d104aa0ace
a029e18c2bf67dd00552b0f4bbc85fa2fa5b973b Use rolling bloom filter of recent block tx's for AlreadyHave() check (Suhas Daftuar)
Pull request description:
In order to determine whether to download or process a relayed transaction, we first try to check whether we already have the transaction -- either in the mempool, in our filter of recently rejected transactions, in our orphan pool, or already confirmed in a block.
Prior to this commit, the heuristic for checking whether a transaction was confirmed in a block is based on whether there's a coin cache entry corresponding to the 0- or 1-index vout of the tx. While that is a quick check, it is very imprecise (eg if those outputs were already spent in another block, we wouldn't detect that the transaction has already been confirmed) -- we can do better by just keeping a rolling bloom filter of the transactions in recent blocks, which will better capture the case of a transaction which has been confirmed and then fully spent.
This should reduce the bandwidth that we waste by requesting transactions which will not be accepted to the mempool.
To avoid relay problems for transactions which have been included in a recent block but then reorged out of the chain, we clear the bloom filter whenever a block is disconnected.
ACKs for top commit:
MarcoFalke:
re-ACK a029e18c2b only stylistic and comment fixups 🍴
sipa:
utACK a029e18c2bf67dd00552b0f4bbc85fa2fa5b973b
jonatack:
Code review ACK a029e18c2bf67dd00552b0f4bbc85fa2fa5b973b also built/ran tests and am running bitcoind with mempool debug logging and custom logging. Looked a bit into CRollingBloomFilter and also the mempool median time past checks mentioned above; I don't have a deep understanding of those areas yet but the concept here and changes LGTM. Tests and other optimisations could be added as a follow-up. In favor of seeing this move forward if no major immediate concerns.
Tree-SHA512: 784c9a35bcd3af5db469063ac7d26b4bac430e451e5637a34d8a538c3ffd1433abdd3f06e5584e7a84bfa9e791449e61819397b5a6c7890fa59d78ec3ba507b2
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