Method ReplacementChecks

src/validation.cpp:999–1043

}

bool MemPoolAccept::ReplacementChecks(Workspace& ws)
{
    AssertLockHeld(cs_main);
    AssertLockHeld(m_pool.cs);

    const CTransaction& tx = *ws.m_ptx;
    const uint256& hash = ws.m_hash;
    TxValidationState& state = ws.m_state;

    CFeeRate newFeeRate(ws.m_modified_fees, ws.m_vsize);
    // The replacement transaction must have a higher feerate than its direct conflicts.
    // - The motivation for this check is to ensure that the replacement transaction is preferable for
    //   block-inclusion, compared to what would be removed from the mempool.
    // - This logic predates ancestor feerate-based transaction selection, which is why it doesn't
    //   consider feerates of descendants.
    // - Note: Ancestor feerate-based transaction selection has made this comparison insufficient to
    //   guarantee that this is incentive-compatible for miners, because it is possible for a
    //   descendant transaction of a direct conflict to pay a higher feerate than the transaction that
    //   might replace them, under these rules.
    if (const auto err_string{PaysMoreThanConflicts(ws.m_iters_conflicting, newFeeRate, hash)}) {
        return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "insufficient fee", *err_string);
    }

    // Calculate all conflicting entries and enforce BIP125 Rule #5.
    if (const auto err_string{GetEntriesForConflicts(tx, m_pool, ws.m_iters_conflicting, ws.m_all_conflicting)}) {
        return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY,
                             "too many potential replacements", *err_string);
    }
    // Enforce BIP125 Rule #2.
    if (const auto err_string{HasNoNewUnconfirmed(tx, m_pool, ws.m_iters_conflicting)}) {
        return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY,
                             "replacement-adds-unconfirmed", *err_string);
    }
    // Check if it's economically rational to mine this transaction rather than the ones it
    // replaces and pays for its own relay fees. Enforce BIP125 Rules #3 and #4.
    for (CTxMemPool::txiter it : ws.m_all_conflicting) {
        ws.m_conflicting_fees += it->GetModifiedFee();
        ws.m_conflicting_size += it->GetTxSize();
    }
    if (const auto err_string{PaysForRBF(ws.m_conflicting_fees, ws.m_modified_fees, ws.m_vsize,
                                         ::incrementalRelayFee, hash)}) {
        return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "insufficient fee", *err_string);
    }
    return true;
}

bool MemPoolAccept::PackageMempoolChecks(const std::vector<CTransactionRef>& txns,
                                         PackageValidationState& package_state)