Persist variables to file (~/.whenjobs/variables).

[whenjobs.git] / daemon / daemon.ml

diff --git a/daemon/daemon.ml b/daemon/daemon.ml
index 078aa3a..f5ba4ff 100644 (file)
--- a/daemon/daemon.ml
+++ b/daemon/daemon.ml
@@ -29,9 +29,41 @@ external _exit : int -> 'a = "whenjobs__exit"
 (* $HOME/.whenjobs *)
 let jobsdir = ref ""
 
-(* The state. *)
+(* The state.
+ *
+ * Note that whenever this is updated, you need to consider if you
+ * should call 'save_variables ()' (which persists the variables to a
+ * file).  XXX We should replace this ref with an accessor
+ * function.
+ *)
 let state = ref Whenstate.empty
 
+(* Format used to save variables.  Note we can't allow any internal
+ * types to "escape" into this definition, else the file format will
+ * change when parts of the program change.
+ *)
+type variables_file_v1 = (string * variable_v1) list
+and variable_v1 =
+  | Vv1_unit
+  | Vv1_bool of bool
+  | Vv1_string of string
+  | Vv1_int of big_int
+  | Vv1_float of float
+
+let variable_of_variable_v1 = function
+  | Vv1_unit -> T_unit
+  | Vv1_bool b -> T_bool b
+  | Vv1_string s -> T_string s
+  | Vv1_int i -> T_int i
+  | Vv1_float f -> T_float f
+
+let variable_v1_of_variable = function
+  | T_unit -> Vv1_unit
+  | T_bool b -> Vv1_bool b
+  | T_string s -> Vv1_string s
+  | T_int i -> Vv1_int i
+  | T_float f -> Vv1_float f
+
 (* Jobs that are running: a map of PID -> (job, tmpdir, serial, start_time).
  * Note that the job may no longer exist *OR* it may have been renamed,
  * eg. if the jobs file was reloaded.
@@ -93,8 +125,48 @@ let rec init j d =
   (* Handle SIGCHLD to clean up jobs. *)
   Sys.set_signal Sys.sigchld (Sys.Signal_handle handle_sigchld);
 
-  (* Initialize the variables. *)
-  state := Whenstate.set_variable !state "JOBSERIAL" (T_int zero_big_int)
+  (* Load or initialize the variables. *)
+  let variables_file = sprintf "%s/variables" !jobsdir in
+  state :=
+    try
+      let chan = open_in variables_file in
+      let r = load_variables !state chan in
+      close_in chan;
+      r
+    with
+    | Sys_error _ ->
+      Whenstate.set_variable !state "JOBSERIAL" (T_int zero_big_int)
+
+(* Try to load the variables from the file.  If the file exists and
+ * cannot be read, raise an exception.
+ *)
+and load_variables state chan =
+  let signature = input_line chan in
+  if signature = "WHENJOBS VARIABLES VERSION 1" then (
+    let variables : variables_file_v1 = input_value chan in
+    List.fold_left (
+      fun state (n, v) ->
+        Whenstate.set_variable state n (variable_of_variable_v1 v)
+    ) state variables
+  ) else (* in future, other signatures, but for now ... *)
+    failwith (sprintf "cannot read variables file: invalid signature: %s"
+                signature)
+
+and save_variables () =
+  let variables_file = sprintf "%s/variables" !jobsdir in
+  let new_file = variables_file ^ ".new" in
+  let chan = open_out new_file in
+  fprintf chan "WHENJOBS VARIABLES VERSION 1\n";
+  let variables = Whenstate.get_variables !state in
+  let variables =
+    List.map (fun (n, v) -> n, variable_v1_of_variable v) variables in
+  output_value chan variables;
+
+  (* Try to arrange that the new file is updated atomically. *)
+  flush chan;
+  Netsys_posix.fsync (descr_of_out_channel chan);
+  close_out chan;
+  rename new_file variables_file
 
 and proc_reload_file () =
   if !debug then Syslog.notice "remote call: reload_file";
@@ -116,6 +188,7 @@ and proc_set_variable (name, value) =
     let jobnames, state' = reevaluate_whenjobs !state jobs in
     let state' = run_whenjobs state' jobnames in
     state := state';
+    save_variables ();
 
     `ok
   with
@@ -172,6 +245,7 @@ and proc_start_job jobname =
     let job = Whenstate.get_job !state jobname in
     let state' = run_job !state job in
     state := state';
+    save_variables ();
     `ok
   with
   | Not_found -> `error "job not found"
@@ -218,6 +292,7 @@ and proc_set_variables vars =
     let jobnames, state' = reevaluate_whenjobs !state jobs in
     let state' = run_whenjobs state' jobnames in
     state := state';
+    save_variables ();
 
     `ok
   with
@@ -284,6 +359,7 @@ and proc_whisper_variables vars =
       fun s (name, value) -> Whenstate.set_variable s name value
     ) !state vars in
     state := s;
+    save_variables ();
 
     (* .. but don't reevaluate or run jobs. *)
 
@@ -363,6 +439,7 @@ and reload_files () =
   let jobnames, state' = reevaluate_whenjobs ~onload:true !state jobs in
   let state' = run_whenjobs state' jobnames in
   state := state';
+  save_variables ();
 
   (* Schedule the next every job to run. *)
   schedule_next_everyjob ()
@@ -471,6 +548,7 @@ and schedule_next_everyjob () =
         delete_timer_group ();          (* Delete the timer. *)
         let state' = List.fold_left run_job !state jobs in
         state := state';
+        save_variables ();
         schedule_next_everyjob ()
       in
       Unixqueue.weak_once esys g t_diff run_jobs;