From 3d3b87010ff9ede82cfb79aee445a30d2c9f88b8 Mon Sep 17 00:00:00 2001 From: Jonathan Davies Date: Thu, 23 Mar 2017 17:40:00 +0000 Subject: [PATCH 10/30] oxenstored: refactor putting response on wire Previously, the functions reply_{ack,data,data_or_ack} and input_handle_error put the response on the wire by invoking Connection.send_{ack,reply,error}. Instead, these functions now return a value indicating what needs to be put on the wire, and that action is done by a send_response function called afterwards. This refactoring gives us a chance to store the value of the response, useful for replaying transactions. Reported-by: Juergen Gross Signed-off-by: Jonathan Davies Reviewed-by: Andrew Cooper Reviewed-by: Jon Ludlam Reviewed-by: Euan Harris Acked-by: David Scott --- tools/ocaml/xenstored/Makefile | 1 + tools/ocaml/xenstored/packet.ml | 4 ++++ tools/ocaml/xenstored/process.ml | 34 ++++++++++++++++++++++++---------- 3 files changed, 29 insertions(+), 10 deletions(-) create mode 100644 tools/ocaml/xenstored/packet.ml diff --git a/tools/ocaml/xenstored/Makefile b/tools/ocaml/xenstored/Makefile index b18f190..7a4c317 100644 --- a/tools/ocaml/xenstored/Makefile +++ b/tools/ocaml/xenstored/Makefile @@ -17,6 +17,7 @@ OBJS = define \ stdext \ trie \ config \ + packet \ logging \ quota \ perms \ diff --git a/tools/ocaml/xenstored/packet.ml b/tools/ocaml/xenstored/packet.ml new file mode 100644 index 0000000..c8ecfe5 --- /dev/null +++ b/tools/ocaml/xenstored/packet.ml @@ -0,0 +1,4 @@ +type response = + | Ack of (unit -> unit) (* function is the action to execute after sending the ack *) + | Reply of string + | Error of string diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml index 89db56c..8be2ff1 100644 --- a/tools/ocaml/xenstored/process.ml +++ b/tools/ocaml/xenstored/process.ml @@ -126,8 +126,7 @@ let do_watch con t rid domains cons data = | _ -> raise Invalid_Cmd_Args in let watch = Connections.add_watch cons con node token in - Connection.send_ack con (Transaction.get_id t) rid Xenbus.Xb.Op.Watch; - Connection.fire_single_watch watch + Packet.Ack (fun () -> Connection.fire_single_watch watch) let do_unwatch con t domains cons data = let (node, token) = @@ -284,20 +283,32 @@ let do_set_target con t domains cons data = | _ -> raise Invalid_Cmd_Args (*------------- Generic handling of ty ------------------*) +let send_response ty con t rid response = + match response with + | Packet.Ack f -> + Connection.send_ack con (Transaction.get_id t) rid ty; + (* Now do any necessary follow-up actions *) + f () + | Packet.Reply ret -> + Connection.send_reply con (Transaction.get_id t) rid ty ret + | Packet.Error e -> + Connection.send_error con (Transaction.get_id t) rid e + let reply_ack fct ty con t rid doms cons data = fct con t doms cons data; - Connection.send_ack con (Transaction.get_id t) rid ty; - if Transaction.get_id t = Transaction.none then - process_watch (Transaction.get_ops t) cons + Packet.Ack (fun () -> + if Transaction.get_id t = Transaction.none then + process_watch (Transaction.get_ops t) cons + ) let reply_data fct ty con t rid doms cons data = let ret = fct con t doms cons data in - Connection.send_reply con (Transaction.get_id t) rid ty ret + Packet.Reply ret let reply_data_or_ack fct ty con t rid doms cons data = match fct con t doms cons data with - | Some ret -> Connection.send_reply con (Transaction.get_id t) rid ty ret - | None -> Connection.send_ack con (Transaction.get_id t) rid ty + | Some ret -> Packet.Reply ret + | None -> Packet.Ack (fun () -> ()) let reply_none fct ty con t rid doms cons data = (* let the function reply *) @@ -329,7 +340,7 @@ let function_of_type ty = let input_handle_error ~cons ~doms ~fct ~ty ~con ~t ~rid ~data = let reply_error e = - Connection.send_error con (Transaction.get_id t) rid e in + Packet.Error e in try fct ty con t rid doms cons data with @@ -362,7 +373,10 @@ let process_packet ~store ~cons ~doms ~con ~tid ~rid ~ty ~data = else Connection.get_transaction con tid in - input_handle_error ~cons ~doms ~fct ~ty ~con ~t ~rid ~data; + let response = input_handle_error ~cons ~doms ~fct ~ty ~con ~t ~rid ~data in + + (* Put the response on the wire *) + send_response ty con t rid response with exn -> error "process packet: %s" (Printexc.to_string exn); Connection.send_error con tid rid "EIO" -- 2.1.4