LedgerMaster.cpp

#include <xrpld/app/consensus/RCLValidations.h>
#include <xrpld/app/ledger/LedgerMaster.h>
#include <xrpld/app/ledger/LedgerPersistence.h>
#include <xrpld/app/ledger/LedgerReplayer.h>
#include <xrpld/app/ledger/OpenLedger.h>
#include <xrpld/app/main/Application.h>
#include <xrpld/app/misc/SHAMapStore.h>
#include <xrpld/app/misc/Transaction.h>
#include <xrpld/app/misc/TxQ.h>
#include <xrpld/app/misc/ValidatorList.h>
#include <xrpld/core/TimeKeeper.h>
#include <xrpld/overlay/Overlay.h>
#include <xrpld/overlay/Peer.h>
#include <xrpld/rpc/detail/PathRequestManager.h>
 
#include <xrpl/basics/MathUtilities.h>
#include <xrpl/basics/UptimeClock.h>
#include <xrpl/basics/contract.h>
#include <xrpl/basics/safe_cast.h>
#include <xrpl/basics/scope.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/ledger/AmendmentTable.h>
#include <xrpl/ledger/Ledger.h>
#include <xrpl/ledger/OrderBookDB.h>
#include <xrpl/ledger/PendingSaves.h>
#include <xrpl/protocol/BuildInfo.h>
#include <xrpl/protocol/HashPrefix.h>
#include <xrpl/protocol/digest.h>
#include <xrpl/rdb/RelationalDatabase.h>
#include <xrpl/resource/Fees.h>
#include <xrpl/server/LoadFeeTrack.h>
#include <xrpl/server/NetworkOPs.h>
 
#include <algorithm>
#include <chrono>
#include <cstdlib>
#include <memory>
#include <vector>
 
namespace xrpl {
 
// Don't catch up more than 100 ledgers (cannot exceed 256)
static constexpr int MAX_LEDGER_GAP{100};
 
// Don't acquire history if ledger is too old
static constexpr std::chrono::minutes MAX_LEDGER_AGE_ACQUIRE{1};
 
// Don't acquire history if write load is too high
static constexpr int MAX_WRITE_LOAD_ACQUIRE{8192};
 
// Helper function for LedgerMaster::doAdvance()
// Return true if candidateLedger should be fetched from the network.
static bool
shouldAcquire(
    std::uint32_t const currentLedger,
    std::uint32_t const ledgerHistory,
    std::optional<LedgerIndex> const minimumOnline,
    std::uint32_t const candidateLedger,
    beast::Journal j)
{
    bool const ret = [&]() {
        // Fetch ledger if it may be the current ledger
        if (candidateLedger >= currentLedger)
            return true;
 
        // Or if it is within our configured history range:
        if (currentLedger - candidateLedger <= ledgerHistory)
            return true;
 
        // Or if greater than or equal to a specific minimum ledger.
        // Do nothing if the minimum ledger to keep online is unknown.
        return minimumOnline.has_value() && candidateLedger >= *minimumOnline;
    }();
 
    JLOG(j.trace()) << "Missing ledger " << candidateLedger << (ret ? " should" : " should NOT")
                    << " be acquired";
    return ret;
}
 
LedgerMaster::LedgerMaster(
    Application& app,
    Stopwatch& stopwatch,
    beast::insight::Collector::ptr const& collector,
    beast::Journal journal)
    : app_(app)
    , m_journal(journal)
    , mLedgerHistory(collector, app)
    , standalone_(app_.config().standalone())
    , fetch_depth_(app_.getSHAMapStore().clampFetchDepth(app_.config().FETCH_DEPTH))
    , ledger_history_(app_.config().LEDGER_HISTORY)
    , ledger_fetch_size_(app_.config().getValueFor(SizedItem::ledgerFetch))
    , fetch_packs_(
          "FetchPack",
          65536,
          std::chrono::seconds{45},
          stopwatch,
          app_.getJournal("TaggedCache"))
    , m_stats(std::bind(&LedgerMaster::collect_metrics, this), collector)
{
}
 
LedgerIndex
LedgerMaster::getCurrentLedgerIndex()
{
    return app_.getOpenLedger().current()->header().seq;
}
 
LedgerIndex
LedgerMaster::getValidLedgerIndex()
{
    return mValidLedgerSeq;
}
 
bool
LedgerMaster::isCompatible(ReadView const& view, beast::Journal::Stream s, char const* reason)
{
    auto validLedger = getValidatedLedger();
 
    if (validLedger && !areCompatible(*validLedger, view, s, reason))
    {
        return false;
    }
 
    {
        std::lock_guard const sl(m_mutex);
 
        if ((mLastValidLedger.second != 0) &&
            !areCompatible(mLastValidLedger.first, mLastValidLedger.second, view, s, reason))
        {
            return false;
        }
    }
 
    return true;
}
 
std::chrono::seconds
LedgerMaster::getPublishedLedgerAge()
{
    using namespace std::chrono_literals;
    std::chrono::seconds const pubClose{mPubLedgerClose.load()};
    if (pubClose == 0s)
    {
        JLOG(m_journal.debug()) << "No published ledger";
        return weeks{2};
    }
 
    std::chrono::seconds ret = app_.getTimeKeeper().closeTime().time_since_epoch();
    ret -= pubClose;
    ret = (ret > 0s) ? ret : 0s;
    static std::chrono::seconds lastRet = -1s;
 
    if (ret != lastRet)
    {
        JLOG(m_journal.trace()) << "Published ledger age is " << ret.count();
        lastRet = ret;
    }
    return ret;
}
 
std::chrono::seconds
LedgerMaster::getValidatedLedgerAge()
{
    using namespace std::chrono_literals;
 
    std::chrono::seconds const valClose{mValidLedgerSign.load()};
    if (valClose == 0s)
    {
        JLOG(m_journal.debug()) << "No validated ledger";
        return weeks{2};
    }
 
    std::chrono::seconds ret = app_.getTimeKeeper().closeTime().time_since_epoch();
    ret -= valClose;
    ret = (ret > 0s) ? ret : 0s;
    static std::chrono::seconds lastRet = -1s;
 
    if (ret != lastRet)
    {
        JLOG(m_journal.trace()) << "Validated ledger age is " << ret.count();
        lastRet = ret;
    }
    return ret;
}
 
bool
LedgerMaster::isCaughtUp(std::string& reason)
{
    using namespace std::chrono_literals;
 
    if (getPublishedLedgerAge() > 3min)
    {
        reason = "No recently-published ledger";
        return false;
    }
    std::uint32_t const validClose = mValidLedgerSign.load();
    std::uint32_t const pubClose = mPubLedgerClose.load();
    if ((validClose == 0u) || (pubClose == 0u))
    {
        reason = "No published ledger";
        return false;
    }
    if (validClose > (pubClose + 90))
    {
        reason = "Published ledger lags validated ledger";
        return false;
    }
    return true;
}
 
void
LedgerMaster::setValidLedger(std::shared_ptr<Ledger const> const& l)
{
    std::vector<NetClock::time_point> times;
    std::optional<uint256> consensusHash;
 
    if (!standalone_)
    {
        auto validations = app_.getValidators().negativeUNLFilter(
            app_.getValidations().getTrustedForLedger(l->header().hash, l->header().seq));
        times.reserve(validations.size());
        for (auto const& val : validations)
            times.push_back(val->getSignTime());
 
        if (!validations.empty())
            consensusHash = validations.front()->getConsensusHash();
    }
 
