Add bridge behind feature gate

internal/filter/filterspan/filterspan.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"fmt"
 
+	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	conventions "go.opentelemetry.io/collector/semconv/v1.6.1"
 
@@ -19,11 +20,36 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/contexts/ottlspan"
 )
 
+var useOTTLBridge = featuregate.GlobalRegistry().MustRegister(
+	"filter.filterspan.useOTTLBridge",
+	featuregate.StageAlpha,
+	featuregate.WithRegisterDescription("When enabled, filterspan will convert filterspan configuration to OTTL and use filterottl evaluation"),
+	featuregate.WithRegisterReferenceURL("https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/18642"),
+)
+
 // NewSkipExpr creates a BoolExpr that on evaluation returns true if a span should NOT be processed or kept.
 // The logic determining if a span should be processed is based on include and exclude settings.
 // Include properties are checked before exclude settings are checked.
 func NewSkipExpr(mp *filterconfig.MatchConfig) (expr.BoolExpr[ottlspan.TransformContext], error) {
-	return filterottl.NewSpanSkipExprBridge(mp)
+	if useOTTLBridge.IsEnabled() {
+		return filterottl.NewSpanSkipExprBridge(mp)
+	}
+	var matchers []expr.BoolExpr[ottlspan.TransformContext]
+	inclExpr, err := newExpr(mp.Include)
+	if err != nil {
+		return nil, err
+	}
+	if inclExpr != nil {
+		matchers = append(matchers, expr.Not(inclExpr))
+	}
+	exclExpr, err := newExpr(mp.Exclude)
+	if err != nil {
+		return nil, err
+	}
+	if exclExpr != nil {
+		matchers = append(matchers, exclExpr)
+	}
+	return expr.Or(matchers...), nil
 }
 
 // propertiesMatcher allows matching a span against various span properties.

internal/filter/filterspan/filterspan_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/ptrace"
 	conventions "go.opentelemetry.io/collector/semconv/v1.6.1"
@@ -333,6 +334,10 @@ func BenchmarkFilterspan_NewSkipExpr(b *testing.B) {
 	}
 
 	for _, tt := range testCases {
+		origVal := useOTTLBridge.IsEnabled()
+		err := featuregate.GlobalRegistry().Set("useOTTLBridge", true)
+		assert.NoError(b, err)
+
 		skipExpr, err := NewSkipExpr(tt.mc)
 		assert.NoError(b, err)
 
@@ -355,10 +360,14 @@ func BenchmarkFilterspan_NewSkipExpr(b *testing.B) {
 
 		b.Run(tt.name, func(b *testing.B) {
 			for i := 0; i < b.N; i++ {
-				skip, err := skipExpr.Eval(context.Background(), tCtx)
+				var skip bool
+				skip, err = skipExpr.Eval(context.Background(), tCtx)
 				assert.NoError(b, err)
 				assert.Equal(b, tt.skip, skip)
 			}
 		})
+
+		err = featuregate.GlobalRegistry().Set("useOTTLBridge", origVal)
+		assert.NoError(b, err)
 	}
 }