libs/pbd/crossthread.cc

   1 /*
   2     Copyright (C) 2009 Paul Davis
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18 */
  19
  20 #include <cstdlib>
  21 #include <cerrno>
  22 #include <cstring>
  23 #include <fcntl.h>
  24 #include <unistd.h>
  25
  26 #include "pbd/error.h"
  27 #include "pbd/crossthread.h"
  28
  29 using namespace std;
  30 using namespace PBD;
  31 using namespace Glib;
  32
  33 CrossThreadChannel::CrossThreadChannel ()
  34 {
  35         _ios = 0;
  36         fds[0] = -1;
  37         fds[1] = -1;
  38
  39         if (pipe (fds)) {
  40                 error << "cannot create x-thread pipe for read (%2)" << ::strerror (errno) << endmsg;
  41                 return;
  42         }
  43
  44         if (fcntl (fds[0], F_SETFL, O_NONBLOCK)) {
  45                 error << "cannot set non-blocking mode for x-thread pipe (read) (" << ::strerror (errno) << ')' << endmsg;
  46                 return;
  47         }
  48
  49         if (fcntl (fds[1], F_SETFL, O_NONBLOCK)) {
  50                 error << "cannot set non-blocking mode for x-thread pipe (write) (%2)" << ::strerror (errno) << ')' << endmsg;
  51                 return;
  52         }
  53 }
  54
  55 CrossThreadChannel::~CrossThreadChannel ()
  56 {
  57         /* glibmm hack */
  58         drop_ios ();
  59
  60         if (fds[0] >= 0) {
  61                 close (fds[0]);
  62                 fds[0] = -1;
  63         }
  64
  65         if (fds[1] >= 0) {
  66                 close (fds[1]);
  67                 fds[1] = -1;
  68         }
  69 }
  70
  71 void
  72 CrossThreadChannel::wakeup ()
  73 {
  74         char c = 0;
  75         (void) ::write (fds[1], &c, 1);
  76 }
  77
  78 RefPtr<IOSource>
  79 CrossThreadChannel::ios ()
  80 {
  81         if (!_ios) {
  82                 _ios = new RefPtr<IOSource> (IOSource::create (fds[0], IOCondition(IO_IN|IO_PRI|IO_ERR|IO_HUP|IO_NVAL)));
  83         }
  84         return *_ios;
  85 }
  86
  87 void
  88 CrossThreadChannel::drop_ios ()
  89 {
  90         delete _ios;
  91         _ios = 0;
  92 }
  93
  94 void
  95 CrossThreadChannel::drain ()
  96 {
  97         drain (fds[0]);
  98 }
  99
 100 void
 101 CrossThreadChannel::drain (int fd)
 102 {
 103         /* drain selectable fd */
 104         char buf[64];
 105         while (::read (fd, buf, sizeof (buf)) > 0);
 106 }
 107
 108 int
 109 CrossThreadChannel::deliver (char msg)
 110 {
 111         return ::write (fds[1], &msg, 1);
 112 }
 113
 114 int
 115 CrossThreadChannel::receive (char& msg)
 116 {
 117         return ::read (fds[0], &msg, 1);
 118 }