txmempool.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2015 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_TXMEMPOOL_H
#define BITCOIN_TXMEMPOOL_H

#include <list>
#include <set>

#include "addressindex.h"
#include "spentindex.h"
#include "amount.h"
#include "coins.h"
#include "primitives/transaction.h"
#include "sync.h"

#undef foreach
#include "boost/multi_index_container.hpp"
#include "boost/multi_index/ordered_index.hpp"

class CAutoFile;
class CBlockIndex;

inline double AllowFreeThreshold()
{
    return COIN * 144 / 250;
}

inline bool AllowFree(double dPriority)
{
    // Large (in bytes) low-priority (new, small-coin) transactions
    // need a fee.
    return dPriority > AllowFreeThreshold();
}


static const unsigned int MEMPOOL_HEIGHT = 0x7FFFFFFF;

struct LockPoints
{
    // Will be set to the blockchain height and median time past
    // values that would be necessary to satisfy all relative locktime
    // constraints (BIP68) of this tx given our view of block chain history
    int height;
    int64_t time;
    // As long as the current chain descends from the highest height block
    // containing one of the inputs used in the calculation, then the cached
    // values are still valid even after a reorg.
    CBlockIndex* maxInputBlock;

    LockPoints() : height(0), time(0), maxInputBlock(NULL) { }
};

class CTxMemPool;

class CTxMemPoolEntry
{
private:
    CTransaction tx;
    CAmount nFee; 
    size_t nTxSize; 
    size_t nModSize; 
    size_t nUsageSize; 
    int64_t nTime; 
    double entryPriority; 
    unsigned int entryHeight; 
    bool hadNoDependencies; 
    CAmount inChainInputValue; 
    bool spendsCoinbase; 
    unsigned int sigOpCount; 
    int64_t feeDelta; 
    LockPoints lockPoints; 

    // Information about descendants of this transaction that are in the
    // mempool; if we remove this transaction we must remove all of these
    // descendants as well.  if nCountWithDescendants is 0, treat this entry as
    // dirty, and nSizeWithDescendants and nModFeesWithDescendants will not be
    // correct.
    uint64_t nCountWithDescendants; 
    uint64_t nSizeWithDescendants;  
    CAmount nModFeesWithDescendants;  

public:
    CTxMemPoolEntry(const CTransaction& _tx, const CAmount& _nFee,
                    int64_t _nTime, double _entryPriority, unsigned int _entryHeight,
                    bool poolHasNoInputsOf, CAmount _inChainInputValue, bool spendsCoinbase,
                    unsigned int nSigOps, LockPoints lp);
    CTxMemPoolEntry(const CTxMemPoolEntry& other);

    const CTransaction& GetTx() const { return this->tx; }
    double GetPriority(unsigned int currentHeight) const;
    const CAmount& GetFee() const { return nFee; }
    size_t GetTxSize() const { return nTxSize; }
    int64_t GetTime() const { return nTime; }
    unsigned int GetHeight() const { return entryHeight; }
    bool WasClearAtEntry() const { return hadNoDependencies; }
    unsigned int GetSigOpCount() const { return sigOpCount; }
    int64_t GetModifiedFee() const { return nFee + feeDelta; }
    size_t DynamicMemoryUsage() const { return nUsageSize; }
    const LockPoints& GetLockPoints() const { return lockPoints; }

    // Adjusts the descendant state, if this entry is not dirty.
    void UpdateState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount);
    // Updates the fee delta used for mining priority score, and the
    // modified fees with descendants.
    void UpdateFeeDelta(int64_t feeDelta);
    // Update the LockPoints after a reorg
    void UpdateLockPoints(const LockPoints& lp);

    void SetDirty();
    bool IsDirty() const { return nCountWithDescendants == 0; }

    uint64_t GetCountWithDescendants() const { return nCountWithDescendants; }
    uint64_t GetSizeWithDescendants() const { return nSizeWithDescendants; }
    CAmount GetModFeesWithDescendants() const { return nModFeesWithDescendants; }

    bool GetSpendsCoinbase() const { return spendsCoinbase; }
};

