Merge #7730: Remove priority estimation

0bd581a add release notes for removal of priority estimation (Alex Morcos)
b2322e0 Remove priority estimation (Alex Morcos)

2 files changed, 76 insertions, 207 deletions

diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
index dae00d08a4..7113390cdf 100644
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -14,10 +14,9 @@
 #include "util.h"
 
 void TxConfirmStats::Initialize(std::vector<double>& defaultBuckets,
-                                unsigned int maxConfirms, double _decay, std::string _dataTypeString)
+                                unsigned int maxConfirms, double _decay)
 {
     decay = _decay;
-    dataTypeString = _dataTypeString;
     for (unsigned int i = 0; i < defaultBuckets.size(); i++) {
         buckets.push_back(defaultBuckets[i]);
         bucketMap[defaultBuckets[i]] = i;
@@ -87,10 +86,10 @@ double TxConfirmStats::EstimateMedianVal(int confTarget, double sufficientTxVal,
 
     int maxbucketindex = buckets.size() - 1;
 
-    // requireGreater means we are looking for the lowest fee/priority such that all higher
-    // values pass, so we start at maxbucketindex (highest fee) and look at successively
+    // requireGreater means we are looking for the lowest feerate such that all higher
+    // values pass, so we start at maxbucketindex (highest feerate) and look at successively
     // smaller buckets until we reach failure.  Otherwise, we are looking for the highest
-    // fee/priority such that all lower values fail, and we go in the opposite direction.
+    // feerate such that all lower values fail, and we go in the opposite direction.
     unsigned int startbucket = requireGreater ? maxbucketindex : 0;
     int step = requireGreater ? -1 : 1;
 
@@ -107,7 +106,7 @@ double TxConfirmStats::EstimateMedianVal(int confTarget, double sufficientTxVal,
     bool foundAnswer = false;
     unsigned int bins = unconfTxs.size();
 
-    // Start counting from highest(default) or lowest fee/pri transactions
+    // Start counting from highest(default) or lowest feerate transactions
     for (int bucket = startbucket; bucket >= 0 && bucket <= maxbucketindex; bucket += step) {
         curFarBucket = bucket;
         nConf += confAvg[confTarget - 1][bucket];
@@ -145,8 +144,8 @@ double TxConfirmStats::EstimateMedianVal(int confTarget, double sufficientTxVal,
     double median = -1;
     double txSum = 0;
 
-    // Calculate the "average" fee of the best bucket range that met success conditions
-    // Find the bucket with the median transaction and then report the average fee from that bucket
+    // Calculate the "average" feerate of the best bucket range that met success conditions
+    // Find the bucket with the median transaction and then report the average feerate from that bucket
     // This is a compromise between finding the median which we can't since we don't save all tx's
     // and reporting the average which is less accurate
     unsigned int minBucket = bestNearBucket < bestFarBucket ? bestNearBucket : bestFarBucket;
@@ -166,8 +165,8 @@ double TxConfirmStats::EstimateMedianVal(int confTarget, double sufficientTxVal,
         }
     }
 
-    LogPrint("estimatefee", "%3d: For conf success %s %4.2f need %s %s: %12.5g from buckets %8g - %8g  Cur Bucket stats %6.2f%%  %8.1f/(%.1f+%d mempool)\n",
-             confTarget, requireGreater ? ">" : "<", successBreakPoint, dataTypeString,
+    LogPrint("estimatefee", "%3d: For conf success %s %4.2f need feerate %s: %12.5g from buckets %8g - %8g  Cur Bucket stats %6.2f%%  %8.1f/(%.1f+%d mempool)\n",
+             confTarget, requireGreater ? ">" : "<", successBreakPoint,
              requireGreater ? ">" : "<", median, buckets[minBucket], buckets[maxBucket],
              100 * nConf / (totalNum + extraNum), nConf, totalNum, extraNum);
 
