bug#22114: 24.5; [PATCH] Allow profiler.el to display reports after stopping

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 8 Dec 2015 09:13:58 +0100
> From: Vasilij Schneidermann <v.schneidermann@gmail.com>
> 
> I've worked with a few other profilers than profiler.el so far and one
> striking difference is that they allowed you to start a profiling run,
> stop it and then retrieve the profiling log between these two points in
> time. profiler.el on the other hand flatout refuses to display a report
> after stopping which is especially puzzling given the `profiler-stop`
> docstring: "Stop started profilers. Profiler logs will be kept." If
> the logs are kept after all, why can't I take a look at them?
> 
> I've attached a patch that solves this by caching the last accessable
> profiler log. This allows both workflows to work, be it displaying a
> report while the profiler is still running or displaying it after
> stopping the profiler.

Thanks.  But I don't see why we would need to keep a copy of the
profile around (and it looks weird to do that anyway, when we have a
function that reports it).  When profiler-cpu-log is called, it
returns the profile before it resets it, so the data is available and
should simply be used.

I don't really understand why profiler.el insists on having the
profiler running for providing the profile.  The much simpler patch
below makes it possible for me to invoke profiler-report whether a
profile is running or not.  Does it work for you?  If not, can you
tell what I missed?

--- lisp/profiler.el~4	2015-11-11 07:57:32.000000000 +0200
+++ lisp/profiler.el	2015-12-08 17:54:27.380084700 +0200
@@ -216,19 +216,17 @@
 
 (defun profiler-cpu-profile ()
   "Return CPU profile."
-  (when (profiler-running-p 'cpu)
-    (profiler-make-profile
-     :type 'cpu
-     :timestamp (current-time)
-     :log (profiler-cpu-log))))
+  (profiler-make-profile
+   :type 'cpu
+   :timestamp (current-time)
+   :log (profiler-cpu-log)))
 
 (defun profiler-memory-profile ()
   "Return memory profile."
-  (when (profiler-memory-running-p)
-    (profiler-make-profile
-     :type 'memory
-     :timestamp (current-time)
-     :log (profiler-memory-log))))
+  (profiler-make-profile
+   :type 'memory
+   :timestamp (current-time)
+   :log (profiler-memory-log)))
 
 \f
 ;;; Calltrees
@@ -846,12 +844,12 @@
 
 (defun profiler-report-cpu ()
   (let ((profile (profiler-cpu-profile)))
-    (when profile
+    (when (and profile (profiler-profile-log profile))
       (profiler-report-profile-other-window profile))))
 
 (defun profiler-report-memory ()
   (let ((profile (profiler-memory-profile)))
-    (when profile
+    (when (and profile (profiler-profile-log profile))
       (profiler-report-profile-other-window profile))))
 
 (defun profiler-report ()