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Speed up RBF detection

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Mononaut 2023-08-04 19:11:49 +09:00
parent 9da9c2750d
commit 3ec676ca90
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GPG Key ID: A3F058E41374C04E
1 changed files with 36 additions and 3 deletions
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39
backend/src/api/common.ts
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@ -61,8 +61,10 @@ export class Common {
static findRbfTransactions(added: MempoolTransactionExtended[], deleted: MempoolTransactionExtended[]): { [txid: string]: MempoolTransactionExtended[] } {
const matches: { [txid: string]: MempoolTransactionExtended[] } = {};
added
.forEach((addedTx) => {
// For small N, a naive nested loop is extremely fast, but it doesn't scale
if (added.length < 1000 && deleted.length < 50) {
added.forEach((addedTx) => {
const foundMatches = deleted.filter((deletedTx) => {
// The new tx must, absolutely speaking, pay at least as much fee as the replaced tx.
return addedTx.fee > deletedTx.fee
@ -73,9 +75,40 @@ export class Common {
addedTx.vin.some((vin) => vin.txid === deletedVin.txid && vin.vout === deletedVin.vout));
});
if (foundMatches?.length) {
matches[addedTx.txid] = foundMatches;
matches[addedTx.txid] = [...new Set(foundMatches)];
}
});
} else {
// for large N, build a lookup table of prevouts we can check in ~constant time
const deletedSpendMap: { [txid: string]: { [vout: number]: MempoolTransactionExtended } } = {};
for (const tx of deleted) {
for (const vin of tx.vin) {
if (!deletedSpendMap[vin.txid]) {
deletedSpendMap[vin.txid] = {};
}
deletedSpendMap[vin.txid][vin.vout] = tx;
}
}
for (const addedTx of added) {
const foundMatches = new Set<MempoolTransactionExtended>();
for (const vin of addedTx.vin) {
const deletedTx = deletedSpendMap[vin.txid]?.[vin.vout];
if (deletedTx && deletedTx.txid !== addedTx.txid
// The new tx must, absolutely speaking, pay at least as much fee as the replaced tx.
&& addedTx.fee > deletedTx.fee
// The new transaction must pay more fee per kB than the replaced tx.
&& addedTx.adjustedFeePerVsize > deletedTx.adjustedFeePerVsize
) {
foundMatches.add(deletedTx);
}
if (foundMatches.size) {
matches[addedTx.txid] = [...foundMatches];
}
}
}
}
return matches;
}