    NetClock::time_point signTime;
 
    if (!times.empty() && times.size() >= app_.getValidators().quorum())
    {
        // Calculate the sample median
        std::sort(times.begin(), times.end());
        auto const t0 = times[(times.size() - 1) / 2];
        auto const t1 = times[times.size() / 2];
        signTime = t0 + (t1 - t0) / 2;
    }
    else
    {
        signTime = l->header().closeTime;
    }
 
    mValidLedger.set(l);
    mValidLedgerSign = signTime.time_since_epoch().count();
    XRPL_ASSERT(
        mValidLedgerSeq || !app_.getMaxDisallowedLedger() ||
            l->header().seq + max_ledger_difference_ > app_.getMaxDisallowedLedger(),
        "xrpl::LedgerMaster::setValidLedger : valid ledger sequence");
    (void)max_ledger_difference_;
    mValidLedgerSeq = l->header().seq;
 
    app_.getOPs().updateLocalTx(*l);
    app_.getSHAMapStore().onLedgerClosed(getValidatedLedger());
    mLedgerHistory.validatedLedger(l, consensusHash);
    app_.getAmendmentTable().doValidatedLedger(l);
    if (!app_.getOPs().isBlocked())
    {
        if (app_.getAmendmentTable().hasUnsupportedEnabled())
        {
            JLOG(m_journal.error()) << "One or more unsupported amendments "
                                       "activated: server blocked.";
            app_.getOPs().setAmendmentBlocked();
        }
        else if (!app_.getOPs().isAmendmentWarned() || l->isFlagLedger())
        {
            // Amendments can lose majority, so re-check periodically (every
            // flag ledger), and clear the flag if appropriate. If an unknown
            // amendment gains majority log a warning as soon as it's
            // discovered, then again every flag ledger until the operator
            // upgrades, the amendment loses majority, or the amendment goes
            // live and the node gets blocked. Unlike being amendment blocked,
            // this message may be logged more than once per session, because
            // the node will otherwise function normally, and this gives
            // operators an opportunity to see and resolve the warning.
            if (auto const first = app_.getAmendmentTable().firstUnsupportedExpected())
            {
                JLOG(m_journal.error()) << "One or more unsupported amendments "
                                           "reached majority. Upgrade before "
                                        << to_string(*first)
                                        << " to prevent your server from "
                                           "becoming amendment blocked.";
                app_.getOPs().setAmendmentWarned();
            }
            else
            {
                app_.getOPs().clearAmendmentWarned();
            }
        }
    }
}
 
void
LedgerMaster::setPubLedger(std::shared_ptr<Ledger const> const& l)
{
    mPubLedger = l;
    mPubLedgerClose = l->header().closeTime.time_since_epoch().count();
    mPubLedgerSeq = l->header().seq;
}
 
void
LedgerMaster::addHeldTransaction(std::shared_ptr<Transaction> const& transaction)
{
    std::lock_guard const ml(m_mutex);
    mHeldTransactions.insert(transaction->getSTransaction());
}
 
// Validate a ledger's close time and sequence number if we're considering
// jumping to that ledger. This helps defend against some rare hostile or
// diverged majority scenarios.
bool
LedgerMaster::canBeCurrent(std::shared_ptr<Ledger const> const& ledger)
{
    XRPL_ASSERT(ledger, "xrpl::LedgerMaster::canBeCurrent : non-null input");
 
    // Never jump to a candidate ledger that precedes our
    // last validated ledger
 
    auto validLedger = getValidatedLedger();
    if (validLedger && (ledger->header().seq < validLedger->header().seq))
    {
        JLOG(m_journal.trace()) << "Candidate for current ledger has low seq "
                                << ledger->header().seq << " < " << validLedger->header().seq;
        return false;
    }
 
    // Ensure this ledger's parent close time is within five minutes of
    // our current time. If we already have a known fully-valid ledger
    // we perform this check. Otherwise, we only do it if we've built a
    // few ledgers as our clock can be off when we first start up
 
    auto closeTime = app_.getTimeKeeper().closeTime();
    auto ledgerClose = ledger->header().parentCloseTime;
 
    using namespace std::chrono_literals;
    if ((validLedger || (ledger->header().seq > 10)) &&
        ((std::max(closeTime, ledgerClose) - std::min(closeTime, ledgerClose)) > 5min))
    {
        JLOG(m_journal.warn()) << "Candidate for current ledger has close time "
                               << to_string(ledgerClose) << " at network time "
                               << to_string(closeTime) << " seq " << ledger->header().seq;
        return false;
    }
 
    if (validLedger)
    {
        // Sequence number must not be too high. We allow ten ledgers
        // for time inaccuracies plus a maximum run rate of one ledger
        // every two seconds. The goal is to prevent a malicious ledger
        // from increasing our sequence unreasonably high
 
        LedgerIndex maxSeq = validLedger->header().seq + 10;
 
        if (closeTime > validLedger->header().parentCloseTime)
        {
            maxSeq += std::chrono::duration_cast<std::chrono::seconds>(
                          closeTime - validLedger->header().parentCloseTime)
                          .count() /
                2;
        }
 
        if (ledger->header().seq > maxSeq)
        {
            JLOG(m_journal.warn()) << "Candidate for current ledger has high seq "
                                   << ledger->header().seq << " > " << maxSeq;
            return false;
        }
 
        JLOG(m_journal.trace()) << "Acceptable seq range: " << validLedger->header().seq
                                << " <= " << ledger->header().seq << " <= " << maxSeq;
    }
 
    return true;
}
 
void
LedgerMaster::switchLCL(std::shared_ptr<Ledger const> const& lastClosed)
{
    XRPL_ASSERT(lastClosed, "xrpl::LedgerMaster::switchLCL : non-null input");
    if (!lastClosed->isImmutable())
        LogicError("mutable ledger in switchLCL");
 
    if (lastClosed->open())
        LogicError("The new last closed ledger is open!");
 
    {
        std::lock_guard const ml(m_mutex);
        mClosedLedger.set(lastClosed);
    }
 
    if (standalone_)
    {
        setFullLedger(lastClosed, true, false);
        tryAdvance();
    }
    else
    {
        checkAccept(lastClosed);
    }
}
 
bool
LedgerMaster::fixIndex(LedgerIndex ledgerIndex, LedgerHash const& ledgerHash)
{
    return mLedgerHistory.fixIndex(ledgerIndex, ledgerHash);
}
 
bool
LedgerMaster::storeLedger(std::shared_ptr<Ledger const> ledger)
{
    bool const validated = ledger->header().validated;
    // Returns true if we already had the ledger
    return mLedgerHistory.insert(ledger, validated);
}
 
void
LedgerMaster::applyHeldTransactions()
{
    CanonicalTXSet const set = [this]() {
        std::lock_guard const sl(m_mutex);
        // VFALCO NOTE The hash for an open ledger is undefined so we use
        // something that is a reasonable substitute.
        CanonicalTXSet set(app_.getOpenLedger().current()->header().parentHash);
        std::swap(mHeldTransactions, set);
        return set;
    }();
 
    if (!set.empty())
        app_.getOPs().processTransactionSet(set);
}
 
std::shared_ptr<STTx const>
LedgerMaster::popAcctTransaction(std::shared_ptr<STTx const> const& tx)
{
    std::lock_guard const sl(m_mutex);
 
    return mHeldTransactions.popAcctTransaction(tx);
}
 
void
LedgerMaster::setBuildingLedger(LedgerIndex i)
{
    mBuildingLedgerSeq.store(i);
}
 
bool
LedgerMaster::haveLedger(std::uint32_t seq)
{
    std::lock_guard const sl(mCompleteLock);
    return boost::icl::contains(mCompleteLedgers, seq);
}
 
void
LedgerMaster::clearLedger(std::uint32_t seq)
{
    std::lock_guard const sl(mCompleteLock);
    mCompleteLedgers.erase(seq);
}
 
bool
LedgerMaster::isValidated(ReadView const& ledger)
{
    if (ledger.open())
        return false;
 
    if (ledger.header().validated)
        return true;
 
    auto const seq = ledger.header().seq;
    try
    {
        // Use the skip list in the last validated ledger to see if ledger
        // comes before the last validated ledger (and thus has been
        // validated).
        auto const hash = walkHashBySeq(seq, InboundLedger::Reason::GENERIC);
 
        if (!hash || ledger.header().hash != *hash)
        {
            // This ledger's hash is not the hash of the validated ledger
            if (hash)
            {
                XRPL_ASSERT(hash->isNonZero(), "xrpl::LedgerMaster::isValidated : nonzero hash");
                uint256 const valHash = app_.getRelationalDatabase().getHashByIndex(seq);
                if (valHash == ledger.header().hash)
                {
                    // SQL database doesn't match ledger chain
                    clearLedger(seq);
                }
            }
            return false;
        }
    }
    catch (SHAMapMissingNode const& mn)
    {
        JLOG(m_journal.warn()) << "Ledger #" << seq << ": " << mn.what();
        return false;
    }
 
    // Mark ledger as validated to save time if we see it again.
    ledger.header().validated = true;
    return true;
}
 