@@ -200,10 +199,10 @@ void TxConfirmStats::Read(CAutoFile& filein)
     filein >> fileBuckets;
     numBuckets = fileBuckets.size();
     if (numBuckets <= 1 || numBuckets > 1000)
-        throw std::runtime_error("Corrupt estimates file. Must have between 2 and 1000 fee/pri buckets");
+        throw std::runtime_error("Corrupt estimates file. Must have between 2 and 1000 feerate buckets");
     filein >> fileAvg;
     if (fileAvg.size() != numBuckets)
-        throw std::runtime_error("Corrupt estimates file. Mismatch in fee/pri average bucket count");
+        throw std::runtime_error("Corrupt estimates file. Mismatch in feerate average bucket count");
     filein >> fileTxCtAvg;
     if (fileTxCtAvg.size() != numBuckets)
         throw std::runtime_error("Corrupt estimates file. Mismatch in tx count bucket count");
@@ -213,9 +212,9 @@ void TxConfirmStats::Read(CAutoFile& filein)
         throw std::runtime_error("Corrupt estimates file.  Must maintain estimates for between 1 and 1008 (one week) confirms");
     for (unsigned int i = 0; i < maxConfirms; i++) {
         if (fileConfAvg[i].size() != numBuckets)
-            throw std::runtime_error("Corrupt estimates file. Mismatch in fee/pri conf average bucket count");
+            throw std::runtime_error("Corrupt estimates file. Mismatch in feerate conf average bucket count");
     }
-    // Now that we've processed the entire fee estimate data file and not
+    // Now that we've processed the entire feerate estimate data file and not
     // thrown any errors, we can copy it to our data structures
     decay = fileDecay;
     buckets = fileBuckets;
@@ -242,8 +241,8 @@ void TxConfirmStats::Read(CAutoFile& filein)
     for (unsigned int i = 0; i < buckets.size(); i++)
         bucketMap[buckets[i]] = i;
 
-    LogPrint("estimatefee", "Reading estimates: %u %s buckets counting confirms up to %u blocks\n",
-             numBuckets, dataTypeString, maxConfirms);
+    LogPrint("estimatefee", "Reading estimates: %u buckets counting confirms up to %u blocks\n",
+             numBuckets, maxConfirms);
 }
 
 unsigned int TxConfirmStats::NewTx(unsigned int nBlockHeight, double val)
@@ -251,7 +250,6 @@ unsigned int TxConfirmStats::NewTx(unsigned int nBlockHeight, double val)
     unsigned int bucketindex = bucketMap.lower_bound(val)->second;
     unsigned int blockIndex = nBlockHeight % unconfTxs.size();
     unconfTxs[blockIndex][bucketindex]++;
-    LogPrint("estimatefee", "adding to %s", dataTypeString);
     return bucketindex;
 }
 
@@ -291,12 +289,10 @@ void CBlockPolicyEstimator::removeTx(uint256 hash)
                  hash.ToString().c_str());
         return;
     }
-    TxConfirmStats *stats = pos->second.stats;
     unsigned int entryHeight = pos->second.blockHeight;
     unsigned int bucketIndex = pos->second.bucketIndex;
 
-    if (stats != NULL)
-        stats->removeTx(entryHeight, nBestSeenHeight, bucketIndex);
+    feeStats.removeTx(entryHeight, nBestSeenHeight, bucketIndex);
     mapMemPoolTxs.erase(hash);
 }
 
