gdb/run-on-main-thread.c

   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
  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
  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
  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 }