// returns Ledgers we have all the nodes for
bool
LedgerMaster::getFullValidatedRange(std::uint32_t& minVal, std::uint32_t& maxVal)
{
    // Validated ledger is likely not stored in the DB yet so we use the
    // published ledger which is.
    maxVal = mPubLedgerSeq.load();
 
    if (maxVal == 0u)
        return false;
 
    std::optional<std::uint32_t> maybeMin;
    {
        std::lock_guard const sl(mCompleteLock);
        maybeMin = prevMissing(mCompleteLedgers, maxVal);
    }
 
    if (maybeMin == std::nullopt)
    {
        minVal = maxVal;
    }
    else
    {
        minVal = 1 + *maybeMin;
    }
 
    return true;
}
 
// Returns Ledgers we have all the nodes for and are indexed
bool
LedgerMaster::getValidatedRange(std::uint32_t& minVal, std::uint32_t& maxVal)
{
    if (!getFullValidatedRange(minVal, maxVal))
        return false;
 
    // Remove from the validated range any ledger sequences that may not be
    // fully updated in the database yet
 
    auto const pendingSaves = app_.getPendingSaves().getSnapshot();
 
    if (!pendingSaves.empty() && ((minVal != 0) || (maxVal != 0)))
    {
        // Ensure we shrink the tips as much as possible. If we have 7-9 and
        // 8,9 are invalid, we don't want to see the 8 and shrink to just 9
        // because then we'll have nothing when we could have 7.
        while (pendingSaves.contains(maxVal))
            --maxVal;
        while (pendingSaves.contains(minVal))
            ++minVal;
 
        // Best effort for remaining exclusions
        for (auto v : pendingSaves)
        {
            if ((v.first >= minVal) && (v.first <= maxVal))
            {
                if (v.first > ((minVal + maxVal) / 2))
                {
                    maxVal = v.first - 1;
                }
                else
                {
                    minVal = v.first + 1;
                }
            }
        }
 
        if (minVal > maxVal)
            minVal = maxVal = 0;
    }
 
    return true;
}
 
// Get the earliest ledger we will let peers fetch
std::uint32_t
LedgerMaster::getEarliestFetch()
{
    // The earliest ledger we will let people fetch is ledger zero,
    // unless that creates a larger range than allowed
    std::uint32_t e = getClosedLedger()->header().seq;
 
    if (e > fetch_depth_)
    {
        e -= fetch_depth_;
    }
    else
    {
        e = 0;
    }
    return e;
}
 
void
LedgerMaster::tryFill(std::shared_ptr<Ledger const> ledger)
{
    std::uint32_t seq = ledger->header().seq;
    uint256 prevHash = ledger->header().parentHash;
 
    std::map<std::uint32_t, LedgerHashPair> ledgerHashes;
 
    std::uint32_t minHas = seq;
    std::uint32_t maxHas = seq;
 
    NodeStore::Database& nodeStore{app_.getNodeStore()};
    while (!app_.getJobQueue().isStopping() && seq > 0)
    {
        {
            std::lock_guard const ml(m_mutex);
            minHas = seq;
            --seq;
 
            if (haveLedger(seq))
                break;
        }
 
        auto it(ledgerHashes.find(seq));
 
        if (it == ledgerHashes.end())
        {
            if (app_.isStopping())
                return;
 
            {
                std::lock_guard const ml(mCompleteLock);
                mCompleteLedgers.insert(range(minHas, maxHas));
            }
            maxHas = minHas;
            ledgerHashes =
                app_.getRelationalDatabase().getHashesByIndex((seq < 500) ? 0 : (seq - 499), seq);
            it = ledgerHashes.find(seq);
 
            if (it == ledgerHashes.end())
                break;
 
            if (!nodeStore.fetchNodeObject(
                    ledgerHashes.begin()->second.ledgerHash, ledgerHashes.begin()->first))
            {
                // The ledger is not backed by the node store
                JLOG(m_journal.warn())
                    << "SQL DB ledger sequence " << seq << " mismatches node store";
                break;
            }
        }
 
        if (it->second.ledgerHash != prevHash)
            break;
 
        prevHash = it->second.parentHash;
    }
 
    {
        std::lock_guard const ml(mCompleteLock);
        mCompleteLedgers.insert(range(minHas, maxHas));
    }
    {
        std::lock_guard const ml(m_mutex);
        mFillInProgress = 0;
        tryAdvance();
    }
}
 
void
LedgerMaster::getFetchPack(LedgerIndex missing, InboundLedger::Reason reason)
{
    LedgerIndex const ledgerIndex = missing + 1;
 
    auto const haveHash{getLedgerHashForHistory(ledgerIndex, reason)};
    if (!haveHash || haveHash->isZero())
    {
        JLOG(m_journal.error()) << "No hash for fetch pack. Missing Index " << missing;
        return;
    }
 
    // Select target Peer based on highest score.  The score is randomized
    // but biased in favor of Peers with low latency.
    std::shared_ptr<Peer> target;
    {
        int maxScore = 0;
        auto peerList = app_.getOverlay().getActivePeers();
        for (auto const& peer : peerList)
        {
            if (peer->hasRange(missing, missing + 1))
            {
                int const score = peer->getScore(true);
                if (!target || (score > maxScore))
                {
                    target = peer;
                    maxScore = score;
                }
            }
        }
    }
 
    if (target)
    {
        protocol::TMGetObjectByHash tmBH;
        tmBH.set_query(true);
        tmBH.set_type(protocol::TMGetObjectByHash::otFETCH_PACK);
        tmBH.set_ledgerhash(haveHash->begin(), 32);
        auto packet = std::make_shared<Message>(tmBH, protocol::mtGET_OBJECTS);
 
        target->send(packet);
        JLOG(m_journal.trace()) << "Requested fetch pack for " << missing;
    }
    else
        JLOG(m_journal.debug()) << "No peer for fetch pack";
}
 
void
LedgerMaster::fixMismatch(ReadView const& ledger)
{
    int invalidate = 0;
    std::optional<uint256> hash;
 
    for (std::uint32_t lSeq = ledger.header().seq - 1; lSeq > 0; --lSeq)
    {
        if (haveLedger(lSeq))
        {
            try
            {
                hash = hashOfSeq(ledger, lSeq, m_journal);
            }
            catch (std::exception const& ex)
            {
                JLOG(m_journal.warn())
                    << "fixMismatch encounters partial ledger. Exception: " << ex.what();
                clearLedger(lSeq);
                return;
            }
 
            if (hash)
            {
                // try to close the seam
                auto otherLedger = getLedgerBySeq(lSeq);
 
                if (otherLedger && (otherLedger->header().hash == *hash))
                {
                    // we closed the seam
                    if (invalidate != 0)
                    {
                        JLOG(m_journal.warn()) << "Match at " << lSeq << ", " << invalidate
                                               << " prior ledgers invalidated";
                    }
 
                    return;
                }
            }
 
            clearLedger(lSeq);
            ++invalidate;
        }
    }
 
    // all prior ledgers invalidated
    if (invalidate != 0)
    {
        JLOG(m_journal.warn()) << "All " << invalidate << " prior ledgers invalidated";
    }
}
 
void
LedgerMaster::setFullLedger(
    std::shared_ptr<Ledger const> const& ledger,
    bool isSynchronous,
    bool isCurrent)
{
    // A new ledger has been accepted as part of the trusted chain
    JLOG(m_journal.debug()) << "Ledger " << ledger->header().seq
                            << " accepted :" << ledger->header().hash;
    XRPL_ASSERT(
        ledger->stateMap().getHash().isNonZero(),
        "xrpl::LedgerMaster::setFullLedger : nonzero ledger state hash");
 
    ledger->setValidated();
    ledger->setFull();
 
    if (isCurrent)
        mLedgerHistory.insert(ledger, true);
 
    {
        // Check the SQL database's entry for the sequence before this
        // ledger, if it's not this ledger's parent, invalidate it
        uint256 const prevHash =
            app_.getRelationalDatabase().getHashByIndex(ledger->header().seq - 1);
        if (prevHash.isNonZero() && prevHash != ledger->header().parentHash)
            clearLedger(ledger->header().seq - 1);
    }
 
    pendSaveValidated(app_, ledger, isSynchronous, isCurrent);
 
    {
        std::lock_guard const ml(mCompleteLock);
        mCompleteLedgers.insert(ledger->header().seq);
    }
 