@@ -309,45 +305,14 @@ CBlockPolicyEstimator::CBlockPolicyEstimator(const CFeeRate& _minRelayFee)
         vfeelist.push_back(bucketBoundary);
     }
     vfeelist.push_back(INF_FEERATE);
-    feeStats.Initialize(vfeelist, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY, "FeeRate");
-
-    minTrackedPriority = AllowFreeThreshold() < MIN_PRIORITY ? MIN_PRIORITY : AllowFreeThreshold();
-    std::vector<double> vprilist;
-    for (double bucketBoundary = minTrackedPriority; bucketBoundary <= MAX_PRIORITY; bucketBoundary *= PRI_SPACING) {
-        vprilist.push_back(bucketBoundary);
-    }
-    vprilist.push_back(INF_PRIORITY);
-    priStats.Initialize(vprilist, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY, "Priority");
-
-    feeUnlikely = CFeeRate(0);
-    feeLikely = CFeeRate(INF_FEERATE);
-    priUnlikely = 0;
-    priLikely = INF_PRIORITY;
-}
-
-bool CBlockPolicyEstimator::isFeeDataPoint(const CFeeRate &fee, double pri)
-{
-    if ((pri < minTrackedPriority && fee >= minTrackedFee) ||
-        (pri < priUnlikely && fee > feeLikely)) {
-        return true;
-    }
-    return false;
-}
-
-bool CBlockPolicyEstimator::isPriDataPoint(const CFeeRate &fee, double pri)
-{
-    if ((fee < minTrackedFee && pri >= minTrackedPriority) ||
-        (fee < feeUnlikely && pri > priLikely)) {
-        return true;
-    }
-    return false;
+    feeStats.Initialize(vfeelist, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY);
 }
 
 void CBlockPolicyEstimator::processTransaction(const CTxMemPoolEntry& entry, bool fCurrentEstimate)
 {
     unsigned int txHeight = entry.GetHeight();
     uint256 hash = entry.GetTx().GetHash();
-    if (mapMemPoolTxs[hash].stats != NULL) {
+    if (mapMemPoolTxs.count(hash)) {
         LogPrint("estimatefee", "Blockpolicy error mempool tx %s already being tracked\n",
                  hash.ToString().c_str());
 	return;
@@ -371,30 +336,11 @@ void CBlockPolicyEstimator::processTransaction(const CTxMemPoolEntry& entry, boo
         return;
     }
 
-    // Fees are stored and reported as BTC-per-kb:
+    // Feerates are stored and reported as BTC-per-kb:
     CFeeRate feeRate(entry.GetFee(), entry.GetTxSize());
 
-    // Want the priority of the tx at confirmation. However we don't know
-    // what that will be and its too hard to continue updating it
-    // so use starting priority as a proxy
-    double curPri = entry.GetPriority(txHeight);
     mapMemPoolTxs[hash].blockHeight = txHeight;
-
-    LogPrint("estimatefee", "Blockpolicy mempool tx %s ", hash.ToString().substr(0,10));
-    // Record this as a priority estimate
-    if (entry.GetFee() == 0 || isPriDataPoint(feeRate, curPri)) {
-        mapMemPoolTxs[hash].stats = &priStats;
-        mapMemPoolTxs[hash].bucketIndex =  priStats.NewTx(txHeight, curPri);
-    }
-    // Record this as a fee estimate
-    else if (isFeeDataPoint(feeRate, curPri)) {
-        mapMemPoolTxs[hash].stats = &feeStats;
-        mapMemPoolTxs[hash].bucketIndex = feeStats.NewTx(txHeight, (double)feeRate.GetFeePerK());
-    }
-    else {
-        LogPrint("estimatefee", "not adding");
-    }
-    LogPrint("estimatefee", "\n");
+    mapMemPoolTxs[hash].bucketIndex = feeStats.NewTx(txHeight, (double)feeRate.GetFeePerK());
 }
 
 void CBlockPolicyEstimator::processBlockTx(unsigned int nBlockHeight, const CTxMemPoolEntry& entry)
@@ -417,21 +363,10 @@ void CBlockPolicyEstimator::processBlockTx(unsigned int nBlockHeight, const CTxM
         return;
     }
 
-    // Fees are stored and reported as BTC-per-kb:
+    // Feerates are stored and reported as BTC-per-kb:
     CFeeRate feeRate(entry.GetFee(), entry.GetTxSize());
 
