Split out the memory backend

1 files changed, 83 insertions, 0 deletions

diff --git a/lib/management/storage/memory.ml b/lib/management/storage/memory.ml
new file mode 100644
index 0000000..041bebe
--- /dev/null
+++ b/lib/management/storage/memory.ml
@@ -0,0 +1,83 @@
+(** In-memory backend for testing and development *)
+module MemoryBackend :
+  Physical.BACKEND with type error = string and type configuration = unit = struct
+  type configuration = unit
+
+  type connection = {
+    data : (string, bytes) Hashtbl.t;
+    mutable in_transaction : bool;
+    mutable transaction_buffer : (string * bytes) list;
+  }
+
+  type error = string
+
+  let parse sexp =
+    match sexp with
+    | Sexplib.Sexp.List [] -> Ok ()
+    | _ ->
+        Error
+          (Printf.sprintf "memory backend takes no configuration, got: %s"
+             (Sexplib.Sexp.to_string sexp))
+
+  let connect () =
+    Ok
+      {
+        data = Hashtbl.create 1024;
+        in_transaction = false;
+        transaction_buffer = [];
+      }
+
+  let disconnect _ = ()
+  let get conn hash = Ok (Hashtbl.find_opt conn.data hash)
+
+  let put conn hash value =
+    if conn.in_transaction then begin
+      conn.transaction_buffer <- (hash, value) :: conn.transaction_buffer;
+      Ok ()
+    end
+    else begin
+      Hashtbl.replace conn.data hash value;
+      Ok ()
+    end
+
+  let exists conn hash = Ok (Hashtbl.mem conn.data hash)
+
+  let begin_transaction conn =
+    if conn.in_transaction then Error "Already in transaction"
+    else begin
+      conn.in_transaction <- true;
+      conn.transaction_buffer <- [];
+      Ok ()
+    end
+
+  let commit conn =
+    if not conn.in_transaction then Error "Not in transaction"
+    else begin
+      List.iter
+        (fun (hash, value) -> Hashtbl.replace conn.data hash value)
+        conn.transaction_buffer;
+      conn.in_transaction <- false;
+      conn.transaction_buffer <- [];
+      Ok ()
+    end
+
+  let rollback conn =
+    if not conn.in_transaction then Error "Not in transaction"
+    else begin
+      conn.in_transaction <- false;
+      conn.transaction_buffer <- [];
+      Ok ()
+    end
+
+  let get_many conn hashes =
+    Ok (List.map (fun h -> Hashtbl.find_opt conn.data h) hashes)
+
+  let put_many conn pairs =
+    List.iter
+      (fun (hash, value) ->
+        if conn.in_transaction then
+          conn.transaction_buffer <- (hash, value) :: conn.transaction_buffer
+        else Hashtbl.replace conn.data hash value)
+      pairs;
+    Ok ()
+end