DRA CEL: add benchmark

Expression evaluation in all scenarios gets benchmarked where compilation
works. A pending optimization in another PR caches compiled expressions, so the
time for compilation will become less important. What matters is the actual
evaluation.

staging/src/k8s.io/dynamic-resource-allocation/cel/compile_test.go

@@ -28,8 +28,7 @@ import (
 	"k8s.io/utils/ptr"
 )
 
-func TestCompile(t *testing.T) {
+var testcases = map[string]struct {
-	for name, scenario := range map[string]struct {
 	expression         string
 	driver             string
 	attributes         map[resourceapi.QualifiedName]resourceapi.DeviceAttribute
@@ -231,7 +230,10 @@ device.attributes["dra.example.com"]["version"].isGreaterThan(semver("0.0.1"))
 		driver:     "dra.example.com",
 		expectCost: 18446744073709551615, // Exceeds limit!
 	},
-	} {
+}
+
+func TestCEL(t *testing.T) {
+	for name, scenario := range testcases {
 		t.Run(name, func(t *testing.T) {
 			_, ctx := ktesting.NewTestContext(t)
 			result := GetCompiler().CompileCELExpression(scenario.expression, environment.StoredExpressions)
@@ -284,3 +286,42 @@ device.attributes["dra.example.com"]["version"].isGreaterThan(semver("0.0.1"))
 		})
 	}
 }
+
+func BenchmarkDeviceMatches(b *testing.B) {
+	for name, scenario := range testcases {
+		if scenario.expectCompileError != "" {
+			continue
+		}
+		b.Run(name, func(b *testing.B) {
+			_, ctx := ktesting.NewTestContext(b)
+			result := GetCompiler().CompileCELExpression(scenario.expression, environment.StoredExpressions)
+			if result.Error != nil {
+				b.Fatalf("unexpected compile error: %s", result.Error.Error())
+			}
+
+			for i := 0; i < b.N; i++ {
+				// It would be nice to measure
+				// time/actual_cost, but the time as observed
+				// here also includes additional preparations
+				// in result.DeviceMatches and thus cannot be
+				// used.
+				match, _, err := result.DeviceMatches(ctx, Device{Attributes: scenario.attributes, Capacity: scenario.capacity, Driver: scenario.driver})
+				if err != nil {
+					if scenario.expectMatchError == "" {
+						b.Fatalf("unexpected evaluation error: %v", err)
+					}
+					if !strings.Contains(err.Error(), scenario.expectMatchError) {
+						b.Fatalf("expected evaluation error to contain %q, but got instead: %v", scenario.expectMatchError, err)
+					}
+					return
+				}
+				if scenario.expectMatchError != "" {
+					b.Fatalf("expected match error %q, got none", scenario.expectMatchError)
+				}
+				if match != scenario.expectMatch {
+					b.Fatalf("expected result %v, got %v", scenario.expectMatch, match)
+				}
+			}
+		})
+	}
+}