-    // Want the priority of the tx at confirmation.  The priority when it
-    // entered the mempool could easily be very small and change quickly
-    double curPri = entry.GetPriority(nBlockHeight);
-
-    // Record this as a priority estimate
-    if (entry.GetFee() == 0 || isPriDataPoint(feeRate, curPri)) {
-        priStats.Record(blocksToConfirm, curPri);
-    }
-    // Record this as a fee estimate
-    else if (isFeeDataPoint(feeRate, curPri)) {
-        feeStats.Record(blocksToConfirm, (double)feeRate.GetFeePerK());
-    }
+    feeStats.Record(blocksToConfirm, (double)feeRate.GetFeePerK());
 }
 
 void CBlockPolicyEstimator::processBlock(unsigned int nBlockHeight,
@@ -452,41 +387,15 @@ void CBlockPolicyEstimator::processBlock(unsigned int nBlockHeight,
     if (!fCurrentEstimate)
         return;
 
-    // Update the dynamic cutoffs
-    // a fee/priority is "likely" the reason your tx was included in a block if >85% of such tx's
-    // were confirmed in 2 blocks and is "unlikely" if <50% were confirmed in 10 blocks
-    LogPrint("estimatefee", "Blockpolicy recalculating dynamic cutoffs:\n");
-    priLikely = priStats.EstimateMedianVal(2, SUFFICIENT_PRITXS, MIN_SUCCESS_PCT, true, nBlockHeight);
-    if (priLikely == -1)
-        priLikely = INF_PRIORITY;
-
-    double feeLikelyEst = feeStats.EstimateMedianVal(2, SUFFICIENT_FEETXS, MIN_SUCCESS_PCT, true, nBlockHeight);
-    if (feeLikelyEst == -1)
-        feeLikely = CFeeRate(INF_FEERATE);
-    else
-        feeLikely = CFeeRate(feeLikelyEst);
-
-    priUnlikely = priStats.EstimateMedianVal(10, SUFFICIENT_PRITXS, UNLIKELY_PCT, false, nBlockHeight);
-    if (priUnlikely == -1)
-        priUnlikely = 0;
-
-    double feeUnlikelyEst = feeStats.EstimateMedianVal(10, SUFFICIENT_FEETXS, UNLIKELY_PCT, false, nBlockHeight);
-    if (feeUnlikelyEst == -1)
-        feeUnlikely = CFeeRate(0);
-    else
-        feeUnlikely = CFeeRate(feeUnlikelyEst);
-
-    // Clear the current block states
+    // Clear the current block state
     feeStats.ClearCurrent(nBlockHeight);
-    priStats.ClearCurrent(nBlockHeight);
 
     // Repopulate the current block states
     for (unsigned int i = 0; i < entries.size(); i++)
         processBlockTx(nBlockHeight, entries[i]);
 
-    // Update all exponential averages with the current block states
+    // Update all exponential averages with the current block state
     feeStats.UpdateMovingAverages();
-    priStats.UpdateMovingAverages();
 
     LogPrint("estimatefee", "Blockpolicy after updating estimates for %u confirmed entries, new mempool map size %u\n",
              entries.size(), mapMemPoolTxs.size());
@@ -522,7 +431,7 @@ CFeeRate CBlockPolicyEstimator::estimateSmartFee(int confTarget, int *answerFoun
     if (answerFoundAtTarget)
         *answerFoundAtTarget = confTarget - 1;
 
-    // If mempool is limiting txs , return at least the min fee from the mempool
+    // 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();
     if (minPoolFee > 0 && minPoolFee > median)
         return CFeeRate(minPoolFee);
@@ -535,51 +444,38 @@ CFeeRate CBlockPolicyEstimator::estimateSmartFee(int confTarget, int *answerFoun
 
 double CBlockPolicyEstimator::estimatePriority(int confTarget)
 {
-    // Return failure if trying to analyze a target we're not tracking
-    if (confTarget <= 0 || (unsigned int)confTarget > priStats.GetMaxConfirms())
-        return -1;
-
-    return priStats.EstimateMedianVal(confTarget, SUFFICIENT_PRITXS, MIN_SUCCESS_PCT, true, nBestSeenHeight);
+    return -1;
 }
 
 double CBlockPolicyEstimator::estimateSmartPriority(int confTarget, int *answerFoundAtTarget, const CTxMemPool& pool)
 {
     if (answerFoundAtTarget)
         *answerFoundAtTarget = confTarget;
-    // Return failure if trying to analyze a target we're not tracking
-    if (confTarget <= 0 || (unsigned int)confTarget > priStats.GetMaxConfirms())
-        return -1;
 
