Change file format for fee estimates.

Move buckets and bucketMap to be stored as part of overall serialization of estimator.
Add some placeholder data so file format is only changed once.
Maintain 3 different TxConfirmStats with potential for different decays and scales.

2 files changed, 156 insertions, 77 deletions

diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
index f3f7f8378e..0f3f2c63d2 100644
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -26,8 +26,8 @@ class TxConfirmStats
 {
 private:
     //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
+    const std::vector<double>& buckets;              // The upper-bound of the range for the bucket (inclusive)
+    const std::map<double, unsigned int>& bucketMap; // Map of bucket upper-bound to index into all vectors by bucket
 
     // For each bucket X:
     // Count the total # of txs in each bucket
@@ -38,9 +38,11 @@ private:
 
     // Count the total # of txs confirmed within Y blocks in each bucket
     // Track the historical moving average of theses totals over blocks
-    std::vector<std::vector<double> > confAvg; // confAvg[Y][X]
+    std::vector<std::vector<double>> confAvg; // confAvg[Y][X]
     // and calculate the totals for the current block to update the moving averages
-    std::vector<std::vector<int> > curBlockConf; // curBlockConf[Y][X]
+    std::vector<std::vector<int>> curBlockConf; // curBlockConf[Y][X]
+
+    std::vector<std::vector<double>> failAvg; // future use
 
     // Sum the total feerate of all tx's in each bucket
     // Track the historical moving average of this total over blocks
@@ -53,6 +55,8 @@ private:
 
     double decay;
 
+    unsigned int scale;
+
     // Mempool counts of outstanding transactions
     // For each bucket X, track the number of transactions in the mempool
     // that are unconfirmed for each possible confirmation value Y
@@ -60,6 +64,8 @@ private:
     // transactions still unconfirmed after MAX_CONFIRMS for each bucket
     std::vector<int> oldUnconfTxs;
 
+    void resizeInMemoryCounters(size_t newbuckets);
+
 public:
     /**
      * Create new TxConfirmStats. This is called by BlockPolicyEstimator's
@@ -68,7 +74,8 @@ public:
      * @param maxConfirms max number of confirms to track
      * @param decay how much to decay the historical moving average per block
      */
-    TxConfirmStats(const std::vector<double>& defaultBuckets, unsigned int maxConfirms, double decay);
+    TxConfirmStats(const std::vector<double>& defaultBuckets, const std::map<double, unsigned int>& defaultBucketMap,
+                   unsigned int maxConfirms, double decay);
 
     /** Clear the state of the curBlock variables to start counting for the new block */
     void ClearCurrent(unsigned int nBlockHeight);
@@ -116,32 +123,39 @@ public:
      * Read saved state of estimation data from a file and replace all internal data structures and
      * variables with this state.
      */
-    void Read(CAutoFile& filein);
+    void Read(CAutoFile& filein, int nFileVersion, size_t numBuckets);
 };
 
 
 TxConfirmStats::TxConfirmStats(const std::vector<double>& defaultBuckets,
+                                const std::map<double, unsigned int>& defaultBucketMap,
                                unsigned int maxConfirms, double _decay)
+    : buckets(defaultBuckets), bucketMap(defaultBucketMap)
 {
     decay = _decay;
-    for (unsigned int i = 0; i < defaultBuckets.size(); i++) {
-        buckets.push_back(defaultBuckets[i]);
-        bucketMap[defaultBuckets[i]] = i;
-    }
+    scale = 1;
     confAvg.resize(maxConfirms);
-    curBlockConf.resize(maxConfirms);
-    unconfTxs.resize(maxConfirms);
     for (unsigned int i = 0; i < maxConfirms; i++) {
         confAvg[i].resize(buckets.size());
-        curBlockConf[i].resize(buckets.size());
-        unconfTxs[i].resize(buckets.size());
     }
 
