[PATCH] Add "thread-group id" and "id in thread-group" info to -thread-info output

[Simon Marchi <simon dot marchi at ericsson dot com>]

The CLI has been showing inferior-qualified thread ids for a while, but
front-ends have no way to do the same, as only the global thread ids are
included in the MI output.  In front-ends in general, but mostly in
those that include a gdb console, it would be interesting to show the
same thread id in the GUI than what "info threads" displays.  The user
would then see consistent thread ids across the two UIs.

This patch adds two extra fields to the -thread-info MI command output.
In this snippet of prettified -thread-info output, the lines marked with
a + are new:

    {
+     tg-id = "2",
+     id-in-tg = "1",
      id = "3",
      target-id = "Thread 0x2aaaaab04640 (LWP 3228)",
      name = "mi-qualified-th",
      ...
    },

Here, the thread has the global id 3 (monotonously increasing across all
inferiors) and the inferior-qualified id 2.1.  The global thread id is
still the one used throughout the rest of MI.  The new fields are simply
intended to be presented to the user.

We chose adding the new information as two separate fields rather than a
single field with the value "2.1".  We think that it gives the front-end
more flexibility about how it want to present the info.

Note thatt I renamed the existing CLI field "id-in-tg" to "qualified-id"
and named one of the new MI field "id-in-tg", because I found that
"id-in-tg" described better the Y in X.Y, and "qualified-id" described
better the whole thing.  It's not a big deal, as the field name is never
shown in the CLI.  We have to carefully choose the new names however,
since they'll be exposed in the MI.

gdb/ChangeLog:

	* thread.c (print_thread_info_1): Rename field id-in-tg to
	qualified-id.  Add new fields id-in-tg and tg-id when printing
	on MI.

gdb/testsuite/ChangeLog:

	* mi-qualified-thread-id.exp: New file.
	* mi-qualified-thread-id.c: New file.
---
 gdb/testsuite/gdb.mi/mi-qualified-thread-id.c   | 57 +++++++++++++++++++
 gdb/testsuite/gdb.mi/mi-qualified-thread-id.exp | 76 +++++++++++++++++++++++++
 gdb/thread.c                                    | 11 +++-
 3 files changed, 141 insertions(+), 3 deletions(-)
 create mode 100644 gdb/testsuite/gdb.mi/mi-qualified-thread-id.c
 create mode 100644 gdb/testsuite/gdb.mi/mi-qualified-thread-id.exp

diff --git a/gdb/testsuite/gdb.mi/mi-qualified-thread-id.c b/gdb/testsuite/gdb.mi/mi-qualified-thread-id.c
new file mode 100644
index 0000000000..cb50e50c32
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/mi-qualified-thread-id.c
@@ -0,0 +1,57 @@
+/* Copyright 2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+
+static pthread_barrier_t barrier;
+
+static void *
+thread_func (void *arg)
+{
+  /* Notify the main thread that this thread has started.  */
+  pthread_barrier_wait (&barrier);
+
+  /* Wait until main gives us the signal that we can quit.  */
+  pthread_barrier_wait (&barrier);
+  return NULL;
+}
+
+static void
+thread_started ()
+{
+}
+
+int main ()
+{
+  pthread_t thread;
+
+  pthread_barrier_init (&barrier, NULL, 2);
+
+  pthread_create (&thread, NULL, thread_func, NULL);
+
+  /* Wait until the thread has started.  */
+  pthread_barrier_wait (&barrier);
+
+  thread_started ();
+
+  /* Tell the thread that it can quit.  */
+  pthread_barrier_wait (&barrier);
+
+  pthread_join (thread, NULL);
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.mi/mi-qualified-thread-id.exp b/gdb/testsuite/gdb.mi/mi-qualified-thread-id.exp
new file mode 100644
index 0000000000..43c1409786
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/mi-qualified-thread-id.exp
@@ -0,0 +1,76 @@
+# Copyright 2017 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib mi-support.exp
+set MIFLAGS "-i=mi"
+
+standard_testfile
+
+if {[use_gdb_stub]} {
+    # There is no point in testing inferior-qualified thread ids if we can't
+    # have multiple inferiors.
+    untested "multi-inferior not supported"
+    return
+}
+
+if  { [gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+     untested ${testfile}
+     return -1
+}
+
+# Prepare the inferiors.  Start and run them until the "thread_started" function.
+
+proc setup { } {
+    global binfile
+    global srcdir
+    global subdir
+    global srcfile
+
+    gdb_exit
+    mi_gdb_start
+    mi_gdb_reinitialize_dir $srcdir/$subdir
+    mi_gdb_load ${binfile}
+
+    mi_create_breakpoint "thread_started" "insert breakpoint at thread_started"
+
+    # Start inferior 1
+    mi_run_cmd
+    mi_expect_stop "breakpoint-hit" "thread_started" ".*" "${srcfile}" ".*" {"" "disp=\"keep\""} "inferior 1 stops"
+
+    # Add and start inferior 2
+    mi_gdb_test "add-inferior -exec ${binfile}" ".*=thread-group-added,id=\"i2\".*" "add second inferior"
+    mi_gdb_test "inferior 2" ".*" "switch to inferior 2"
+    mi_run_cmd
+    mi_expect_stop "breakpoint-hit" "thread_started" ".*" "${srcfile}" ".*" {"" "disp=\"keep\""} "inferior 2 stops"
+}
+
+proc test_thread_info_qualified_thread_id { } {
+    setup
+
+    set expected [join \
+	{ "111\\^done,threads=.*" \
+	  "tg-id=\"1\",id-in-tg=\"1\",id=\"1\".*" \
+	  "tg-id=\"1\",id-in-tg=\"2\",id=\"2\".*" \
+	  "tg-id=\"2\",id-in-tg=\"1\",id=\"3\".*" \
+	  "tg-id=\"2\",id-in-tg=\"2\",id=\"4\".*" \
+	} ""]
+
+    mi_gdb_test \
+	"111-thread-info" \
+	 $expected \
+	"thread ids in -thread-info"
+}
+
+test_thread_info_qualified_thread_id
diff --git a/gdb/thread.c b/gdb/thread.c
index e45b25750e..29cfa61e13 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -1247,7 +1247,7 @@ print_thread_info_1 (struct ui_out *uiout, char *requested_threads,
       uiout->table_header (1, ui_left, "current", "");
 
       if (!uiout->is_mi_like_p ())
-	uiout->table_header (4, ui_left, "id-in-tg", "Id");
+	uiout->table_header (4, ui_left, "qualified-id", "Id");
       if (show_global_ids || uiout->is_mi_like_p ())
 	uiout->table_header (4, ui_left, "id", "GId");
       uiout->table_header (17, ui_left, "target-id", "Target Id");
@@ -1282,8 +1282,13 @@ print_thread_info_1 (struct ui_out *uiout, char *requested_threads,
 	    uiout->field_skip ("current");
 	}
 
-      if (!uiout->is_mi_like_p ())
-	uiout->field_string ("id-in-tg", print_thread_id (tp));
+      if (uiout->is_mi_like_p ())
+	{
+	  uiout->field_int ("tg-id", tp->inf->num);
+	  uiout->field_int ("id-in-tg", tp->per_inf_num);
+	}
+      else
+	uiout->field_string ("qualified-id", print_thread_id (tp));
 
       if (show_global_ids || uiout->is_mi_like_p ())
 	uiout->field_int ("id", tp->global_num);
-- 
2.11.0