     // If mempool is limiting txs, no priority txs are allowed
     CAmount minPoolFee = pool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFeePerK();
     if (minPoolFee > 0)
         return INF_PRIORITY;
 
-    double median = -1;
-    while (median < 0 && (unsigned int)confTarget <= priStats.GetMaxConfirms()) {
-        median = priStats.EstimateMedianVal(confTarget++, SUFFICIENT_PRITXS, MIN_SUCCESS_PCT, true, nBestSeenHeight);
-    }
-
-    if (answerFoundAtTarget)
-        *answerFoundAtTarget = confTarget - 1;
-
-    return median;
+    return -1;
 }
 
 void CBlockPolicyEstimator::Write(CAutoFile& fileout)
 {
     fileout << nBestSeenHeight;
     feeStats.Write(fileout);
-    priStats.Write(fileout);
 }
 
-void CBlockPolicyEstimator::Read(CAutoFile& filein)
+void CBlockPolicyEstimator::Read(CAutoFile& filein, int nFileVersion)
 {
     int nFileBestSeenHeight;
     filein >> nFileBestSeenHeight;
     feeStats.Read(filein);
-    priStats.Read(filein);
     nBestSeenHeight = nFileBestSeenHeight;
+    if (nFileVersion < 139900) {
+        TxConfirmStats priStats;
+        priStats.Read(filein);
+    }
 }
 
 FeeFilterRounder::FeeFilterRounder(const CFeeRate& minIncrementalFee)
diff --git a/src/policy/fees.h b/src/policy/fees.h
index bff6488d08..c7d2febfa5 100644
--- a/src/policy/fees.h
+++ b/src/policy/fees.h
@@ -19,60 +19,50 @@ class CTxMemPoolEntry;
 class CTxMemPool;
 
 /** \class CBlockPolicyEstimator
- * The BlockPolicyEstimator is used for estimating the fee or priority needed
+ * The BlockPolicyEstimator is used for estimating the feerate 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
+ * based on having similar feerates 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
+ * the assumption that in general transactions of higher feerate will be
+ * included in blocks before transactions of lower feerate.   So for
+ * example if you wanted to know what feerate 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
+ * at the bucket with the highest feerate 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
+ * then you would look at the next highest feerate bucket, and so on, stopping at
+ * the last bucket to pass the test.   The average feerate of transactions in this
+ * bucket will give you an indication of the lowest feerate 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
+ * Here is a brief description of the implementation:
+ * When a transaction 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
+ * we count the number of transactions in each bucket and the total amount of feerate
  * 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
+ * counter of the total number of transactions that happened in a given feerate
  * 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
+ * the number of transactions we've seen in that feerate bucket when calculating
  * an estimate for any number of confirmations below the number of blocks
  * they've been outstanding.
  */
 
 /**
- * We will instantiate two instances of this class, one to track transactions
- * that were included in a block due to fee, and one for tx's included due to
- * priority.  We will lump transactions into a bucket according to their approximate
- * fee or priority and then track how long it took for those txs to be included in a block
+ * We will instantiate an instance of this class to track transactions that were
+ * included in a block. We will lump transactions into a bucket according to their
+ * approximate feerate and then track how long it took for those txs to be included in a block
  *
  * The tracking of unconfirmed (mempool) transactions is completely independent of the
  * historical tracking of transactions that have been confirmed in a block.
@@ -80,7 +70,7 @@ class CTxMemPool;
 class TxConfirmStats
 {
 private:
-    //Define the buckets we will group transactions into (both fee buckets and priority buckets)
+    //Define the buckets we will group transactions into
     std::vector<double> buckets;              // The upper-bound of the range for the bucket (inclusive)
     std::map<double, unsigned int> bucketMap; // Map of bucket upper-bound to index into all vectors by bucket
 
