This is a documentation-only change following up on suggestions made in the
#30526 review.
Motivation for this change is that I was recently reviewing #31583, which
reminded me how confusing the arithmetic blob code was and made me want to
write better comments.
Also known as Ephemeral Dust.
We try to ensure that dust is spent in blocks by requiring:
- ephemeral dust tx is 0-fee
- ephemeral dust tx only has one dust output
- If the ephemeral dust transaction has a child,
the dust is spent by by that child.
0-fee requirement means there is no incentive to mine
a transaction which doesn't have a child bringing its
own fees for the transaction package.
Also, remove not needed and possibly redundant function name and class
names from the log string. Also, minimally reword the log messages.
Also, remove redundant trailing newlines from log messages, while
touching.
There is no need to compare the field to CLIENT_VERSION. Either the
format remains compatible and the value can be left unchanged, or it is
incompatible and the value needs to be increased to at least 289900+1.
Keep mentions of v3 in debug strings to help people who might not know
that TRUC is applied when version=3.
Also keep variable names in tests, as it is less verbose to keep v3 and v2.
94ed4fbf8e Add release note for size 2 package rbf (Greg Sanders)
afd52d8e63 doc: update package RBF comment (Greg Sanders)
6e3c4394cf mempool: Improve logging of replaced transactions (Greg Sanders)
d3466e4cc5 CheckPackageMempoolAcceptResult: Check package rbf invariants (Greg Sanders)
316d7b63c9 Fuzz: pass mempool to CheckPackageMempoolAcceptResult (Greg Sanders)
4d15bcf448 [test] package rbf (glozow)
dc21f61c72 [policy] package rbf (Suhas Daftuar)
5da3967815 PackageV3Checks: Relax assumptions (Greg Sanders)
Pull request description:
Allows any 2 transaction package with no in-mempool ancestors to do package RBF when directly conflicting with other mempool clusters of size two or less.
Proposed validation steps:
1) If the transaction package is of size 1, legacy rbf rules apply.
2) Otherwise the transaction package consists of a (parent, child) pair with no other in-mempool ancestors (or descendants, obviously), so it is also going to create a cluster of size 2. If larger, fail.
3) The package rbf may not evict more than 100 transactions from the mempool(bip125 rule 5)
4) The package is a single chunk
5) Every directly conflicted mempool transaction is connected to at most 1 other in-mempool transaction (ie the cluster size of the conflict is at most 2).
6) Diagram check: We ensure that the replacement is strictly superior, improving the mempool
7) The total fee of the package, minus the total fee of what is being evicted, is at least the minrelayfee * size of the package (equivalent to bip125 rule 3 and 4)
Post-cluster mempool this will likely be expanded to general package rbf, but this is what we can safely support today.
ACKs for top commit:
achow101:
ACK 94ed4fbf8e
glozow:
reACK 94ed4fbf8e via range-diff
ismaelsadeeq:
re-ACK 94ed4fbf8e
theStack:
Code-review ACK 94ed4fbf8e
murchandamus:
utACK 94ed4fbf8e
Tree-SHA512: 9bd383e695964f362f147482bbf73b1e77c4d792bda2e91d7f30d74b3540a09146a5528baf86854a113005581e8c75f04737302517b7d5124296bd7a151e3992
Relax assumptions about in-mempool children of in-mempool
parents. With package RBF, we will allow a package of size
2 with conflicts on its parent and reconsider the parent
if its fee is insufficient on its own.
Consider:
TxA (in mempool) <- TxB (in mempool)
TxA (in mempool) <- TxB' (in package, conflicts with TxB) <-
TxC (in package)
If TxB' fails to RBF TxB due to insufficient feerate, the
package TxB' + TxC will be considered. PackageV3Checks
called on TxB' will see an in-mempool parent TxA, and
see the in-mempool child TxB. We cannot assume there is
no in-mempool sibling, rather detect it and fail normally.
Prior to package RBF, this would have failed on the first
conflict in package.
In order to ensure that the change of nVersion to a uint32_t in the
previous commit has no effect, rename nVersion to version in this commit
so that reviewers can easily spot if a spot was missed or if there is a
check somewhere whose semantics have changed.
154b2b2296 [fuzz] V3_MAX_VSIZE and effective ancestor/descendant size limits (glozow)
a29f1df289 [policy] restrict all v3 transactions to 10kvB (glozow)
d578e2e354 [policy] explicitly require non-v3 for CPFP carve out (glozow)
Pull request description:
Opening for discussion / conceptual review.
