[tracing]: add fee estimator tracing

doc/tracing.md

@@ -263,6 +263,35 @@ Arguments passed:
 1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian)
 2. Reject reason as `pointer to C-style String` (max. length 118 characters)
 
+### Context `fee_estimator`
+#### Tracepoint `fee_estimator:estimate_calculated`
+
+Is called when a fee estimate is generated from forecasters and the best estimate is selected. It Passes information about the estimate and which forecaster provided the
+estimate.
+
+Arguments passed:
+1. Confirmation target in `int`
+2. Forecaster that provided the estimate as `pointer to C-style String` (max. length 16 characters)
+3. Block Height the estimate was made as `unsigned int`
+4. Low priority estimate in sat/kvB as `int64`
+5. High priority estimate in sat/kvB as `int64`
+
+### Context `feerate_forecast`
+#### Tracepoint `feerate_forecast:forecast_generated`
+
+Is called when a fee rate forecaster estimate a fee rate for a confirmation target. It Passes the quartile fee rates.
+
+Arguments passed:
+1. Confirmation target in `int`
+2. Block Height the estimate was made as `unsigned int`
+3. Forecaster that provided the estimate as `pointer to C-style String` (max. length 16 characters)
+4. 5th Quartile fee rate in sat/kvB as `int64`
+5. 25th Quartile fee rate in sat/kvB as `int64`
+6. 50th Quartile fee rate in sat/kvB as `int64`
+7. 75th Quartile fee rate in sat/kvB as `int64`
+
+
+
 ## Adding tracepoints to Bitcoin Core
 
 To add a new tracepoint, `#include <util/trace.h>` in the compilation unit where

src/policy/fee_estimator.cpp

@@ -7,6 +7,7 @@
 #include <policy/forecaster.h>
 #include <policy/forecaster_util.h>
 #include <txmempool.h>
+#include <util/trace.h>
 
 void FeeEstimator::RegisterForecaster(std::unique_ptr<Forecaster> forecaster)
 {
@@ -87,6 +88,12 @@ std::pair<ForecastResult, std::vector<std::string>> FeeEstimator::GetFeeEstimate
         LogDebug(BCLog::ESTIMATEFEE, "FeeEst %s: Block height %s, low priority feerate %s %s/kvB, high priority feerate %s %s/kvB.\n",
                  forecastTypeToString(forecast.m_opt.forecaster), forecast.m_opt.block_height, forecast.m_opt.low_priority.GetFeePerK(),
                  CURRENCY_ATOM, forecast.m_opt.high_priority.GetFeePerK(), CURRENCY_ATOM);
+        TRACE5(fee_estimator, estimate_calculated,
+               targetBlocks,
+               forecastTypeToString(forecast.m_opt.forecaster).c_str(),
+               forecast.m_opt.block_height,
+               forecast.m_opt.low_priority.GetFeePerK(),
+               forecast.m_opt.high_priority.GetFeePerK());
     }
     return std::make_pair(forecast, err_messages);
 };

src/policy/forecasters/mempool.cpp

@@ -5,6 +5,7 @@
 #include <logging.h>
 #include <node/miner.h>
 #include <policy/forecasters/mempool.h>
+#include <util/trace.h>
 #include <validation.h>
 
 
@@ -40,6 +41,15 @@ ForecastResult MemPoolForecaster::EstimateFee(int targetBlocks)
              forecastTypeToString(m_forecastType), forecast_options.block_height, fee_rate_estimate_result.p75.GetFeePerK(), CURRENCY_ATOM, fee_rate_estimate_result.p50.GetFeePerK(), CURRENCY_ATOM,
              fee_rate_estimate_result.p25.GetFeePerK(), CURRENCY_ATOM, fee_rate_estimate_result.p5.GetFeePerK(), CURRENCY_ATOM);
 
+    TRACE7(feerate_forecast, forecast_generated,
+           targetBlocks,
+           forecast_options.block_height,
+           forecastTypeToString(m_forecastType).c_str(),
+           fee_rate_estimate_result.p5.GetFeePerK(),
+           fee_rate_estimate_result.p25.GetFeePerK(),
+           fee_rate_estimate_result.p50.GetFeePerK(),
+           fee_rate_estimate_result.p75.GetFeePerK());
+
     cache.update(fee_rate_estimate_result);
     forecast_options.low_priority = fee_rate_estimate_result.p25;
     forecast_options.high_priority = fee_rate_estimate_result.p50;