feat(logic): implement telemetry for predicate execution duration metrics

Author: ccamel

x/logic/keeper/interpreter.go

@@ -106,6 +106,7 @@ func (k Keeper) newInterpreter(ctx context.Context, params types.Params) (*prolo
 			whitelistBlacklistHookFn(whitelistPredicates, blacklistPredicates),
 			gasMeterHookFn(sdkctx, params.GetGasPolicy()),
 			telemetryPredicateCallCounterHookFn(),
+			telemetryPredicateDurationHookFn(),
 		),
 		interpreter.WithPredicates(ctx, interpreter.RegistryNames),
 		interpreter.WithBootstrap(ctx, util.NonZeroOrDefault(interpreterParams.GetBootstrap(), bootstrap.Bootstrap())),

x/logic/keeper/metrics.go

@@ -2,6 +2,7 @@ package keeper
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/axone-protocol/prolog/engine"
 	"github.com/hashicorp/go-metrics"
@@ -45,6 +46,30 @@ func telemetryPredicateCallCounterHookFn() engine.HookFunc {
 	}
 }
 
+func telemetryPredicateDurationHookFn() engine.HookFunc {
+	var predicate string
+	var start time.Time
+	return func(opcode engine.Opcode, operand engine.Term, _ *engine.Env) error {
+		if opcode != engine.OpCall {
+			if predicate != "" {
+				telemetry.MeasureSince(start, append(metricsKeys, predicate)...)
+				predicate = ""
+				start = time.Time{}
+			}
+			return nil
+		}
+
+		var ok bool
+		if predicate, ok = stringifyOperand(operand); !ok {
+			return nil
+		}
+
+		start = telemetry.Now()
+
+		return nil
+	}
+}
+
 // stringifyOperand returns the string representation of the operand if it implements fmt.Stringer.
 // It returns an empty string and false if the operand does not have a string representation.
 func stringifyOperand(operand engine.Term) (string, bool) {