feat: move native communication to FFI (#1457)

pkg/api/events.go

@@ -0,0 +1,82 @@
+package api
+
+import (
+	"encoding/json"
+	"sync"
+
+	"github.com/GopeedLab/gopeed/pkg/download"
+)
+
+type TaskEventMask uint64
+
+const (
+	TaskEventDone TaskEventMask = 1 << iota
+	TaskEventError
+)
+
+type TaskEvent struct {
+	Type   string `json:"type"`
+	TaskID string `json:"taskId"`
+	Name   string `json:"name,omitempty"`
+	Error  string `json:"error,omitempty"`
+}
+
+type TaskEventListener func(payload string)
+
+type taskEventSubscription struct {
+	mu       sync.RWMutex
+	mask     TaskEventMask
+	listener TaskEventListener
+}
+
+func (s *Service) SubscribeTaskEvents(mask TaskEventMask, listener TaskEventListener) {
+	s.taskEvents.mu.Lock()
+	defer s.taskEvents.mu.Unlock()
+	s.taskEvents.mask = mask
+	s.taskEvents.listener = listener
+}
+
+func (s *Service) emitTaskEvent(event *download.Event) {
+	if event == nil || event.Task == nil {
+		return
+	}
+
+	var mask TaskEventMask
+	switch event.Key {
+	case download.EventKeyDone:
+		mask = TaskEventDone
+	case download.EventKeyError:
+		mask = TaskEventError
+	default:
+		return
+	}
+
+	s.taskEvents.mu.RLock()
+	if s.taskEvents.mask&mask == 0 || s.taskEvents.listener == nil {
+		s.taskEvents.mu.RUnlock()
+		return
+	}
+	listener := s.taskEvents.listener
+	s.taskEvents.mu.RUnlock()
+
+	payload := TaskEvent{
+		Type:   "task." + string(event.Key),
+		TaskID: event.Task.ID,
+	}
+	if event.Task.Meta != nil {
+		payload.Name = event.Task.Name()
+	}
+	if event.Err != nil {
+		payload.Error = event.Err.Error()
+	}
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return
+	}
+
+	// A platform callback must never be able to crash a download worker.
+	func() {
+		defer func() { _ = recover() }()
+		listener(string(data))
+	}()
+}