[tahoe-dev] Physical Meetup 2013-12-10: Minutes of the Meeting

[Tony Arcieri]

Oops, just realized next Thursday is the Github meetup. Week after that? ;)


On Fri, Jan 11, 2013 at 4:51 PM, Tony Arcieri <tony.arcieri at gmail.com>wrote:

> Sorry I missed this, and seeing Zooko in town. Next time! ;)
>
> Also I'd love to get my UI patch up for review at the next in-person
> meetup and if it's on the schedule I can confirm I will show up
>
>
> On Fri, Jan 11, 2013 at 4:31 PM, Zancas Dearana <zancas at leastauthority.com
> > wrote:
>
>> Summary:
>>   This was a brief meeting.  The technical content was focused on the
>> "Lease Database" documentation.
>>
>>
>> https://github.com/davidsarah/tahoe-lafs/blob/5161b1fb8dea9ad9dce23db5f8f7c89c3d7ea82d/docs/proposed/leasedb.rst
>>
>> Discussion:
>>
>> freddyb (having reviewed the document prior to the meetup) felt that
>> an understanding of the "pre-leasedb" architecture was implied by the
>> format of "leasedb.rst".
>>
>> warner mentioned a "Theory of Operation" (I believe this is what he
>> was referring to: https://en.wikipedia.org/wiki/Theory_of_operation)
>> and suggested the following format:
>>
>>  1) motivation
>>  2) description of the "Steady State" operating result
>>  3) subsequent description of edge cases (e.g. startup)
>>
>> Zooko suggested that the section currently titled "Motivation" should
>> be an appendix.  (I'm unclear on whether or not this is consistent
>> with the format warner advocated.)
>>
>> Warner described some aspects of peer-to-peer communication in the
>> context of Tahoe to Tom, at the edge of my hearing (i.e. I have no
>> details to report).
>>
>> freddyb and I discussed the notion of a "share" he said
>> (approximately):  "Your data is divided into a set of shares a subset
>> of which is sufficient to recover that data."
>>
>> [Caveat Emptor:  We didn't talk about the fact that the subset is not
>> strict, in the sense that you may need _all_ of the shares.   For
>> example, in the LeastAuthority TLOS3 case there's only 1 share. We
>> assume decryption capability.]
>>
>> Our conversation was stimulated by my experience scanning the document
>> related code in preparation for the meeting.
>>
>> The following assumes "immutables" as context:
>>  Before the Lease Database existed leases were stored with the data in
>> "ShareFiles".
>>
>>
>> https://github.com/tahoe-lafs/tahoe-lafs/blob/a9272522d5aff5342d08892992bf669b047c17fe/src/allmydata/storage/immutable.py#L39
>>
>>   These ShareFiles then provided  methods both for data management
>> (reading, writing, etc.) and for _meta_data management (renew_lease,
>> etc.).
>>
>>  There did not exist a class implementing an interface for a share as
>> an object independent of the ShareFile.
>>
>>  The accounting architecture permits the excision of the ShareFile class.
>>
>>  Classes implementing the IShareBase, IShareForWriting, and
>> IShareForReading interfaces replace the data management functionality,
>> while the AccountingCrawler class handles lease data.
>>
>>   Because the storage media is abstracted away in the cloud backend
>> there are different types of IShareBase implementing classes:
>>
>>
>> https://github.com/davidsarah/tahoe-lafs/blob/5161b1fb8dea9ad9dce23db5f8f7c89c3d7ea82d/src/allmydata/interfaces.py#L476
>>
>>   The AccountingCrawler is defined in the allmydata/storage directory
>> as it uses the abstract "backend" object to interface with backends in
>> general:
>>
>>
>> https://github.com/davidsarah/tahoe-lafs/blob/5161b1fb8dea9ad9dce23db5f8f7c89c3d7ea82d/src/allmydata/storage/accounting_crawler.py#L13
>>
>>   In short, as reflected in the document the commonly understood
>> concept of the "Share" is now more closely reified as a "IShareBase"
>> than was possible in the pre-accounting architecture.
>>
>>
>>  We did not discuss the states of a share and the possible transitions
>> between them.   I propose those topics as the agenda for the next
>> meetup!
>>
>>
>>   Changes to the content of the document as a result of the meeting are
>> here:
>>
>>
>> https://github.com/zancas/tahoe-lafs-1/blob/bc0e3766805f3f8842b6158ccf0b49d44d09ef30/docs/proposed/leasedb.rst
>>
>> --
>> -- ظ
>>
>> P.S.-- Dinner afterwards was great fun!
>> _______________________________________________
>> tahoe-dev mailing list
>> tahoe-dev at tahoe-lafs.org
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>>
>
>
>
> --
> Tony Arcieri
>



-- 
Tony Arcieri
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