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 2.1 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