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Re: Storage Quota API

From: Michael Nordman <michaeln@google.com>
Date: Tue, 27 Sep 2011 13:43:03 -0700
Message-ID: <CAHpoE=jN9sgZtVFQkWdcuVHnE3wd2v6i8iwmmaSN1Nyg2CCciA@mail.gmail.com>
To: Charles Pritchard <chuck@jumis.com>
Cc: Jonas Sicking <jonas@sicking.cc>, Kinuko Yasuda <kinuko@chromium.org>, public-webapps <public-webapps@w3.org>
On Tue, Sep 27, 2011 at 1:26 PM, Charles Pritchard <chuck@jumis.com> wrote:

> On 9/27/2011 9:43 AM, Jonas Sicking wrote:
>> On Tue, Sep 27, 2011 at 6:12 AM, Kinuko Yasuda<kinuko@chromium.org>
>>  wrote:
>>> Just to confirm:  Yes the interfaces are vendor prefixed (WebKit), and
>>> WebSQL, AppCache, IDB are treated as temporary in the current chromium
>>> implementation.
>>> On Tue, Sep 27, 2011 at 8:53 AM, Charles Pritchard<chuck@jumis.com>
>>>  wrote:
>>>> Any ideas on how to express temp v. Perm to IndexedDB?
>>> IIRC there's been a proposal to have a way to hint that an IndexedDB
>>> ObjectStore is 'evictable' or not:
>>> http://www.w3.org/Bugs/Public/**show_bug.cgi?id=11350<http://www.w3.org/Bugs/Public/show_bug.cgi?id=11350>
>>> Though it seems to be put off until later (version 2), I was assuming
>>> that
>>> once we have the 'evictable' option it would indicate the data's
>>> Temp/Perm
>>> attribute.
>>> Other storage APIs do not have a way to express temp/perm either.
>>>  Chromium's current policy is defaulting to conservative or less
>>> astonishment to the users (in our belief), so that they won't see
>>> unexpected
>>> prompts or unknown data pressing their disk space.
>> And instead getting unexpected data loss :)
> What does happen in Chrome? From what I've seen, the AppData directory
> continues to balloon.

It's pretty primitive right now. There's a pool of TEMP storage that's
shared between all origins. A single origin can consume no more than 20% of
that pool. As usage approaches the limit, chrome will reclaim space consumed
by the LRU origins. The eviction grain size is an origin. We're adding
browser settings UI so users can control the TEMP pool size (if they

There's an additional mechanims avialable to 'chrome applications'.  In the
chrome-app manifest file, and app can say "unlimitedStorage". The storage
associated with those apps is not counted against the TEMP pool, and is not
subject to eviction, it's as if some app outside of the browser is using the
diskspace. This mechanism was put in place prior to us having the TEMP
management system. As TEMP management gets more sophisticated, i hope we can
phase out the 'unlimited' thing.

> I had an old SSD, about 32Gigs: Chrome is pretty liberal in its use of disk
> space. Short of the user
> clearing their history, I've not quite understood when and how the
> temporary caches vacate.
> Now that we are targeting Chromebooks, the "unexpected data loss" scenario
> is something
> that's getting baked into the application ux.
> -Charles
Received on Tuesday, 27 September 2011 20:43:31 UTC

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