beginning of an Lwt_flow to track the various transport mechanisms

lib/Lwt_flow.ml

@@ -0,0 +1,71 @@
+(*
+ * Copyright (c) 2012 Anil Madhavapeddy <anil@recoil.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *)
+
+open Lwt
+open Printf
+
+(* Buffers are all wrapped in Bigarrays *)
+type ba = (char, Bigarray.int8_unsigned_elt, Bigarray.c_layout) Bigarray.Array1.t
+
+type 'a tx = {
+  tx_send: 'a -> unit Lwt.t;
+  tx_close: unit -> unit Lwt.t;
+  tx_alloc: int -> 'a Lwt.t;
+  tx_release: 'a -> unit Lwt.t;
+}
+
+type 'a rx = {
+  rx_stream: 'a Lwt_stream.t;
+  rx_release: 'a -> unit Lwt.t;
+}
+
+type ('a, 'b) t = {
+  rx: 'a rx;
+  tx: 'b tx;
+}
+
+(* A flow of shared memory extents *)
+let make ~rx_stream ~rx_release ~tx_send ~tx_release ~tx_close ~tx_alloc =
+  let tx = { tx_send; tx_release; tx_close; tx_alloc } in
+  let rx = { rx_stream; rx_release } in
+  {tx; rx}
+
+module TX = struct
+
+  let alloc ch len =
+    ch.tx.tx_alloc len
+
+  let send ch buf =
+    ch.tx.tx_send buf
+
+  let release ch buf =
+    ch.tx.tx_release buf
+
+end
+
+module RX = struct
+
+  let recv fn ch =
+    Lwt_stream.iter_s fn ch.rx.rx_stream
+
+  let release ch buf =
+    ch.rx.rx_release buf
+
+end
+
+let close ch =
+  eprintf "Lwt_flow: close\n%!";
+  return ()