void BlockAssembler::SortForBlock(const CTxMemPool::setEntries& package, CTxMemPool::txiter entry, std::vector<CTxMemPool::txiter>& sortedEntries)
{
    // Sort package by ancestor count
    // If a transaction A depends on transaction B, then A's ancestor count
    // must be greater than B's.  So this is sufficient to validly order the
    // transactions for block inclusion.
    sortedEntries.clear();
    sortedEntries.insert(sortedEntries.begin(), package.begin(), package.end());
    std::sort(sortedEntries.begin(), sortedEntries.end(), CompareTxIterByAncestorCount());
}

void BlockAssembler::onlyUnconfirmed(CTxMemPool::setEntries& testSet)
{
    for (CTxMemPool::setEntries::iterator iit = testSet.begin(); iit != testSet.end(); ) {
        // Only test txs not already in the block
        if (inBlock.count(*iit)) {
            testSet.erase(iit++);
        }
        else {
            iit++;
        }
    }
}

int BlockAssembler::UpdatePackagesForAdded(const CTxMemPool::setEntries& alreadyAdded,
        indexed_modified_transaction_set &mapModifiedTx)
{
    int nDescendantsUpdated = 0;
    for (const CTxMemPool::txiter it : alreadyAdded) {
        CTxMemPool::setEntries descendants;
        mempool.CalculateDescendants(it, descendants);
        // Insert all descendants (not yet in block) into the modified set
        for (CTxMemPool::txiter desc : descendants) {
            if (alreadyAdded.count(desc))
                continue;
            ++nDescendantsUpdated;
            modtxiter mit = mapModifiedTx.find(desc);
            if (mit == mapModifiedTx.end()) {
                CTxMemPoolModifiedEntry modEntry(desc);
                modEntry.nSizeWithAncestors -= it->GetTxSize();
                modEntry.nModFeesWithAncestors -= it->GetModifiedFee();
                modEntry.nSigOpCostWithAncestors -= it->GetSigOpCost();
                mapModifiedTx.insert(modEntry);
            } else {
                mapModifiedTx.modify(mit, update_for_parent_inclusion(it));
            }
        }
    }
    return nDescendantsUpdated;
}

// This transaction selection algorithm orders the mempool based
// on feerate of a transaction including all unconfirmed ancestors.
// Since we don't remove transactions from the mempool as we select them
// for block inclusion, we need an alternate method of updating the feerate
// of a transaction with its not-yet-selected ancestors as we go.
// This is accomplished by walking the in-mempool descendants of selected
// transactions and storing a temporary modified state in mapModifiedTxs.
// Each time through the loop, we compare the best transaction in
// mapModifiedTxs with the next transaction in the mempool to decide what
// transaction package to work on next.
void BlockAssembler::addPackageTxs(int &nPackagesSelected, int &nDescendantsUpdated)
{
    // mapModifiedTx will store sorted packages after they are modified
    // because some of their txs are already in the block
    indexed_modified_transaction_set mapModifiedTx;
    // Keep track of entries that failed inclusion, to avoid duplicate work
    CTxMemPool::setEntries failedTx;

    // Start by adding all descendants of previously added txs to mapModifiedTx
    // and modifying them for their already included ancestors
    UpdatePackagesForAdded(inBlock, mapModifiedTx);

    CTxMemPool::indexed_transaction_set::index<ancestor_score>::type::iterator mi = mempool.mapTx.get<ancestor_score>().begin();
    CTxMemPool::txiter iter;

    // Limit the number of attempts to add transactions to the block when it is
    // close to full; this is just a simple heuristic to finish quickly if the
    // mempool has a lot of entries.
    const int64_t MAX_CONSECUTIVE_FAILURES = 1000;
    int64_t nConsecutiveFailed = 0;

    while (mi != mempool.mapTx.get<ancestor_score>().end() || !mapModifiedTx.empty())
    {
        // First try to find a new transaction in mapTx to evaluate.
        if (mi != mempool.mapTx.get<ancestor_score>().end() &&
                SkipMapTxEntry(mempool.mapTx.project<0>(mi), mapModifiedTx, failedTx)) {
            ++mi;
            continue;
        }

