Add benchmarks in go port and corrected minor bug.

Author: viferga

source/ports/go_port/source/README.md

@@ -50,3 +50,33 @@ func main() {
 	}
 }
 ```
+
+## Building
+
+[Build and install MetaCall from source](https://github.com/metacall/core/blob/develop/docs/README.md#6-build-system) or [install precompiled binaries](https://github.com/metacall/install#install). Then run:
+
+```sh
+go build
+```
+
+In case of using precompiled binaries (in Linux), when running any application using MetaCall, you must set the environment variable `LD_LIBRARY_PATH` pointing to the MetaCall library (a part of setting any other required environment variable related to MetaCall if needed). For example:
+
+```sh
+export LD_LIBRARY_PATH="/gnu/store/`ls /gnu/store/ | grep metacall | head -n 1`/lib"
+```
+
+## Testing
+
+For running tests:
+
+```sh
+go test
+```
+
+## Benchmarks
+
+For running tests:
+
+```sh
+go test -bench=.
+```

source/ports/go_port/source/go_port.go

@@ -33,6 +33,8 @@ package metacall
 // their address to pass to clibrary; thus, they are moved to a separate Go
 // file.
 
+// Based on: https://eli.thegreenplace.net/2019/passing-callbacks-and-pointers-to-cgo/
+
 extern void *resolveCgo(void *, void *);
 extern void *rejectCgo(void *, void *);
 
@@ -354,7 +356,7 @@ func getFunction(function string) (unsafe.Pointer, error) {
 	defer C.free(unsafe.Pointer(cFunction))
 	cFunc := C.metacall_function(cFunction)
 	if cFunc == nil {
-		return nil, errors.New("function %s not found: " + function)
+		return nil, errors.New("function not found: " + function)
 	}
 	return cFunc, nil
 }

source/ports/go_port/source/go_port_test.go

@@ -11,6 +11,16 @@ func TestMain(m *testing.M) {
 	if err := Initialize(); err != nil {
 		log.Fatal(err)
 	}
+
+	// if benchmark {
+		buffer := "module.exports = { benchmark: async x => x }"
+
+		if err := LoadFromMemory("node", buffer); err != nil {
+			log.Fatal(err)
+			return
+		}
+	// }
+
 	code := m.Run()
 	Destroy()
 	os.Exit(code)
@@ -72,3 +82,42 @@ func TestNodeJS(t *testing.T) {
 
 	wg.Wait()
 }
+
+func benchmarkNodeJS(b *testing.B, n int) {
+	var wg sync.WaitGroup
+
+	wg.Add(n)
+
+	for i := 0; i < n; i++ {
+		_, err := Await("benchmark",
+			func(interface{}, interface{}) interface{} {
+				wg.Done()
+				return nil
+			},
+			func(interface{}, interface{}) interface{} {
+				wg.Done()
+				return nil
+			},
+			nil,
+		)
+
+		if err != nil {
+			b.Fatal(err)
+			return
+		}
+	}
+
+	wg.Wait()
+}
+
+func BenchmarkNodeJSSequential(b *testing.B) {
+	benchmarkNodeJS(b, 5)
+}
+
+func BenchmarkNodeJSParallel(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			benchmarkNodeJS(b, 5)
+		}
+	})
+}