bug#20843: 24.5; Profiler error: "Invalid sampling interval"

[Ken Brown <kbrown@cornell.edu>]

On 6/22/2015 11:35 AM, Eli Zaretskii wrote:
>> Date: Sun, 21 Jun 2015 18:17:27 -0400
>> From: Ken Brown <kbrown@cornell.edu>
>> CC: sva-news@mygooglest.com, 20843@debbugs.gnu.org
>>
>>> If so, we cannot test this at
>>> configure time, because it means we will have to run a program, which
>>> is not a good idea.
>>>
>>> So in that case, I think we should simply disable the CPU profiler on
>>> Cygwin using "#ifndef __CYGWIN__" or some such.
>>
>> Done as commit 5fac0de.
>
> Thanks.
>
>>>>>    Also, the diagnostics should be improved, as the
>>>>> wording is misleading in that case.
>>>>
>>>> As it stands, profiler-cpu-start reports "Invalid sampling interval"
>>>> whenever setup_cpu_timer fails to start the timer, regardless of the
>>>> reason.  I'll try to improve this.
>>>
>>> Yes, please.
>>
>> How's this:
>
> Looks fine, but perhaps it would be cleaner to return the actual
> message string or some distinctive code from setup_cpu_timer.  This
> would avoid the need for a global variable.

Is this better?

--- a/src/profiler.c
+++ b/src/profiler.c
@@ -250,7 +250,7 @@ deliver_profiler_signal (int signal)
    deliver_process_signal (signal, handle_profiler_signal);
  }

-static enum profiler_cpu_running
+static int
  setup_cpu_timer (Lisp_Object sampling_interval)
  {
    struct sigaction action;
@@ -263,7 +263,7 @@ setup_cpu_timer (Lisp_Object sampling_interval)
                           ? ((EMACS_INT) TYPE_MAXIMUM (time_t) * billion
                              + (billion - 1))
                           : EMACS_INT_MAX)))
-    return NOT_RUNNING;
+    return -1;

    current_sampling_interval = XINT (sampling_interval);
    interval = make_timespec (current_sampling_interval / billion,
@@ -336,9 +336,18 @@ See also `profiler-log-size' and 
`profiler-max-stack-depth'.  */)
                           profiler_max_stack_depth);
      }

-  profiler_cpu_running = setup_cpu_timer (sampling_interval);
-  if (! profiler_cpu_running)
-    error ("Invalid sampling interval");
+  int status = setup_cpu_timer (sampling_interval);
+  if (status == -1)
+    {
+      profiler_cpu_running = NOT_RUNNING;
+      error ("Invalid sampling interval");
+    }
+  else
+    {
+      profiler_cpu_running = status;
+      if (! profiler_cpu_running)
+       error ("Unable to start profiler timer");
+    }

    return Qt;
  }

Ken