On 05/09/11 20:06, Bron Gondwana wrote: > On Mon, Sep 05, 2011 at 02:32:40PM +1000, Greg Banks wrote: >> Ok, I'm now convinced my first attempt at annotation quotas sucked too >> hard, here's how I want to re-implement it. Let me know what you think. > >> - add a 32b mailbox index header entry to track the storage in bytes >> used by all annotations for the mailbox itself or for messages in the >> mailbox > > Why not 64b? Admittedly hanging gigabytes of annotations off a single > folders is probably evil,
Do we even have a db backend that would support that? > but this is the mailbox header - 4 bytes per > mailbox to not even have to think about it is super-cheap. We keep a > handful of "blanks" around in the header already. > >> - at header upgrade time, write the special value ~0 into this field, >> meaning "unknown" > > Funky. If you didn't want to get all special-value about it, you could > use a flag over in the flags field as well, there are only about 5 of > the 32 in use so far. Sure. >> - in mailbox_commit_quota(), if the field is not "unknown", then >> calculate the delta in usage and apply to the quota db. > > I assume this is done the same way it's done now? Something like that. > By taking a "snapshot" > of the value at the start, and calculating a diff to apply at the end. > That was actually a filthy workaround (one of many, dammit) for using > unsigned datatypes. If we made this a signed 64 bit datatype as well, > with a flag off to the side for "unknown", then we could actually store > a diff in the mailbox object directly - and update both this field and > the quota's value during the commit. Ok. >> - make reconstruct scan the annotations db to figure out the correct >> value for this new field. > > Yep - that makes sense. Reconstruct already does this for the > quota_mailbox_used field, doesn't it. Yes. > And any other derived > "aggregate" values in the header. > >> This means that the annotation STORE and SETMETADATA paths will be >> updating the quota db in the same place that APPEND et al do, >> mailbox_commit_quota(). This should work around Bug #3529 and also make >> the code neater. > > Nice. Yeah, all I have to do is work out how to futz with the annotate API yet again :( -- Greg.
