Benchmark Results of govaluate vs cel-go

bench_expression_engines_test.go

package main

import (
	"fmt"
	"testing"

	"github.com/Knetic/govaluate"
	"github.com/google/cel-go/cel"
	"github.com/google/cel-go/checker/decls"
	"github.com/google/cel-go/common/types"
	"github.com/google/cel-go/common/types/ref"
	"github.com/google/cel-go/interpreter/functions"

	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
)

func BenchmarkCelGo(b *testing.B) {
	expr := "((TestDouble >= 1.0 || TestString.TestFunction() == 'HelloWorld') && (TestDouble + 1.0 >= 0.0)) || Now > TestTime"
	decls := cel.Declarations(
		// Identifiers used within this expression.
		decls.NewIdent("TestDouble", decls.Double, nil),
		decls.NewIdent("TestString", decls.String, nil),
		decls.NewIdent("TestTime", decls.Uint, nil),
		decls.NewIdent("Now", decls.Uint, nil),
		decls.NewFunction("TestFunction", decls.NewInstanceOverload("TestFunction",
			[]*exprpb.Type{decls.String},
			decls.String)),
	)

	e, err := cel.NewEnv(decls)
	if err != nil {
		b.Fatalf("environment creation error: %s\n", err)
	}

	// Parse and check the expression.
	p, iss := e.Parse(expr)
	if iss != nil && iss.Err() != nil {
		b.Fatal(iss.Err())
	}

	c, iss := e.Check(p)
	if iss != nil && iss.Err() != nil {
		b.Fatal(iss.Err())
	}

	// Create the program.
	funcs := cel.Functions(
		&functions.Overload{
			Operator: "TestFunction",
			Unary: func(value ref.Val) ref.Val {
				ts, ok := value.(types.String)
				if !ok {
					return types.NewErr(
						"invalid key of type '%v' and value '%v' to obj.get(key, def)",
						value.Type(), ts)
				}
				return types.String("Hello" + ts)
			},
		})

	prg, err := e.Program(c, funcs)
	if err != nil {
		b.Fatalf("program creation error: %s\n", err)
	}
	parameters := map[string]interface{}{
		"TestDouble": 0.0,
		"TestString": "World",
		"TestTime":   0,
		"Now":        1,
	}

	for n := 0; n < b.N; n++ {
		prg.Eval(parameters)
	}
}

func BenchmarkGovaluate(b *testing.B) {
	expr := "((TestDouble >= 1.0 || TestFunction(TestString) == 'HelloWorld') && (TestDouble + 1.0 >= 0.0)) || Now > TestTime"
	functions := map[string]govaluate.ExpressionFunction{
		"TestFunction": func(args ...interface{}) (interface{}, error) {
			ts, ok := args[0].(string)
			if !ok {
				return nil, fmt.Errorf("error: %v", ts)
			}
			return "Hello" + ts, nil
		},
	}

	expression, _ := govaluate.NewEvaluableExpressionWithFunctions(expr, functions)

	parameters := map[string]interface{}{
		"TestDouble": 0.0,
		"TestString": "World",
		"TestTime":   0,
		"Now":        1,
	}

	for n := 0; n < b.N; n++ {
		expression.Evaluate(parameters)
	}
}

results.txt

go test -cpuprofile cpu.prof -memprofile mem.prof -benchmem -bench .
goos: linux
goarch: amd64
pkg: benchcelgo
BenchmarkCelGo-4         2000000               656 ns/op              88 B/op          5 allocs/op
BenchmarkGovaluate-4     2000000               702 ns/op              72 B/op          5 allocs/op
PASS
ok      benchcelgo      4.321s

@RegisMelgaco We ended up using go-plugins instead for our usecase. You can read more here:

https://zerodha.tech/blog/a-lesson-in-niche-business-dsls-at-scale/

Although, I think there is also a place for expression engines like Govaluate and Cel-Go but it's best to evaluate on a case-by-case basis based on the requirements of your project.

Thx!

Another benchmark for different lang including cel-go and https://expr-lang.org:

• https://github.com/antonmedv/golang-expression-evaluation-comparison