disallow box and runner comparability

.github/workflows/build.yml

@@ -32,8 +32,8 @@ jobs:
           1.18.10,
           1.19.13,
           1.20.14,
-          1.21.10,
-          1.22.3,
+          1.21.12,
+          1.22.5,
         ]
     permissions:
       contents: read

ctor.go

@@ -15,6 +15,9 @@ import (
 	"go.uber.org/zap"
 )
 
+// DoNotCompare prevents == and != comparisons on the containing struct.
+type DoNotCompare [0]func()
+
 // StarlarkFunc is a function that can be called from Starlark.
 type StarlarkFunc func(thread *starlark.Thread, fn *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error)
 
@@ -30,6 +33,7 @@ type DynamicModuleLoader func(string) (starlet.ModuleLoader, error)
 
 // Starbox is a wrapper of starlet.Machine with additional features.
 type Starbox struct {
+	_          DoNotCompare
 	mac        *starlet.Machine
 	mu         sync.RWMutex
 	hasExec    bool

exec_test.go

@@ -1,8 +1,10 @@
 package starbox_test
 
 import (
+	"fmt"
 	"net/http"
 	"reflect"
+	"sync"
 	"testing"
 	"time"
 
@@ -1237,6 +1239,22 @@ func TestAddHTTPContext(t *testing.T) {
 	}
 }
 
+func TestConcurrentRun(t *testing.T) {
+	b := starbox.New("test")
+	var wg sync.WaitGroup
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			_, err := b.Run(fmt.Sprintf(`a = (%d * (1 << 20)) * %d; print(a)`, i+1, i+2))
+			if err != nil {
+				t.Error(err)
+			}
+		}(i)
+	}
+	wg.Wait()
+}
+
 func BenchmarkRunBox(b *testing.B) {
 	s := hereDoc(`
 		a = 10
@@ -1260,6 +1278,19 @@ func BenchmarkRunBox(b *testing.B) {
 	}
 }
 
+func BenchmarkRunSimpleScript(b *testing.B) {
+	box := starbox.New("test")
+	b.ReportAllocs()
+	b.ResetTimer()
+	script := `a = 10; b = 20; c = a + b`
+	for i := 0; i < b.N; i++ {
+		_, err := box.Run(script)
+		if err != nil {
+			b.Error(err)
+		}
+	}
+}
+
 func BenchmarkRunScript(b *testing.B) {
 	s := hereDoc(`
 		a = 10

runner.go

@@ -17,6 +17,7 @@ var (
 
 // RunnerConfig defines the execution configuration for a Starbox instance.
 type RunnerConfig struct {
+	_        DoNotCompare
 	box      *Starbox
 	fileName string
 	script   []byte