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Rewrite estimateSmartFee 

Change the logic of estimateSmartFee to check a 60% threshold at half the target, a 85% threshold at the target and a 95% threshold at double the target. Always check the shortest time horizon possible and ensure that estimates are monotonically decreasing.  Add a conservative mode, which makes sure that the 95% threshold is also met at longer time horizons as well.
This commit is contained in:
Alex Morcos 2017-03-07 11:33:44 -05:00
parent c7447ec303
commit 3810e976d6
6 changed files with 104 additions and 22 deletions
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89
src/policy/fees.cpp
View File

@ -658,31 +658,107 @@ CFeeRate CBlockPolicyEstimator::estimateRawFee(int confTarget, double successThr
return CFeeRate(median);
}
CFeeRate CBlockPolicyEstimator::estimateSmartFee(int confTarget, int *answerFoundAtTarget, const CTxMemPool& pool) const
/** Return a fee estimate at the required successThreshold from the shortest
* time horizon which tracks confirmations up to the desired target. If
* checkShorterHorizon is requested, also allow short time horizon estimates
* for a lower target to reduce the given answer */
double CBlockPolicyEstimator::estimateCombinedFee(unsigned int confTarget, double successThreshold, bool checkShorterHorizon) const
{
double estimate = -1;
if (confTarget >= 1 && confTarget <= longStats->GetMaxConfirms()) {
// Find estimate from shortest time horizon possible
if (confTarget <= shortStats->GetMaxConfirms()) { // short horizon
estimate = shortStats->EstimateMedianVal(confTarget, SUFFICIENT_TXS_SHORT, successThreshold, true, nBestSeenHeight);
}
else if (confTarget <= feeStats->GetMaxConfirms()) { // medium horizon
estimate = feeStats->EstimateMedianVal(confTarget, SUFFICIENT_FEETXS, successThreshold, true, nBestSeenHeight);
}
else { // long horizon
estimate = longStats->EstimateMedianVal(confTarget, SUFFICIENT_FEETXS, successThreshold, true, nBestSeenHeight);
}
if (checkShorterHorizon) {
// If a lower confTarget from a more recent horizon returns a lower answer use it.
if (confTarget > feeStats->GetMaxConfirms()) {
double medMax = feeStats->EstimateMedianVal(feeStats->GetMaxConfirms(), SUFFICIENT_FEETXS, successThreshold, true, nBestSeenHeight);
if (medMax > 0 && (estimate == -1 || medMax < estimate))
estimate = medMax;
}
if (confTarget > shortStats->GetMaxConfirms()) {
double shortMax = shortStats->EstimateMedianVal(shortStats->GetMaxConfirms(), SUFFICIENT_TXS_SHORT, successThreshold, true, nBestSeenHeight);
if (shortMax > 0 && (estimate == -1 || shortMax < estimate))
estimate = shortMax;
}
}
}
return estimate;
}
double CBlockPolicyEstimator::estimateConservativeFee(unsigned int doubleTarget) const
{
double estimate = -1;
if (doubleTarget <= shortStats->GetMaxConfirms()) {
estimate = feeStats->EstimateMedianVal(doubleTarget, SUFFICIENT_FEETXS, DOUBLE_SUCCESS_PCT, true, nBestSeenHeight);
}
if (doubleTarget <= feeStats->GetMaxConfirms()) {
double longEstimate = longStats->EstimateMedianVal(doubleTarget, SUFFICIENT_FEETXS, DOUBLE_SUCCESS_PCT, true, nBestSeenHeight);
if (longEstimate > estimate) {
estimate = longEstimate;
}
}
return estimate;
}
CFeeRate CBlockPolicyEstimator::estimateSmartFee(int confTarget, int *answerFoundAtTarget, const CTxMemPool& pool, bool conservative) const
{
if (answerFoundAtTarget)
*answerFoundAtTarget = confTarget;
double median = -1;
{
LOCK(cs_feeEstimator);
// Return failure if trying to analyze a target we're not tracking
if (confTarget <= 0 || (unsigned int)confTarget > feeStats->GetMaxConfirms())
if (confTarget <= 0 || (unsigned int)confTarget > longStats->GetMaxConfirms())
return CFeeRate(0);
// It's not possible to get reasonable estimates for confTarget of 1
if (confTarget == 1)
confTarget = 2;
while (median < 0 && (unsigned int)confTarget <= feeStats->GetMaxConfirms()) {
median = feeStats->EstimateMedianVal(confTarget++, SUFFICIENT_FEETXS, DOUBLE_SUCCESS_PCT, true, nBestSeenHeight);
assert(confTarget > 0); //estimateCombinedFee and estimateConservativeFee take unsigned ints
/** true is passed to estimateCombined fee for target/2 and target so
* that we check the max confirms for shorter time horizons as well.
* This is necessary to preserve monotonically increasing estimates.
* For non-conservative estimates we do the same thing for 2*target, but
* for conservative estimates we want to skip these shorter horizons
* checks for 2*target becuase we are taking the max over all time
* horizons so we already have monotonically increasing estimates and
* the purpose of conservative estimates is not to let short term
* fluctuations lower our estimates by too much.
*/
double halfEst = estimateCombinedFee(confTarget/2, HALF_SUCCESS_PCT, true);
double actualEst = estimateCombinedFee(confTarget, SUCCESS_PCT, true);
double doubleEst = estimateCombinedFee(2 * confTarget, DOUBLE_SUCCESS_PCT, !conservative);
median = halfEst;
if (actualEst > median) {
median = actualEst;
}
if (doubleEst > median) {
median = doubleEst;
}
if (conservative || median == -1) {
double consEst = estimateConservativeFee(2 * confTarget);
if (consEst > median) {
median = consEst;
}
}
} // Must unlock cs_feeEstimator before taking mempool locks
if (answerFoundAtTarget)
*answerFoundAtTarget = confTarget - 1;
*answerFoundAtTarget = confTarget;
// If mempool is limiting txs , return at least the min feerate from the mempool
CAmount minPoolFee = pool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFeePerK();
@ -695,6 +771,7 @@ CFeeRate CBlockPolicyEstimator::estimateSmartFee(int confTarget, int *answerFoun
return CFeeRate(median);
}
bool CBlockPolicyEstimator::Write(CAutoFile& fileout) const
{
try {

