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
Merkle-block and merkle-tree classes and methods are pretty much stand-
alone and can be moved with no efforts.
Also move the relevent unit test to qtestlib.
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.
Move some globals and all stuff pulling in crypto to the
server/serverutil.cpp file
Remove dead code.
Move several items that were used in only one place to the respective
files using them.
Move the class WaitUntilFinishedHelper into its own file.
Made sure no header includes utils.h
remove a handfull of files including utils.h for nothing.
This removes the attempt at magic (predicting future) component
called the fee-estimator.
The direct effect is that all transactions have as a mempool acceptance
the same minimum fee. Regardless of how full the mempool or blocks were.
This mempool-acceptance minimum fee is 0 sat/byte. (aka free)
Notice the node-wide free-tx accept-limiter is going to avoid us getting
overloaded.
This also includes a little blockchain of 114 blocks (the first 100 just
coinbase to reach coin-maturity) with transactions generated by the
txVulcano. So lots of outputs.
I adjusted the BlackBoxTest to load this data into any hub with ease.
The "UAHF" one used to be "more equal", mostly just because it happened
to be the first.
This makes them all equally equal.
Specifically this removes the special casing and the enum for the 201708
HF (aka BCH fork-point).
We select the right branch now purely based on the historical check-
points.
When a blackbox test fails add the logs from the nodes
into the output of the log itself so they are all in one
place.
Especially handy for CI or docker usage where getting files
is a lot harder than getting standard-out.
The 'server' library has always been a catch-all and
ideally only the hub links it in (far future goal).
In line with this I move a list of files out of server
into the utils lib.
I choose 'utils' because all these are plain old data
objects that many crypto apps will find useful.
now in utils/primitives/
* CScript
* CPubKey
* CTransaction
* CBlock
* FastTransaction
* FastBlock
* CScript
streams.h is now in utils/streaming/
hash.h is now in utils/
This change makes the limits be static variables, which means they are
only settable once for a process. The only usecase so far is to use much
smaller limits in testing situations.
Duplicate the test_bitcoin file into the common dir,
I hope to remove the original in future.
Make the common dir a new static lib and create a new
qtestlib based unit test out of the old doublespend unit test.
TomZ