private/os/alloc_once_impl.h

   1 /*
   2  * Copyright (c) 2012-2013 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #ifndef __OS_ALLOC_ONCE_IMPL__
  30 #define __OS_ALLOC_ONCE_IMPL__
  31
  32 #ifndef __OS_ALLOC_INDIRECT__
  33 #error "Please include <os/alloc_once_private.h> instead of this file directly."
  34 #endif
  35
  36 #include <Availability.h>
  37 #include <sys/types.h>
  38 #include <os/base_private.h>
  39 #include <os/once_private.h>
  40
  41 __BEGIN_DECLS
  42
  43 #define OS_ALLOC_SPI_VERSION 20120430
  44
  45 #define OS_ALLOC_ONCE_KEY_MAX 100
  46
  47 typedef os_once_t os_alloc_token_t;
  48 struct _os_alloc_once_s {
  49         os_alloc_token_t once;
  50         void *ptr;
  51 };
  52
  53 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_6_0)
  54 extern struct _os_alloc_once_s _os_alloc_once_table[];
  55
  56 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_6_0)
  57 OS_EXPORT OS_NONNULL1
  58 void*
  59 _os_alloc_once(struct _os_alloc_once_s *slot, size_t sz, os_function_t init);
  60
  61 /*
  62  * The region allocated by os_alloc_once is 0-filled when initially
  63  * returned (or handed off to the initializer).
  64  */
  65 OS_WARN_RESULT OS_NOTHROW OS_CONST
  66 __header_always_inline void*
  67 os_alloc_once(os_alloc_token_t token, size_t sz, os_function_t init)
  68 {
  69         struct _os_alloc_once_s *slot = &_os_alloc_once_table[token];
  70         if (OS_EXPECT(slot->once, ~0l) != ~0l) {
  71                 void *ptr = _os_alloc_once(slot, sz, init);
  72                 OS_COMPILER_CAN_ASSUME(slot->once == ~0l);
  73                 return ptr;
  74         }
  75         return slot->ptr;
  76 }
  77
  78 __END_DECLS
  79
  80 #endif // __OS_ALLOC_ONCE_IMPL__