From f5e25b30077afe8b7dab03c1059932ac981c47bb Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Sat, 10 Mar 2012 13:15:19 +0000
Subject: [PATCH] Implement 'whenjobs --test' to test the effect of variable
 setting.

---
 tools/whenjobs.ml  | 35 +++++++++++++++++++++++++++++++++--
 tools/whenjobs.pod | 11 +++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/tools/whenjobs.ml b/tools/whenjobs.ml
index 582f259..e0f3cc9 100644
--- a/tools/whenjobs.ml
+++ b/tools/whenjobs.ml
@@ -110,6 +110,7 @@ let rec main () =
     "--set", Arg.Unit (set_mode `Set), " Set the variable";
     "--start", Arg.Unit (set_mode `Start), "name Start a job manually";
     "--tail", Arg.Unit (set_mode `Tail), "serial Tail job output";
+    "--test", Arg.Unit (set_mode `Test), " Test the effect of setting variables";
     "--type", Arg.String set_type, "bool|int|float|string|.. Set the variable type";
     "--upload", Arg.Unit (set_mode `Upload), " Upload the script";
     "--variables", Arg.Unit (set_mode `Variables), " Display all variables and values";
@@ -119,8 +120,9 @@ let rec main () =
 
   (* anon_fun normally just collects up the anonymous arguments as
    * strings, and most modes just use 'args' as a list of strings.
-   * However for `Set mode we need to record the type of each argument
-   * as well, so we keep that in a separate list (argtypes).
+   * However for `Set and `Test modes we need to record the type of
+   * each argument as well, so we keep that in a separate list
+   * (argtypes).
    *)
   let argtypes = ref [] in
   let anon_fun str = argtypes := (str, !typ) :: !argtypes in
@@ -189,6 +191,10 @@ Options:
     if nr_args > 0 then
       set_variables argtypes
 
+  | Some `Test ->
+    if nr_args > 0 then
+      test_variables argtypes
+
   | Some `Get ->
     if nr_args != 1 then (
       eprintf "whenjobs --get variable\n";
@@ -359,6 +365,31 @@ and set_variables argtypes =
   );
   stop_client client
 
+and test_variables argtypes =
+  let vars = List.map (
+    fun (def, typ) ->
+      (* 'def' should have the form "name=value".  The value part may
+       * be missing, but the equals sign is required.
+       *)
+      let i =
+        try String.index def '='
+        with Not_found ->
+          eprintf "whenjobs: set: missing = sign in variable definition\n";
+          suggest_help ();
+          exit 1 in
+      let name = String.sub def 0 i in
+      let value = String.sub def (i+1) (String.length def - (i+1)) in
+      let value = value_of_string value typ in
+      { Whenproto_aux.sv_name = name; sv_value = value }
+  ) argtypes in
+  let vars = Array.of_list vars in
+
+  let client = start_client () in
+  let jobnames = Whenproto_clnt.When.V1.test_variables client vars in
+  stop_client client;
+
+  Array.iter print_endline jobnames
+
 and get_variable name =
   let client = start_client () in
   let value = Whenproto_clnt.When.V1.get_variable client name in
diff --git a/tools/whenjobs.pod b/tools/whenjobs.pod
index 7c9e8ee..120608b 100644
--- a/tools/whenjobs.pod
+++ b/tools/whenjobs.pod
@@ -202,6 +202,17 @@ may cause unexpected results, so use with caution.
 Tail the output of the running job identified by its serial number.
 Use the I<--jobs> flag to get a list of running jobs.
 
+=item B<--test> variable=value [variable=value ...]
+
+This works the same way as the I<--set> option, but the difference is
+that the variables are set.  Instead, it lists out the jobs that
+I<would> run, I<if> the variables were updated to these new values.
+
+The variables are not actually updated, and the jobs are not actually
+run.
+
+The output is a list of job names that would run.
+
 =item B<--upload>
 
 Compile the jobs script and upload it to the daemon, without editing.
-- 
1.8.3.1