We like the idea of a smaller maximum transaction size because:
- It lowers potential replacement cost (i.e. harder to do Rule 3 pinning via gigantic transaction)
- They are easier to bin-pack in block template production
- They equate to a tighter memory limit in data structures that are bounded by a number of transactions (e.g. orphanage and vExtraTxnForCompact). For example, the current memory bounds for orphanage is 100KvB * 100 = 40MB, and guaranteeing 1 tx per peer would require reserving a pretty large space.
History for `MAX_STANDARD_TX_WEIGHT=100KvB` (copied from https://github.com/bitcoin/bitcoin/pull/29873#issuecomment-2115459510):
- 2010-09-13 In 3df62878c3 satoshi added a 100kB (MAX_BLOCK_SIZE_GEN/5 with MBS_GEN = MAX_BLOCK_SIZE/2) limit on new transactions in CreateTransaction()
- 2013-02-04 https://github.com/bitcoin/bitcoin/pull/2273 In gavin gave that constant a name, and made it apply to transaction relay as well
Lowering `MAX_STANDARD_TX_WEIGHT` for all txns is not being proposed, as there are existing apps/protocols that rely on large transactions. However, it's been brought up that we should consider this for TRUCs (which is especially designed to avoid Rule 3 pinning).
This reduction should be ok because using nVersion=3 isn't standard yet, so this wouldn't break somebody's existing use case. If we find that this is too small, we can always increase it later. Decreasing would be much more difficult.
~[Expected size of a commitment transaction](https://github.com/lightning/bolts/blob/master/03-transactions.md#expected-weight-of-the-commitment-transaction) is within (900 + 172 * 483 + 224) / 4 = 21050vB~ EDIT: this is incorrect, but perhaps not something that should affect how we choose this number.
ACKs for top commit:
sdaftuar:
ACK 154b2b2296
achow101:
ACK 154b2b2296
instagibbs:
ACK 154b2b2296
t-bast:
ACK 154b2b2296
murchandamus:
crACK 154b2b2296
Tree-SHA512: 89392a460908a8ea9f547d90e00f5181de0eaa9d2c4f2766140a91294ade3229b3d181833cad9afc93a0d0e8c4b96ee2f5aeda7c50ad7e6f3a8320b9e0c5ae97
ffc674595c Replace remaining "520" magic numbers with MAX_SCRIPT_ELEMENT_SIZE (Jon Atack)
Pull request description:
Noticed these while reviewing BIPs yesterday.
It would be clearer and more future-proof to refer to their constant name.
ACKs for top commit:
instagibbs:
ACK ffc674595c
sipa:
ACK ffc674595c
achow101:
ACK ffc674595c
glozow:
ACK ffc674595c, agree it's clearer for these comments to refer to the greppable name of the limit rather than the number
Tree-SHA512: 462afc1c64543877ac58cb3acdb01d42c6d08abfb362802f29f3482d75401a2a8adadbc2facd222a9a9fefcaab6854865ea400f50ad60bec17831d29f7798afe
e518a8bf8a [functional test] opportunistic 1p1c package submission (glozow)
87c5c524d6 [p2p] opportunistically accept 1-parent-1-child packages (glozow)
6c51e1d7d0 [p2p] add separate rejections cache for reconsiderable txns (glozow)
410ebd6efa [fuzz] break out parent functions and add GetChildrenFrom* coverage (glozow)
d095316c1c [unit test] TxOrphanage::GetChildrenFrom* (glozow)
2f51cd680f [txorphanage] add method to get all orphans spending a tx (glozow)
092c978a42 [txpackages] add canonical way to get hash of package (glozow)
c3c1e15831 [doc] restore comment about why we check if ptx HasWitness before caching rejected txid (glozow)
6f4da19cc3 guard against MempoolAcceptResult::m_replaced_transactions (glozow)
Pull request description:
This enables 1p1c packages to propagate in the "happy case" (i.e. not reliable if there are adversaries) and contains a lot of package relay-related code. See https://github.com/bitcoin/bitcoin/issues/27463 for overall package relay tracking.
Rationale: This is "non-robust 1-parent-1-child package relay" which is immediately useful.
- Relaying 1-parent-1-child CPFP when mempool min feerate is high would be a subset of all package relay use cases, but a pretty significant improvement over what we have today, where such transactions don't propagate at all. [1]
- Today, a miner can run this with a normal/small maxmempool to get revenue from 1p1c CPFP'd transactions without losing out on the ones with parents below mempool minimum feerate.
- The majority of this code is useful for building more featureful/robust package relay e.g. see the code in #27742.
The first 2 commits are followups from #29619:
- https://github.com/bitcoin/bitcoin/pull/29619#discussion_r1523094034
- https://github.com/bitcoin/bitcoin/pull/29619#discussion_r1519819257
Q: What makes this short of a more full package relay feature?