// Helpers for modifying CTxMemPool::mapTx, which is a boost multi_index.
struct update_descendant_state
{
    update_descendant_state(int64_t _modifySize, CAmount _modifyFee, int64_t _modifyCount) :
        modifySize(_modifySize), modifyFee(_modifyFee), modifyCount(_modifyCount)
    {}

    void operator() (CTxMemPoolEntry &e)
        { e.UpdateState(modifySize, modifyFee, modifyCount); }

    private:
        int64_t modifySize;
        CAmount modifyFee;
        int64_t modifyCount;
};

struct set_dirty
{
    void operator() (CTxMemPoolEntry &e)
        { e.SetDirty(); }
};

struct update_fee_delta
{
    update_fee_delta(int64_t _feeDelta) : feeDelta(_feeDelta) { }

    void operator() (CTxMemPoolEntry &e) { e.UpdateFeeDelta(feeDelta); }

private:
    int64_t feeDelta;
};

struct update_lock_points
{
    update_lock_points(const LockPoints& _lp) : lp(_lp) { }

    void operator() (CTxMemPoolEntry &e) { e.UpdateLockPoints(lp); }

private:
    const LockPoints& lp;
};

// extracts a TxMemPoolEntry's transaction hash
struct mempoolentry_txid
{
    typedef uint256 result_type;
    result_type operator() (const CTxMemPoolEntry &entry) const
    {
        return entry.GetTx().GetHash();
    }
};

class CompareTxMemPoolEntryByDescendantScore
{
public:
    bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b)
    {
        bool fUseADescendants = UseDescendantScore(a);
        bool fUseBDescendants = UseDescendantScore(b);

        double aModFee = fUseADescendants ? a.GetModFeesWithDescendants() : a.GetModifiedFee();
        double aSize = fUseADescendants ? a.GetSizeWithDescendants() : a.GetTxSize();

        double bModFee = fUseBDescendants ? b.GetModFeesWithDescendants() : b.GetModifiedFee();
        double bSize = fUseBDescendants ? b.GetSizeWithDescendants() : b.GetTxSize();

        // Avoid division by rewriting (a/b > c/d) as (a*d > c*b).
        double f1 = aModFee * bSize;
        double f2 = aSize * bModFee;

        if (f1 == f2) {
            return a.GetTime() >= b.GetTime();
        }
        return f1 < f2;
    }

    // Calculate which score to use for an entry (avoiding division).
    bool UseDescendantScore(const CTxMemPoolEntry &a)
    {
        double f1 = (double)a.GetModifiedFee() * a.GetSizeWithDescendants();
        double f2 = (double)a.GetModFeesWithDescendants() * a.GetTxSize();
        return f2 > f1;
    }
};

class CompareTxMemPoolEntryByScore
{
public:
    bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b)
    {
        double f1 = (double)a.GetModifiedFee() * b.GetTxSize();
        double f2 = (double)b.GetModifiedFee() * a.GetTxSize();
        if (f1 == f2) {
            return b.GetTx().GetHash() < a.GetTx().GetHash();
        }
        return f1 > f2;
    }
};

class CompareTxMemPoolEntryByEntryTime
{
public:
    bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b)
    {
        return a.GetTime() < b.GetTime();
    }
};

class CBlockPolicyEstimator;

class CInPoint
{
public:
    const CTransaction* ptx;
    uint32_t n;

    CInPoint() { SetNull(); }
    CInPoint(const CTransaction* ptxIn, uint32_t nIn) { ptx = ptxIn; n = nIn; }
    void SetNull() { ptx = NULL; n = (uint32_t) -1; }
    bool IsNull() const { return (ptx == NULL && n == (uint32_t) -1); }
    size_t DynamicMemoryUsage() const { return 0; }
};

class CTxMemPool
{
private:
    uint32_t nCheckFrequency; 
    unsigned int nTransactionsUpdated;
    CBlockPolicyEstimator* minerPolicyEstimator;

    uint64_t totalTxSize; 
    uint64_t cachedInnerUsage; 

