#include <fees.h>

Classes
struct	TxStatsInfo

Public Member Functions
	CBlockPolicyEstimator (const CFeeRate &minRelayFee)

void	processBlock (unsigned int nBlockHeight, std::vector< CTxMemPoolEntry > &entries, bool fCurrentEstimate)

void	processBlockTx (unsigned int nBlockHeight, const CTxMemPoolEntry &entry)

void	processTransaction (const CTxMemPoolEntry &entry, bool fCurrentEstimate)

void	removeTx (uint256 hash)

bool	isFeeDataPoint (const CFeeRate &fee, double pri)

bool	isPriDataPoint (const CFeeRate &fee, double pri)

CFeeRate	estimateFee (int confTarget)

CFeeRate	estimateSmartFee (int confTarget, int *answerFoundAtTarget, const CTxMemPool &pool)

double	estimatePriority (int confTarget)

double	estimateSmartPriority (int confTarget, int *answerFoundAtTarget, const CTxMemPool &pool)

void	Write (CAutoFile &fileout)

void	Read (CAutoFile &filein)

Private Attributes
CFeeRate	minTrackedFee

double	minTrackedPriority
	Passed to constructor to avoid dependency on main. More...

unsigned int	nBestSeenHeight
	Set to AllowFreeThreshold. More...

std::map< uint256, TxStatsInfo >	mapMemPoolTxs

TxConfirmStats	feeStats

TxConfirmStats	priStats

CFeeRate	feeLikely

CFeeRate	feeUnlikely

double	priLikely

double	priUnlikely

Detailed Description

We want to be able to estimate fees or priorities that are needed on tx's to be included in a certain number of blocks. Every time a block is added to the best chain, this class records stats on the transactions included in that block

The BlockPolicyEstimator is used for estimating the fee or priority needed for a transaction to be included in a block within a certain number of blocks.

At a high level the algorithm works by grouping transactions into buckets based on having similar priorities or fees and then tracking how long it takes transactions in the various buckets to be mined. It operates under the assumption that in general transactions of higher fee/priority will be included in blocks before transactions of lower fee/priority. So for example if you wanted to know what fee you should put on a transaction to be included in a block within the next 5 blocks, you would start by looking at the bucket with the highest fee transactions and verifying that a sufficiently high percentage of them were confirmed within 5 blocks and then you would look at the next highest fee bucket, and so on, stopping at the last bucket to pass the test. The average fee of transactions in this bucket will give you an indication of the lowest fee you can put on a transaction and still have a sufficiently high chance of being confirmed within your desired 5 blocks.

When a transaction enters the mempool or is included within a block we decide whether it can be used as a data point for fee estimation, priority estimation or neither. If the value of exactly one of those properties was below the required minimum it can be used to estimate the other. In addition, if a priori our estimation code would indicate that the transaction would be much more quickly included in a block because of one of the properties compared to the other, we can also decide to use it as an estimate for that property.

Here is a brief description of the implementation for fee estimation. When a transaction that counts for fee estimation enters the mempool, we track the height of the block chain at entry. Whenever a block comes in, we count the number of transactions in each bucket and the total amount of fee paid in each bucket. Then we calculate how many blocks Y it took each transaction to be mined and we track an array of counters in each bucket for how long it to took transactions to get confirmed from 1 to a max of 25 and we increment all the counters from Y up to 25. This is because for any number Z>=Y the transaction was successfully mined within Z blocks. We want to save a history of this information, so at any time we have a counter of the total number of transactions that happened in a given fee bucket and the total number that were confirmed in each number 1-25 blocks or less for any bucket. We save this history by keeping an exponentially decaying moving average of each one of these stats. Furthermore we also keep track of the number unmined (in mempool) transactions in each bucket and for how many blocks they have been outstanding and use that to increase the number of transactions we've seen in that fee bucket when calculating an estimate for any number of confirmations below the number of blocks they've been outstanding.

Definition at line 218 of file fees.h.

Constructor & Destructor Documentation

◆ CBlockPolicyEstimator()

CBlockPolicyEstimator::CBlockPolicyEstimator ( const CFeeRate & minRelayFee )

Create new BlockPolicyEstimator and initialize stats tracking classes with default values

Definition at line 301 of file fees.cpp.

Member Function Documentation

◆ estimateFee()

CFeeRate CBlockPolicyEstimator::estimateFee ( int confTarget )

Return a fee estimate

Definition at line 492 of file fees.cpp.

Referenced by CTxMemPool::estimateFee().

◆ estimatePriority()

double CBlockPolicyEstimator::estimatePriority ( int confTarget )

Return a priority estimate

Definition at line 533 of file fees.cpp.

Referenced by CTxMemPool::estimatePriority().

◆ estimateSmartFee()

CFeeRate CBlockPolicyEstimator::estimateSmartFee	(	int	confTarget,
		int *	answerFoundAtTarget,
		const CTxMemPool &	pool
	)

Estimate fee rate needed to get be included in a block within confTarget blocks. If no answer can be given at confTarget, return an estimate at the lowest target where one can be given.

Definition at line 506 of file fees.cpp.

Referenced by CTxMemPool::estimateSmartFee().

◆ estimateSmartPriority()

double CBlockPolicyEstimator::estimateSmartPriority	(	int	confTarget,
		int *	answerFoundAtTarget,
		const CTxMemPool &	pool
	)

Estimate priority needed to get be included in a block within confTarget blocks. If no answer can be given at confTarget, return an estimate at the lowest target where one can be given.

Definition at line 542 of file fees.cpp.

Referenced by CTxMemPool::estimateSmartPriority().

