This is part of the "UTXO Set Statistics" project in Core, which aims
to make things like "checking coin supply" faster. This stuff, and
related things in coinstats.cpp, have always been broken for Elements
in the sense that we consider only explicit outputs and we ignore
assets (so everything just gets added together to get a meaningless
total). It probably wouldn't be too hard to restrict this to only
consider policyAsset, but it's out of scope for a rebase IMO.
Also, I think this situation is fine .. I don't understand the motivation
for this or why Core is merging this when they refuse to merge an address
index .. but I guess we'll see if there are users who care about this data
and who care about it being meaningful on Elements.
Also, apologies for the big diff -- there were some mechanical changes
to deal with CT amounts, but most of the changes related to the difference
in how fees are accounted for. While I'm not thrilled with this PR, its
functional test is really good! So I think what I eventually came up with
is internally consistent.
Note: up to this point I still had the old "sort by UNIX timestamp"
behavior on, which may have meant that some PRs were merged out of
order (i.e. multiple merged at once, followed by no-op merges). I
turned this off, and now just use git's default topo-sort (and manually
switch between Elements merges and Bitcoin merges).
Looks like James hardcoded a couple hashes in hard-to-find places, which
caused a unit test to fail. I just changed the hash (which covers UTXO
data which naturally will be different for us on account of our differently
formatted CTxOuts).
TODO: determine how Assumeutxo interacts with the fact that we don't save
out nonces in our normal UTXO serialization. Probably we will need to remove
the nonce from the CCoinStats serialization to avoid having inconsistent
hashes across nodes, since these hashes are now checked in assumeutxo?
13650fe2e5 [policy] detect unsorted packages (glozow)
9ef643e21b [doc] add release note for package testmempoolaccept (glozow)
c4259f4b7e [test] functional test for packages in RPCs (glozow)
9ede34a6f2 [rpc] allow multiple txns in testmempoolaccept (glozow)
ae8e6df709 [policy] limit package sizes (glozow)
c9e1a26d1f [fuzz] add ProcessNewPackage call in tx_pool fuzzer (glozow)
363e3d916c [test] unit tests for ProcessNewPackage (glozow)
cd9a11ac96 [test] make submit optional in CreateValidMempoolTransaction (glozow)
2ef187941d [validation] package validation for test accepts (glozow)
578148ded6 [validation] explicit Success/Failure ctors for MempoolAcceptResult (glozow)
b88d77aec5 [policy] Define packages (glozow)
249f43f3cc [refactor] add option to disable RBF (glozow)
897e348f59 [coins/mempool] extend CCoinsViewMemPool to track temporary coins (glozow)
42cf8b25df [validation] make CheckSequenceLocks context-free (glozow)
Pull request description:
This PR enables validation dry-runs of packages through the `testmempoolaccept` RPC. The expectation is that the results returned from `testmempoolaccept` are what you'd get from test-then-submitting each transaction individually, in that order (this means the package is expected to be sorted in topological order, for now at least). The validation is also atomic: in the case of failure, it immediately halts and may return "unfinished" `MempoolAcceptResult`s for transactions that weren't fully validated. The API for 1 transaction stays the same.
**Motivation:**
- This allows you to test validity for transaction chains (e.g. with multiple spending paths and where you don't want to broadcast yet); closes#18480.
- It's also a first step towards package validation in a minimally invasive way.
- The RPC commit happens to close#21074 by clarifying the "allowed" key.
There are a few added restrictions on the packages, mostly to simplify the logic for areas that aren't critical to main package use cases:
- No package can have conflicts, i.e. none of them can spend the same inputs, even if it would be a valid BIP125 replacement.
- The package cannot conflict with the mempool, i.e. RBF is disabled.
- The total count of the package cannot exceed 25 (the default descendant count limit), and total size cannot exceed 101KvB (the default descendant size limit).
If you're looking for review comments and github isn't loading them, I have a gist compiling some topics of discussion [here](https://gist.github.com/glozow/c3acaf161c95bba491fce31585b2aaf7)
ACKs for top commit:
laanwj:
Code review re-ACK 13650fe2e5
jnewbery:
Code review ACK 13650fe2e5
ariard:
ACK 13650fe
Tree-SHA512: 8c5cbfa91a6c714e1c8710bb281d5ff1c5af36741872a7c5df6b24874d6272b4a09f816cb8a4c7de33ef8e1c2a2c252c0df5105b7802f70bc6ff821ed7cc1a2f
Maximum number of transactions allowed in a package is 25, equal to the
default mempool descendant limit: if a package has more transactions
than this, either it would fail default mempool descendant limit or the
transactions don't all have a dependency relationship (but then they
shouldn't be in a package together). Same rationale for 101KvB virtual
size package limit.
Note that these policies are only used in test accepts so far.
Only allow test accepts for now. Use the CoinsViewTemporary to keep
track of coins created by each transaction so that subsequent
transactions can spend them. Uncache all coins since we only
ever do test accepts (Note this is different from ATMP which doesn't
uncache for valid test_accepts) to minimize impact on the coins cache.
Require that the input txns have no conflicts and be ordered
topologically. This commit isn't able to detect unsorted packages.
Allow CheckSequenceLocks to use heights and coins from any CoinsView and
CBlockIndex provided. This means that CheckSequenceLocks() doesn't need
to hold the mempool lock or cs_main. The caller is responsible for
ensuring the CoinsView and CBlockIndex are consistent before passing
them in. The typical usage is still to create a CCoinsViewMemPool from
the mempool and grab the CBlockIndex from the chainstate tip.
