Method UpdateForRemoveFromMempool

src/txmempool.cpp:398–457

}

void CTxMemPool::UpdateForRemoveFromMempool(const setEntries &entriesToRemove, bool updateDescendants)
{
    // For each entry, walk back all ancestors and decrement size associated with this
    // transaction
    const uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
    if (updateDescendants) {
        // updateDescendants should be true whenever we're not recursively
        // removing a tx and all its descendants, eg when a transaction is
        // confirmed in a block.
        // Here we only update statistics and not data in CTxMemPool::Parents
        // and CTxMemPoolEntry::Children (which we need to preserve until we're
        // finished with all operations that need to traverse the mempool).
        for (txiter removeIt : entriesToRemove) {
            setEntries setDescendants;
            CalculateDescendants(removeIt, setDescendants);
            setDescendants.erase(removeIt); // don't update state for self
            int64_t modifySize = -((int64_t)removeIt->GetTxSize());
            CAmount modifyFee = -removeIt->GetModifiedFee();
            int modifySigOps = -removeIt->GetSigOpCost();
            int64_t discountSize = -((int64_t)removeIt->GetDiscountTxSize());
            for (txiter dit : setDescendants) {
                mapTx.modify(dit, update_ancestor_state(modifySize, modifyFee, -1, modifySigOps, discountSize));
            }
        }
    }
    for (txiter removeIt : entriesToRemove) {
        setEntries setAncestors;
        const CTxMemPoolEntry &entry = *removeIt;
        std::string dummy;
        // Since this is a tx that is already in the mempool, we can call CMPA
        // with fSearchForParents = false.  If the mempool is in a consistent
        // state, then using true or false should both be correct, though false
        // should be a bit faster.
        // However, if we happen to be in the middle of processing a reorg, then
        // the mempool can be in an inconsistent state.  In this case, the set
        // of ancestors reachable via GetMemPoolParents()/GetMemPoolChildren()
        // will be the same as the set of ancestors whose packages include this
        // transaction, because when we add a new transaction to the mempool in
        // addUnchecked(), we assume it has no children, and in the case of a
        // reorg where that assumption is false, the in-mempool children aren't
        // linked to the in-block tx's until UpdateTransactionsFromBlock() is
        // called.
        // So if we're being called during a reorg, ie before
        // UpdateTransactionsFromBlock() has been called, then
        // GetMemPoolParents()/GetMemPoolChildren() will differ from the set of
        // mempool parents we'd calculate by searching, and it's important that
        // we use the cached notion of ancestor transactions as the set of
        // things to update for removal.
        CalculateMemPoolAncestors(entry, setAncestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
        // Note that UpdateAncestorsOf severs the child links that point to
        // removeIt in the entries for the parents of removeIt.
        UpdateAncestorsOf(false, removeIt, setAncestors);
    }
    // After updating all the ancestor sizes, we can now sever the link between each
    // transaction being removed and any mempool children (ie, update CTxMemPoolEntry::m_parents
    // for each direct child of a transaction being removed).
    for (txiter removeIt : entriesToRemove) {
        UpdateChildrenForRemoval(removeIt);