[gnome-builder] directory: add notes about thread safety

[Christian Hergert <chergert src gnome org>]

commit 33a7edc58d9c4c7a1545211c9892d53802b43a97
Author: Christian Hergert <chergert redhat com>
Date:   Fri Oct 13 16:34:41 2017 -0700

    directory: add notes about thread safety
    
    Certainly functions must remain thread-safe, and we should
    document those so we don't break that invariant later.

 src/libide/directory/ide-directory-vcs.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/src/libide/directory/ide-directory-vcs.c b/src/libide/directory/ide-directory-vcs.c
index 7d2c894..4327fcf 100644
--- a/src/libide/directory/ide-directory-vcs.c
+++ b/src/libide/directory/ide-directory-vcs.c
@@ -62,6 +62,12 @@ ide_directory_vcs_get_working_directory (IdeVcs *vcs)
 
   g_return_val_if_fail (IDE_IS_DIRECTORY_VCS (vcs), NULL);
 
+  /* Note: This function is expected to be thread-safe for
+   *       those holding a reference to @vcs. So
+   *       @working_directory cannot be changed after creation
+   *       and must be valid for the lifetime of @vcs.
+   */
+
   return self->working_directory;
 }
 
@@ -177,6 +183,11 @@ ide_directory_vcs_init_worker (GTask        *task,
 
   file_type = g_file_info_get_file_type (file_info);
 
+  /*
+   * Note: Working directory may only be setup creation time of
+   *       the vcs. So we set it in our GAsyncInitable worker only.
+   */
+
   if (file_type == G_FILE_TYPE_DIRECTORY)
     self->working_directory = g_object_ref (file);
   else