txmempool.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 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 <memory>
#include <set>
#include <map>
#include <vector>
#include <utility>
#include <string>
 
#include "amount.h"
#include "coins.h"
#include "indirectmap.h"
#include "primitives/transaction.h"
#include "sync.h"
#include "random.h"
 
#undef foreach
#include "boost/multi_index_container.hpp"
#include "boost/multi_index/ordered_index.hpp"
#include "boost/multi_index/hashed_index.hpp"
 
#include <boost/signals2/signal.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:
    CTransactionRef tx;
    CAmount nFee;              
    size_t nTxWeight;          
    size_t nModSize;           
    size_t nUsageSize;         
    int64_t nTime;             
    double entryPriority;      
    unsigned int entryHeight;  
    CAmount inChainInputValue; 
    bool spendsCoinbase;       
    int64_t sigOpCost;         
    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; 
 
    // Analogous statistics for ancestor transactions
    uint64_t nCountWithAncestors;
    uint64_t nSizeWithAncestors;
    CAmount nModFeesWithAncestors;
    int64_t nSigOpCostWithAncestors;
 
public:
    CTxMemPoolEntry(const CTransactionRef& _tx, const CAmount& _nFee,
                    int64_t _nTime, double _entryPriority, unsigned int _entryHeight,
                    CAmount _inChainInputValue, bool spendsCoinbase,
                    int64_t nSigOpsCost, LockPoints lp);
 
    CTxMemPoolEntry(const CTxMemPoolEntry& other);
 
    const CTransaction& GetTx() const { return *this->tx; }
    CTransactionRef GetSharedTx() const { return this->tx; }
    double GetPriority(unsigned int currentHeight) const;
    const CAmount& GetFee() const { return nFee; }
    size_t GetTxSize() const;
    size_t GetTxWeight() const { return nTxWeight; }
    int64_t GetTime() const { return nTime; }
    unsigned int GetHeight() const { return entryHeight; }
    int64_t GetSigOpCost() const { return sigOpCost; }
    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 UpdateDescendantState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount);
    // Adjusts the ancestor state
    void UpdateAncestorState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount, int modifySigOps);
    // 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);
 
    uint64_t GetCountWithDescendants() const { return nCountWithDescendants; }
    uint64_t GetSizeWithDescendants() const { return nSizeWithDescendants; }
    CAmount GetModFeesWithDescendants() const { return nModFeesWithDescendants; }
 
    bool GetSpendsCoinbase() const { return spendsCoinbase; }
 
    uint64_t GetCountWithAncestors() const { return nCountWithAncestors; }
    uint64_t GetSizeWithAncestors() const { return nSizeWithAncestors; }
    CAmount GetModFeesWithAncestors() const { return nModFeesWithAncestors; }
    int64_t GetSigOpCostWithAncestors() const { return nSigOpCostWithAncestors; }
 
    mutable size_t vTxHashesIdx; 
};
 
// 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.UpdateDescendantState(modifySize, modifyFee, modifyCount); }
 
    private:
        int64_t modifySize;
        CAmount modifyFee;
        int64_t modifyCount;
};
 
struct update_ancestor_state
{
    update_ancestor_state(int64_t _modifySize, CAmount _modifyFee, int64_t _modifyCount, int64_t _modifySigOpsCost) :
        modifySize(_modifySize), modifyFee(_modifyFee), modifyCount(_modifyCount), modifySigOpsCost(_modifySigOpsCost)
    {}
 
    void operator() (CTxMemPoolEntry &e)
        { e.UpdateAncestorState(modifySize, modifyFee, modifyCount, modifySigOpsCost); }
 
    private:
        int64_t modifySize;
        CAmount modifyFee;
        int64_t modifyCount;
        int64_t modifySigOpsCost;
};
 
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) const
    {
        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) const
    {
        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) const
    {
        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) const
    {
        return a.GetTime() < b.GetTime();
    }
};
 
class CompareTxMemPoolEntryByAncestorFee
{
public:
    bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b) const
    {
        double aFees = a.GetModFeesWithAncestors();
        double aSize = a.GetSizeWithAncestors();
 
        double bFees = b.GetModFeesWithAncestors();
        double bSize = b.GetSizeWithAncestors();
 
        // Avoid division by rewriting (a/b > c/d) as (a*d > c*b).
        double f1 = aFees * bSize;
        double f2 = aSize * bFees;
 
        if (f1 == f2) {
            return a.GetTx().GetHash() < b.GetTx().GetHash();
        }
 
        return f1 > f2;
    }
};
 
