commander interface

commander.go

@@ -0,0 +1,63 @@
+package core
+
+import (
+	"sync"
+
+	"google.golang.org/grpc"
+)
+
+// ServiceRegistryCallback is a callback function for registering services.
+type ServiceRegistryCallback func(s *grpc.Server)
+
+// Commander is a feature that accepts commands from external source.
+type Commander interface {
+	Feature
+
+	// RegisterService registers a service into this Commander.
+	RegisterService(ServiceRegistryCallback)
+}
+
+type syncCommander struct {
+	sync.RWMutex
+	Commander
+}
+
+func (c *syncCommander) RegisterService(callback ServiceRegistryCallback) {
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.Commander == nil {
+		return
+	}
+
+	c.Commander.RegisterService(callback)
+}
+
+func (c *syncCommander) Start() error {
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.Commander == nil {
+		return nil
+	}
+
+	return c.Commander.Start()
+}
+
+func (c *syncCommander) Close() {
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.Commander == nil {
+		return
+	}
+
+	c.Commander.Close()
+}
+
+func (c *syncCommander) Set(commander Commander) {
+	c.Lock()
+	defer c.Unlock()
+
+	c.Commander = commander
+}