[patchv2] Sort threads for thread apply all (bt)

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Thu, 15 Jan 2015 20:29:07 +0100, Doug Evans wrote:
> On Thu, Jan 15, 2015 at 10:33 AM, Jan Kratochvil <jan.kratochvil@redhat.com> wrote:
> > I find maybe as good enough and with no risk of UI change flamewar to just
> > sort the threads by their number.  Currently they are printed as they happen
> > in the internal GDB list which has no advantage.  Printing thread #1 as the
> > first one with assumed 'thread apply all bt' (after the core file is loaded)
> > should make the complaint resolved I guess.
> >
> > No regressions on {x86_64,x86_64-m32,i686}-fedora22pre-linux-gnu.
> 
> No objection to sorting the list, but if thread #1 is the important one,
> then a concern could be it'll have scrolled off the screen (such a
> concern has been voiced in another thread in another context),
> and if not lost (say it's in an emacs buffer) one would still have
> to scroll back to see it.
> So one *could* still want #1 to be last.
> Do we want an option to choose the sort direction?
> [I wouldn't make it a global parameter, just an option to
> thread apply.]

Done.


Thanks,
Jan

gdb/ChangeLog
2015-01-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* thread.c (tp_array_compar_asc, tp_array_compar): New.
	(thread_apply_all_command): Parse CMD for tp_array_compar_asc.  Sort
	tp_array using tp_array_compar.
	(_initialize_thread): Extend thread_apply_all_command help.

gdb/doc/ChangeLog
2015-01-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.texinfo (Threads): Describe -asc for thread apply all.

diff --git a/gdb/thread.c b/gdb/thread.c
index ed20fbe..9685351 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -1382,6 +1382,20 @@ make_cleanup_restore_current_thread (void)
 			    restore_current_thread_cleanup_dtor);
 }
 
+static int tp_array_compar_asc;
+
+/* Sort an array for struct thread_info pointers by their ascending NUM.  */
+
+static int
+tp_array_compar (const void *ap_voidp, const void *bp_voidp)
+{
+  const struct thread_info *const *ap = ap_voidp;
+  const struct thread_info *const *bp = bp_voidp;
+
+  return ((((*ap)->num > (*bp)->num) - ((*ap)->num < (*bp)->num))
+	  * (tp_array_compar_asc ? +1 : -1));
+}
+
 /* Apply a GDB command to a list of threads.  List syntax is a whitespace
    seperated list of numbers, or ranges, or the keyword `all'.  Ranges consist
    of two numbers seperated by a hyphen.  Examples:
@@ -1398,6 +1412,13 @@ thread_apply_all_command (char *cmd, int from_tty)
   int tc;
   struct thread_array_cleanup ta_cleanup;
 
+  tp_array_compar_asc = 0;
+  if (cmd && (check_for_argument (&cmd, "-asc", strlen ("-asc"))))
+    {
+      cmd = skip_spaces (cmd);
+      tp_array_compar_asc = 1;
+    }
+
   if (cmd == NULL || *cmd == '\000')
     error (_("Please specify a command following the thread ID list"));
 
@@ -1431,6 +1452,8 @@ thread_apply_all_command (char *cmd, int from_tty)
           i++;
         }
 
+      qsort (tp_array, i, sizeof (*tp_array), tp_array_compar);
+
       make_cleanup (set_thread_refcount, &ta_cleanup);
 
       for (k = 0; k != i; k++)
@@ -1739,7 +1762,14 @@ The new thread ID must be currently known."),
 		  &thread_apply_list, "thread apply ", 1, &thread_cmd_list);
 
   add_cmd ("all", class_run, thread_apply_all_command,
-	   _("Apply a command to all threads."), &thread_apply_list);
+	   _("\
+Apply a command to all threads.\n\
+\n\
+Usage: thread apply all [-asc] <command>\n\
+-asc: Call <command> for all threads in ascending order.\n\
+      The default is descending order.\n\
+"),
+	   &thread_apply_list);
 
   add_cmd ("name", class_run, thread_name_command,
 	   _("Set the current thread's name.\n\
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index f413e23..2207ce4 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -2959,14 +2959,17 @@ information on convenience variables.
 
 @kindex thread apply
 @cindex apply command to several threads
-@item thread apply [@var{threadno} | all] @var{command}
+@item thread apply [@var{threadno} | all [-asc]] @var{command}
 The @code{thread apply} command allows you to apply the named
 @var{command} to one or more threads.  Specify the numbers of the
 threads that you want affected with the command argument
 @var{threadno}.  It can be a single thread number, one of the numbers
 shown in the first field of the @samp{info threads} display; or it
-could be a range of thread numbers, as in @code{2-4}.  To apply a
-command to all threads, type @kbd{thread apply all @var{command}}.
+could be a range of thread numbers, as in @code{2-4}.  To apply
+a command to all threads in descending order, type @kbd{thread apply all
+@var{command}}.  To apply a command to all threads in ascending order,
+type @kbd{thread apply all -asc @var{command}}.
+
 
 @kindex thread name
 @cindex name a thread