This is part of the protocol upgrade for 2020-05-15, and in general it
seems to go the direction of "we did this before, lets do this again".
The spec is clear enough, but there is still a lack of questioning and
testing. The problem this attempts to fix has been neutered for years[1].
The spec states:
> The essential idea of SigChecks is to perform counting solely in the
> spending transaction, and count actual executed signature check
> operations.
This, however nobel and logical, ignores that the
check-for-being-too-costly just pulled in a UTXO lookup and the loading
of the output script from the historical chain.
The goal that we protect against CPU over-use may be reached, but the
price is a total system slowdown. You can have multiple CPUs, but the
bus to permanent storage has one, max 2 parallel pipes.
To ensure theHub stays the number one scalable node, I didn't blindly
follow the spec, while making sure that the Hub is correctly going to
follow/reject consensus violations of newly mined blocks.
As a result the implementation in Flowee the Hub:
* does not check sigcheck-counts on historical blocks (more than 1000
blocks in the past).
This may increase the risk of chain-splits ever so slightly, but the cost
of disk-IO would be too high.
* No longer stores the value in the mempool, nor uses it for the
CPU-miner.
* Ties the sigcheck-limits to the user-set block-size-accept-limit.
This is contrary to the spec which mistakenly thinks that BCH has a
max block-size in the consensus rules. The effect is the same, though.
* The per-intput standardness suggestion is not implemented because
standardness checks don't currently fetch the previous outputs and
that would be too expensive to add.
* Standardness rules for the whole transaction are moved to the
mempool-acceptance logic instead. The cost would be too great
otherwise, similar to the previous point.
Again, the effect is the same as likely intented.
---
1) since the intro of the CachingTransactionSignatureChecker
It was only called twice, and in very close proximity. The class didn't
add anything.
This improves readability and with the new state its easier to write
too.
To allow the UTXO to actually use the power of checkpoints we need to
make sure that the block-validation state is not stored separately from
it.
The goal is that when we have some curruption we can just go back to an
earlier state of the UTXO and re-validate the blocks to get to the
current tip. The often seen problem is that corruption will instead
leave the block-index (leveldb) with an incorrect state so the replay
fails.
This change solves that by no longer reading the block-validation-state
and no longer writing it on a state change.
Move some files back to the server "library".
Merge the 'console' lib with server, as it doesn't really make sense with
just one file and nobody exclusively linking to it.
The server "libary" is not really a library, its the place we put all
the files shared by hub-qt hub-cli and hub.
We no longer depend on these files from other places (mostly due to
moving to the new logging framework) and as such we can move the files
back.
We used various ways to enable new features over the last 10 years.
We can remove that legacy code and just set the blockheight.
This cleans up the code quite a bit.
before disconnecting.
As this only applies to IBD, we can take into account that we have a
higher number of connections typically and this helps stability.
Remove txIndex option, its move to Flowee Indexer
Also remove the GUI option for setting the amount
of "script validator threads". :D
Remove DBCash command line option too, equally obsolete.
As the miners have started using the block-version bits for their
own purposes this means that BIP9 checks are rather irrelevant.
Signalling using version bits is rather silly anyway.
In Flowee there will no longer be warnings generated based on
these now outdated assumptions.
And this means less code :)
On all mature operating systems and filesystems creation of a 1GB file
will not actually use that data, only when we start using blocks does
the disk space get used.
As such this is a premature optimization that Core added and I ported to
Flowee which this commit removes.
Additionally, increase the block file size to 1GiB
The new UnspentOutputDatabase classes are only very loosly a database, we
purely register and store unspent outputs there. But unline a DB we don't
allow modification (just insert and delete).
This replaces the coin-db (which was based on leveldb) and as first goal
this gives us a higher level of stability. The level-database was known
to give corruption issues.
Notice that users will need to do a manual reindex on first update.
Get rid of the weird boost signals setup
Move it to a new library 'interfaces' which is
for stuff that has no dependencies and can avoid
creating inter-library or cicular dependencies.
TomZ