// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 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 "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;
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();
}
/** Fake height value used in CCoins to signify they are only in the memory pool (since 0.8) */
static const unsigned int MEMPOOL_HEIGHT = 0x7FFFFFFF;
class CTxMemPool;
/** \class CTxMemPoolEntry
*
* CTxMemPoolEntry stores data about the correponding transaction, as well
* as data about all in-mempool transactions that depend on the transaction
* ("descendant" transactions).
*
* When a new entry is added to the mempool, we update the descendant state
* (nCountWithDescendants, nSizeWithDescendants, and nFeesWithDescendants) for
* all ancestors of the newly added transaction.
*
* If updating the descendant state is skipped, we can mark the entry as
* "dirty", and set nSizeWithDescendants/nFeesWithDescendants to equal nTxSize/
* nTxFee. (This can potentially happen during a reorg, where we limit the
* amount of work we're willing to do to avoid consuming too much CPU.)
*
*/
class CTxMemPoolEntry
{
private:
CTransaction tx;
CAmount nFee; //! Cached to avoid expensive parent-transaction lookups
size_t nTxSize; //! ... and avoid recomputing tx size
size_t nModSize; //! ... and modified size for priority
size_t nUsageSize; //! ... and total memory usage
int64_t nTime; //! Local time when entering the mempool
double entryPriority; //! Priority when entering the mempool
unsigned int entryHeight; //! Chain height when entering the mempool
bool hadNoDependencies; //! Not dependent on any other txs when it entered the mempool
CAmount inChainInputValue; //! Sum of all txin values that are already in blockchain
bool spendsCoinbase; //! keep track of transactions that spend a coinbase
unsigned int sigOpCount; //! Legacy sig ops plus P2SH sig op count
int64_t feeDelta; //! Used for determining the priority of the transaction for mining in a block
// 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 nFeesWithDescendants will not be
// correct.
uint64_t nCountWithDescendants; //! number of descendant transactions
uint64_t nSizeWithDescendants; //! ... and size
CAmount nFeesWithDescendants; //! ... and total fees (all including us)
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);
CTxMemPoolEntry(const CTxMemPoolEntry& other);
const CTransaction& GetTx() const { return this->tx; }
/**
* Fast calculation of lower bound of current priority as update
* from entry priority. Only inputs that were originally in-chain will age.
*/
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; }
// 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
void UpdateFeeDelta(int64_t feeDelta);
/** We can set the entry to be dirty if doing the full calculation of in-
* mempool descendants will be too expensive, which can potentially happen
* when re-adding transactions from a block back to the mempool.
*/
void SetDirty();
bool IsDirty() const { return nCountWithDescendants == 0; }
uint64_t GetCountWithDescendants() const { return nCountWithDescendants; }
uint64_t GetSizeWithDescendants() const { return nSizeWithDescendants; }
CAmount GetFeesWithDescendants() const { return nFeesWithDescendants; }
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;
};
// 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 CompareTxMemPoolEntryByFee
*
* Sort an entry by max(feerate of entry's tx, feerate with all descendants).
*/
class CompareTxMemPoolEntryByFee
{
public:
bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b)
{
bool fUseADescendants = UseDescendantFeeRate(a);
bool fUseBDescendants = UseDescendantFeeRate(b);
double aFees = fUseADescendants ? a.GetFeesWithDescendants() : a.GetFee();
double aSize = fUseADescendants ? a.GetSizeWithDescendants() : a.GetTxSize();
double bFees = fUseBDescendants ? b.GetFeesWithDescendants() : b.GetFee();
double bSize = fUseBDescendants ? b.GetSizeWithDescendants() : b.GetTxSize();
// 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.GetTime() >= b.GetTime();
}
return f1 < f2;
}
// Calculate which feerate to use for an entry (avoiding division).
bool UseDescendantFeeRate(const CTxMemPoolEntry &a)
{
double f1 = (double)a.GetFee() * a.GetSizeWithDescendants();
double f2 = (double)a.GetFeesWithDescendants() * a.GetTxSize();
return f2 > f1;
}
};
/** \class CompareTxMemPoolEntryByScore
*
* Sort by score of entry ((fee+delta)/size) in descending order
*/
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;
/** An inpoint - a combination of a transaction and an index n into its vin */
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; }
};
/**
* CTxMemPool stores valid-according-to-the-current-best-chain
* transactions that may be included in the next block.
*
* Transactions are added when they are seen on the network
* (or created by the local node), but not all transactions seen
* are added to the pool: if a new transaction double-spends
* an input of a transaction in the pool, it is dropped,
* as are non-standard transactions.