// Multi_index tag names
struct descendant_score {};
struct entry_time {};
struct mining_score {};
struct ancestor_score {};
 
class CBlockPolicyEstimator;
 
struct TxMempoolInfo
{
    CTransactionRef tx;
 
    int64_t nTime;
 
    CFeeRate feeRate;
 
    int64_t nFeeDelta;
};
 
enum class MemPoolRemovalReason {
    UNKNOWN = 0, 
    EXPIRY,      
    SIZELIMIT,   
    REORG,       
    BLOCK,       
    CONFLICT,    
    REPLACED     
};
 
class CTxMemPool
{
private:
    uint32_t nCheckFrequency; 
    unsigned int nTransactionsUpdated; 
    CBlockPolicyEstimator* minerPolicyEstimator;
 
    uint64_t totalTxSize;      
    uint64_t cachedInnerUsage; 
 
    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::hashed_unique<mempoolentry_txid, SaltedTxidHasher>,
            // sorted by fee rate
            boost::multi_index::ordered_non_unique<
                boost::multi_index::tag<descendant_score>,
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByDescendantScore
            >,
            // sorted by entry time
            boost::multi_index::ordered_non_unique<
                boost::multi_index::tag<entry_time>,
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByEntryTime
            >,
            // sorted by score (for mining prioritization)
            boost::multi_index::ordered_unique<
                boost::multi_index::tag<mining_score>,
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByScore
            >,
            // sorted by fee rate with ancestors
            boost::multi_index::ordered_non_unique<
                boost::multi_index::tag<ancestor_score>,
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByAncestorFee
            >
        >
    > indexed_transaction_set;
 
    mutable CCriticalSection cs;
    indexed_transaction_set mapTx;
 
    typedef indexed_transaction_set::nth_index<0>::type::iterator txiter;
    std::vector<std::pair<uint256, txiter> > vTxHashes; 
 
    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;
 
    void UpdateParent(txiter entry, txiter parent, bool add);
    void UpdateChild(txiter entry, txiter child, bool add);
 
    std::vector<indexed_transaction_set::const_iterator> GetSortedDepthAndScore() const;
 
public:
    indirectmap<COutPoint, const CTransaction*> 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 validFeeEstimate = true);
    bool addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, setEntries &setAncestors, bool validFeeEstimate = true);
 
    void removeRecursive(const CTransaction &tx, MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
    void removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMemPoolHeight, int flags);
    void removeConflicts(const CTransaction &tx);
    void removeForBlock(const std::vector<CTransactionRef>& vtx, unsigned int nBlockHeight);
 
    void clear();
    void _clear(); //lock free
    bool CompareDepthAndScore(const uint256& hasha, const uint256& hashb);
    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, bool updateDescendants, MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
 
    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) const;
 
    void CalculateDescendants(txiter it, setEntries &setDescendants);
 
    CFeeRate GetMinFee(size_t sizelimit) const;
 
    void TrimToSize(size_t sizelimit, std::vector<uint256>* pvNoSpendsRemaining=NULL);
 
    int Expire(int64_t time);
 
    bool TransactionWithinChainLimit(const uint256& txid, size_t chainLimit) const;
 
    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);
    }
 
    CTransactionRef get(const uint256& hash) const;
    TxMempoolInfo info(const uint256& hash) const;
    std::vector<TxMempoolInfo> infoAll() 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;
 
    boost::signals2::signal<void (CTransactionRef)> NotifyEntryAdded;
    boost::signals2::signal<void (CTransactionRef, MemPoolRemovalReason)> NotifyEntryRemoved;
 
private:
    void UpdateForDescendants(txiter updateIt,
            cacheMap &cachedDescendants,
            const std::set<uint256> &setExclude);
    void UpdateAncestorsOf(bool add, txiter hash, setEntries &setAncestors);
    void UpdateEntryForAncestors(txiter it, const setEntries &setAncestors);
    void UpdateForRemoveFromMempool(const setEntries &entriesToRemove, bool updateDescendants);
    void UpdateChildrenForRemoval(txiter entry);
 
    void removeUnchecked(txiter entry, MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
};
 
class CCoinsViewMemPool : public CCoinsViewBacked
{
protected:
    const CTxMemPool& mempool;
 
public:
    CCoinsViewMemPool(CCoinsView* baseIn, const 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