[tahoe-dev] [tahoe-lafs] #800: improve alacrity by downloading only the part of the Merkle Tree that you need

[tahoe-lafs]

#800: improve alacrity by downloading only the part of the Merkle Tree that you
need
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 Reporter:  zooko        |           Owner:  somebody 
     Type:  enhancement  |          Status:  new      
 Priority:  major        |       Milestone:  undecided
Component:  code         |         Version:  1.5.0    
 Keywords:  easy         |   Launchpad_bug:           
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Changes (by kevan):

 * cc: kevan@… (added)


Comment:

 In playing around with this, I noticed that if I change the logic in
 [http://allmydata.org/trac/tahoe/browser/src/allmydata/immutable/layout.py?rev=4048#L415]
 to download only the requested hashes, a number of unit tests that enforce
 upper limits on the number of reads start to fail. This makes sense --
 instead of downloading the entire hash tree at once with one read
 operation when we need any part of it, we download (with my modifications)
 each chunk of the hash tree in a separate read operation, so there will of
 course be more reads.

 I probably need to look more deeply into how block hashes are used before
 coming up with an opinion on this; so I guess this is an FYI note for the
 moment.

-- 
Ticket URL: <http://allmydata.org/trac/tahoe/ticket/800#comment:2>
tahoe-lafs <http://allmydata.org>
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