2 files changed, 40 insertions, 0 deletions
diff --git a/lib/kernel/BranchManager.ml b/lib/kernel/BranchManager.ml
new file mode 100644
index 0000000..6884219
--- /dev/null
+++ b/lib/kernel/BranchManager.ml
@@ -0,0 +1,29 @@
+module BranchValue = Merkle.StringKey (* FIXME *)
+
+type branch = string
+
+module Make (S : Abstract.Storage.STORAGE) = struct
+  module I = Merkle.Interface (S) (Merkle.StringKey) (BranchValue)
+  module SI = Storage.Make (S)
+
+  type manager = { storage: S.connection; head: I.node Atomic.t }
+
+  let initialize storage addr =
+    let open Utilities.Result in
+    SI.with_transaction storage (fun tx ->
+        let* head = I.find tx addr in
+        Ok { storage; head = Option.value head ~default:I.empty |> Atomic.make })
+
+  let fetch { storage; head } branch_name =
+    SI.with_transaction storage (fun tx ->
+        let head = Atomic.get head in
+        I.lookup tx branch_name head)
+
+  let update ({ storage; head } as manager) branch_name f =
+    let open Utilities.Result in
+    SI.with_transaction storage (fun tx ->
+        let* new_head = Utilities.Atomic.mswap head (fun head ->
+                            let* branch = I.lookup tx branch_name head in
+                            f branch) in
+        Ok { manager with head = new_head })
+end
diff --git a/lib/kernel/BranchManager.mli b/lib/kernel/BranchManager.mli
new file mode 100644
index 0000000..1b572af
--- /dev/null
+++ b/lib/kernel/BranchManager.mli
@@ -0,0 +1,11 @@
+type branch = string            (* FIXME *)
+
+module Make (S : Abstract.Storage.STORAGE) : sig
+  type manager
+
+  val initialize : S.connection -> Concepts.Hash.hash -> (manager, Concepts.Condition.condition) result
+  val fetch : manager -> string -> (Concepts.Branch.t option, Concepts.Condition.condition) result
+  val update : manager -> string -> (branch -> branch) -> (manager, Concepts.Condition.condition) result
+
+  (* TODO: fork, join *)
+end