eventmanager: add support for filesystem actions

Fixes #931

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/common/actions.go

@@ -43,8 +43,17 @@ var (
 	errUnconfiguredAction    = errors.New("no hook is configured for this action")
 	errNoHook                = errors.New("unable to execute action, no hook defined")
 	errUnexpectedHTTResponse = errors.New("unexpected HTTP hook response code")
+	hooksConcurrencyGuard    = make(chan struct{}, 150)
 )
 
+func startNewHook() {
+	hooksConcurrencyGuard <- struct{}{}
+}
+
+func hookEnded() {
+	<-hooksConcurrencyGuard
+}
+
 // ProtocolActions defines the action to execute on file operations and SSH commands
 type ProtocolActions struct {
 	// Valid values are download, upload, pre-delete, delete, rename, ssh_cmd. Empty slice to disable
@@ -135,7 +144,12 @@ func ExecuteActionNotification(conn *BaseConnection, operation, filePath, virtua
 				errRes = errHook
 			}
 		} else {
-			go actionHandler.Handle(notification) //nolint:errcheck
+			go func() {
+				startNewHook()
+				defer hookEnded()
+
+				actionHandler.Handle(notification) //nolint:errcheck
+			}()
 		}
 	}
 	return errRes