Merge pull request #725 from onflow/mpeter/eth-estimate-gas-track-iterations

Add metric to count iterations taken for `eth_estimateGas`

Author: m-Peter

metrics/collector.go

@@ -19,22 +19,24 @@ type Collector interface {
 	MeasureRequestDuration(start time.Time, method string)
 	OperatorBalance(account *flow.Account)
 	AvailableSigningKeys(count int)
+	GasEstimationIterations(count int)
 }
 
 var _ Collector = &DefaultCollector{}
 
 type DefaultCollector struct {
 	// TODO: for now we cannot differentiate which api request failed number of times
-	apiErrorsCounter       prometheus.Counter
-	serverPanicsCounters   *prometheus.CounterVec
-	cadenceBlockHeight     prometheus.Gauge
-	evmBlockHeight         prometheus.Gauge
-	evmBlockIndexedCounter prometheus.Counter
-	evmTxIndexedCounter    prometheus.Counter
-	operatorBalance        prometheus.Gauge
-	evmAccountCallCounters *prometheus.CounterVec
-	requestDurations       *prometheus.HistogramVec
-	availableSigningkeys   prometheus.Gauge
+	apiErrorsCounter        prometheus.Counter
+	serverPanicsCounters    *prometheus.CounterVec
+	cadenceBlockHeight      prometheus.Gauge
+	evmBlockHeight          prometheus.Gauge
+	evmBlockIndexedCounter  prometheus.Counter
+	evmTxIndexedCounter     prometheus.Counter
+	operatorBalance         prometheus.Gauge
+	evmAccountCallCounters  *prometheus.CounterVec
+	requestDurations        *prometheus.HistogramVec
+	availableSigningkeys    prometheus.Gauge
+	gasEstimationIterations prometheus.Gauge
 }
 
 func NewCollector(logger zerolog.Logger) Collector {
@@ -90,6 +92,11 @@ func NewCollector(logger zerolog.Logger) Collector {
 		Help: "Number of keys available for transaction signing",
 	})
 
+	gasEstimationIterations := prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: prefixedName("gas_estimation_iterations"),
+		Help: "Number of iterations taken to estimate the gas of a EVM call/tx",
+	})
+
 	metrics := []prometheus.Collector{
 		apiErrors,
 		serverPanicsCounters,
@@ -101,23 +108,25 @@ func NewCollector(logger zerolog.Logger) Collector {
 		evmAccountCallCounters,
 		requestDurations,
 		availableSigningKeys,
+		gasEstimationIterations,
 	}
 	if err := registerMetrics(logger, metrics...); err != nil {
 		logger.Info().Msg("using noop collector as metric register failed")
 		return NopCollector
 	}
 
 	return &DefaultCollector{
-		apiErrorsCounter:       apiErrors,
-		serverPanicsCounters:   serverPanicsCounters,
-		cadenceBlockHeight:     cadenceBlockHeight,
-		evmBlockHeight:         evmBlockHeight,
-		evmBlockIndexedCounter: evmBlockIndexedCounter,
-		evmTxIndexedCounter:    evmTxIndexedCounter,
-		evmAccountCallCounters: evmAccountCallCounters,
-		requestDurations:       requestDurations,
-		operatorBalance:        operatorBalance,
-		availableSigningkeys:   availableSigningKeys,
+		apiErrorsCounter:        apiErrors,
+		serverPanicsCounters:    serverPanicsCounters,
+		cadenceBlockHeight:      cadenceBlockHeight,
+		evmBlockHeight:          evmBlockHeight,
+		evmBlockIndexedCounter:  evmBlockIndexedCounter,
+		evmTxIndexedCounter:     evmTxIndexedCounter,
+		evmAccountCallCounters:  evmAccountCallCounters,
+		requestDurations:        requestDurations,
+		operatorBalance:         operatorBalance,
+		availableSigningkeys:    availableSigningKeys,
+		gasEstimationIterations: gasEstimationIterations,
 	}
 }
 
@@ -172,6 +181,10 @@ func (c *DefaultCollector) AvailableSigningKeys(count int) {
 	c.availableSigningkeys.Set(float64(count))
 }
 
+func (c *DefaultCollector) GasEstimationIterations(count int) {
+	c.gasEstimationIterations.Set(float64(count))
+}
+
 func prefixedName(name string) string {
 	return fmt.Sprintf("evm_gateway_%s", name)
 }

metrics/nop.go

@@ -21,3 +21,4 @@ func (c *nopCollector) EVMAccountInteraction(string)             {}
 func (c *nopCollector) MeasureRequestDuration(time.Time, string) {}
 func (c *nopCollector) OperatorBalance(*flow.Account)            {}
 func (c *nopCollector) AvailableSigningKeys(count int)           {}
+func (c *nopCollector) GasEstimationIterations(count int)        {}

services/requester/requester.go

@@ -310,6 +310,15 @@ func (e *EVM) EstimateGas(
 	height uint64,
 	stateOverrides *ethTypes.StateOverride,
 ) (uint64, error) {
+	iterations := 0
+
+	dryRun := func(gasLimit uint64) (*evmTypes.Result, error) {
+		tx.Gas = gasLimit
+		result, err := e.dryRunTx(tx, from, height, stateOverrides, nil)
+		iterations += 1
+		return result, err
+	}
+
 	// Note: The following algorithm, is largely inspired from
 	// https://github.com/onflow/go-ethereum/blob/master/eth/gasestimator/gasestimator.go#L49-L192,
 	// and adapted to fit our use-case.
@@ -323,10 +332,10 @@ func (e *EVM) EstimateGas(
 	if tx.Gas >= gethParams.TxGas {
 		passingGasLimit = tx.Gas
 	}
-	tx.Gas = passingGasLimit
+
 	// We first execute the transaction at the highest allowable gas limit,
 	// since if this fails we can return the error immediately.
-	result, err := e.dryRunTx(tx, from, height, stateOverrides, nil)
+	result, err := dryRun(passingGasLimit)
 	if err != nil {
 		return 0, err
 	}
@@ -338,6 +347,12 @@ func (e *EVM) EstimateGas(
 		return 0, errs.NewFailedTransactionError(resultSummary.ErrorMessage)
 	}
 
+	// We do not want to report iterations for calls/transactions
+	// that errored out or had their execution reverted.
+	defer func() {
+		e.collector.GasEstimationIterations(iterations)
+	}()
+
 	// For almost any transaction, the gas consumed by the unconstrained execution
 	// above lower-bounds the gas limit required for it to succeed. One exception
 	// is those that explicitly check gas remaining in order to execute within a
@@ -350,8 +365,7 @@ func (e *EVM) EstimateGas(
 	// Explicitly check that gas amount and use as a limit for the binary search.
 	optimisticGasLimit := (result.GasConsumed + result.GasRefund + gethParams.CallStipend) * 64 / 63
 	if optimisticGasLimit < passingGasLimit {
-		tx.Gas = optimisticGasLimit
-		result, err = e.dryRunTx(tx, from, height, stateOverrides, nil)
+		result, err := dryRun(optimisticGasLimit)
 		if err != nil {
 			// This should not happen under normal conditions since if we make it this far the
 			// transaction had run without error at least once before.
@@ -380,8 +394,7 @@ func (e *EVM) EstimateGas(
 			// range here is skewed to favor the low side.
 			mid = failingGasLimit * 2
 		}
-		tx.Gas = mid
-		result, err = e.dryRunTx(tx, from, height, stateOverrides, nil)
+		result, err := dryRun(mid)
 		if err != nil {
 			return 0, err
 		}