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

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