(1) it only supports packages in which 1 of the parents needs to be CPFP'd by the child. That includes 1-parent-1-child packages and situations in which the other parents already pay for themselves (and are thus in mempool already when the package is submitted). More general package relay is a future improvement that requires more engineering in mempool and validation - see #27463.
(2) We rely on having kept the child in orphanage, and don't make any attempt to protect it while we wait to receive the parent. If we are experiencing a lot of orphanage churn (e.g. an adversary is purposefully sending us a lot of transactions with missing inputs), we will fail to submit packages. This limitation has been around for 12+ years, see #27742 which adds a token bucket scheme for protecting package-related orphans at a limited rate per peer.
(3) Our orphan-handling logic is somewhat opportunistic; we don't make much effort to resolve an orphan beyond asking the child's sender for the parents. This means we may miss packages if the first sender fails to give us the parent (intentionally or unintentionally). To make this more robust, we need receiver-side logic to retry orphan resolution with multiple peers. This is also an existing problem which has a proposed solution in #28031.
[1]: see this writeup and its links 02ec218c78/bip-0331.mediawiki (propagate-high-feerate-transactions)
ACKs for top commit:
sr-gi:
tACK e518a8bf8a
instagibbs:
reACK e518a8bf8a
theStack:
Code-review ACK e518a8bf8a📦
dergoegge:
light Code review ACK e518a8bf8a
achow101:
ACK e518a8bf8a
Tree-SHA512: 632579fbe7160cb763bbec6d82ca0dab484d5dbbc7aea90c187c0b9833b8d7c1e5d13b8587379edd3a3b4a02a5a1809020369e9cd09a4ebaf729921f65c15943
7295986778 Unit tests for CalculateFeerateDiagramsForRBF (Greg Sanders)
b767e6bd47 test: unit test for ImprovesFeerateDiagram (Greg Sanders)
7e89b659e1 Add fuzz test for FeeFrac (Greg Sanders)
4d6528a3d6 fuzz: fuzz diagram creation and comparison (Greg Sanders)
e9c5aeb11d test: Add tests for CompareFeerateDiagram and CheckConflictTopology (Greg Sanders)
588a98dccc fuzz: Add fuzz target for ImprovesFeerateDiagram (Greg Sanders)
2079b80854 Implement ImprovesFeerateDiagram (Greg Sanders)
66d966dcfa Add FeeFrac unit tests (Greg Sanders)
ce8e22542e Add FeeFrac utils (Greg Sanders)
Pull request description:
This is a smaller piece of https://github.com/bitcoin/bitcoin/pull/28984 broken off for easier review.
Up to date explanation of diagram checks are here: https://delvingbitcoin.org/t/mempool-incentive-compatibility/553
This infrastructure has two near term applications prior to cluster mempool:
1) Limited Package RBF(https://github.com/bitcoin/bitcoin/pull/28984): We want to allow package RBF only when we know it improves the mempool. This narrowly scoped functionality allows use with v3-like topologies, and will be expanded at some point post-cluster mempool when diagram checks can be done efficiently against bounded cluster sizes.
2) Replacement for single tx RBF(in a cluster size of up to two) against conflicts of up to cluster size two. `ImprovesFeerateDiagram` interface will have to change for this use-case, which is a future direction to solve certain pins and improve mempool incentive compatibility: https://delvingbitcoin.org/t/ephemeral-anchors-and-mev/383#diagram-checks-fix-this-3
And longer-term, this would be the proposed way we would compute incentive compatibility for all conflicts, post-cluster mempool.
ACKs for top commit:
sipa:
utACK 7295986778
glozow:
code review ACK 7295986778
murchandamus:
utACK 7295986778
ismaelsadeeq:
Re-ACK 7295986778
willcl-ark:
crACK 7295986778
sdaftuar:
ACK 7295986778
Tree-SHA512: 79593e5a087801c06f06cc8b73aa3e7b96ab938d3b90f5d229c4e4bfca887a77b447605c49aa5eb7ddcead85706c534ac5eb6146ae2396af678f4beaaa5bea8e
This new function takes the populated sets of
direct and all conflicts computed in the current
mempool, assuming the replacements are a single
chunk, and computes a diagram check.
The diagram check only works against cluster
sizes of 2 or less, and fails if it encounters
a different topology.
Co-authored-by: Suhas Daftuar <sdaftuar@chaincode.com>
29029df5c7 [doc] v3 signaling in mempool-replacements.md (glozow)
e643ea795e [fuzz] v3 transactions and sigop-adjusted vsize (glozow)
1fd16b5c62 [functional test] v3 transaction submission (glozow)
27c8786ba9 test framework: Add and use option for tx-version in MiniWallet methods (MarcoFalke)
9a1fea55b2 [policy/validation] allow v3 transactions with certain restrictions (glozow)
eb8d5a2e7d [policy] add v3 policy rules (glozow)
9a29d470fb [rpc] return full string for package_msg and package-error (glozow)
158623b8e0 [refactor] change Workspace::m_conflicts and adjacent funcs/structs to use Txid (glozow)
Pull request description:
See #27463 for overall package relay tracking.