    CFeeRate minReasonableRelayFee;

    mutable int64_t lastRollingFeeUpdate;
    mutable bool blockSinceLastRollingFeeBump;
    mutable double rollingMinimumFeeRate; 

    void trackPackageRemoved(const CFeeRate& rate);

public:

    static const int ROLLING_FEE_HALFLIFE = 60 * 60 * 12; // public only for testing

    typedef boost::multi_index_container<
        CTxMemPoolEntry,
        boost::multi_index::indexed_by<
            // sorted by txid
            boost::multi_index::ordered_unique<mempoolentry_txid>,
            // sorted by fee rate
            boost::multi_index::ordered_non_unique<
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByDescendantScore
            >,
            // sorted by entry time
            boost::multi_index::ordered_non_unique<
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByEntryTime
                >,
            // sorted by score (for mining prioritization)
            boost::multi_index::ordered_unique<
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByScore
            >
        >
    > indexed_transaction_set;

    mutable CCriticalSection cs;
    indexed_transaction_set mapTx;
    typedef indexed_transaction_set::nth_index<0>::type::iterator txiter;
    struct CompareIteratorByHash {
        bool operator()(const txiter &a, const txiter &b) const {
            return a->GetTx().GetHash() < b->GetTx().GetHash();
        }
    };
    typedef std::set<txiter, CompareIteratorByHash> setEntries;

    const setEntries & GetMemPoolParents(txiter entry) const;
    const setEntries & GetMemPoolChildren(txiter entry) const;
private:
    typedef std::map<txiter, setEntries, CompareIteratorByHash> cacheMap;

    struct TxLinks {
        setEntries parents;
        setEntries children;
    };

    typedef std::map<txiter, TxLinks, CompareIteratorByHash> txlinksMap;
    txlinksMap mapLinks;

    typedef std::map<CMempoolAddressDeltaKey, CMempoolAddressDelta, CMempoolAddressDeltaKeyCompare> addressDeltaMap;
    addressDeltaMap mapAddress;

    typedef std::map<uint256, std::vector<CMempoolAddressDeltaKey> > addressDeltaMapInserted;
    addressDeltaMapInserted mapAddressInserted;

    typedef std::map<CSpentIndexKey, CSpentIndexValue, CSpentIndexKeyCompare> mapSpentIndex;
    mapSpentIndex mapSpent;

    typedef std::map<uint256, std::vector<CSpentIndexKey> > mapSpentIndexInserted;
    mapSpentIndexInserted mapSpentInserted;

    void UpdateParent(txiter entry, txiter parent, bool add);
    void UpdateChild(txiter entry, txiter child, bool add);

public:
    std::map<COutPoint, CInPoint> mapNextTx;
    std::map<uint256, std::pair<double, CAmount> > mapDeltas;

    CTxMemPool(const CFeeRate& _minReasonableRelayFee);
    ~CTxMemPool();

    void check(const CCoinsViewCache *pcoins) const;
    void setSanityCheck(double dFrequency = 1.0) { nCheckFrequency = dFrequency * 4294967295.0; }

    // addUnchecked must updated state for all ancestors of a given transaction,
    // to track size/count of descendant transactions.  First version of
    // addUnchecked can be used to have it call CalculateMemPoolAncestors(), and
    // then invoke the second version.
    bool addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, bool fCurrentEstimate = true);
    bool addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, setEntries &setAncestors, bool fCurrentEstimate = true);

    void addAddressIndex(const CTxMemPoolEntry &entry, const CCoinsViewCache &view);
    bool getAddressIndex(std::vector<std::pair<uint160, int> > &addresses,
                         std::vector<std::pair<CMempoolAddressDeltaKey, CMempoolAddressDelta> > &results);
    bool removeAddressIndex(const uint256 txhash);

    void addSpentIndex(const CTxMemPoolEntry &entry, const CCoinsViewCache &view);
    bool getSpentIndex(CSpentIndexKey &key, CSpentIndexValue &value);
    bool removeSpentIndex(const uint256 txhash);

