revise log and console subscription protocol, require either since or count

client/albatross_client_bistro.ml

@@ -115,14 +115,14 @@ let create _ endp cert key ca force name image cpuid memory argv block network c
   | Ok cmd -> jump endp cert key ca name (`Unikernel_cmd cmd)
   | Error (`Msg msg) -> Error (`Msg msg)
 
-let console _ endp cert key ca name since =
+let console _ endp cert key ca name since count =
-  jump endp cert key ca name (`Console_cmd (`Console_subscribe since))
+  jump endp cert key ca name (`Console_cmd (`Console_subscribe (Albatross_cli.since_count since count)))
 
 let stats _ endp cert key ca name =
   jump endp cert key ca name (`Stats_cmd `Stats_subscribe)
 
-let event_log _ endp cert key ca name since =
+let event_log _ endp cert key ca name since count =
-  jump endp cert key ca name (`Log_cmd (`Log_subscribe since))
+  jump endp cert key ca name (`Log_cmd (`Log_subscribe (Albatross_cli.since_count since count)))
 
 let block_info _ endp cert key ca block_name =
   jump endp cert key ca block_name (`Block_cmd `Block_info)
@@ -217,7 +217,7 @@ let console_cmd =
     [`S "DESCRIPTION";
      `P "Shows console output of a VM."]
   in
-  Term.(term_result (const console $ setup_log $ destination $ ca_cert $ ca_key $ server_ca $ vm_name $ since)),
+  Term.(term_result (const console $ setup_log $ destination $ ca_cert $ ca_key $ server_ca $ vm_name $ since $ count)),
   Term.info "console" ~doc ~man
 
 let stats_cmd =
@@ -235,7 +235,7 @@ let log_cmd =
     [`S "DESCRIPTION";
      `P "Shows event log of VM."]
   in
-  Term.(term_result (const event_log $ setup_log $ destination $ ca_cert $ ca_key $ server_ca $ opt_vm_name $ since)),
+  Term.(term_result (const event_log $ setup_log $ destination $ ca_cert $ ca_key $ server_ca $ opt_vm_name $ since $ count)),
   Term.info "log" ~doc ~man
 
 let block_info_cmd =

client/albatross_client_local.ml

@@ -66,8 +66,8 @@ let create _ opt_socket force name image cpuid memory argv block network compres
   | Ok cmd -> jump opt_socket name (`Unikernel_cmd cmd)
   | Error (`Msg msg) -> Error (`Msg msg)
 
-let console _ opt_socket name since =
+let console _ opt_socket name since count =
-  jump opt_socket name (`Console_cmd (`Console_subscribe since))
+  jump opt_socket name (`Console_cmd (`Console_subscribe (Albatross_cli.since_count since count)))
 
 let stats_add _ opt_socket name vmmdev pid bridge_taps =
   jump opt_socket name (`Stats_cmd (`Stats_add (vmmdev, pid, bridge_taps)))
@@ -78,8 +78,8 @@ let stats_remove _ opt_socket name =
 let stats_subscribe _ opt_socket name =
   jump opt_socket name (`Stats_cmd `Stats_subscribe)
 
-let event_log _ opt_socket name since =
+let event_log _ opt_socket name since count =
-  jump opt_socket name (`Log_cmd (`Log_subscribe since))
+  jump opt_socket name (`Log_cmd (`Log_subscribe (Albatross_cli.since_count since count)))
 
 let block_info _ opt_socket block_name =
   jump opt_socket block_name (`Block_cmd `Block_info)
@@ -162,7 +162,7 @@ let console_cmd =
     [`S "DESCRIPTION";
      `P "Shows console output of a VM."]
   in
-  Term.(term_result (const console $ setup_log $ socket $ vm_name $ since)),
+  Term.(term_result (const console $ setup_log $ socket $ vm_name $ since $ count)),
   Term.info "console" ~doc ~man
 
 let stats_subscribe_cmd =
@@ -198,7 +198,7 @@ let log_cmd =
     [`S "DESCRIPTION";
      `P "Shows event log of VM."]
   in
-  Term.(term_result (const event_log $ setup_log $ socket $ opt_vm_name $ since)),
+  Term.(term_result (const event_log $ setup_log $ socket $ opt_vm_name $ since $ count)),
   Term.info "log" ~doc ~man
 
 let block_info_cmd =

command-line/albatross_cli.ml

@@ -232,6 +232,10 @@ let exit_code =
 
 let timestamp_c =
   let parse s = match Ptime.of_rfc3339 s with
+    | Ok (t, _, _) -> `Ok t
+    | Error _ ->
+      (* let's try to add T00:00:00-00:00 *)
+      match Ptime.of_rfc3339 (s ^ "T00:00:00-00:00") with
       | Ok (t, _, _) -> `Ok t
       | Error _ -> `Error "couldn't parse timestamp"
   in
@@ -240,3 +244,11 @@ let timestamp_c =
 let since =
   let doc = "Receive data since a specified timestamp (RFC 3339 encoded)" in
   Arg.(value & opt (some timestamp_c) None & info [ "since" ] ~doc)
+
+let count =
+  let doc = "Receive N data records" in
+  Arg.(value & opt int 20 & info [ "count" ] ~doc)
+
+let since_count since count = match since with
+  | None -> `Count count
+  | Some since -> `Since since

