move virStoragePoolObjRemove closer to AssignDef
>   storagepool: Alter virStoragePoolObjRemove processing

Side note:
Wouldn’t is be useful to refactor all the vir*ObjList* things as they’re
looking quite similar? Not sure if it’s easily feasible in all places.

[…snip]

--
Beste Grüße / Kind regards
   Marc Hartmayer

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