Delving Bitcoin discussion thread: https://delvingbitcoin.org/t/v3-transaction-policy-for-anti-pinning/340
Delving Bitcoin discussion for LN usage: https://delvingbitcoin.org/t/lightning-transactions-with-v3-and-ephemeral-anchors/418
Rationale:
- There are various pinning problems with RBF and our general ancestor/descendant limits. These policies help mitigate many pinning attacks and make package RBF feasible (see #28984 which implements package RBF on top of this). I would focus the most here on Rule 3 pinning. [1][2]
- Switching to a cluster-based mempool (see #27677 and #28676) requires the removal of CPFP carve out, which applications depend on. V3 + package RBF + ephemeral anchors + 1-parent-1-child package relay provides an intermediate solution.
V3 policy is for "Priority Transactions." [3][4] It allows users to opt in to more restrictive topological limits for shared transactions, in exchange for the more robust fee-bumping abilities that offers. Even though we don't have cluster limits, we are able to treat these transactions as having as having a maximum cluster size of 2.
Immediate benefits:
- You can presign a transaction with 0 fees (not just 1sat/vB!) and add a fee-bump later.
- Rule 3 pinning is reduced by a significant amount, since the attacker can only attach a maximum of 1000vB to your shared transaction.
This also enables some other cool things (again see #27463 for overall roadmap):
- Ephemeral Anchors
- Package RBF for these 1-parent-1-child packages. That means e.g. a commitment tx + child can replace another commitment tx using the child's fees.
- We can transition to a "single anchor" universe without worrying about package limit pinning. So current users of CPFP carve out would have something else to use.
- We can switch to a cluster-based mempool [5] (#27677#28676), which removes CPFP carve out [6].
[1]: Original mailing list post and discussion about RBF pinning problems https://gist.github.com/glozow/25d9662c52453bd08b4b4b1d3783b9ff, https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-January/019817.html
[2]: A FAQ is "we need this for cluster mempool, but is this still necessary afterwards?" There are some pinning issues that are fixed here and not fully fixed in cluster mempool, so we will still want this or something similar afterward.
[3]: Mailing list post for v3 https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-September/020937.html
[4]: Original PR #25038 also contains a lot of the discussion
[5]: https://delvingbitcoin.org/t/an-overview-of-the-cluster-mempool-proposal/393/7
[6]: https://delvingbitcoin.org/t/an-overview-of-the-cluster-mempool-proposal/393#the-cpfp-carveout-rule-can-no-longer-be-supported-12
ACKs for top commit:
sdaftuar:
ACK 29029df5c7
achow101:
ACK 29029df5c7
instagibbs:
ACK 29029df5c7 modulo that
Tree-SHA512: 9664b078890cfdca2a146439f8835c9d9ab483f43b30af8c7cd6962f09aa557fb1ce7689d5e130a2ec142235dbc8f21213881baa75241c5881660f9008d68450
It's preferable to use type-safe transaction identifiers to avoid
confusing txid and wtxid. The next commit will add a reference to this
set; we use this opportunity to change it to Txid ahead of time instead
of adding new uses of uint256.
b1318dcc56 test: change `m_submitted_in_package` input to fuzz data provider boolean (ismaelsadeeq)
5615e16b70 tx fees: update `m_from_disconnected_block` to `m_mempool_limit_bypassed` (ismaelsadeeq)
fcd4296648 doc: fix typo and update incorrect comment (ismaelsadeeq)
562664d263 test: wait for fee estimator to catch up before estimating fees (ismaelsadeeq)
Pull request description:
This is a simple PR that does two things
1. Fixes #29000 by waiting for the fee estimator to catch up after `removeForBlock` calls before calling `estimateFee` in the `BlockPolicyEstimates` unit test.
2. Addressed some outstanding review comments from #28368
- Updated `NewMempoolTransactionInfo::m_from_disconnected_block` to `NewMempoolTransactionInfo::m_mempool_limit_bypassed` which now correctly indicates what the boolean does.
- Changed input of `processTransaction`'s tx_info `m_submitted_in_package` input from false to fuzz data provider boolean.
- Fixed some typos, and update incorrect comment
ACKs for top commit:
martinus:
re-ACK b1318dcc56
glozow:
utACK b1318dcc56
Tree-SHA512: 45268729bc044da4748fe004524e0df696d2ec92c5bd053db9aad6e15675f3838429b2a7b9061a6b694be4dc319d1782a876b44df506ddd439d62ad07252d0e1