daemon/albatross_console.ml

@@ -104,8 +104,8 @@ let subscribe s id =
 let send_history s r id since =
   let entries =
     match since with
-    | None -> Vmm_ring.read r
+    | `Count n -> Vmm_ring.read_last r n
-    | Some ts -> Vmm_ring.read_history r ts
+    | `Since ts -> Vmm_ring.read_history r ts
   in
   Logs.debug (fun m -> m "%a found %d history" Vmm_core.Name.pp id (List.length entries)) ;
   Lwt_list.iter_s (fun (i, v) ->

daemon/albatross_log.ml

@@ -67,19 +67,15 @@ let write_to_file mvar file =
   loop fd >|= fun _ ->
   ()
 
-let send_history s ring id ts =
+let send_history s ring id what =
-  let elements =
+  let tst event =
-    match ts with
-    | None -> Vmm_ring.read ring
-    | Some since -> Vmm_ring.read_history ring since
-  in
-  let res =
-    List.fold_left (fun acc (ts, event) ->
     let sub = Vmm_core.Log.name event in
-        if Vmm_core.Name.is_sub ~super:id ~sub
+    Vmm_core.Name.is_sub ~super:id ~sub
-        then (ts, event) :: acc
+  in
-        else acc)
+  let elements =
-      [] elements
+    match what with
+    | `Since since -> Vmm_ring.read_history ~tst ring since
+    | `Count n -> Vmm_ring.read_last ~tst ring n
   in
   (* just need a wrapper in tag = Log.Data, id = reqid *)
   Lwt_list.fold_left_s (fun r (ts, event) ->
@@ -88,7 +84,7 @@ let send_history s ring id ts =
         let header = Vmm_commands.{ version = my_version ; sequence = 0L ; name = id } in
         Vmm_lwt.write_wire s (header, `Data (`Log_data (ts, event)))
       | Error e -> Lwt.return (Error e))
-    (Ok ()) (List.rev res)
+    (Ok ()) elements
 
 let tree = ref Vmm_trie.empty
 

provision/albatross_provision_request.ml

@@ -45,14 +45,14 @@ let create _ force name image cpuid memory argv block network compression restar
   | Ok cmd -> jump name (`Unikernel_cmd cmd)
   | Error (`Msg msg) -> Error (`Msg msg)
 
-let console _ name since =
+let console _ name since count =
-  jump name (`Console_cmd (`Console_subscribe since))
+  jump name (`Console_cmd (`Console_subscribe (Albatross_cli.since_count since count)))
 
 let stats _ name =
   jump name (`Stats_cmd `Stats_subscribe)
 
-let event_log _ name since =
+let event_log _ name since count =
-  jump name (`Log_cmd (`Log_subscribe since))
+  jump name (`Log_cmd (`Log_subscribe (Albatross_cli.since_count since count)))
 
 let block_info _ block_name =
   jump block_name (`Block_cmd `Block_info)
@@ -131,7 +131,7 @@ let console_cmd =
     [`S "DESCRIPTION";
      `P "Shows console output of a VM."]
   in
-  Term.(term_result (const console $ setup_log $ vm_name $ since)),
+  Term.(term_result (const console $ setup_log $ vm_name $ since $ count)),
   Term.info "console" ~doc ~man
 
 let stats_cmd =
@@ -149,7 +149,7 @@ let log_cmd =
     [`S "DESCRIPTION";
      `P "Shows event log of VM."]
   in
-  Term.(term_result (const event_log $ setup_log $ opt_vm_name $ since)),
+  Term.(term_result (const event_log $ setup_log $ opt_vm_name $ since $ count)),
   Term.info "log" ~doc ~man
 
 let block_info_cmd =

src/vmm_asn.ml

@@ -53,15 +53,17 @@ let policy =
 let console_cmd =
   let f = function
     | `C1 () -> `Console_add
-    | `C2 ts -> `Console_subscribe ts
+    | `C2 `C1 ts -> `Console_subscribe (`Since ts)
+    | `C2 `C2 c -> `Console_subscribe (`Count c)
   and g = function
     | `Console_add -> `C1 ()
-    | `Console_subscribe ts -> `C2 ts
+    | `Console_subscribe `Since ts -> `C2 (`C1 ts)
+    | `Console_subscribe `Count c -> `C2 (`C2 c)
   in
   Asn.S.map f g @@
   Asn.S.(choice2
            (explicit 0 null)
-           (explicit 1 (sequence (single (optional ~label:"since" utc_time)))))
+           (explicit 1 (choice2 (explicit 0 utc_time) (explicit 1 int))))
 
