Re: non-undoable storage using directorystorage?

Discussion about adjusting Minimal.py to produce a workable non-undoing
storage.  dirstorage-users cc'd in...


Toby Dickenson said:
> On Friday 19 November 2004 12:39, Tim Hicks wrote:

> Sometimes renaming a file from transaction directory to storage directory
> will
> replace a pre-existing file of the same name.


[... which is how most of the non-undoing part gets done ...]
[... just need to implement proper pack to complete the functionality ...]


> More details at
> http://dirstorage.sourceforge.net/operation.html
>
>> I've had a look at Full.Full._pack, but seeing as I'm coming at this
>> almost completely new to ZODB and dirstorage, I'm not sure in which
>> places
>> Minimal needs adjustment to the Full.Full._pack to make things work.
>> Have
>> you got any pointers?
>
> A comment in _pack says:
>         # Reachable objects and transactions will be marked.
>         # An object is reachable if:
>         # 1. It is the root object
>         # 2. it is referenced by a sufficiently recent revision
>         #    of another object which is reachable. This catches
>         #    most objects
>         # 3. It was written in a sufficiently recent transaction.
>         #    This catches a few weird boundary cases, because
>         #    most objects are caught by 2.
>
> The 'marking' phase is all that needs to change. It doesnt need to loop
> over
> old revisions of objects because they only have one revision.


Ok, so would that involve writing an adjusted version of
_mark_reachable_objects or perhaps _mark_reachable_objects_impl?  I had a
look at those methods and... eek!  It all looks rather complicated and I
couldn't even figure out where the looping over the old revisions actually
happens.  Got any pointers?


tim

ps Is there a reason why there are two _mark_reachable_objects methods
declared on Full.Full?


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