    {
        std::lock_guard const ml(m_mutex);
 
        if (ledger->header().seq > mValidLedgerSeq)
            setValidLedger(ledger);
        if (!mPubLedger)
        {
            setPubLedger(ledger);
            app_.getOrderBookDB().setup(ledger);
        }
 
        if (ledger->header().seq != 0 && haveLedger(ledger->header().seq - 1))
        {
            // we think we have the previous ledger, double check
            auto prevLedger = getLedgerBySeq(ledger->header().seq - 1);
 
            if (!prevLedger || (prevLedger->header().hash != ledger->header().parentHash))
            {
                JLOG(m_journal.warn()) << "Acquired ledger invalidates previous ledger: "
                                       << (prevLedger ? "hashMismatch" : "missingLedger");
                fixMismatch(*ledger);
            }
        }
    }
}
 
void
LedgerMaster::failedSave(std::uint32_t seq, uint256 const& hash)
{
    clearLedger(seq);
    app_.getInboundLedgers().acquire(hash, seq, InboundLedger::Reason::GENERIC);
}
 
// Check if the specified ledger can become the new last fully-validated
// ledger.
void
LedgerMaster::checkAccept(uint256 const& hash, std::uint32_t seq)
{
    std::size_t valCount = 0;
 
    if (seq != 0)
    {
        // Ledger is too old
        if (seq < mValidLedgerSeq)
            return;
 
        auto validations = app_.getValidators().negativeUNLFilter(
            app_.getValidations().getTrustedForLedger(hash, seq));
        valCount = validations.size();
        if (valCount >= app_.getValidators().quorum())
        {
            std::lock_guard const ml(m_mutex);
            if (seq > mLastValidLedger.second)
                mLastValidLedger = std::make_pair(hash, seq);
        }
 
        if (seq == mValidLedgerSeq)
            return;
 
        // Ledger could match the ledger we're already building
        if (seq == mBuildingLedgerSeq)
            return;
    }
 
    auto ledger = mLedgerHistory.getLedgerByHash(hash);
 
    if (!ledger)
    {
        if ((seq != 0) && (getValidLedgerIndex() == 0))
        {
            // Set peers converged early if we can
            if (valCount >= app_.getValidators().quorum())
                app_.getOverlay().checkTracking(seq);
        }
 
        // FIXME: We may not want to fetch a ledger with just one
        // trusted validation
        ledger = app_.getInboundLedgers().acquire(hash, seq, InboundLedger::Reason::GENERIC);
    }
 
    if (ledger)
        checkAccept(ledger);
}
 
std::size_t
LedgerMaster::getNeededValidations()
{
    return standalone_ ? 0 : app_.getValidators().quorum();
}
 
void
LedgerMaster::checkAccept(std::shared_ptr<Ledger const> const& ledger)
{
    // Can we accept this ledger as our new last fully-validated ledger
 
    if (!canBeCurrent(ledger))
        return;
 
    // Can we advance the last fully-validated ledger? If so, can we
    // publish?
    std::lock_guard const ml(m_mutex);
 
    if (ledger->header().seq <= mValidLedgerSeq)
        return;
 
    auto const minVal = getNeededValidations();
    auto validations = app_.getValidators().negativeUNLFilter(
        app_.getValidations().getTrustedForLedger(ledger->header().hash, ledger->header().seq));
    auto const tvc = validations.size();
    if (tvc < minVal)  // nothing we can do
    {
        JLOG(m_journal.trace()) << "Only " << tvc << " validations for " << ledger->header().hash;
        return;
    }
 
    JLOG(m_journal.info()) << "Advancing accepted ledger to " << ledger->header().seq
                           << " with >= " << minVal << " validations";
 
    ledger->setValidated();
    ledger->setFull();
    setValidLedger(ledger);
    if (!mPubLedger)
    {
        pendSaveValidated(app_, ledger, true, true);
        setPubLedger(ledger);
        app_.getOrderBookDB().setup(ledger);
    }
 
    std::uint32_t const base = app_.getFeeTrack().getLoadBase();
    auto fees = app_.getValidations().fees(ledger->header().hash, base);
    {
        auto fees2 = app_.getValidations().fees(ledger->header().parentHash, base);
        fees.reserve(fees.size() + fees2.size());
        std::copy(fees2.begin(), fees2.end(), std::back_inserter(fees));
    }
    std::uint32_t fee = 0;
    if (!fees.empty())
    {
        std::sort(fees.begin(), fees.end());
        if (auto stream = m_journal.debug())
        {
            std::stringstream s;
            s << "Received fees from validations: (" << fees.size() << ") ";
            for (auto const fee1 : fees)
            {
                s << " " << fee1;
            }
            stream << s.str();
        }
        fee = fees[fees.size() / 2];  // median
    }
    else
    {
        fee = base;
    }
 
    app_.getFeeTrack().setRemoteFee(fee);
 
    tryAdvance();
 
    if (ledger->seq() % 256 == 0)
    {
        // Check if the majority of validators run a higher version rippled
        // software. If so print a warning.
        //
        // Validators include their rippled software version in the validation
        // messages of every (flag - 1) ledger. We wait for one ledger time
        // before checking the version information to accumulate more validation
        // messages.
 
        auto currentTime = app_.getTimeKeeper().now();
        bool needPrint = false;
 
        // The variable upgradeWarningPrevTime_ will be set when and only when
        // the warning is printed.
        if (upgradeWarningPrevTime_ == TimeKeeper::time_point())
        {
            // Have not printed the warning before, check if need to print.
            auto const vals = app_.getValidations().getTrustedForLedger(
                ledger->header().parentHash, ledger->header().seq - 1);
            std::size_t higherVersionCount = 0;
            std::size_t rippledCount = 0;
            for (auto const& v : vals)
            {
                if (v->isFieldPresent(sfServerVersion))
                {
                    auto version = v->getFieldU64(sfServerVersion);
                    higherVersionCount += BuildInfo::isNewerVersion(version) ? 1 : 0;
                    rippledCount += BuildInfo::isRippledVersion(version) ? 1 : 0;
                }
            }
            // We report only if (1) we have accumulated validation messages
            // from 90% validators from the UNL, (2) 60% of validators
            // running the rippled implementation have higher version numbers,
            // and (3) the calculation won't cause divide-by-zero.
            if (higherVersionCount > 0 && rippledCount > 0)
            {
                constexpr std::size_t reportingPercent = 90;
                constexpr std::size_t cutoffPercent = 60;
                auto const unlSize{app_.getValidators().getQuorumKeys().second.size()};
                needPrint = unlSize > 0 &&
                    calculatePercent(vals.size(), unlSize) >= reportingPercent &&
                    calculatePercent(higherVersionCount, rippledCount) >= cutoffPercent;
            }
        }
        // To throttle the warning messages, instead of printing a warning
        // every flag ledger, we print every week.
        else if (currentTime - upgradeWarningPrevTime_ >= weeks{1})
        {
            // Printed the warning before, and assuming most validators
            // do not downgrade, we keep printing the warning
            // until the local server is restarted.
            needPrint = true;
        }
 
        if (needPrint)
        {
            upgradeWarningPrevTime_ = currentTime;
            auto const upgradeMsg =
                "Check for upgrade: "
                "A majority of trusted validators are "
                "running a newer version.";
            std::cerr << upgradeMsg << std::endl;
            JLOG(m_journal.error()) << upgradeMsg;
        }
    }
}
 
void
LedgerMaster::consensusBuilt(
    std::shared_ptr<Ledger const> const& ledger,
    uint256 const& consensusHash,
    Json::Value consensus)
{
    // Because we just built a ledger, we are no longer building one
    setBuildingLedger(0);
 
    // No need to process validations in standalone mode
    if (standalone_)
        return;
 
    mLedgerHistory.builtLedger(ledger, consensusHash, std::move(consensus));
 
    if (ledger->header().seq <= mValidLedgerSeq)
    {
        auto stream = app_.getJournal("LedgerConsensus").info();
        JLOG(stream) << "Consensus built old ledger: " << ledger->header().seq
                     << " <= " << mValidLedgerSeq;
        return;
    }
 
    // See if this ledger can be the new fully-validated ledger
    checkAccept(ledger);
 
    if (ledger->header().seq <= mValidLedgerSeq)
    {
        auto stream = app_.getJournal("LedgerConsensus").debug();
        JLOG(stream) << "Consensus ledger fully validated";
        return;
    }
 