-    oldUnconfTxs.resize(buckets.size());
-    curBlockTxCt.resize(buckets.size());
     txCtAvg.resize(buckets.size());
-    curBlockVal.resize(buckets.size());
     avg.resize(buckets.size());
+
+    resizeInMemoryCounters(buckets.size());
+}
+
+void TxConfirmStats::resizeInMemoryCounters(size_t newbuckets) {
+    curBlockConf.resize(GetMaxConfirms());
+    // newbuckets must be passed in because the buckets referred to during Read have not been updated yet.
+    unconfTxs.resize(GetMaxConfirms());
+    for (unsigned int i = 0; i < unconfTxs.size(); i++) {
+        curBlockConf[i].resize(newbuckets);
+        unconfTxs[i].resize(newbuckets);
+    }
+    oldUnconfTxs.resize(newbuckets);
+    curBlockTxCt.resize(newbuckets);
+    curBlockVal.resize(newbuckets);
 }
 
 // Zero out the data for the current block
@@ -283,70 +297,55 @@ double TxConfirmStats::EstimateMedianVal(int confTarget, double sufficientTxVal,
 void TxConfirmStats::Write(CAutoFile& fileout) const
 {
     fileout << decay;
-    fileout << buckets;
+    fileout << scale;
     fileout << avg;
     fileout << txCtAvg;
     fileout << confAvg;
+    fileout << failAvg;
 }
 
-void TxConfirmStats::Read(CAutoFile& filein)
+void TxConfirmStats::Read(CAutoFile& filein, int nFileVersion, size_t numBuckets)
 {
-    // Read data file into temporary variables and do some very basic sanity checking
-    std::vector<double> fileBuckets;
-    std::vector<double> fileAvg;
-    std::vector<std::vector<double> > fileConfAvg;
-    std::vector<double> fileTxCtAvg;
-    double fileDecay;
+    // Read data file and do some very basic sanity checking
+    // buckets and bucketMap are not updated yet, so don't access them
+    // If there is a read failure, we'll just discard this entire object anyway
     size_t maxConfirms;
-    size_t numBuckets;
-
-    filein >> fileDecay;
-    if (fileDecay <= 0 || fileDecay >= 1)
-        throw std::runtime_error("Corrupt estimates file. Decay must be between 0 and 1 (non-inclusive)");
-    filein >> fileBuckets;
-    numBuckets = fileBuckets.size();
-    if (numBuckets <= 1 || numBuckets > 1000)
-        throw std::runtime_error("Corrupt estimates file. Must have between 2 and 1000 feerate buckets");
-    filein >> fileAvg;
-    if (fileAvg.size() != numBuckets)
+
+    // The current version will store the decay with each individual TxConfirmStats and also keep a scale factor
+    if (nFileVersion >= 149900) {
+        filein >> decay;
+        if (decay <= 0 || decay >= 1) {
+            throw std::runtime_error("Corrupt estimates file. Decay must be between 0 and 1 (non-inclusive)");
+        }
+        filein >> scale; //Unused for now
+    }
+
+    filein >> avg;
+    if (avg.size() != numBuckets) {
         throw std::runtime_error("Corrupt estimates file. Mismatch in feerate average bucket count");
-    filein >> fileTxCtAvg;
-    if (fileTxCtAvg.size() != numBuckets)
+    }
+    filein >> txCtAvg;
+    if (txCtAvg.size() != numBuckets) {
         throw std::runtime_error("Corrupt estimates file. Mismatch in tx count bucket count");
-    filein >> fileConfAvg;
-    maxConfirms = fileConfAvg.size();
-    if (maxConfirms <= 0 || maxConfirms > 6 * 24 * 7) // one week
+    }
+    filein >> confAvg;
+    maxConfirms = confAvg.size();
+    if (maxConfirms <= 0 || maxConfirms > 6 * 24 * 7) { // one week
         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 feerate conf average bucket count");
     }
-    // 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;
-    avg = fileAvg;
-    confAvg = fileConfAvg;
-    txCtAvg = fileTxCtAvg;
-    bucketMap.clear();
-
-    // Resize the current block variables which aren't stored in the data file
-    // to match the number of confirms and buckets
-    curBlockConf.resize(maxConfirms);
     for (unsigned int i = 0; i < maxConfirms; i++) {
-        curBlockConf[i].resize(buckets.size());
+        if (confAvg[i].size() != numBuckets) {
+            throw std::runtime_error("Corrupt estimates file. Mismatch in feerate conf average bucket count");
+        }
     }
-    curBlockTxCt.resize(buckets.size());
-    curBlockVal.resize(buckets.size());
 