        // Now that mi is not stale, determine which transaction to evaluate:
        // the next entry from mapTx, or the best from mapModifiedTx?
        bool fUsingModified = false;

        modtxscoreiter modit = mapModifiedTx.get<ancestor_score>().begin();
        if (mi == mempool.mapTx.get<ancestor_score>().end()) {
            // We're out of entries in mapTx; use the entry from mapModifiedTx
            iter = modit->iter;
            fUsingModified = true;
        } else {
            // Try to compare the mapTx entry to the mapModifiedTx entry
            iter = mempool.mapTx.project<0>(mi);
            if (modit != mapModifiedTx.get<ancestor_score>().end() &&
                    CompareModifiedEntry()(*modit, CTxMemPoolModifiedEntry(iter))) {
                // The best entry in mapModifiedTx has higher score
                // than the one from mapTx.
                // Switch which transaction (package) to consider
                iter = modit->iter;
                fUsingModified = true;
            } else {
                // Either no entry in mapModifiedTx, or it's worse than mapTx.
                // Increment mi for the next loop iteration.
                ++mi;
            }
        }

        // We skip mapTx entries that are inBlock, and mapModifiedTx shouldn't
        // contain anything that is inBlock.
        assert(!inBlock.count(iter));

        uint64_t packageSize = iter->GetSizeWithAncestors();
        CAmount packageFees = iter->GetModFeesWithAncestors();
        int64_t packageSigOpsCost = iter->GetSigOpCostWithAncestors();
        if (fUsingModified) {
            packageSize = modit->nSizeWithAncestors;
            packageFees = modit->nModFeesWithAncestors;
            packageSigOpsCost = modit->nSigOpCostWithAncestors;
        }

        if (packageFees < blockMinFeeRate.GetFee(packageSize)) {
            // Everything else we might consider has a lower fee rate
            return;
        }

        if (!TestPackage(packageSize, packageSigOpsCost)) {
            if (fUsingModified) {
                // Since we always look at the best entry in mapModifiedTx,
                // we must erase failed entries so that we can consider the
                // next best entry on the next loop iteration
                mapModifiedTx.get<ancestor_score>().erase(modit);
                failedTx.insert(iter);
            }

            ++nConsecutiveFailed;

            if (nConsecutiveFailed > MAX_CONSECUTIVE_FAILURES && nBlockWeight >
                    nBlockMaxWeight - 4000) {
                // Give up if we're close to full and haven't succeeded in a while
                break;
            }
//.........这里部分代码省略.........

// Skip entries in mapTx that are already in a block or are present
// in mapModifiedTx (which implies that the mapTx ancestor state is
// stale due to ancestor inclusion in the block)
// Also skip transactions that we've already failed to add. This can happen if
// we consider a transaction in mapModifiedTx and it fails: we can then
// potentially consider it again while walking mapTx.  It's currently
// guaranteed to fail again, but as a belt-and-suspenders check we put it in
// failedTx and avoid re-evaluation, since the re-evaluation would be using
// cached size/sigops/fee values that are not actually correct.
bool BlockAssembler::SkipMapTxEntry(CTxMemPool::txiter it, indexed_modified_transaction_set &mapModifiedTx, CTxMemPool::setEntries &failedTx)
{
    assert (it != mempool.mapTx.end());
    return mapModifiedTx.count(it) || inBlock.count(it) || failedTx.count(it);
}

void CTxMemPool::check(const CCoinsViewCache *pcoins) const
{
    LOCK(cs);
    if (nCheckFrequency == 0)
        return;

    if (GetRand(std::numeric_limits<uint32_t>::max()) >= nCheckFrequency)
        return;

    LogPrint(BCLog::MEMPOOL, "Checking mempool with %u transactions and %u inputs\n", (unsigned int)mapTx.size(), (unsigned int)mapNextTx.size());

    uint64_t checkTotal = 0;
    uint64_t innerUsage = 0;