    // This ledger cannot be the new fully-validated ledger, but
    // maybe we saved up validations for some other ledger that can be
 
    auto validations =
        app_.getValidators().negativeUNLFilter(app_.getValidations().currentTrusted());
 
    // Track validation counts with sequence numbers
    class valSeq
    {
    public:
        valSeq() = default;
 
        void
        mergeValidation(LedgerIndex seq)
        {
            valCount_++;
 
            // If we didn't already know the sequence, now we do
            if (ledgerSeq_ == 0)
                ledgerSeq_ = seq;
        }
 
        std::size_t valCount_{0};
        LedgerIndex ledgerSeq_{0};
    };
 
    // Count the number of current, trusted validations
    hash_map<uint256, valSeq> count;
    for (auto const& v : validations)
    {
        valSeq& vs = count[v->getLedgerHash()];
        vs.mergeValidation(v->getFieldU32(sfLedgerSequence));
    }
 
    auto const neededValidations = getNeededValidations();
    auto maxSeq = mValidLedgerSeq.load();
    auto maxLedger = ledger->header().hash;
 
    // Of the ledgers with sufficient validations,
    // find the one with the highest sequence
    for (auto& v : count)
    {
        if (v.second.valCount_ > neededValidations)
        {
            // If we still don't know the sequence, get it
            if (v.second.ledgerSeq_ == 0)
            {
                if (auto l = getLedgerByHash(v.first))
                    v.second.ledgerSeq_ = l->header().seq;
            }
 
            if (v.second.ledgerSeq_ > maxSeq)
            {
                maxSeq = v.second.ledgerSeq_;
                maxLedger = v.first;
            }
        }
    }
 
    if (maxSeq > mValidLedgerSeq)
    {
        auto stream = app_.getJournal("LedgerConsensus").debug();
        JLOG(stream) << "Consensus triggered check of ledger";
        checkAccept(maxLedger, maxSeq);
    }
}
 
std::optional<LedgerHash>
LedgerMaster::getLedgerHashForHistory(LedgerIndex index, InboundLedger::Reason reason)
{
    // Try to get the hash of a ledger we need to fetch for history
    std::optional<LedgerHash> ret;
    auto const& l{mHistLedger};
 
    if (l && l->header().seq >= index)
    {
        ret = hashOfSeq(*l, index, m_journal);
        if (!ret)
            ret = walkHashBySeq(index, l, reason);
    }
 
    if (!ret)
        ret = walkHashBySeq(index, reason);
 
    return ret;
}
 
std::vector<std::shared_ptr<Ledger const>>
LedgerMaster::findNewLedgersToPublish(std::unique_lock<std::recursive_mutex>& sl)
{
    std::vector<std::shared_ptr<Ledger const>> ret;
 
    JLOG(m_journal.trace()) << "findNewLedgersToPublish<";
 
    // No valid ledger, nothing to do
    if (mValidLedger.empty())
    {
        JLOG(m_journal.trace()) << "No valid journal, nothing to publish.";
        return {};
    }
 
    if (!mPubLedger)
    {
        JLOG(m_journal.info()) << "First published ledger will be " << mValidLedgerSeq;
        return {mValidLedger.get()};
    }
 
    if (mValidLedgerSeq > (mPubLedgerSeq + MAX_LEDGER_GAP))
    {
        JLOG(m_journal.warn()) << "Gap in validated ledger stream " << mPubLedgerSeq << " - "
                               << mValidLedgerSeq - 1;
 
        auto valLedger = mValidLedger.get();
        ret.push_back(valLedger);
        setPubLedger(valLedger);
        app_.getOrderBookDB().setup(valLedger);
 
        return {valLedger};
    }
 
    if (mValidLedgerSeq <= mPubLedgerSeq)
    {
        JLOG(m_journal.trace()) << "No valid journal, nothing to publish.";
        return {};
    }
 
    int acqCount = 0;
 
    auto pubSeq = mPubLedgerSeq + 1;  // Next sequence to publish
    auto valLedger = mValidLedger.get();
    std::uint32_t const valSeq = valLedger->header().seq;
 
    scope_unlock const sul{sl};
    try
    {
        for (std::uint32_t seq = pubSeq; seq <= valSeq; ++seq)
        {
            JLOG(m_journal.trace()) << "Trying to fetch/publish valid ledger " << seq;
 
            std::shared_ptr<Ledger const> ledger;
            // This can throw
            auto hash = hashOfSeq(*valLedger, seq, m_journal);
            // VFALCO TODO Restructure this code so that zero is not
            // used.
            if (!hash)
                hash = beast::zero;  // kludge
            if (seq == valSeq)
            {
                // We need to publish the ledger we just fully validated
                ledger = valLedger;
            }
            else if (hash->isZero())
            {
                // LCOV_EXCL_START
                JLOG(m_journal.fatal())
                    << "Ledger: " << valSeq << " does not have hash for " << seq;
                UNREACHABLE(
                    "xrpl::LedgerMaster::findNewLedgersToPublish : ledger "
                    "not found");
                // LCOV_EXCL_STOP
            }
            else
            {
                ledger = mLedgerHistory.getLedgerByHash(*hash);
            }
 
            if (!app_.config().LEDGER_REPLAY)
            {
                // Can we try to acquire the ledger we need?
                if (!ledger && (++acqCount < ledger_fetch_size_))
                {
                    ledger = app_.getInboundLedgers().acquire(
                        *hash, seq, InboundLedger::Reason::GENERIC);
                }
            }
 
            // Did we acquire the next ledger we need to publish?
            if (ledger && (ledger->header().seq == pubSeq))
            {
                ledger->setValidated();
                ret.push_back(ledger);
                ++pubSeq;
            }
        }
 
        JLOG(m_journal.trace()) << "ready to publish " << ret.size() << " ledgers.";
    }
    catch (std::exception const& ex)
    {
        JLOG(m_journal.error()) << "Exception while trying to find ledgers to publish: "
                                << ex.what();
    }
 
    if (app_.config().LEDGER_REPLAY)
    {
        /* Narrow down the gap of ledgers, and try to replay them.
         * When replaying a ledger gap, if the local node has
         * the start ledger, it saves an expensive InboundLedger
         * acquire. If the local node has the finish ledger, it
         * saves a skip list acquire.
         */
        auto const& startLedger = ret.empty() ? mPubLedger : ret.back();
        auto finishLedger = valLedger;
        while (startLedger->seq() + 1 < finishLedger->seq())
        {
            if (auto const parent =
                    mLedgerHistory.getLedgerByHash(finishLedger->header().parentHash);
                parent)
            {
                finishLedger = parent;
            }
            else
            {
                auto numberLedgers = finishLedger->seq() - startLedger->seq() + 1;
                JLOG(m_journal.debug())
                    << "Publish LedgerReplays " << numberLedgers
                    << " ledgers, from seq=" << startLedger->header().seq << ", "
                    << startLedger->header().hash << " to seq=" << finishLedger->header().seq
                    << ", " << finishLedger->header().hash;
                app_.getLedgerReplayer().replay(
                    InboundLedger::Reason::GENERIC, finishLedger->header().hash, numberLedgers);
                break;
            }
        }
    }
 
    return ret;
}
 
void
LedgerMaster::tryAdvance()
{
    std::lock_guard const ml(m_mutex);
 
    // Can't advance without at least one fully-valid ledger
    mAdvanceWork = true;
    if (!mAdvanceThread && !mValidLedger.empty())
    {
        mAdvanceThread = true;
        app_.getJobQueue().addJob(jtADVANCE, "AdvanceLedger", [this]() {
            std::unique_lock sl(m_mutex);
 
            XRPL_ASSERT(
                !mValidLedger.empty() && mAdvanceThread,
                "xrpl::LedgerMaster::tryAdvance : has valid ledger");
 
