[tahoe-lafs-trac-stream] [tahoe-lafs] #1240: remove ResponseCache in favour of MDMFSlotReadProxy's cache (was: add functional test of ResponseCache)

[tahoe-lafs]

#1240: remove ResponseCache in favour of MDMFSlotReadProxy's cache
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     Reporter:  davidsarah    |      Owner:  lebek
         Type:  defect        |     Status:  new
     Priority:  major         |  Milestone:  1.10.0
    Component:  code-mutable  |    Version:  1.8.0
   Resolution:                |   Keywords:  review-needed mutable cache
Launchpad Bug:                |
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Description changed by lebek:

Old description:

> There are unit tests of the mutable {{{ResponseCache}}} (at
> [source:src/allmydata/test/test_mutable.py at 4772#L1719], but no functional
> tests of how it is used. (As noted in [ticket:1045#comment:39],
> deactivating the cache by commenting out the line that adds entries to it
> will currently cause all tests to pass.)
>
> One way to test that the cache is working would be to download a file,
> then break all of the servers holding its shares, then download it again
> in order to check that the shares are retrieved from cache rather than
> from the servers.

New description:

 {{{MDMFSlotReadProxy}}} can already be initialised with share data which
 it uses in preference to fetching from the server. By exploiting this
 behaviour we can remove {{{ResponseCache}}} which does essentially the
 same thing.

 {{{ResponseCache}}} had no functional tests of how it is used (as noted in
 [ticket:1045#comment:39], deactivating the cache by commenting out the
 line that adds entries to it will currently cause all tests to pass). The
 {{{MDMFSlotReadProxy}}}  cache will require a test of this type.

 One way to test that the cache is working would be to download a file,
 then break all of the servers holding its shares, then download it again
 in order to check that the shares are retrieved from cache rather than
 from the servers.

--

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1240#comment:12>
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