[PATCH v2] gdb/Python: Added ThreadExitedEvent

[Simon Farre via Gdb-patches <gdb-patches@sourceware.org>]

Currently no event is emitted for a thread exit.

This adds this functionality by emitting a new gdb.ThreadExitedEvent.

It currently provides three attributes, the LWP id, the TID and
the GLOBAL NUM. A case could be made to also add the per-inferior
number, but, I wasn't sure if it is actually any useful.

Added info to docs & the NEWS file as well.

Added test to test suite.

Fixed formatting.

Feedback wanted and appreciated.
---
 gdb/NEWS                                      |  3 ++
 gdb/doc/python.texi                           | 16 ++++++
 gdb/python/py-all-events.def                  |  1 +
 gdb/python/py-event-types.def                 |  5 ++
 gdb/python/py-event.h                         |  3 ++
 gdb/python/py-inferior.c                      |  7 +++
 gdb/python/py-threadevent.c                   | 22 ++++++++
 gdb/testsuite/gdb.python/py-thread-exited.c   | 41 +++++++++++++++
 gdb/testsuite/gdb.python/py-thread-exited.exp | 52 +++++++++++++++++++
 gdb/testsuite/gdb.python/py-thread-exited.py  | 31 +++++++++++
 10 files changed, 181 insertions(+)
 create mode 100644 gdb/testsuite/gdb.python/py-thread-exited.c
 create mode 100644 gdb/testsuite/gdb.python/py-thread-exited.exp
 create mode 100644 gdb/testsuite/gdb.python/py-thread-exited.py

diff --git a/gdb/NEWS b/gdb/NEWS
index 760cb2b7abc..985121d5818 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -38,6 +38,9 @@ maintenance info line-table
      This is the same format that GDB uses when printing address, symbol,
      and offset information from the disassembler.
 
+  ** gdb.ThreadExitedEvent added. Emits LWP ID, TID and GLOBAL NUM of the
+     exiting thread.
+
 *** Changes in GDB 12
 
 * DBX mode is deprecated, and will be removed in GDB 13
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 7c414b01d70..9a410dc18f8 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -3568,6 +3568,22 @@ This has a single attribute:
 The new thread.
 @end defvar
 
+@item events.thread_exited
+This is emitted when @value{GDBN} notices a thread has exited.  The event
+is of type @code{gdb.ThreadExitedEvent}.  This has three attributes:
+
+@defvar ThreadExitedEvent.num
+Global thread number.
+@end defvar
+
+@defvar ThreadExitedEvent.lwp
+The light weight process ID.
+@end defvar
+
+@defvar ThreadExitedEvent.tid
+The thread's thread id
+@end defvar
+
 @item events.gdb_exiting
 This is emitted when @value{GDBN} exits.  This event is not emitted if
 @value{GDBN} exits as a result of an internal error, or after an
diff --git a/gdb/python/py-all-events.def b/gdb/python/py-all-events.def
index 7db8efa1390..0dd1a295135 100644
--- a/gdb/python/py-all-events.def
+++ b/gdb/python/py-all-events.def
@@ -31,6 +31,7 @@ GDB_PY_DEFINE_EVENT(clear_objfiles)
 GDB_PY_DEFINE_EVENT(new_inferior)
 GDB_PY_DEFINE_EVENT(inferior_deleted)
 GDB_PY_DEFINE_EVENT(new_thread)
+GDB_PY_DEFINE_EVENT(thread_exited)
 GDB_PY_DEFINE_EVENT(inferior_call)
 GDB_PY_DEFINE_EVENT(memory_changed)
 GDB_PY_DEFINE_EVENT(register_changed)
diff --git a/gdb/python/py-event-types.def b/gdb/python/py-event-types.def
index 596e68a852a..4529ddc7caa 100644
--- a/gdb/python/py-event-types.def
+++ b/gdb/python/py-event-types.def
@@ -51,6 +51,11 @@ GDB_PY_DEFINE_EVENT_TYPE (new_thread,
 			  "GDB new thread event object",
 			  thread_event_object_type);
 
+GDB_PY_DEFINE_EVENT_TYPE (thread_exited,
+			  "ThreadExitedEvent",
+			  "GDB thread exited event object",
+			  event_object_type);
+
 GDB_PY_DEFINE_EVENT_TYPE (new_inferior,
 			  "NewInferiorEvent",
 			  "GDB new inferior event object",
diff --git a/gdb/python/py-event.h b/gdb/python/py-event.h
index 56e53b7a1e7..2274c63b0b8 100644
--- a/gdb/python/py-event.h
+++ b/gdb/python/py-event.h
@@ -61,6 +61,9 @@ extern int emit_memory_changed_event (CORE_ADDR addr, ssize_t len);
 extern int evpy_emit_event (PyObject *event,
 			    eventregistry_object *registry);
 
+/* Emits a thread exit event for thread with PTID and GLOBAL_NUM */
+extern int emit_thread_exit_event (ptid_t ptid, int global_num);
+
 extern gdbpy_ref<> create_event_object (PyTypeObject *py_type);
 