 (* TODO is this good? *)
 let int64 =
@@ -283,12 +285,14 @@ let log_event =
 
 let log_cmd =
   let f = function
-    | ts -> `Log_subscribe ts
+    | `C1 since -> `Log_subscribe (`Since since)
+    | `C2 n -> `Log_subscribe (`Count n)
   and g = function
-    | `Log_subscribe ts -> ts
+    | `Log_subscribe `Since since -> `C1 since
+    | `Log_subscribe `Count n -> `C2 n
   in
   Asn.S.map f g @@
-  Asn.S.(sequence (single (optional ~label:"since" utc_time)))
+  Asn.S.(choice2 (explicit 0 utc_time) (explicit 1 int))
 
 let typ =
   let f = function

src/vmm_commands.ml

@@ -19,16 +19,20 @@ let version_eq a b =
   | `AV2, `AV2 -> true
   | _ -> false
 
+type since_count = [ `Since of Ptime.t | `Count of int ]
+
+let pp_since_count ppf = function
+  | `Since since -> Fmt.pf ppf "since %a" (Ptime.pp_rfc3339 ()) since
+  | `Count n -> Fmt.pf ppf "number %d" n
+
 type console_cmd = [
   | `Console_add
-  | `Console_subscribe of Ptime.t option
+  | `Console_subscribe of since_count
 ]
 
 let pp_console_cmd ppf = function
   | `Console_add -> Fmt.string ppf "console add"
-  | `Console_subscribe ts ->
+  | `Console_subscribe ts -> Fmt.pf ppf "console subscribe %a" pp_since_count ts
-    Fmt.pf ppf "console subscribe since %a"
-      Fmt.(option ~none:(unit "epoch") (Ptime.pp_rfc3339 ())) ts
 
 type stats_cmd = [
   | `Stats_add of string * int * (string * string) list
@@ -44,13 +48,11 @@ let pp_stats_cmd ppf = function
   | `Stats_subscribe -> Fmt.string ppf "stat subscribe"
 
 type log_cmd = [
-  | `Log_subscribe of Ptime.t option
+  | `Log_subscribe of since_count
 ]
 
 let pp_log_cmd ppf = function
-  | `Log_subscribe ts ->
+  | `Log_subscribe x -> Fmt.pf ppf "log subscribe since %a" pp_since_count x
-    Fmt.pf ppf "log subscribe since %a"
-      Fmt.(option ~none:(unit "epoch") (Ptime.pp_rfc3339 ())) ts
 
 type unikernel_cmd = [
   | `Unikernel_info

src/vmm_commands.mli

@@ -11,9 +11,11 @@ val version_eq : version -> version -> bool
 (** [pp_version ppf version] pretty prints [version] onto [ppf]. *)
 val pp_version : version Fmt.t
 
+type since_count = [ `Since of Ptime.t | `Count of int ]
+
 type console_cmd = [
   | `Console_add
-  | `Console_subscribe of Ptime.t option
+  | `Console_subscribe of since_count
 ]
 
 type stats_cmd = [
@@ -23,7 +25,7 @@ type stats_cmd = [
 ]
 
 type log_cmd = [
-  | `Log_subscribe of Ptime.t option
+  | `Log_subscribe of since_count
 ]
 
 type unikernel_cmd = [

src/vmm_ring.ml

@@ -19,25 +19,30 @@ let write t entry =
 
 let dec t n = (pred n + t.size) mod t.size
 
-let not_written ts = Ptime.equal ts Ptime.min
+let read_last t ?(tst = fun _ -> true) n =
+  let rec one idx count acc =
+    let our = Array.get t.data idx in
+    if tst (snd our) then
+      if pred count = 0 then
+        our :: acc
+      else
+        one (dec t idx) (pred count) (our :: acc)
+    else
+      one (dec t idx) count acc
+  in
+  one (dec t t.write) n []
 
-let entry_not_written (ts, _) = not_written ts
+let read_history t ?(tst = fun _ -> true) since =
-
+  let rec go acc idx =
-let earlier than (ts, _) =
+    let entry = Array.get t.data idx in
-  if not_written ts then true else Ptime.is_earlier ts ~than
+    if Ptime.equal (fst entry) Ptime.min then
-
+      acc
-let read_some tst t =
+    else if tst (snd entry) then
-  let rec go s acc idx =
+      if Ptime.is_earlier (fst entry) ~than:since then
-    if idx = s then (* don't read it twice *)
         acc
       else
-      let entry = Array.get t.data idx in
+        go (entry :: acc) (dec t idx)
-      if tst entry then acc else go s (entry :: acc) (dec t idx)
+    else
+      go acc (dec t idx)
   in
-  let idx = dec t t.write in
+  go [] (dec t t.write)
-  let entry = Array.get t.data idx in
-  if tst entry then [] else go idx [entry] (dec t idx)
-
-let read t = read_some entry_not_written t
-
-let read_history t than = read_some (earlier than) t

src/vmm_ring.mli

@@ -5,5 +5,6 @@ type 'a t
 val create : ?size:int -> 'a -> unit -> 'a t
 
 val write : 'a t -> Ptime.t * 'a -> unit
-val read : 'a t -> (Ptime.t * 'a) list
+
-val read_history : 'a t -> Ptime.t -> (Ptime.t * 'a) list
+val read_last : 'a t -> ?tst:('a -> bool) -> int -> (Ptime.t * 'a) list
+val read_history : 'a t -> ?tst:('a -> bool) -> Ptime.t -> (Ptime.t * 'a) list