            JLOG(m_journal.trace()) << "advanceThread<";
 
            try
            {
                doAdvance(sl);
            }
            catch (std::exception const& ex)
            {
                JLOG(m_journal.fatal()) << "doAdvance throws: " << ex.what();
            }
 
            mAdvanceThread = false;
            JLOG(m_journal.trace()) << "advanceThread>";
        });
    }
}
 
void
LedgerMaster::updatePaths()
{
    {
        std::lock_guard const ml(m_mutex);
        if (app_.getOPs().isNeedNetworkLedger())
        {
            --mPathFindThread;
            mPathLedger.reset();
            JLOG(m_journal.debug()) << "Need network ledger for updating paths";
            return;
        }
    }
 
    while (!app_.getJobQueue().isStopping())
    {
        JLOG(m_journal.debug()) << "updatePaths running";
        std::shared_ptr<ReadView const> lastLedger;
        {
            std::lock_guard const ml(m_mutex);
 
            if (!mValidLedger.empty() &&
                (!mPathLedger || (mPathLedger->header().seq != mValidLedgerSeq)))
            {  // We have a new valid ledger since the last full pathfinding
                mPathLedger = mValidLedger.get();
                lastLedger = mPathLedger;
            }
            else if (mPathFindNewRequest)
            {  // We have a new request but no new ledger
                lastLedger = app_.getOpenLedger().current();
            }
            else
            {  // Nothing to do
                --mPathFindThread;
                mPathLedger.reset();
                JLOG(m_journal.debug()) << "Nothing to do for updating paths";
                return;
            }
        }
 
        if (!standalone_)
        {  // don't pathfind with a ledger that's more than 60 seconds old
            using namespace std::chrono;
            auto age = time_point_cast<seconds>(app_.getTimeKeeper().closeTime()) -
                lastLedger->header().closeTime;
            if (age > 1min)
            {
                JLOG(m_journal.debug()) << "Published ledger too old for updating paths";
                std::lock_guard const ml(m_mutex);
                --mPathFindThread;
                mPathLedger.reset();
                return;
            }
        }
 
        try
        {
            auto& pathRequests = app_.getPathRequestManager();
            {
                std::lock_guard const ml(m_mutex);
                if (!pathRequests.requestsPending())
                {
                    --mPathFindThread;
                    mPathLedger.reset();
                    JLOG(m_journal.debug()) << "No path requests found. Nothing to do for updating "
                                               "paths. "
                                            << mPathFindThread << " jobs remaining";
                    return;
                }
            }
            JLOG(m_journal.debug()) << "Updating paths";
            pathRequests.updateAll(lastLedger);
 
            std::lock_guard const ml(m_mutex);
            if (!pathRequests.requestsPending())
            {
                JLOG(m_journal.debug()) << "No path requests left. No need for further updating "
                                           "paths";
                --mPathFindThread;
                mPathLedger.reset();
                return;
            }
        }
        catch (SHAMapMissingNode const& mn)
        {
            JLOG(m_journal.info()) << "During pathfinding: " << mn.what();
            if (lastLedger->open())
            {
                // our parent is the problem
                app_.getInboundLedgers().acquire(
                    lastLedger->header().parentHash,
                    lastLedger->header().seq - 1,
                    InboundLedger::Reason::GENERIC);
            }
            else
            {
                // this ledger is the problem
                app_.getInboundLedgers().acquire(
                    lastLedger->header().hash,
                    lastLedger->header().seq,
                    InboundLedger::Reason::GENERIC);
            }
        }
    }
}
 
bool
LedgerMaster::newPathRequest()
{
    std::unique_lock ml(m_mutex);
    mPathFindNewRequest = newPFWork("PthFindNewReq", ml);
    return mPathFindNewRequest;
}
 
bool
LedgerMaster::isNewPathRequest()
{
    std::lock_guard const ml(m_mutex);
    bool const ret = mPathFindNewRequest;
    mPathFindNewRequest = false;
    return ret;
}
 
// If the order book is radically updated, we need to reprocess all
// pathfinding requests.
bool
LedgerMaster::newOrderBookDB()
{
    std::unique_lock ml(m_mutex);
    mPathLedger.reset();
 
    return newPFWork("PthFindOBDB", ml);
}
 
bool
LedgerMaster::newPFWork(char const* name, std::unique_lock<std::recursive_mutex>&)
{
    if (!app_.isStopping() && mPathFindThread < 2 && app_.getPathRequestManager().requestsPending())
    {
        JLOG(m_journal.debug()) << "newPFWork: Creating job. path find threads: "
                                << mPathFindThread;
        if (app_.getJobQueue().addJob(jtUPDATE_PF, name, [this]() { updatePaths(); }))
        {
            ++mPathFindThread;
        }
    }
    // If we're stopping don't give callers the expectation that their
    // request will be fulfilled, even if it may be serviced.
    return mPathFindThread > 0 && !app_.isStopping();
}
 
std::recursive_mutex&
LedgerMaster::peekMutex()
{
    return m_mutex;
}
 
// The current ledger is the ledger we believe new transactions should go in
std::shared_ptr<ReadView const>
LedgerMaster::getCurrentLedger()
{
    return app_.getOpenLedger().current();
}
 
std::shared_ptr<Ledger const>
LedgerMaster::getValidatedLedger()
{
    return mValidLedger.get();
}
 
Rules
LedgerMaster::getValidatedRules()
{
    // Once we have a guarantee that there's always a last validated
    // ledger then we can dispense with the if.
 
    // Return the Rules from the last validated ledger.
    if (auto const ledger = getValidatedLedger())
        return ledger->rules();
 
    return Rules(app_.config().features);
}
 
// This is the last ledger we published to clients and can lag the validated
// ledger.
std::shared_ptr<ReadView const>
LedgerMaster::getPublishedLedger()
{
    std::lock_guard const lock(m_mutex);
    return mPubLedger;
}
 
std::string
LedgerMaster::getCompleteLedgers()
{
    std::lock_guard const sl(mCompleteLock);
    return to_string(mCompleteLedgers);
}
 
std::optional<NetClock::time_point>
LedgerMaster::getCloseTimeBySeq(LedgerIndex ledgerIndex)
{
    uint256 const hash = getHashBySeq(ledgerIndex);
    return hash.isNonZero() ? getCloseTimeByHash(hash, ledgerIndex) : std::nullopt;
}
 
std::optional<NetClock::time_point>
LedgerMaster::getCloseTimeByHash(LedgerHash const& ledgerHash, std::uint32_t index)
{
    auto nodeObject = app_.getNodeStore().fetchNodeObject(ledgerHash, index);
    if (nodeObject && (nodeObject->getData().size() >= 120))
    {
        SerialIter it(nodeObject->getData().data(), nodeObject->getData().size());
        if (safe_cast<HashPrefix>(it.get32()) == HashPrefix::ledgerMaster)
        {
            it.skip(
                4 + 8 + 32 +   // seq drops parentHash
                32 + 32 + 4);  // txHash acctHash parentClose
            return NetClock::time_point{NetClock::duration{it.get32()}};
        }
    }
 
    return std::nullopt;
}
 
uint256
LedgerMaster::getHashBySeq(std::uint32_t index)
{
    uint256 hash = mLedgerHistory.getLedgerHash(index);
 
    if (hash.isNonZero())
        return hash;
 
    return app_.getRelationalDatabase().getHashByIndex(index);
}
 
std::optional<LedgerHash>
LedgerMaster::walkHashBySeq(std::uint32_t index, InboundLedger::Reason reason)
{
    std::optional<LedgerHash> ledgerHash;
 
    if (auto referenceLedger = mValidLedger.get())
        ledgerHash = walkHashBySeq(index, referenceLedger, reason);
 
    return ledgerHash;
}
 
std::optional<LedgerHash>
LedgerMaster::walkHashBySeq(
    std::uint32_t index,
    std::shared_ptr<ReadView const> const& referenceLedger,
    InboundLedger::Reason reason)
{
    if (!referenceLedger || (referenceLedger->header().seq < index))
    {
        // Nothing we can do. No validated ledger.
        return std::nullopt;
    }
 
    // See if the hash for the ledger we need is in the reference ledger
    auto ledgerHash = hashOfSeq(*referenceLedger, index, m_journal);
    if (ledgerHash)
        return ledgerHash;
 
    // The hash is not in the reference ledger. Get another ledger which can
    // be located easily and should contain the hash.
    LedgerIndex const refIndex = getCandidateLedger(index);
    auto const refHash = hashOfSeq(*referenceLedger, refIndex, m_journal);
    XRPL_ASSERT(refHash, "xrpl::LedgerMaster::walkHashBySeq : found ledger");
    if (refHash)
    {
        // Try the hash and sequence of a better reference ledger just found
        auto ledger = mLedgerHistory.getLedgerByHash(*refHash);
 
        if (ledger)
        {
            try
            {
                ledgerHash = hashOfSeq(*ledger, index, m_journal);
            }
            catch (SHAMapMissingNode const&)
            {
                ledger.reset();
            }
        }
 