 /* thread events can either be thread specific or process wide.  If gdb is
diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index ebcd5b0a70f..407e1bae4a3 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -363,6 +363,13 @@ delete_thread_object (struct thread_info *tp, int ignore)
     return;
 
   tmp = *entry;
+  if (!evregpy_no_listeners_p (gdb_py_events.thread_exited))
+    {
+      ptid_t ptid = tmp->thread_obj->thread->ptid;
+      int global_num = tmp->thread_obj->thread->global_num;
+      if (emit_thread_exit_event (ptid, global_num) < 0)
+	gdbpy_print_stack();
+    }
   tmp->thread_obj->thread = NULL;
 
   *entry = (*entry)->next;
diff --git a/gdb/python/py-threadevent.c b/gdb/python/py-threadevent.c
index 0a5d30087fb..8cb1a187f12 100644
--- a/gdb/python/py-threadevent.c
+++ b/gdb/python/py-threadevent.c
@@ -54,3 +54,25 @@ create_thread_event_object (PyTypeObject *py_type, PyObject *thread)
 
   return thread_event_obj;
 }
+
+int
+emit_thread_exit_event (ptid_t ptid, int global_num)
+{
+  gdbpy_ref<> thread_event_obj = create_event_object (&thread_exited_event_object_type);
+  if (thread_event_obj == NULL)
+    return -1;
+
+  if (evpy_add_attribute (thread_event_obj.get (), "num",
+			  PyLong_FromLong (global_num)) < 0)
+    return -1;
+  long lwp = ptid.lwp();
+  if (evpy_add_attribute (thread_event_obj.get (), "lwp",
+			  PyLong_FromLong (lwp)) < 0)
+    return -1;
+  int tid = ptid.tid ();
+  if (evpy_add_attribute (thread_event_obj.get (),
+			  "tid",
+			  PyLong_FromLong (tid)) < 0)
+    return -1;
+  return evpy_emit_event (thread_event_obj.get (), gdb_py_events.thread_exited);
+}
diff --git a/gdb/testsuite/gdb.python/py-thread-exited.c b/gdb/testsuite/gdb.python/py-thread-exited.c
new file mode 100644
index 00000000000..4a12e584f9c
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-thread-exited.c
@@ -0,0 +1,41 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2010-2022 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/>.  */
+
+#include <stdio.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <signal.h>
+
+pthread_t thread2_id;
+pthread_t thread3_id;
+
+void* do_thread (void* d)
+{
+  return NULL;
+}
+
+int main (void)
+{
+  /* Use single line to not to race whether `thread2' breakpoint or `next' over
+     pthread_create will stop first.  */
+
+  pthread_create (&thread2_id, NULL, do_thread, NULL);
+  pthread_join (thread2_id, NULL);
+  pthread_create (&thread3_id, NULL, do_thread, NULL);
+  pthread_join (thread3_id, NULL);
+  return 12;
+}
diff --git a/gdb/testsuite/gdb.python/py-thread-exited.exp b/gdb/testsuite/gdb.python/py-thread-exited.exp
new file mode 100644
index 00000000000..90f07e8b3b5
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-thread-exited.exp
@@ -0,0 +1,52 @@
+# Copyright (C) 2022-2022 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/>.
+
+if { ![support_displaced_stepping] } {
+    unsupported "displaced stepping"
+    return -1
+}
+
+load_lib gdb-python.exp
+
+standard_testfile
+
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    return -1
+}
+
+save_vars { GDBFLAGS } {
+    append GDBFLAGS " -ex \"set non-stop on\""
+    clean_restart $testfile
+}
+
+if { [skip_python_tests] } { continue }
+
+set pyfile [gdb_remote_download host ${srcdir}/${subdir}/py-thread-exited.py]
+gdb_test_no_output "source ${pyfile}" "load python file"
+
+gdb_test "test-events" "Event testers registered."
+
+if ![runto_main] {
+    return -1
+}
+
+gdb_breakpoint 40 "last of main"
+
+gdb_continue_to_breakpoint "continue to breakpoint"
+
+gdb_test "python print(threadOneExit)" \
+	 ".*event type: thread-exited. global num: 2.*"
+gdb_test "python print(threadTwoExit)" \
+	 ".*event type: thread-exited. global num: 3.*"
diff --git a/gdb/testsuite/gdb.python/py-thread-exited.py b/gdb/testsuite/gdb.python/py-thread-exited.py
new file mode 100644
index 00000000000..ebd6532b158
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-thread-exited.py
@@ -0,0 +1,31 @@
+import gdb
+
+threadOneExit = ""
+threadTwoExit = ""
+# we don't want to overwrite the 2nd thread's exit event, thus
+# store it here. we don't care about it though.
+mainThreadExit = ""
+
+def thread_exited_handler(event):
+    global threadOneExit, threadTwoExit, mainThreadExit
+    print("{}".format(event))
+    assert isinstance(event, gdb.ThreadExitedEvent)
+    if threadOneExit == "":
+        threadOneExit = "event type: thread-exited. global num: %s" % event.num
+    else:
+        if threadTwoExit == "":
+            threadTwoExit = "event type: thread-exited. global num: %s" % event.num
+        else:
+            mainThreadExit = "event type: thread-exited. global num: %s" % event.num
+
+class test_events(gdb.Command):
+    """Test events."""
+
+    def __init__(self):
+        gdb.Command.__init__(self, "test-events", gdb.COMMAND_STACK)
+
+    def invoke(self, arg, from_tty):
+        gdb.events.thread_exited.connect(thread_exited_handler)
+        print("Event testers registered.")
+
+test_events()

base-commit: bd1c798f0aef38493c5292917e47f76e1205f4e3
-- 
2.32.0