*
* CTxMemPool::mapTx, and CTxMemPoolEntry bookkeeping:
*
* mapTx is a boost::multi_index that sorts the mempool on 4 criteria:
* - transaction hash
* - feerate [we use max(feerate of tx, feerate of tx with all descendants)]
* - time in mempool
* - mining score (feerate modified by any fee deltas from PrioritiseTransaction)
*
* Note: the term "descendant" refers to in-mempool transactions that depend on
* this one, while "ancestor" refers to in-mempool transactions that a given
* transaction depends on.
*
* In order for the feerate sort to remain correct, we must update transactions
* in the mempool when new descendants arrive. To facilitate this, we track
* the set of in-mempool direct parents and direct children in mapLinks. Within
* each CTxMemPoolEntry, we track the size and fees of all descendants.
*
* Usually when a new transaction is added to the mempool, it has no in-mempool
* children (because any such children would be an orphan). So in
* addUnchecked(), we:
* - update a new entry's setMemPoolParents to include all in-mempool parents
* - update the new entry's direct parents to include the new tx as a child
* - update all ancestors of the transaction to include the new tx's size/fee
*
* When a transaction is removed from the mempool, we must:
* - update all in-mempool parents to not track the tx in setMemPoolChildren
* - update all ancestors to not include the tx's size/fees in descendant state
* - update all in-mempool children to not include it as a parent
*
* These happen in UpdateForRemoveFromMempool(). (Note that when removing a
* transaction along with its descendants, we must calculate that set of
* transactions to be removed before doing the removal, or else the mempool can
* be in an inconsistent state where it's impossible to walk the ancestors of
* a transaction.)
*
* In the event of a reorg, the assumption that a newly added tx has no
* in-mempool children is false. In particular, the mempool is in an
* inconsistent state while new transactions are being added, because there may
* be descendant transactions of a tx coming from a disconnected block that are
* unreachable from just looking at transactions in the mempool (the linking
* transactions may also be in the disconnected block, waiting to be added).
* Because of this, there's not much benefit in trying to search for in-mempool
* children in addUnchecked(). Instead, in the special case of transactions
* being added from a disconnected block, we require the caller to clean up the
* state, to account for in-mempool, out-of-block descendants for all the
* in-block transactions by calling UpdateTransactionsFromBlock(). Note that
* until this is called, the mempool state is not consistent, and in particular
* mapLinks may not be correct (and therefore functions like
* CalculateMemPoolAncestors() and CalculateDescendants() that rely
* on them to walk the mempool are not generally safe to use).
*
* Computational limits:
*
* Updating all in-mempool ancestors of a newly added transaction can be slow,
* if no bound exists on how many in-mempool ancestors there may be.
* CalculateMemPoolAncestors() takes configurable limits that are designed to
* prevent these calculations from being too CPU intensive.
*
* Adding transactions from a disconnected block can be very time consuming,
* because we don't have a way to limit the number of in-mempool descendants.
* To bound CPU processing, we limit the amount of work we're willing to do
* to properly update the descendant information for a tx being added from
* a disconnected block. If we would exceed the limit, then we instead mark
* the entry as "dirty", and set the feerate for sorting purposes to be equal
* the feerate of the transaction without any descendants.
*
*/
class CTxMemPool
{
private:
uint32_t nCheckFrequency; //! Value n means that n times in 2^32 we check.
unsigned int nTransactionsUpdated;
CBlockPolicyEstimator* minerPolicyEstimator;
uint64_t totalTxSize; //! sum of all mempool tx' byte sizes
uint64_t cachedInnerUsage; //! sum of dynamic memory usage of all the map elements (NOT the maps themselves)
CFeeRate minReasonableRelayFee;
mutable int64_t lastRollingFeeUpdate;
mutable bool blockSinceLastRollingFeeBump;
mutable double rollingMinimumFeeRate; //! minimum fee to get into the pool, decreases exponentially
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>,
CompareTxMemPoolEntryByFee
>,
// 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;
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;
/** Create a new CTxMemPool.
* minReasonableRelayFee should be a feerate which is, roughly, somewhere
* around what it "costs" to relay a transaction around the network and
* below which we would reasonably say a transaction has 0-effective-fee.
*/
CTxMemPool(const CFeeRate& _minReasonableRelayFee);
~CTxMemPool();
/**
* If sanity-checking is turned on, check makes sure the pool is
* consistent (does not contain two transactions that spend the same inputs,
* all inputs are in the mapNextTx array). If sanity-checking is turned off,
* check does nothing.
*/
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 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);
/**
* Check that none of this transactions inputs are in the mempool, and thus
* the tx is not dependent on other mempool transactions to be included in a block.
*/
bool HasNoInputsOf(const CTransaction& tx) const;
/** Affect CreateNewBlock prioritisation of transactions */
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:
/** Remove a set of transactions from the mempool.
