Introduce run_on_main_thread

This introduces a way for a callback to be run on the main thread.

gdb/ChangeLog
2019-11-26  Tom Tromey  <tom@tromey.com>

	* run-on-main-thread.c: New file.
	* run-on-main-thread.h: New file.
	* unittests/main-thread-selftests.c: New file.
	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	main-thread-selftests.c.
	(HFILES_NO_SRCDIR): Add run-on-main-thread.h.
	(COMMON_SFILES): Add run-on-main-thread.c.

Change-Id: I16ef82f0564e9f8a524bdc64cb31df79a988ad9f

1 files changed, 80 insertions, 0 deletions

diff --git a/gdb/unittests/main-thread-selftests.c b/gdb/unittests/main-thread-selftests.c
new file mode 100644
index 0000000..2324e98
--- /dev/null
+++ b/gdb/unittests/main-thread-selftests.c
@@ -0,0 +1,80 @@
+/* Self tests for run_on_main_thread
+
+   Copyright (C) 2019 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 "defs.h"
+#include "gdbsupport/selftest.h"
+#include "gdbsupport/block-signals.h"
+#include "run-on-main-thread.h"
+#include "event-loop.h"
+#if CXX_STD_THREAD
+#include <thread>
+#endif
+
+namespace selftests {
+namespace main_thread_tests {
+
+#if CXX_STD_THREAD
+
+static bool done;
+
+static void
+set_done ()
+{
+  run_on_main_thread ([] ()
+    {
+      done = true;
+    });
+}
+
+static void
+run_tests ()
+{
+  std::thread thread;
+
+  done = false;
+
+  {
+    gdb::block_signals blocker;
+
+    thread = std::thread (set_done);
+  }
+
+  while (!done && gdb_do_one_event () >= 0)
+    ;
+
+  /* Actually the test will just hang, but we want to test
+     something.  */
+  SELF_CHECK (done);
+
+  thread.join ();
+}
+
+#endif
+
+}
+}
+
+void
+_initialize_main_thread_selftests ()
+{
+#if CXX_STD_THREAD
+  selftests::register_test ("run_on_main_thread",
+			    selftests::main_thread_tests::run_tests);
+#endif
+}