        // Try to acquire the complete ledger
        if (!ledger)
        {
            if (auto const l = app_.getInboundLedgers().acquire(*refHash, refIndex, reason))
            {
                ledgerHash = hashOfSeq(*l, index, m_journal);
                XRPL_ASSERT(
                    ledgerHash,
                    "xrpl::LedgerMaster::walkHashBySeq : has complete "
                    "ledger");
            }
        }
    }
    return ledgerHash;
}
 
std::shared_ptr<Ledger const>
LedgerMaster::getLedgerBySeq(std::uint32_t index)
{
    if (index <= mValidLedgerSeq)
    {
        // Always prefer a validated ledger
        if (auto valid = mValidLedger.get())
        {
            if (valid->header().seq == index)
                return valid;
 
            try
            {
                auto const hash = hashOfSeq(*valid, index, m_journal);
 
                if (hash)
                    return mLedgerHistory.getLedgerByHash(*hash);
            }
            catch (std::exception const&)  // NOLINT(bugprone-empty-catch)
            {
                // Missing nodes are already handled
            }
        }
    }
 
    if (auto ret = mLedgerHistory.getLedgerBySeq(index))
        return ret;
 
    auto ret = mClosedLedger.get();
    if (ret && (ret->header().seq == index))
        return ret;
 
    clearLedger(index);
    return {};
}
 
std::shared_ptr<Ledger const>
LedgerMaster::getLedgerByHash(uint256 const& hash)
{
    if (auto ret = mLedgerHistory.getLedgerByHash(hash))
        return ret;
 
    auto ret = mClosedLedger.get();
    if (ret && (ret->header().hash == hash))
        return ret;
 
    return {};
}
 
void
LedgerMaster::setLedgerRangePresent(std::uint32_t minV, std::uint32_t maxV)
{
    std::lock_guard const sl(mCompleteLock);
    mCompleteLedgers.insert(range(minV, maxV));
}
 
void
LedgerMaster::sweep()
{
    mLedgerHistory.sweep();
    fetch_packs_.sweep();
}
 
float
LedgerMaster::getCacheHitRate()
{
    return mLedgerHistory.getCacheHitRate();
}
 
void
LedgerMaster::clearPriorLedgers(LedgerIndex seq)
{
    std::lock_guard const sl(mCompleteLock);
    if (seq > 0)
        mCompleteLedgers.erase(range(0u, seq - 1));
}
 
void
LedgerMaster::clearLedgerCachePrior(LedgerIndex seq)
{
    mLedgerHistory.clearLedgerCachePrior(seq);
}
 
void
LedgerMaster::takeReplay(std::unique_ptr<LedgerReplay> replay)
{
    replayData = std::move(replay);
}
 
std::unique_ptr<LedgerReplay>
LedgerMaster::releaseReplay()
{
    return std::move(replayData);
}
 
void
LedgerMaster::fetchForHistory(
    std::uint32_t missing,
    bool& progress,
    InboundLedger::Reason reason,
    std::unique_lock<std::recursive_mutex>& sl)
{
    scope_unlock const sul{sl};
    if (auto hash = getLedgerHashForHistory(missing, reason))
    {
        XRPL_ASSERT(hash->isNonZero(), "xrpl::LedgerMaster::fetchForHistory : found ledger");
        auto ledger = getLedgerByHash(*hash);
        if (!ledger)
        {
            if (!app_.getInboundLedgers().isFailure(*hash))
            {
                ledger = app_.getInboundLedgers().acquire(*hash, missing, reason);
                if (!ledger && missing != fetch_seq_ &&
                    missing > app_.getNodeStore().earliestLedgerSeq())
                {
                    JLOG(m_journal.trace()) << "fetchForHistory want fetch pack " << missing;
                    fetch_seq_ = missing;
                    getFetchPack(missing, reason);
                }
                else
                    JLOG(m_journal.trace()) << "fetchForHistory no fetch pack for " << missing;
            }
            else
                JLOG(m_journal.debug()) << "fetchForHistory found failed acquire";
        }
        if (ledger)
        {
            auto seq = ledger->header().seq;
            XRPL_ASSERT(seq == missing, "xrpl::LedgerMaster::fetchForHistory : sequence match");
            JLOG(m_journal.trace()) << "fetchForHistory acquired " << seq;
            setFullLedger(ledger, false, false);
            int fillInProgress = 0;
            {
                std::lock_guard const lock(m_mutex);
                mHistLedger = ledger;
                fillInProgress = mFillInProgress;
            }
            if (fillInProgress == 0 &&
                app_.getRelationalDatabase().getHashByIndex(seq - 1) == ledger->header().parentHash)
            {
                {
                    // Previous ledger is in DB
                    std::lock_guard const lock(m_mutex);
                    mFillInProgress = seq;
                }
                app_.getJobQueue().addJob(
                    jtADVANCE, "TryFill", [this, ledger]() { tryFill(ledger); });
            }
            progress = true;
        }
        else
        {
            std::uint32_t fetchSz = 0;
            // Do not fetch ledger sequences lower
            // than the earliest ledger sequence
            fetchSz = app_.getNodeStore().earliestLedgerSeq();
            fetchSz =
                missing >= fetchSz ? std::min(ledger_fetch_size_, (missing - fetchSz) + 1) : 0;
            try
            {
                for (std::uint32_t i = 0; i < fetchSz; ++i)
                {
                    std::uint32_t const seq = missing - i;
                    if (auto h = getLedgerHashForHistory(seq, reason))
                    {
                        XRPL_ASSERT(
                            h->isNonZero(),
                            "xrpl::LedgerMaster::fetchForHistory : "
                            "prefetched ledger");
                        app_.getInboundLedgers().acquire(*h, seq, reason);
                    }
                }
            }
            catch (std::exception const& ex)
            {
                JLOG(m_journal.warn()) << "Threw while prefetching: " << ex.what();
            }
        }
    }
    else
    {
        JLOG(m_journal.fatal()) << "Can't find ledger following prevMissing " << missing;
        JLOG(m_journal.fatal()) << "Pub:" << mPubLedgerSeq << " Val:" << mValidLedgerSeq;
        JLOG(m_journal.fatal()) << "Ledgers: " << app_.getLedgerMaster().getCompleteLedgers();
        JLOG(m_journal.fatal()) << "Acquire reason: "
                                << (reason == InboundLedger::Reason::HISTORY ? "HISTORY"
                                                                             : "NOT HISTORY");
        clearLedger(missing + 1);
        progress = true;
    }
}
 
// Try to publish ledgers, acquire missing ledgers
void
LedgerMaster::doAdvance(std::unique_lock<std::recursive_mutex>& sl)
{
    do
    {
        mAdvanceWork = false;  // If there's work to do, we'll make progress
        bool progress = false;
 
        auto const pubLedgers = findNewLedgersToPublish(sl);
        if (pubLedgers.empty())
        {
            if (!standalone_ && !app_.getFeeTrack().isLoadedLocal() &&
                (app_.getJobQueue().getJobCount(jtPUBOLDLEDGER) < 10) &&
                (mValidLedgerSeq == mPubLedgerSeq) &&
                (getValidatedLedgerAge() < MAX_LEDGER_AGE_ACQUIRE) &&
                (app_.getNodeStore().getWriteLoad() < MAX_WRITE_LOAD_ACQUIRE))
            {
                // We are in sync, so can acquire
                InboundLedger::Reason const reason = InboundLedger::Reason::HISTORY;
                std::optional<std::uint32_t> missing;
                {
                    std::lock_guard const sll(mCompleteLock);
                    missing = prevMissing(
                        mCompleteLedgers,
                        mPubLedger->header().seq,
                        app_.getNodeStore().earliestLedgerSeq());
                }
                if (missing)
                {
                    JLOG(m_journal.trace()) << "tryAdvance discovered missing " << *missing;
                    if ((mFillInProgress == 0 || *missing > mFillInProgress) &&
                        shouldAcquire(
                            mValidLedgerSeq,
                            ledger_history_,
                            app_.getSHAMapStore().minimumOnline(),
                            *missing,
                            m_journal))
                    {
                        JLOG(m_journal.trace()) << "advanceThread should acquire";
                    }
                    else
                    {
                        missing = std::nullopt;
                    }
                }
                if (missing)
                {
                    fetchForHistory(*missing, progress, reason, sl);
                    if (mValidLedgerSeq != mPubLedgerSeq)
                    {
                        JLOG(m_journal.debug()) << "tryAdvance found last valid changed";
                        progress = true;
                    }
                }
            }
            else
            {
                mHistLedger.reset();
                JLOG(m_journal.trace()) << "tryAdvance not fetching history";
            }
        }
        else
        {
            JLOG(m_journal.trace())
                << "tryAdvance found " << pubLedgers.size() << " ledgers to publish";
            for (auto const& ledger : pubLedgers)
            {
                {
                    scope_unlock const sul{sl};
                    JLOG(m_journal.debug()) << "tryAdvance publishing seq " << ledger->header().seq;
                    setFullLedger(ledger, true, true);
                }
 
                setPubLedger(ledger);
 
