This fork never ported Bitcoin's mempool size-limiting: CTxMemPool had no TrimToSize/
Expire and LimitMempoolSize was commented out. An earlier commit added a blunt
DynamicMemoryUsage admission cap that bounded memory but bluntly REJECTED new txs when
full -- so a high-fee tx could not push out a low-fee one. This implements proper
fee-ordered eviction using the per-tx feerate index that already exists (mapTx index 1,
CompareTxMemPoolEntryByFee), with no new index and no descendant-tracking port.
- CTxMemPool::TrimToSize(sizelimit, pvNoSpendsRemaining): while DynamicMemoryUsage() is
over the limit, evict the lowest-feerate tx (the tail of the feerate index) and its
in-mempool descendants (recursive remove), re-deriving the tail each iteration.
Terminates (pool strictly shrinks) and cleans every secondary index via remove().
- CTxMemPool::Expire(time): age-based sweep (entry time older than `time`), for
LimitMempoolSize's -mempoolexpiry.
- LimitMempoolSize re-enabled (Expire + TrimToSize) and called from ConnectTip on every
block connect. (No pcoinsTip->Uncache -- CCoinsViewCache has none in this fork; it is
only a UTXO-cache perf hint.)
- AcceptToMemoryPool now ADDS the tx then TrimToSizes: a higher-fee tx displaces
lower-fee ones; if this tx was itself the lowest-feerate (evicted), it is rejected
("mempool full"). Replaces the blunt reject-when-full cap.
- DEFAULT_MEMPOOL_EXPIRY 1 -> 72 hours (age-Expire is now live; 1h was too aggressive).
Known simplification (documented in code): per-tx feerate, not descendant-aggregate
(CPFP) scoring, and no rollingMinimumFeeRate anti-thrash. Adversarially reviewed
(termination, iterator safety, recursive-lock safety, index cleanup all confirmed) and
runtime-tested on the fleet: pool stays bounded under a 1600-tx flood, verifychain ok,
no hang/crash.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
CTxMemPool::removeExpired() declared `transactionsToRemove` and looped over it
without ever populating it -- the mapTx scan that collects expired txs had been
dropped, so it evicted nothing. Expired txs (past nExpiryHeight) can never be mined
yet were never removed, so a peer could wedge them into every node's mempool
permanently at ~zero cost (never mined -> never pay a fee), growing the mempool
without bound: a memory-exhaustion DoS against every node (incl. pool/payout nodes).
Restore the upstream Zcash/Komodo scan: iterate mapTx, collect txs failing
IsExpiredTx(tx, tipHeight) into a separate list, then remove() them (collect-then-
remove avoids iterator invalidation; recursive=true also evicts the now-unmineable
descendants). Also drops an unused CBlockIndex* local.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Any projects which want to use Hush code from now on will need to be licensed as
GPLv3 or we will send the lawyers: https://www.softwarefreedom.org/
Notably, Komodo (KMD) is licensed as GPLv2 and is no longer compatible to receive
code changes, without causing legal issues. MIT projects, such as Zcash, also cannot pull
in changes from the Hush Full Node without permission from The Hush Developers,
which may in some circumstances grant an MIT license on a case-by-case basis.
In CreateNewBlock of miner https://github.com/KomodoPlatform/komodo/blob/master/src/miner.cpp#L331
we have a condition that prevents miners to include certain txes in
block if tx violates komodo_validate_interest check. so, if such txes
will exist in mempool and in some reason they was not miner earlier, if
they have nExpiryHeight = 0 - they NEVER will be included in block by miners.
Also, code in CTxMemPool::removeExpired that should remove such txes
from mempool didn't do it due to mistake. As a result these txes
stucks in mempool. No one can mine it, bcz no one can include it in block,
and no one get success to remove it from mempool.
Look on old code:
```
(ASSETCHAINS_SYMBOL[0] == 0
&& tipindex != 0 && komodo_validate_interest(...) ) < 0
```
But should be:
```
(ASSETCHAINS_SYMBOL[0] == 0
&& tipindex != 0 && komodo_validate_interest(...) < 0 )
```
Bcz we should compare with 0 result of komodo_validate_interest, but we
had different behaviour, due to typo.
