[tahoe-lafs-trac-stream] [Tahoe-LAFS] #1515: more precise progress indication for MDMF retrieve

[Tahoe-LAFS]

#1515: more precise progress indication for MDMF retrieve
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     Reporter:  davidsarah    |      Owner:
         Type:  enhancement   |     Status:  new
     Priority:  normal        |  Milestone:  undecided
    Component:  code-mutable  |    Version:  1.9.0a1
   Resolution:                |   Keywords:  mdmf statistics
Launchpad Bug:                |
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Old description:

> From the commit message for [changeset:9756146d61673552]:
>
> More improvements to consider:
>
> * progress is currently 0% or 100%: should calculate how many segments
> are involved (remembering retrieve can be less than the whole file) and
> set it to a fraction
> * "fetch" time is fuzzy: what we want is to know how much of the delay is
> not our own fault, but since we do decode/decrypt work while waiting for
> more shares, it's not straightforward

New description:

 From the commit message for [changeset:9756146d61673552]:

 More improvements to consider:

 * progress is currently 0% or 100%: should calculate how many segments are
 involved (remembering retrieve can be less than the whole file) and set it
 to a fraction
 * "fetch" time is fuzzy: what we want is to know how much of the delay is
 not our own fault, but since we do decode/decrypt work while waiting for
 more shares, it's not straightforward

--

Comment (by warner):

 Yeah, mutable/retrieve.py currently only calls `set_progress()` twice:
 once with 0.0 at the start, and once with 1.0 at the end. This was correct
 for SDMF, but with MDMF we can make an update after each segment is
 finished downloading. The place to do this will be inside
 `_decode_blocks()`, in the `_process()` function, where it logs "now
 decoding segment X of Y". Basically add a `set_progress(X/Y)` there.

--
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1515#comment:4>
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