-    unconfTxs.resize(maxConfirms);
-    for (unsigned int i = 0; i < maxConfirms; i++) {
-        unconfTxs[i].resize(buckets.size());
+    if (nFileVersion >= 149900) {
+        filein >> failAvg;
     }
-    oldUnconfTxs.resize(buckets.size());
 
-    for (unsigned int i = 0; i < buckets.size(); i++)
-        bucketMap[buckets[i]] = i;
+    // Resize the current block variables which aren't stored in the data file
+    // to match the number of confirms and buckets
+    resizeInMemoryCounters(numBuckets);
 
     LogPrint(BCLog::ESTIMATEFEE, "Reading estimates: %u buckets counting confirms up to %u blocks\n",
              numBuckets, maxConfirms);
@@ -413,17 +412,25 @@ CBlockPolicyEstimator::CBlockPolicyEstimator()
 {
     static_assert(MIN_BUCKET_FEERATE > 0, "Min feerate must be nonzero");
     minTrackedFee = CFeeRate(MIN_BUCKET_FEERATE);
-    std::vector<double> vfeelist;
-    for (double bucketBoundary = minTrackedFee.GetFeePerK(); bucketBoundary <= MAX_BUCKET_FEERATE; bucketBoundary *= FEE_SPACING) {
-        vfeelist.push_back(bucketBoundary);
+    size_t bucketIndex = 0;
+    for (double bucketBoundary = minTrackedFee.GetFeePerK(); bucketBoundary <= MAX_BUCKET_FEERATE; bucketBoundary *= FEE_SPACING, bucketIndex++) {
+        buckets.push_back(bucketBoundary);
+        bucketMap[bucketBoundary] = bucketIndex;
     }
-    vfeelist.push_back(INF_FEERATE);
-    feeStats = new TxConfirmStats(vfeelist, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY);
+    buckets.push_back(INF_FEERATE);
+    bucketMap[INF_FEERATE] = bucketIndex;
+    assert(bucketMap.size() == buckets.size());
+
+    feeStats = new TxConfirmStats(buckets, bucketMap, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY);
+    shortStats = new TxConfirmStats(buckets, bucketMap, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY);
+    longStats = new TxConfirmStats(buckets, bucketMap, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY);
 }
 
 CBlockPolicyEstimator::~CBlockPolicyEstimator()
 {
     delete feeStats;
+    delete shortStats;
+    delete longStats;
 }
 
