gdbsupport/event-pipe.h

   1 /* Event pipe for GDB, the GNU debugger.
   2
   3    Copyright (C) 2021-2023 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef COMMON_EVENT_PIPE_H
  21 #define COMMON_EVENT_PIPE_H
  22
  23 /* An event pipe used as a waitable file in the event loop in place of
  24    some other event associated with a signal.  The handler for the
  25    signal marks the event pipe to force a wakeup in the event loop.
  26    This uses the well-known self-pipe trick.  */
  27
  28 class event_pipe
  29 {
  30 public:
  31   event_pipe() = default;
  32   ~event_pipe();
  33
  34   DISABLE_COPY_AND_ASSIGN (event_pipe);
  35
  36   /* Create a new pipe.  */
  37   bool open_pipe ();
  38
  39   /* Close the pipe.  */
  40   void close_pipe ();
  41
  42   /* True if the event pipe has been opened.  */
  43   bool is_open () const
  44   { return m_fds[0] != -1; }
  45
  46   /* The file descriptor of the waitable file to use in the event
  47      loop.  */
  48   int event_fd () const
  49   { return m_fds[0]; }
  50
  51   /* Flush the event pipe.  */
  52   void flush ();
  53
  54   /* Put something in the pipe, so the event loop wakes up.  */
  55   void mark ();
  56 private:
  57   int m_fds[2] = { -1, -1 };
  58 };
  59
  60 #endif /* COMMON_EVENT_PIPE_H */