@@ -97,16 +87,15 @@ private:
     // and calculate the totals for the current block to update the moving averages
     std::vector<std::vector<int> > curBlockConf; // curBlockConf[Y][X]
 
-    // Sum the total priority/fee of all tx's in each bucket
+    // Sum the total feerate of all tx's in each bucket
     // Track the historical moving average of this total over blocks
     std::vector<double> avg;
     // and calculate the total for the current block to update the moving average
     std::vector<double> curBlockVal;
 
     // Combine the conf counts with tx counts to calculate the confirmation % for each Y,X
-    // Combine the total value with the tx counts to calculate the avg fee/priority per bucket
+    // Combine the total value with the tx counts to calculate the avg feerate per bucket
 
-    std::string dataTypeString;
     double decay;
 
     // Mempool counts of outstanding transactions
@@ -123,9 +112,8 @@ public:
      * @param defaultBuckets contains the upper limits for the bucket boundaries
      * @param maxConfirms max number of confirms to track
      * @param decay how much to decay the historical moving average per block
-     * @param dataTypeString for logging purposes
      */
-    void Initialize(std::vector<double>& defaultBuckets, unsigned int maxConfirms, double decay, std::string dataTypeString);
+    void Initialize(std::vector<double>& defaultBuckets, unsigned int maxConfirms, double decay);
 
     /** Clear the state of the curBlock variables to start counting for the new block */
     void ClearCurrent(unsigned int nBlockHeight);
@@ -133,7 +121,7 @@ public:
     /**
      * Record a new transaction data point in the current block stats
      * @param blocksToConfirm the number of blocks it took this transaction to confirm
-     * @param val either the fee or the priority when entered of the transaction
+     * @param val the feerate of the transaction
      * @warning blocksToConfirm is 1-based and has to be >= 1
      */
     void Record(int blocksToConfirm, double val);
@@ -150,14 +138,14 @@ public:
     void UpdateMovingAverages();
 
     /**
-     * Calculate a fee or priority estimate.  Find the lowest value bucket (or range of buckets
+     * Calculate a feerate estimate.  Find the lowest value bucket (or range of buckets
      * to make sure we have enough data points) whose transactions still have sufficient likelihood
      * of being confirmed within the target number of confirmations
      * @param confTarget target number of confirmations
      * @param sufficientTxVal required average number of transactions per block in a bucket range
      * @param minSuccess the success probability we require
-     * @param requireGreater return the lowest fee/pri such that all higher values pass minSuccess OR
-     *        return the highest fee/pri such that all lower values fail minSuccess
+     * @param requireGreater return the lowest feerate such that all higher values pass minSuccess OR
+     *        return the highest feerate such that all lower values fail minSuccess
      * @param nBlockHeight the current block height
      */
     double EstimateMedianVal(int confTarget, double sufficientTxVal,
@@ -184,35 +172,27 @@ static const unsigned int MAX_BLOCK_CONFIRMS = 25;
 /** Decay of .998 is a half-life of 346 blocks or about 2.4 days */
 static const double DEFAULT_DECAY = .998;
 
-/** Require greater than 95% of X fee transactions to be confirmed within Y blocks for X to be big enough */
+/** Require greater than 95% of X feerate transactions to be confirmed within Y blocks for X to be big enough */
 static const double MIN_SUCCESS_PCT = .95;
 static const double UNLIKELY_PCT = .5;
 
-/** Require an avg of 1 tx in the combined fee bucket per block to have stat significance */
+/** Require an avg of 1 tx in the combined feerate bucket per block to have stat significance */
 static const double SUFFICIENT_FEETXS = 1;
 