    void remove(const CTransaction &tx, std::list<CTransaction>& removed, bool fRecursive = false);
    void removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMemPoolHeight, int flags);
    void removeConflicts(const CTransaction &tx, std::list<CTransaction>& removed);
    void removeForBlock(const std::vector<CTransaction>& vtx, unsigned int nBlockHeight,
                        std::list<CTransaction>& conflicts, bool fCurrentEstimate = true);
    void clear();
    void _clear(); //lock free
    void queryHashes(std::vector<uint256>& vtxid);
    void pruneSpent(const uint256& hash, CCoins &coins);
    unsigned int GetTransactionsUpdated() const;
    void AddTransactionsUpdated(unsigned int n);
    bool HasNoInputsOf(const CTransaction& tx) const;

    void PrioritiseTransaction(const uint256 hash, const std::string strHash, double dPriorityDelta, const CAmount& nFeeDelta);
    void ApplyDeltas(const uint256 hash, double &dPriorityDelta, CAmount &nFeeDelta) const;
    void ClearPrioritisation(const uint256 hash);

public:
    void RemoveStaged(setEntries &stage);

    void UpdateTransactionsFromBlock(const std::vector<uint256> &hashesToUpdate);

    bool CalculateMemPoolAncestors(const CTxMemPoolEntry &entry, setEntries &setAncestors, uint64_t limitAncestorCount, uint64_t limitAncestorSize, uint64_t limitDescendantCount, uint64_t limitDescendantSize, std::string &errString, bool fSearchForParents = true);

    void CalculateDescendants(txiter it, setEntries &setDescendants);

    CFeeRate GetMinFee(size_t sizelimit) const;
    void UpdateMinFee(const CFeeRate& _minReasonableRelayFee);

    void TrimToSize(size_t sizelimit, std::vector<uint256>* pvNoSpendsRemaining=NULL);

    int Expire(int64_t time);

    unsigned long size()
    {
        LOCK(cs);
        return mapTx.size();
    }

    uint64_t GetTotalTxSize()
    {
        LOCK(cs);
        return totalTxSize;
    }

    bool exists(uint256 hash) const
    {
        LOCK(cs);
        return (mapTx.count(hash) != 0);
    }

    bool lookup(uint256 hash, CTransaction& result) const;

    CFeeRate estimateSmartFee(int nBlocks, int *answerFoundAtBlocks = NULL) const;

    CFeeRate estimateFee(int nBlocks) const;

    double estimateSmartPriority(int nBlocks, int *answerFoundAtBlocks = NULL) const;

    double estimatePriority(int nBlocks) const;
    
    bool WriteFeeEstimates(CAutoFile& fileout) const;
    bool ReadFeeEstimates(CAutoFile& filein);

    size_t DynamicMemoryUsage() const;

private:
    bool UpdateForDescendants(txiter updateIt,
            int maxDescendantsToVisit,
            cacheMap &cachedDescendants,
            const std::set<uint256> &setExclude);
    void UpdateAncestorsOf(bool add, txiter hash, setEntries &setAncestors);
    void UpdateForRemoveFromMempool(const setEntries &entriesToRemove);
    void UpdateChildrenForRemoval(txiter entry);

    void removeUnchecked(txiter entry);
};

class CCoinsViewMemPool : public CCoinsViewBacked
{
protected:
    CTxMemPool &mempool;

public:
    CCoinsViewMemPool(CCoinsView *baseIn, CTxMemPool &mempoolIn);
    bool GetCoins(const uint256 &txid, CCoins &coins) const;
    bool HaveCoins(const uint256 &txid) const;
};

// We want to sort transactions by coin age priority
typedef std::pair<double, CTxMemPool::txiter> TxCoinAgePriority;

struct TxCoinAgePriorityCompare
{
    bool operator()(const TxCoinAgePriority& a, const TxCoinAgePriority& b)
    {
        if (a.first == b.first)
            return CompareTxMemPoolEntryByScore()(*(b.second), *(a.second)); //Reverse order to make sort less than
        return a.first < b.first;
    }
};

#endif // BITCOIN_TXMEMPOOL_H