4
src/policy/fees.h
View File

@ -155,7 +155,7 @@ public:
* confTarget blocks. If no answer can be given at confTarget, return an
* estimate at the lowest target where one can be given.
*/
CFeeRate estimateSmartFee(int confTarget, int *answerFoundAtTarget, const CTxMemPool& pool) const;
CFeeRate estimateSmartFee(int confTarget, int *answerFoundAtTarget, const CTxMemPool& pool, bool conservative = true) const;
/** Return a specific fee estimate calculation with a given success threshold and time horizon.
*/
@ -199,6 +199,8 @@ private:
/** Process a transaction confirmed in a block*/
bool processBlockTx(unsigned int nBlockHeight, const CTxMemPoolEntry* entry);
double estimateCombinedFee(unsigned int confTarget, double successThreshold, bool checkShorterHorizon) const;
double estimateConservativeFee(unsigned int doubleTarget) const;
};
class FeeFilterRounder

1
src/rpc/client.cpp
View File

@ -106,6 +106,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
{ "getrawmempool", 0, "verbose" },
{ "estimatefee", 0, "nblocks" },
{ "estimatesmartfee", 0, "nblocks" },
{ "estimatesmartfee", 1, "conservative" },
{ "estimaterawfee", 0, "nblocks" },
{ "estimaterawfee", 1, "threshold" },
{ "estimaterawfee", 2, "horizon" },

19
src/rpc/mining.cpp
View File

@ -828,16 +828,20 @@ UniValue estimatefee(const JSONRPCRequest& request)
UniValue estimatesmartfee(const JSONRPCRequest& request)
{
if (request.fHelp || request.params.size() != 1)
if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
throw std::runtime_error(
"estimatesmartfee nblocks\n"
"estimatesmartfee nblocks (conservative)\n"
"\nWARNING: This interface is unstable and may disappear or change!\n"
"\nEstimates the approximate fee per kilobyte needed for a transaction to begin\n"
"confirmation within nblocks blocks if possible and return the number of blocks\n"
"for which the estimate is valid. Uses virtual transaction size as defined\n"
"in BIP 141 (witness data is discounted).\n"
"\nArguments:\n"
"1. nblocks (numeric)\n"
"1. nblocks (numeric)\n"
"2. conservative (bool, optional, default=true) Whether to return a more conservative estimate which\n"
" also satisfies a longer history. A conservative estimate potentially returns a higher\n"
" feerate and is more likely to be sufficient for the desired target, but is not as\n"
" responsive to short term drops in the prevailing fee market\n"
"\nResult:\n"
"{\n"
" \"feerate\" : x.x, (numeric) estimate fee-per-kilobyte (in BTC)\n"
@ -854,10 +858,15 @@ UniValue estimatesmartfee(const JSONRPCRequest& request)
RPCTypeCheck(request.params, boost::assign::list_of(UniValue::VNUM));
int nBlocks = request.params[0].get_int();
bool conservative = true;
if (request.params.size() > 1 && !request.params[1].isNull()) {
RPCTypeCheckArgument(request.params[1], UniValue::VBOOL);
conservative = request.params[1].get_bool();
}
UniValue result(UniValue::VOBJ);
int answerFound;
CFeeRate feeRate = ::feeEstimator.estimateSmartFee(nBlocks, &answerFound, ::mempool);
CFeeRate feeRate = ::feeEstimator.estimateSmartFee(nBlocks, &answerFound, ::mempool, conservative);
result.push_back(Pair("feerate", feeRate == CFeeRate(0) ? -1.0 : ValueFromAmount(feeRate.GetFeePerK())));
result.push_back(Pair("blocks", answerFound));
return result;
@ -951,7 +960,7 @@ static const CRPCCommand commands[] =
{ "generating", "generatetoaddress", &generatetoaddress, true, {"nblocks","address","maxtries"} },
{ "util", "estimatefee", &estimatefee, true, {"nblocks"} },
{ "util", "estimatesmartfee", &estimatesmartfee, true, {"nblocks"} },
{ "util", "estimatesmartfee", &estimatesmartfee, true, {"nblocks", "conservative"} },
{ "hidden", "estimaterawfee", &estimaterawfee, true, {"nblocks", "threshold", "horizon"} },
};

