2 files changed, 23 insertions, 2 deletions
diff --git a/lib/kernel/Lifecycle.ml b/lib/kernel/Lifecycle.ml
index ff67ecf..772cb6e 100644
--- a/lib/kernel/Lifecycle.ml
+++ b/lib/kernel/Lifecycle.ml
@@ -23,7 +23,18 @@ class virtual counted = object (self)
     true
 
   method release =
-    Atomic.decr references;
-    if Atomic.get references <= 0 then
+    if Atomic.fetch_and_add references (-1) = 1 then
       self#destroy
 end
+
+class retaining inner (owner : lifecycle) = object
+  inherit counted
+  initializer ignore owner#reference
+
+  method destroy =
+    Protocols.Handle.release inner;
+    owner#release
+
+  method hash = Protocols.Handle.hash inner
+  method protocols = Protocols.Handle.protocols inner
+end
diff --git a/lib/kernel/Lifecycle.mli b/lib/kernel/Lifecycle.mli
index f110768..fa3abee 100644
--- a/lib/kernel/Lifecycle.mli
+++ b/lib/kernel/Lifecycle.mli
@@ -10,3 +10,13 @@ end
 
 class null : lifecycle
 class virtual counted : controlled_lifecycle
+
+(** stands for [inner], carrying what it carries, while holding a
+    reference to [owner], so what [inner] reads outlives a release of
+    the object that produced it. *)
+class retaining : Protocols.Handle.t -> lifecycle -> object
+  inherit lifecycle
+  method destroy : unit
+  method hash : Concepts.Hash.hash
+  method protocols : Protocols.Handle.protocol list
+end