1/*
2 * Copyright (c) 2008-2013 Apple Inc. All rights reserved.
3 *
4 * @APPLE_APACHE_LICENSE_HEADER_START@
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 *     http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 *
18 * @APPLE_APACHE_LICENSE_HEADER_END@
19 */
20
21/*
22 * IMPORTANT: This header file describes INTERNAL interfaces to libdispatch
23 * which are subject to change in future releases of Mac OS X. Any applications
24 * relying on these interfaces WILL break.
25 */
26
27#ifndef __DISPATCH_SEMAPHORE_INTERNAL__
28#define __DISPATCH_SEMAPHORE_INTERNAL__
29
30struct dispatch_queue_s;
31
32DISPATCH_CLASS_DECL(semaphore);
33struct dispatch_semaphore_s {
34	DISPATCH_STRUCT_HEADER(semaphore);
35#if USE_MACH_SEM
36	semaphore_t dsema_port;
37#elif USE_POSIX_SEM
38	sem_t dsema_sem;
39#elif USE_WIN32_SEM
40	HANDLE dsema_handle;
41#else
42#error "No supported semaphore type"
43#endif
44	long dsema_orig;
45	long volatile dsema_value;
46	union {
47		long volatile dsema_sent_ksignals;
48		long volatile dsema_group_waiters;
49	};
50	struct dispatch_continuation_s *volatile dsema_notify_head;
51	struct dispatch_continuation_s *volatile dsema_notify_tail;
52};
53
54DISPATCH_CLASS_DECL(group);
55
56#define DISPATCH_GROUP_INITIALIZER(s) \
57		{ \
58			.do_vtable = (const void*)DISPATCH_VTABLE(group), \
59			.do_ref_cnt = DISPATCH_OBJECT_GLOBAL_REFCNT, \
60			.do_xref_cnt = DISPATCH_OBJECT_GLOBAL_REFCNT, \
61			.dsema_value = LONG_MAX - (s), \
62			.dsema_orig = LONG_MAX, \
63		}
64
65void _dispatch_semaphore_dispose(dispatch_object_t dou);
66size_t _dispatch_semaphore_debug(dispatch_object_t dou, char *buf,
67		size_t bufsiz);
68
69typedef uintptr_t _dispatch_thread_semaphore_t;
70
71_dispatch_thread_semaphore_t _dispatch_thread_semaphore_create(void);
72void _dispatch_thread_semaphore_dispose(_dispatch_thread_semaphore_t);
73void _dispatch_thread_semaphore_wait(_dispatch_thread_semaphore_t);
74void _dispatch_thread_semaphore_signal(_dispatch_thread_semaphore_t);
75
76DISPATCH_ALWAYS_INLINE
77static inline _dispatch_thread_semaphore_t
78_dispatch_get_thread_semaphore(void)
79{
80	_dispatch_thread_semaphore_t sema = (_dispatch_thread_semaphore_t)
81			_dispatch_thread_getspecific(dispatch_sema4_key);
82	if (slowpath(!sema)) {
83		return _dispatch_thread_semaphore_create();
84	}
85	_dispatch_thread_setspecific(dispatch_sema4_key, NULL);
86	return sema;
87}
88
89DISPATCH_ALWAYS_INLINE
90static inline void
91_dispatch_put_thread_semaphore(_dispatch_thread_semaphore_t sema)
92{
93	_dispatch_thread_semaphore_t old_sema = (_dispatch_thread_semaphore_t)
94			_dispatch_thread_getspecific(dispatch_sema4_key);
95	_dispatch_thread_setspecific(dispatch_sema4_key, (void*)sema);
96	if (slowpath(old_sema)) {
97		return _dispatch_thread_semaphore_dispose(old_sema);
98	}
99}
100
101#endif
102