◆ isFeeDataPoint()

bool CBlockPolicyEstimator::isFeeDataPoint	(	const CFeeRate &	fee,
		double	pri
	)

Is this transaction likely included in a block because of its fee?

Definition at line 326 of file fees.cpp.

Referenced by processBlockTx(), and processTransaction().

◆ isPriDataPoint()

bool CBlockPolicyEstimator::isPriDataPoint	(	const CFeeRate &	fee,
		double	pri
	)

Is this transaction likely included in a block because of its priority?

Definition at line 335 of file fees.cpp.

Referenced by processBlockTx(), and processTransaction().

◆ processBlock()

void CBlockPolicyEstimator::processBlock	(	unsigned int	nBlockHeight,
		std::vector< CTxMemPoolEntry > &	entries,
		bool	fCurrentEstimate
	)

Process all the transactions that have been included in a block

Definition at line 434 of file fees.cpp.

Referenced by CTxMemPool::removeForBlock().

◆ processBlockTx()

void CBlockPolicyEstimator::processBlockTx	(	unsigned int	nBlockHeight,
		const CTxMemPoolEntry &	entry
	)

Process a transaction confirmed in a block

Definition at line 397 of file fees.cpp.

Referenced by processBlock().

◆ processTransaction()

void CBlockPolicyEstimator::processTransaction	(	const CTxMemPoolEntry &	entry,
		bool	fCurrentEstimate
	)

Process a transaction accepted to the mempool

Definition at line 344 of file fees.cpp.

Referenced by CTxMemPool::addUnchecked().

◆ Read()

void CBlockPolicyEstimator::Read ( CAutoFile & filein )

Read estimation data from a file

Definition at line 573 of file fees.cpp.

Referenced by CTxMemPool::ReadFeeEstimates().

◆ removeTx()

void CBlockPolicyEstimator::removeTx ( uint256 hash )

Remove a transaction from the mempool tracking stats

Definition at line 285 of file fees.cpp.

Referenced by CTxMemPool::removeUnchecked().

◆ Write()

void CBlockPolicyEstimator::Write ( CAutoFile & fileout )

Write estimation data to a file

Definition at line 566 of file fees.cpp.

Referenced by CTxMemPool::WriteFeeEstimates().

Member Data Documentation

◆ feeLikely

CFeeRate CBlockPolicyEstimator::feeLikely

private

Breakpoints to help determine whether a transaction was confirmed by priority or Fee

Definition at line 286 of file fees.h.

Referenced by CBlockPolicyEstimator(), isFeeDataPoint(), and processBlock().

◆ feeStats

TxConfirmStats CBlockPolicyEstimator::feeStats

private

Classes to track historical data on transaction confirmations

Definition at line 283 of file fees.h.

Referenced by CBlockPolicyEstimator(), estimateFee(), estimateSmartFee(), processBlock(), processBlockTx(), processTransaction(), Read(), and Write().

◆ feeUnlikely

CFeeRate CBlockPolicyEstimator::feeUnlikely

private

Definition at line 286 of file fees.h.

Referenced by CBlockPolicyEstimator(), and processBlock().

◆ mapMemPoolTxs

std::map<uint256, TxStatsInfo> CBlockPolicyEstimator::mapMemPoolTxs

private

Definition at line 280 of file fees.h.

Referenced by processBlock(), processTransaction(), and removeTx().

◆ minTrackedFee

CFeeRate CBlockPolicyEstimator::minTrackedFee

private

Definition at line 268 of file fees.h.

Referenced by CBlockPolicyEstimator(), and isFeeDataPoint().

◆ minTrackedPriority

double CBlockPolicyEstimator::minTrackedPriority

private

Passed to constructor to avoid dependency on main.

Definition at line 269 of file fees.h.

Referenced by CBlockPolicyEstimator(), and isPriDataPoint().

◆ nBestSeenHeight

unsigned int CBlockPolicyEstimator::nBestSeenHeight

private

Set to AllowFreeThreshold.

Definition at line 270 of file fees.h.

Referenced by estimateFee(), estimatePriority(), estimateSmartFee(), estimateSmartPriority(), processBlock(), processTransaction(), Read(), removeTx(), and Write().

◆ priLikely

double CBlockPolicyEstimator::priLikely

private

Definition at line 287 of file fees.h.

Referenced by CBlockPolicyEstimator(), isPriDataPoint(), and processBlock().

◆ priStats

TxConfirmStats CBlockPolicyEstimator::priStats

private

Definition at line 283 of file fees.h.

Referenced by CBlockPolicyEstimator(), estimatePriority(), estimateSmartPriority(), processBlock(), processBlockTx(), processTransaction(), Read(), and Write().

◆ priUnlikely

double CBlockPolicyEstimator::priUnlikely

private

Definition at line 287 of file fees.h.

Referenced by CBlockPolicyEstimator(), and processBlock().

The documentation for this class was generated from the following files:

src/policy/fees.h
src/policy/fees.cpp

Classes

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ CBlockPolicyEstimator()

Member Function Documentation

◆ estimateFee()

◆ estimatePriority()

◆ estimateSmartFee()

◆ estimateSmartPriority()

◆ isFeeDataPoint()

◆ isPriDataPoint()

◆ processBlock()

◆ processBlockTx()

◆ processTransaction()

◆ Read()

◆ removeTx()

◆ Write()

Member Data Documentation

◆ feeLikely

◆ feeStats

◆ feeUnlikely

◆ mapMemPoolTxs

◆ minTrackedFee

◆ minTrackedPriority

◆ nBestSeenHeight

◆ priLikely

◆ priStats

◆ priUnlikely