code.delx.au - pulseaudio/blob - src/pulsecore/once.h

   1 #ifndef foopulseoncehfoo
   2 #define foopulseoncehfoo
   3
   4 /* $Id$ */
   5
   6 /***
   7   This file is part of PulseAudio.
   8
   9   Copyright 2006 Lennart Poettering
  10
  11   PulseAudio is free software; you can redistribute it and/or modify
  12   it under the terms of the GNU Lesser General Public License as
  13   published by the Free Software Foundation; either version 2 of the
  14   License, or (at your option) any later version.
  15
  16   PulseAudio is distributed in the hope that it will be useful, but
  17   WITHOUT ANY WARRANTY; without even the implied warranty of
  18   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19   General Public License for more details.
  20
  21   You should have received a copy of the GNU Lesser General Public
  22   License along with PulseAudio; if not, write to the Free Software
  23   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  24   USA.
  25 ***/
  26
  27 #include <pulsecore/mutex.h>
  28 #include <pulsecore/atomic.h>
  29
  30 typedef struct pa_once {
  31     pa_atomic_ptr_t mutex;
  32     pa_atomic_t ref, done;
  33 } pa_once;
  34
  35 #define PA_ONCE_INIT                                                    \
  36     {                                                                   \
  37         .mutex = PA_ATOMIC_PTR_INIT(NULL),                              \
  38         .ref = PA_ATOMIC_INIT(0),                                       \
  39         .done = PA_ATOMIC_INIT(0)                                       \
  40     }
  41
  42 /* Not to be called directly, use the macros defined below instead */
  43 int pa_once_begin(pa_once *o);
  44 void pa_once_end(pa_once *o);
  45
  46 #define PA_ONCE_BEGIN                                                   \
  47     do {                                                                \
  48         static pa_once _once = PA_ONCE_INIT;                            \
  49         if (pa_once_begin(&_once)) {{
  50
  51 #define PA_ONCE_END                                                     \
  52             }                                                           \
  53             pa_once_end(&_once);                                        \
  54         }                                                               \
  55     } while(0)
  56
  57 /*
  58
  59   Usage of these macros is like this:
  60
  61   void foo() {
  62
  63       PA_ONCE_BEGIN {
  64
  65           ... stuff to be called just once ...
  66
  67       } PA_ONCE_END;
  68   }
  69
  70 */
  71
  72 /* Same API but calls a function */
  73 typedef void (*pa_once_func_t) (void);
  74 void pa_run_once(pa_once *o, pa_once_func_t f);
  75
  76 #endif