-/** Require only an avg of 1 tx every 5 blocks in the combined pri bucket (way less pri txs) */
-static const double SUFFICIENT_PRITXS = .2;
-
-// Minimum and Maximum values for tracking fees and priorities
+// Minimum and Maximum values for tracking feerates
 static const double MIN_FEERATE = 10;
 static const double MAX_FEERATE = 1e7;
 static const double INF_FEERATE = MAX_MONEY;
-static const double MIN_PRIORITY = 10;
-static const double MAX_PRIORITY = 1e16;
 static const double INF_PRIORITY = 1e9 * MAX_MONEY;
 
-// We have to lump transactions into buckets based on fee or priority, but we want to be able
-// to give accurate estimates over a large range of potential fees and priorities
+// We have to lump transactions into buckets based on feerate, but we want to be able
+// to give accurate estimates over a large range of potential feerates
 // Therefore it makes sense to exponentially space the buckets
 /** Spacing of FeeRate buckets */
 static const double FEE_SPACING = 1.1;
 
-/** Spacing of Priority buckets */
-static const double PRI_SPACING = 2;
-
 /**
- *  We want to be able to estimate fees or priorities that are needed on tx's to be included in
+ *  We want to be able to estimate feerates 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
  */
@@ -235,27 +215,26 @@ public:
     /** Remove a transaction from the mempool tracking stats*/
     void removeTx(uint256 hash);
 
-    /** Is this transaction likely included in a block because of its fee?*/
-    bool isFeeDataPoint(const CFeeRate &fee, double pri);
-
-    /** Is this transaction likely included in a block because of its priority?*/
-    bool isPriDataPoint(const CFeeRate &fee, double pri);
-
-    /** Return a fee estimate */
+    /** Return a feerate estimate */
     CFeeRate estimateFee(int confTarget);
 
-    /** Estimate fee rate needed to get be included in a block within
+    /** Estimate feerate 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.
      */
     CFeeRate estimateSmartFee(int confTarget, int *answerFoundAtTarget, const CTxMemPool& pool);
 
-    /** Return a priority estimate */
+    /** Return a priority estimate.
+     *  DEPRECATED
+     *  Returns -1
+     */
     double estimatePriority(int confTarget);
 
     /** 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.
+     *  confTarget blocks.
+     *  DEPRECATED
+     *  Returns -1 unless mempool is currently limited then returns INF_PRIORITY
+     *  answerFoundAtTarget is set to confTarget
      */
     double estimateSmartPriority(int confTarget, int *answerFoundAtTarget, const CTxMemPool& pool);
 
@@ -263,29 +242,23 @@ public:
     void Write(CAutoFile& fileout);
 
     /** Read estimation data from a file */
-    void Read(CAutoFile& filein);
+    void Read(CAutoFile& filein, int nFileVersion);
 
 private:
     CFeeRate minTrackedFee;    //!< Passed to constructor to avoid dependency on main
-    double minTrackedPriority; //!< Set to AllowFreeThreshold
     unsigned int nBestSeenHeight;
     struct TxStatsInfo
     {
-        TxConfirmStats *stats;
         unsigned int blockHeight;
         unsigned int bucketIndex;
-        TxStatsInfo() : stats(NULL), blockHeight(0), bucketIndex(0) {}
+        TxStatsInfo() : blockHeight(0), bucketIndex(0) {}
     };
 
     // map of txids to information about that transaction
     std::map<uint256, TxStatsInfo> mapMemPoolTxs;
 
     /** Classes to track historical data on transaction confirmations */
-    TxConfirmStats feeStats, priStats;
-
-    /** Breakpoints to help determine whether a transaction was confirmed by priority or Fee */
-    CFeeRate feeLikely, feeUnlikely;
-    double priLikely, priUnlikely;
+    TxConfirmStats feeStats;
 };
 
 class FeeFilterRounder