1 /* Run a function on the main thread
2 Copyright (C) 2019-2021 Free Software Foundation, Inc.
3
4 This file is part of GDB.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18
19 #include "defs.h"
20 #include "run-on-main-thread.h"
21 #include "ser-event.h"
22 #if CXX_STD_THREAD
23 #include <mutex>
24 #endif
25 #include "gdbsupport/event-loop.h"
26
27 /* The serial event used when posting runnables. */
28
29 static struct serial_event *runnable_event;
30
31 /* Runnables that have been posted. */
32
33 static std::vector<std::function<void ()>> runnables;
34
35 #if CXX_STD_THREAD
36
37 /* Mutex to hold when handling RUNNABLE_EVENT or RUNNABLES. */
38
39 static std::mutex runnable_mutex;
40
41 #endif
42
43 /* Run all the queued runnables. */
44
45 static void
run_events(int error,gdb_client_data client_data)46 run_events (int error, gdb_client_data client_data)
47 {
48 std::vector<std::function<void ()>> local;
49
50 /* Hold the lock while changing the globals, but not while running
51 the runnables. */
52 {
53 #if CXX_STD_THREAD
54 std::lock_guard<std::mutex> lock (runnable_mutex);
55 #endif
56
57 /* Clear the event fd. Do this before flushing the events list,
58 so that any new event post afterwards is sure to re-awaken the
59 event loop. */
60 serial_event_clear (runnable_event);
61
62 /* Move the vector in case running a runnable pushes a new
63 runnable. */
64 local = std::move (runnables);
65 }
66
67 for (auto &item : local)
68 {
69 try
70 {
71 item ();
72 }
73 catch (...)
74 {
75 /* Ignore exceptions in the callback. */
76 }
77 }
78 }
79
80 /* See run-on-main-thread.h. */
81
82 void
run_on_main_thread(std::function<void ()> && func)83 run_on_main_thread (std::function<void ()> &&func)
84 {
85 #if CXX_STD_THREAD
86 std::lock_guard<std::mutex> lock (runnable_mutex);
87 #endif
88 runnables.emplace_back (std::move (func));
89 serial_event_set (runnable_event);
90 }
91
92 void _initialize_run_on_main_thread ();
93 void
_initialize_run_on_main_thread()94 _initialize_run_on_main_thread ()
95 {
96 runnable_event = make_serial_event ();
97 add_file_handler (serial_event_fd (runnable_event), run_events, nullptr,
98 "run-on-main-thread");
99 }
100