I was considering names like getcheckpoints() to use the terminology that
already seemed to be in place, but they were too long :)
I have been using getheaders() in my thick client to quickly grab all the
headers before downloading the full blocks since I can grab more at a time.
Even with getblocks(), there is the case for a getgist() call. Right now you
call getblocks(), which can take some time to get the corresponding inv(), at
which time you can then start the call to getdata() as well as the next call to
getblocks().
With a gist, for example of segment_count 50, you could call getgist(), then
with the response, you could request 50 getblocks() each with a block_locator
of 1 hash from the gist (and optimally the stop_hash of the next hash in the
gist) to 50 different peers, providing 25,000 (50 x 500) block hashes.
Currently:
>>> getblocks()
<<< inv()
>>> getdata()
<<< block(), block(), block(), … (x 500)
Saturates one peer, while leaving the rest un-used. Step 1 and 2 can be
repeated and dispatched to different peers, but there is still the latency
between the two calls.
Gist:
>>> getgist()
<<< inv()
>>> getblocks(), getblocks(), getblocks(), … (x segment_count, 1 per peer)
<<< inv(), inv(), inv(), … (x segment_count, 1 per peer)
>>> getdata(), getdata(), getdata(), … (x segment_count, 1 per peer)
<<< block(), block(), block(), … (x (500 * segment_count), ie. 500 in per peer)
Each peer can be saturated.
I will try to run some experiments this weekend to get numbers as to whether
there is actually any performance improvement using a gist, or whether the
getdata(), block() latency ends up dominating the time anyways.
RicMoo
On Jun 4, 2014, at 11:42 PM, Mike Hearn <m...@plan99.net> wrote:
> Why do you want to optimise this? getheaders is used by SPV clients not full
> nodes. SPV clients like bitcoinj can and do simply ship with gist files in
> them, then getheaders from the last "checkpoint" (I wish I hadn't reused
> terminology like that but this is what bitcoinj calls them).
>
> In practice when I look at performance issues with current SPV clients,
> getheaders speed is not on my radar.
.·´¯`·.¸¸.·´¯`·.¸¸.·´¯`·.¸¸.·´¯`·.¸¸.·´¯`·.¸><(((º>
Richard Moore ~ Founder
Genetic Mistakes Software inc.
phone: (778) 882-6125
email: ric...@geneticmistakes.com
www: http://GeneticMistakes.com
------------------------------------------------------------------------------
Learn Graph Databases - Download FREE O'Reilly Book
"Graph Databases" is the definitive new guide to graph databases and their
applications. Written by three acclaimed leaders in the field,
this first edition is now available. Download your free book today!
http://p.sf.net/sfu/NeoTech
_______________________________________________
Bitcoin-development mailing list
Bitcoin-development@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/bitcoin-development
