add support for GstPromise

gst/gst_promise_test.go

@@ -0,0 +1,123 @@
+package gst
+
+import (
+	"context"
+	"errors"
+	"runtime"
+	"sync"
+	"testing"
+	"time"
+	"unsafe"
+)
+
+//go:noinline
+func awaitGC() {
+	type tmp struct{ v string }
+
+	setup := make(chan struct{})
+	done := make(chan struct{})
+
+	go func() {
+		v := &tmp{"foo"}
+
+		runtime.SetFinalizer(v, func(v *tmp) {
+			close(done)
+		})
+
+		close(setup)
+	}()
+
+	<-setup
+	runtime.GC()
+	<-done
+	runtime.GC()
+	time.Sleep(1 * time.Second)
+}
+
+func TestPromise(t *testing.T) {
+	initOnce.Do(func() {
+		Init(nil)
+	})
+
+	prom := NewPromise()
+	cprom := prom.Instance()
+
+	reply := NewStructure("foo/bar")
+	errchan := make(chan error)
+
+	go func() {
+		res, err := prom.Await(context.Background())
+
+		if err != nil {
+			errchan <- err
+		}
+
+		// even though we don't use the promise, the result structure should be still accessible.
+		// the returned structure is owned by the promise, so the promise must not get GC'ed until
+		// we don't use the structure anymore
+		awaitGC()
+
+		if res.Name() != reply.Name() {
+			errchan <- errors.New("name mismatch")
+		}
+
+		runtime.GC()
+		runtime.GC()
+		runtime.GC()
+
+		close(errchan)
+	}()
+
+	prom.Reply(reply)
+
+	err := <-errchan
+
+	if err != nil {
+		t.FailNow()
+	}
+
+	awaitGC()
+
+	if cprom.parent.refcount != 1 {
+		panic("refcount too high")
+	}
+
+	runtime.KeepAlive(prom)
+
+	awaitGC()
+}
+
+var initOnce sync.Once
+
+func TestPromiseMarshal(t *testing.T) {
+	initOnce.Do(func() {
+		Init(nil)
+	})
+
+	prom := NewPromise()
+
+	gv, err := prom.ToGValue()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	receivedPromI, err := marshalPromise(unsafe.Pointer(gv.GValue))
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	receivedProm, ok := receivedPromI.(*Promise)
+
+	if !ok {
+		t.Fatal("could not cast")
+	}
+
+	// Awaiting received promise should error immediately
+	_, err = receivedProm.Await(context.Background())
+
+	if err == nil {
+		t.FailNow()
+	}
+}