                {
                    scope_unlock const sul{sl};
                    app_.getOPs().pubLedger(ledger);
                }
            }
 
            app_.getOPs().clearNeedNetworkLedger();
            progress = newPFWork("PthFindNewLed", sl);
        }
        if (progress)
            mAdvanceWork = true;
    } while (mAdvanceWork);
}
 
void
LedgerMaster::addFetchPack(uint256 const& hash, std::shared_ptr<Blob> data)
{
    fetch_packs_.canonicalize_replace_client(hash, data);
}
 
std::optional<Blob>
LedgerMaster::getFetchPack(uint256 const& hash)
{
    Blob data;
    if (fetch_packs_.retrieve(hash, data))
    {
        fetch_packs_.del(hash, false);
        if (hash == sha512Half(makeSlice(data)))
            return data;
    }
    return std::nullopt;
}
 
void
LedgerMaster::gotFetchPack(bool progress, std::uint32_t seq)
{
    if (!mGotFetchPackThread.test_and_set(std::memory_order_acquire))
    {
        app_.getJobQueue().addJob(jtLEDGER_DATA, "GotFetchPack", [&]() {
            app_.getInboundLedgers().gotFetchPack();
            mGotFetchPackThread.clear(std::memory_order_release);
        });
    }
}
 
static void
populateFetchPack(
    SHAMap const& want,
    SHAMap const* have,
    std::uint32_t cnt,
    protocol::TMGetObjectByHash* into,
    std::uint32_t seq,
    bool withLeaves = true)
{
    XRPL_ASSERT(cnt, "xrpl::populateFetchPack : nonzero count input");
 
    Serializer s(1024);
 
    want.visitDifferences(have, [&s, withLeaves, &cnt, into, seq](SHAMapTreeNode const& n) -> bool {
        if (!withLeaves && n.isLeaf())
            return true;
 
        s.erase();
        n.serializeWithPrefix(s);
 
        auto const& hash = n.getHash().as_uint256();
 
        protocol::TMIndexedObject* obj = into->add_objects();
        obj->set_ledgerseq(seq);
        obj->set_hash(hash.data(), hash.size());
        obj->set_data(s.getDataPtr(), s.getLength());
 
        return --cnt != 0;
    });
}
 
void
LedgerMaster::makeFetchPack(
    std::weak_ptr<Peer> const& wPeer,
    std::shared_ptr<protocol::TMGetObjectByHash> const& request,
    uint256 haveLedgerHash,
    UptimeClock::time_point uptime)
{
    using namespace std::chrono_literals;
    if (UptimeClock::now() > uptime + 1s)
    {
        JLOG(m_journal.info()) << "Fetch pack request got stale";
        return;
    }
 
    if (app_.getFeeTrack().isLoadedLocal() || (getValidatedLedgerAge() > 40s))
    {
        JLOG(m_journal.info()) << "Too busy to make fetch pack";
        return;
    }
 
    auto peer = wPeer.lock();
 
    if (!peer)
        return;
 
    auto have = getLedgerByHash(haveLedgerHash);
 
    if (!have)
    {
        JLOG(m_journal.info()) << "Peer requests fetch pack for ledger we don't have: " << have;
        peer->charge(Resource::feeRequestNoReply, "get_object ledger");
        return;
    }
 
    if (have->open())
    {
        JLOG(m_journal.warn()) << "Peer requests fetch pack from open ledger: " << have;
        peer->charge(Resource::feeMalformedRequest, "get_object ledger open");
        return;
    }
 
    if (have->header().seq < getEarliestFetch())
    {
        JLOG(m_journal.debug()) << "Peer requests fetch pack that is too early";
        peer->charge(Resource::feeMalformedRequest, "get_object ledger early");
        return;
    }
 
    auto want = getLedgerByHash(have->header().parentHash);
 
    if (!want)
    {
        JLOG(m_journal.info()) << "Peer requests fetch pack for ledger whose predecessor we "
                               << "don't have: " << have;
        peer->charge(Resource::feeRequestNoReply, "get_object ledger no parent");
        return;
    }
 
    try
    {
        Serializer hdr(128);
 
        protocol::TMGetObjectByHash reply;
        reply.set_query(false);
 
        if (request->has_seq())
            reply.set_seq(request->seq());
 
        reply.set_ledgerhash(request->ledgerhash());
        reply.set_type(protocol::TMGetObjectByHash::otFETCH_PACK);
 
        // Building a fetch pack:
        //  1. Add the header for the requested ledger.
        //  2. Add the nodes for the AccountStateMap of that ledger.
        //  3. If there are transactions, add the nodes for the
        //     transactions of the ledger.
        //  4. If the FetchPack now contains at least 512 entries then stop.
        //  5. If not very much time has elapsed, then loop back and repeat
        //     the same process adding the previous ledger to the FetchPack.
        do
        {
            std::uint32_t const lSeq = want->header().seq;
 
            {
                // Serialize the ledger header:
                hdr.erase();
 
                hdr.add32(HashPrefix::ledgerMaster);
                addRaw(want->header(), hdr);
 
                // Add the data
                protocol::TMIndexedObject* obj = reply.add_objects();
                obj->set_hash(want->header().hash.data(), want->header().hash.size());
                obj->set_data(hdr.getDataPtr(), hdr.getLength());
                obj->set_ledgerseq(lSeq);
            }
 
            populateFetchPack(want->stateMap(), &have->stateMap(), 16384, &reply, lSeq);
 
            // We use nullptr here because transaction maps are per ledger
            // and so the requestor is unlikely to already have it.
            if (want->header().txHash.isNonZero())
                populateFetchPack(want->txMap(), nullptr, 512, &reply, lSeq);
 
            if (reply.objects().size() >= 512)
                break;
 
            have = std::move(want);
            want = getLedgerByHash(have->header().parentHash);
        } while (want && UptimeClock::now() <= uptime + 1s);
 
        auto msg = std::make_shared<Message>(reply, protocol::mtGET_OBJECTS);
 
        JLOG(m_journal.info()) << "Built fetch pack with " << reply.objects().size() << " nodes ("
                               << msg->getBufferSize() << " bytes)";
 
        peer->send(msg);
    }
    catch (std::exception const& ex)
    {
        JLOG(m_journal.warn()) << "Exception building fetch pack. Exception: " << ex.what();
    }
}
 
std::size_t
LedgerMaster::getFetchPackCacheSize() const
{
    return fetch_packs_.getCacheSize();
}
 
// Returns the minimum ledger sequence in SQL database, if any.
std::optional<LedgerIndex>
LedgerMaster::minSqlSeq()
{
    return app_.getRelationalDatabase().getMinLedgerSeq();
}
 
std::optional<uint256>
LedgerMaster::txnIdFromIndex(uint32_t ledgerSeq, uint32_t txnIndex)
{
    uint32_t first = 0, last = 0;
 
    if (!getValidatedRange(first, last) || last < ledgerSeq)
        return {};
 
    auto const lgr = getLedgerBySeq(ledgerSeq);
    if (!lgr || lgr->txs.empty())
        return {};
 
    for (auto it = lgr->txs.begin(); it != lgr->txs.end(); ++it)
    {
        if (it->first && it->second && it->second->isFieldPresent(sfTransactionIndex) &&
            it->second->getFieldU32(sfTransactionIndex) == txnIndex)
            return it->first->getTransactionID();
    }
 
    return {};
}
 
}  // namespace xrpl