{

public:

enum class AddResult

{

ADD_STATUS_PENDING = 0,

ADD_STATUS_DUPLICATE,

ADD_STATUS_ERROR,

ADD_STATUS_TRY_AGAIN_LATER,

ADD_STATUS_COUNT

};

struct AccountTxQueueInfo

{

SequenceNumber mMaxSeq{0};

int64_t mTotalFees{0};

friend bool operator==(AccountTxQueueInfo const& x,

AccountTxQueueInfo const& y);

};

struct TxMap

{

AccountTxQueueInfo mCurrentQInfo;

std::unordered_map<Hash, TransactionFramePtr> mTransactions;

void addTx(TransactionFramePtr);

void recalculate();

};

typedef std::unordered_map<AccountID, std::shared_ptr<TxMap>> AccountTxMap;

explicit TransactionQueue(Application& app, int pendingDepth, int banDepth);

AddResult tryAdd(TransactionFramePtr tx);

// it is the responsibility of the caller to always remove such sets of

// transactions that remaining ones have their sequence numbers increasing

// by one

void remove(std::vector<TransactionFramePtr> const& txs);

// remove oldest transactions and move all other transactions to slots older

// by one, this results in newest queue slot being empty

void shift();

AccountTxQueueInfo

getAccountTransactionQueueInfo(AccountID const& accountID) const;

int countBanned(int index) const;

bool isBanned(Hash const& hash) const;

std::shared_ptr<TxSetFrame> toTxSet(Hash const& lclHash) const;

private:

Application& mApp;

std::vector<medida::Counter*> mSizeByAge;

std::deque<AccountTxMap> mPendingTransactions;

std::deque<std::unordered_set<Hash>> mBannedTransactions;

bool contains(TransactionFramePtr tx) const;