Re: [Bitcoin-development] Draft BIP for Bloom filtering

[Andreas Schildbach <andreas@schildbach.de>]

Matt, I saw your commit and immediately started using it for testing.
Now I think the bitcoinj side needs some love because not one
transaction is being confirmed (all just pending) when replaying the
blockchain.


On 01/18/2013 05:38 PM, Mike Hearn wrote:
> I'm thinking we should actually make the change we talked about before
> and have the filtered block sent before the transaction data.
> 
> For one, it's not intuitive (API wise) that you'd get a callback
> saying "new pending tx" immediately before another callback saying "tx
> was confirmed", but that's what the current setup makes most natural.
> To fix it we'd have to notice that a tx message wasn't requested by
> us, buffer it, and wait for the corresponding filteredblock message.
> It seems cleaner to receive a filteredblock and then for any tx that
> matches it, attach it to the FilteredBlock object and wait until it is
> full up, then pass it to the wallet code all at once.
> 
> Another issue is that to risk analyze unconfirmed transactions you
> really have to download all dependencies. That has to be triggered by
> seeing an unconfirmed transaction. It's dumb to start this process for
> a tx that is actually in the chain, so you need to have some notion of
> whether it came from a filtered block anyway. I only realized this
> today.
> 
> I think when we discussed this before, the justification for having it
> work the current way was that it was simpler to integrate with the SPV
> client code if it was done this way around. But I don't think it's
> really simpler. There are enough odd side effects of doing it this
> way, that I feel it'd be better to tweak the protocol now whilst we
> have the chance.
> 
> On Wed, Jan 16, 2013 at 4:00 PM, Matt Corallo <bitcoin-list@bluematt.me> wrote:
>> Actually, there is one more minor algorithmic change I would like to
>> make to the way the hash function is computed really quick before it
>> gets merged, I'll have that finished up by the end of today.
>>
>> Matt
>>
>> On Wed, 2013-01-16 at 11:43 +0100, Mike Hearn wrote:
>>> Matts latest code has been tested by Andreas and seems to work
>>> correctly. He had to extend the client a bit to refresh the filter
>>> every 25k blocks because even with the extra flag, eventually the
>>> filter degrades into uselessness, but it did still improve the
>>> situation quite a bit.
>>>
>>> Because it's unit tested, been reviewed by me several times, has an
>>> interoperable implementation that has also been tested by Andreas in a
>>> build of his smartphone app,  I'm going to ACK the current code and
>>> request that it be merged in to 0.8. What do you say Gavin?
>>>
>>> The next step after that would be profiling. It's a big performance
>>> improvement for SPV clients already, but not as much as I anticipated.
>>> I suspect there's a simple bottleneck or missed optimization
>>> somewhere. But that can obviously come post-0.8
>>
>>
> 
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