    CCoinsViewCache mempoolDuplicate(const_cast<CCoinsViewCache*>(pcoins));
    const int64_t spendheight = GetSpendHeight(mempoolDuplicate);

    std::list<const CTxMemPoolEntry*> waitingOnDependants;
    for (indexed_transaction_set::const_iterator it = mapTx.begin(); it != mapTx.end(); it++) {
        unsigned int i = 0;
        checkTotal += it->GetTxSize();
        innerUsage += it->DynamicMemoryUsage();
        const CTransaction& tx = it->GetTx();
        txlinksMap::const_iterator linksiter = mapLinks.find(it);
        assert(linksiter != mapLinks.end());
        const TxLinks &links = linksiter->second;
        innerUsage += memusage::DynamicUsage(links.parents) + memusage::DynamicUsage(links.children);
        bool fDependsWait = false;
        setEntries setParentCheck;
        int64_t parentSizes = 0;
        int64_t parentSigOpCost = 0;
        for (const CTxIn &txin : tx.vin) {
            // Check that every mempool transaction's inputs refer to available coins, or other mempool tx's.
            indexed_transaction_set::const_iterator it2 = mapTx.find(txin.prevout.hash);
            if (it2 != mapTx.end()) {
                const CTransaction& tx2 = it2->GetTx();
                assert(tx2.vout.size() > txin.prevout.n && !tx2.vout[txin.prevout.n].IsNull());
                fDependsWait = true;
                if (setParentCheck.insert(it2).second) {
                    parentSizes += it2->GetTxSize();
                    parentSigOpCost += it2->GetSigOpCost();
                }
            } else {
                assert(pcoins->HaveCoin(txin.prevout));
            }
            // Check whether its inputs are marked in mapNextTx.
            auto it3 = mapNextTx.find(txin.prevout);
            assert(it3 != mapNextTx.end());
            assert(it3->first == &txin.prevout);
            assert(it3->second == &tx);
            i++;
        }
        assert(setParentCheck == GetMemPoolParents(it));
        // Verify ancestor state is correct.
        setEntries setAncestors;
        uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
        std::string dummy;
        CalculateMemPoolAncestors(*it, setAncestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy);
        uint64_t nCountCheck = setAncestors.size() + 1;
        uint64_t nSizeCheck = it->GetTxSize();
        CAmount nFeesCheck = it->GetModifiedFee();
        int64_t nSigOpCheck = it->GetSigOpCost();

        for (txiter ancestorIt : setAncestors) {
            nSizeCheck += ancestorIt->GetTxSize();
            nFeesCheck += ancestorIt->GetModifiedFee();
            nSigOpCheck += ancestorIt->GetSigOpCost();
        }

        assert(it->GetCountWithAncestors() == nCountCheck);
        assert(it->GetSizeWithAncestors() == nSizeCheck);
        assert(it->GetSigOpCostWithAncestors() == nSigOpCheck);
        assert(it->GetModFeesWithAncestors() == nFeesCheck);

        // Check children against mapNextTx
        CTxMemPool::setEntries setChildrenCheck;
        auto iter = mapNextTx.lower_bound(COutPoint(it->GetTx().GetHash(), 0));
        int64_t childSizes = 0;
        for (; iter != mapNextTx.end() && iter->first->hash == it->GetTx().GetHash(); ++iter) {
            txiter childit = mapTx.find(iter->second->GetHash());
            assert(childit != mapTx.end()); // mapNextTx points to in-mempool transactions
            if (setChildrenCheck.insert(childit).second) {
                childSizes += childit->GetTxSize();
            }
        }
        assert(setChildrenCheck == GetMemPoolChildren(it));
        // Also check to make sure size is greater than sum with immediate children.
        // just a sanity check, not definitive that this calc is correct...
        assert(it->GetSizeWithDescendants() >= childSizes + it->GetTxSize());

        if (fDependsWait)
            waitingOnDependants.push_back(&(*it));
        else {
            CheckInputsAndUpdateCoins(tx, mempoolDuplicate, spendheight);
        }
    }
    unsigned int stepsSinceLastRemove = 0;
    while (!waitingOnDependants.empty()) {
        const CTxMemPoolEntry* entry = waitingOnDependants.front();
        waitingOnDependants.pop_front();
//.........这里部分代码省略.........