 void CBlockPolicyEstimator::processTransaction(const CTxMemPoolEntry& entry, bool validFeeEstimate)
@@ -580,10 +587,15 @@ bool CBlockPolicyEstimator::Write(CAutoFile& fileout) const
 {
     try {
         LOCK(cs_feeEstimator);
-        fileout << 139900; // version required to read: 0.13.99 or later
+        fileout << 149900; // version required to read: 0.14.99 or later
         fileout << CLIENT_VERSION; // version that wrote the file
         fileout << nBestSeenHeight;
+        unsigned int future1 = 0, future2 = 0;
+        fileout << future1 << future2;
+        fileout << buckets;
         feeStats->Write(fileout);
+        shortStats->Write(fileout);
+        longStats->Write(fileout);
     }
     catch (const std::exception&) {
         LogPrintf("CBlockPolicyEstimator::Write(): unable to read policy estimator data (non-fatal)\n");
@@ -596,17 +608,79 @@ bool CBlockPolicyEstimator::Read(CAutoFile& filein)
 {
     try {
         LOCK(cs_feeEstimator);
-        int nVersionRequired, nVersionThatWrote, nFileBestSeenHeight;
+        int nVersionRequired, nVersionThatWrote;
+        unsigned int nFileBestSeenHeight;
         filein >> nVersionRequired >> nVersionThatWrote;
         if (nVersionRequired > CLIENT_VERSION)
             return error("CBlockPolicyEstimator::Read(): up-version (%d) fee estimate file", nVersionRequired);
+
+        // Read fee estimates file into temporary variables so existing data
+        // structures aren't corrupted if there is an exception.
         filein >> nFileBestSeenHeight;
-        feeStats->Read(filein);
-        nBestSeenHeight = nFileBestSeenHeight;
-        // if nVersionThatWrote < 139900 then another TxConfirmStats (for priority) follows but can be ignored.
+
+        if (nVersionThatWrote < 149900) {
+            // Read the old fee estimates file for temporary use, but then discard.  Will start collecting data from scratch.
+            // decay is stored before buckets in old versions, so pre-read decay and pass into TxConfirmStats constructor
+            double tempDecay;
+            filein >> tempDecay;
+            if (tempDecay <= 0 || tempDecay >= 1)
+                throw std::runtime_error("Corrupt estimates file. Decay must be between 0 and 1 (non-inclusive)");
+
+            std::vector<double> tempBuckets;
+            filein >> tempBuckets;
+            size_t tempNum = tempBuckets.size();
+            if (tempNum <= 1 || tempNum > 1000)
+                throw std::runtime_error("Corrupt estimates file. Must have between 2 and 1000 feerate buckets");
+
+            std::map<double, unsigned int> tempMap;
+
+            std::unique_ptr<TxConfirmStats> tempFeeStats(new TxConfirmStats(tempBuckets, tempMap, MAX_BLOCK_CONFIRMS, tempDecay));
+            tempFeeStats->Read(filein, nVersionThatWrote, tempNum);
+            // if nVersionThatWrote < 139900 then another TxConfirmStats (for priority) follows but can be ignored.
+
+            tempMap.clear();
+            for (unsigned int i = 0; i < tempBuckets.size(); i++) {
+                tempMap[tempBuckets[i]] = i;
+            }
+        }
+        else { // nVersionThatWrote >= 149900
+            unsigned int future1, future2;
+            filein >> future1 >> future2;
+
+            std::vector<double> fileBuckets;
+            filein >> fileBuckets;
+            size_t numBuckets = fileBuckets.size();
+            if (numBuckets <= 1 || numBuckets > 1000)
+                throw std::runtime_error("Corrupt estimates file. Must have between 2 and 1000 feerate buckets");
+
+            std::unique_ptr<TxConfirmStats> fileFeeStats(new TxConfirmStats(buckets, bucketMap, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY));
+            std::unique_ptr<TxConfirmStats> fileShortStats(new TxConfirmStats(buckets, bucketMap, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY));
+            std::unique_ptr<TxConfirmStats> fileLongStats(new TxConfirmStats(buckets, bucketMap, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY));
+            fileFeeStats->Read(filein, nVersionThatWrote, numBuckets);
+            fileShortStats->Read(filein, nVersionThatWrote, numBuckets);
+            fileLongStats->Read(filein, nVersionThatWrote, numBuckets);
+
+            // Fee estimates file parsed correctly
+            // Copy buckets from file and refresh our bucketmap
+            buckets = fileBuckets;
+            bucketMap.clear();
+            for (unsigned int i = 0; i < buckets.size(); i++) {
+                bucketMap[buckets[i]] = i;
+            }
+
+            // Destroy old TxConfirmStats and point to new ones that already reference buckets and bucketMap
+            delete feeStats;
+            delete shortStats;
+            delete longStats;
+            feeStats = fileFeeStats.release();
+            shortStats = fileShortStats.release();
+            longStats = fileLongStats.release();
+
+            nBestSeenHeight = nFileBestSeenHeight;
+        }
     }
-    catch (const std::exception&) {
-        LogPrintf("CBlockPolicyEstimator::Read(): unable to read policy estimator data (non-fatal)\n");
+    catch (const std::exception& e) {
+        LogPrintf("CBlockPolicyEstimator::Read(): unable to read policy estimator data (non-fatal): %s\n",e.what());
         return false;
     }
     return true;
diff --git a/src/policy/fees.h b/src/policy/fees.h
index 34f07c7270..7aaba7d7d5 100644
--- a/src/policy/fees.h
+++ b/src/policy/fees.h
@@ -141,10 +141,15 @@ private:
 
     /** Classes to track historical data on transaction confirmations */
     TxConfirmStats* feeStats;
+    TxConfirmStats* shortStats;
+    TxConfirmStats* longStats;
 
     unsigned int trackedTxs;
     unsigned int untrackedTxs;
 
+    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
+
     mutable CCriticalSection cs_feeEstimator;
 
     /** Process a transaction confirmed in a block*/