Add the guarantee to the Registry that KeyManagers returned by get_key_manager() remain valid, even in the presence of concurrent registering calls.

This was previously already the case, except for calls to RegisterAsymmetricKeyManagers after a non-asymmetric register call. Hence, there's a bit of a change of behavior, but if someone does this already I think they will prefer the new failure to the previous potential one.

I also remove the reference_wrapper TODO, since I think it's infeasible to change this at this point (see e.g. [1]). Let me know if you want to keep it.

PiperOrigin-RevId: 279289623

1 files changed, 5 insertions, 5 deletions

diff --git a/cc/registry.h b/cc/registry.h
index 2de4ebf47..47348af8c 100644
--- a/cc/registry.h
+++ b/cc/registry.h
@@ -142,11 +142,11 @@ class Registry {
   }
 
   // Returns a key manager for the given type_url (if any found).
-  // Keeps the ownership of the manager.
-  // TODO(przydatek): consider changing return value to
-  //   StatusOr<std::reference_wrapper<KeyManager<P>>>
-  // (cannot return reference directly, as StatusOr does not support it,
-  // see https://goo.gl/x0ymDz)
+  // Keeps the ownership of the manager. Returned key_managers are guaranteed
+  // to stay valid for the lifetime of the binary (with the exception of a user
+  // calling Reset()).
+  // TODO(tholenst): Remove Reset() from the interface, as it could violate this
+  // but should be test only anyhow.
   template <class P>
   static crypto::tink::util::StatusOr<const KeyManager<P>*> get_key_manager(
       const std::string& type_url) {