9
src/test/policyestimator_tests.cpp
View File

@ -83,11 +83,6 @@ BOOST_AUTO_TEST_CASE(BlockPolicyEstimates)
BOOST_CHECK(feeEst.estimateFee(1) == CFeeRate(0));
BOOST_CHECK(feeEst.estimateFee(2).GetFeePerK() < 9*baseRate.GetFeePerK() + deltaFee);
BOOST_CHECK(feeEst.estimateFee(2).GetFeePerK() > 9*baseRate.GetFeePerK() - deltaFee);
int answerFound;
BOOST_CHECK(feeEst.estimateSmartFee(1, &answerFound, mpool) == feeEst.estimateFee(2) && answerFound == 2);
BOOST_CHECK(feeEst.estimateSmartFee(2, &answerFound, mpool) == feeEst.estimateFee(2) && answerFound == 2);
BOOST_CHECK(feeEst.estimateSmartFee(4, &answerFound, mpool) == feeEst.estimateFee(4) && answerFound == 4);
BOOST_CHECK(feeEst.estimateSmartFee(8, &answerFound, mpool) == feeEst.estimateFee(8) && answerFound == 8);
}
}
@ -143,10 +138,8 @@ BOOST_AUTO_TEST_CASE(BlockPolicyEstimates)
mpool.removeForBlock(block, ++blocknum);
}
int answerFound;
for (int i = 1; i < 10;i++) {
BOOST_CHECK(feeEst.estimateFee(i) == CFeeRate(0) || feeEst.estimateFee(i).GetFeePerK() > origFeeEst[i-1] - deltaFee);
BOOST_CHECK(feeEst.estimateSmartFee(i, &answerFound, mpool).GetFeePerK() > origFeeEst[answerFound-1] - deltaFee);
}
// Mine all those transactions
@ -194,7 +187,7 @@ BOOST_AUTO_TEST_CASE(BlockPolicyEstimates)
mpool.TrimToSize(1);
BOOST_CHECK(mpool.GetMinFee(1).GetFeePerK() > feeV[5]);
for (int i = 1; i < 10; i++) {
BOOST_CHECK(feeEst.estimateSmartFee(i, NULL, mpool).GetFeePerK() >= feeEst.estimateFee(i).GetFeePerK());
BOOST_CHECK(feeEst.estimateSmartFee(i, NULL, mpool).GetFeePerK() >= feeEst.estimateRawFee(i, 0.85, FeeEstimateHorizon::MED_HALFLIFE).GetFeePerK());
BOOST_CHECK(feeEst.estimateSmartFee(i, NULL, mpool).GetFeePerK() >= mpool.GetMinFee(1).GetFeePerK());
}
}

4
test/functional/smartfees.py
View File

@ -116,8 +116,8 @@ def check_estimates(node, fees_seen, max_invalid, print_estimates = True):
for i,e in enumerate(all_estimates): # estimate is for i+1
if e >= 0:
valid_estimate = True
# estimatesmartfee should return the same result
assert_equal(node.estimatesmartfee(i+1)["feerate"], e)
if i >= 13: # for n>=14 estimatesmartfee(n/2) should be at least as high as estimatefee(n)
assert(node.estimatesmartfee((i+1)//2)["feerate"] > float(e) - delta)
else:
invalid_estimates += 1