* If a transaction is in this set, then all in-mempool descendants must
* also be in the set.*/
void RemoveStaged(setEntries &stage);
/** When adding transactions from a disconnected block back to the mempool,
* new mempool entries may have children in the mempool (which is generally
* not the case when otherwise adding transactions).
* UpdateTransactionsFromBlock() will find child transactions and update the
* descendant state for each transaction in hashesToUpdate (excluding any
* child transactions present in hashesToUpdate, which are already accounted
* for). Note: hashesToUpdate should be the set of transactions from the
* disconnected block that have been accepted back into the mempool.
*/
void UpdateTransactionsFromBlock(const std::vector<uint256> &hashesToUpdate);
/** Try to calculate all in-mempool ancestors of entry.
* (these are all calculated including the tx itself)
* limitAncestorCount = max number of ancestors
* limitAncestorSize = max size of ancestors
* limitDescendantCount = max number of descendants any ancestor can have
* limitDescendantSize = max size of descendants any ancestor can have
* errString = populated with error reason if any limits are hit
* fSearchForParents = whether to search a tx's vin for in-mempool parents, or
* look up parents from mapLinks. Must be true for entries not in the mempool
*/
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);
/** Populate setDescendants with all in-mempool descendants of hash.
* Assumes that setDescendants includes all in-mempool descendants of anything
* already in it. */
void CalculateDescendants(txiter it, setEntries &setDescendants);
/** The minimum fee to get into the mempool, which may itself not be enough
* for larger-sized transactions.
* The minReasonableRelayFee constructor arg is used to bound the time it
* takes the fee rate to go back down all the way to 0. When the feerate
* would otherwise be half of this, it is set to 0 instead.
*/
CFeeRate GetMinFee(size_t sizelimit) const;
/** Remove transactions from the mempool until its dynamic size is <= sizelimit.
* pvNoSpendsRemaining, if set, will be populated with the list of transactions
* which are not in mempool which no longer have any spends in this mempool.
*/
void TrimToSize(size_t sizelimit, std::vector<uint256>* pvNoSpendsRemaining=NULL);
/** Expire all transaction (and their dependencies) in the mempool older than time. Return the number of removed transactions. */
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;
/** Estimate fee rate needed to get into the next nBlocks
* If no answer can be given at nBlocks, return an estimate
* at the lowest number of blocks where one can be given
*/
CFeeRate estimateSmartFee(int nBlocks, int *answerFoundAtBlocks = NULL) const;
/** Estimate fee rate needed to get into the next nBlocks */
CFeeRate estimateFee(int nBlocks) const;
/** Estimate priority needed to get into the next nBlocks
* If no answer can be given at nBlocks, return an estimate
* at the lowest number of blocks where one can be given
*/
double estimateSmartPriority(int nBlocks, int *answerFoundAtBlocks = NULL) const;
/** Estimate priority needed to get into the next nBlocks */
double estimatePriority(int nBlocks) const;
/** Write/Read estimates to disk */
bool WriteFeeEstimates(CAutoFile& fileout) const;
bool ReadFeeEstimates(CAutoFile& filein);
size_t DynamicMemoryUsage() const;
private:
/** UpdateForDescendants is used by UpdateTransactionsFromBlock to update
* the descendants for a single transaction that has been added to the
* mempool but may have child transactions in the mempool, eg during a
* chain reorg. setExclude is the set of descendant transactions in the
* mempool that must not be accounted for (because any descendants in
* setExclude were added to the mempool after the transaction being
* updated and hence their state is already reflected in the parent
* state).
*
* If updating an entry requires looking at more than maxDescendantsToVisit
* transactions, outside of the ones in setExclude, then give up.
*
* cachedDescendants will be updated with the descendants of the transaction
* being updated, so that future invocations don't need to walk the
* same transaction again, if encountered in another transaction chain.
*/
bool UpdateForDescendants(txiter updateIt,
int maxDescendantsToVisit,
cacheMap &cachedDescendants,
const std::set<uint256> &setExclude);
/** Update ancestors of hash to add/remove it as a descendant transaction. */
void UpdateAncestorsOf(bool add, txiter hash, setEntries &setAncestors);
/** For each transaction being removed, update ancestors and any direct children. */
void UpdateForRemoveFromMempool(const setEntries &entriesToRemove);
/** Sever link between specified transaction and direct children. */
void UpdateChildrenForRemoval(txiter entry);
/** Before calling removeUnchecked for a given transaction,
* UpdateForRemoveFromMempool must be called on the entire (dependent) set
* of transactions being removed at the same time. We use each
* CTxMemPoolEntry's setMemPoolParents in order to walk ancestors of a
* given transaction that is removed, so we can't remove intermediate
* transactions in a chain before we've updated all the state for the
* removal.
*/
void removeUnchecked(txiter entry);
};
/**
* CCoinsView that brings transactions from a memorypool into view.
* It does not check for spendings by memory pool transactions.
*/
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