src/queue_internal.h

   1 /*
   2  * Copyright (c) 2008-2009 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_QUEUE_INTERNAL__
  28 #define __DISPATCH_QUEUE_INTERNAL__
  29
  30 #ifndef __DISPATCH_INDIRECT__
  31 #error "Please #include <dispatch/dispatch.h> instead of this file directly."
  32 #include <dispatch/base.h> // for HeaderDoc
  33 #endif
  34
  35 // If dc_vtable is less than 127, then the object is a continuation.
  36 // Otherwise, the object has a private layout and memory management rules. The
  37 // first two words must align with normal objects.
  38 #define DISPATCH_CONTINUATION_HEADER(x) \
  39         const void *                            do_vtable;      \
  40         struct x *volatile      do_next;        \
  41         dispatch_function_t     dc_func;        \
  42         void *                                          dc_ctxt
  43
  44 #define DISPATCH_OBJ_ASYNC_BIT  0x1
  45 #define DISPATCH_OBJ_BARRIER_BIT        0x2
  46 #define DISPATCH_OBJ_GROUP_BIT  0x4
  47 // vtables are pointers far away from the low page in memory
  48 #define DISPATCH_OBJ_IS_VTABLE(x)       ((unsigned long)(x)->do_vtable > 127ul)
  49
  50 struct dispatch_continuation_s {
  51         DISPATCH_CONTINUATION_HEADER(dispatch_continuation_s);
  52         dispatch_group_t        dc_group;
  53         void *                          dc_data[3];
  54 };
  55
  56 typedef struct dispatch_continuation_s *dispatch_continuation_t;
  57
  58
  59 struct dispatch_queue_vtable_s {
  60         DISPATCH_VTABLE_HEADER(dispatch_queue_s);
  61 };
  62
  63 #define DISPATCH_QUEUE_MIN_LABEL_SIZE   64
  64
  65 #define DISPATCH_QUEUE_HEADER \
  66         uint32_t dq_running; \
  67         uint32_t dq_width; \
  68         struct dispatch_object_s *dq_items_tail; \
  69         struct dispatch_object_s *volatile dq_items_head; \
  70         unsigned long dq_serialnum; \
  71         void *dq_finalizer_ctxt; \
  72         dispatch_queue_finalizer_function_t dq_finalizer_func
  73
  74 struct dispatch_queue_s {
  75         DISPATCH_STRUCT_HEADER(dispatch_queue_s, dispatch_queue_vtable_s);
  76         DISPATCH_QUEUE_HEADER;
  77         char dq_label[DISPATCH_QUEUE_MIN_LABEL_SIZE];   // must be last
  78 };
  79
  80 extern struct dispatch_queue_s _dispatch_mgr_q;
  81
  82 void _dispatch_queue_init(dispatch_queue_t dq);
  83 void _dispatch_queue_drain(dispatch_queue_t dq);
  84 void _dispatch_queue_dispose(dispatch_queue_t dq);
  85
  86 __attribute__((always_inline))
  87 static inline void
  88 _dispatch_queue_push_list(dispatch_queue_t dq, dispatch_object_t _head, dispatch_object_t _tail)
  89 {
  90         struct dispatch_object_s *prev, *head = _head._do, *tail = _tail._do;
  91
  92         tail->do_next = NULL;
  93         prev = fastpath(dispatch_atomic_xchg(&dq->dq_items_tail, tail));
  94         if (prev) {
  95                 // if we crash here with a value less than 0x1000, then we are at a known bug in client code
  96                 // for example, see _dispatch_queue_dispose or _dispatch_atfork_child
  97                 prev->do_next = head;
  98         } else {
  99                 dq->dq_items_head = head;
 100                 _dispatch_wakeup(dq);
 101         }
 102 }
 103
 104 #define _dispatch_queue_push(x, y) _dispatch_queue_push_list((x), (y), (y))
 105
 106 #define DISPATCH_QUEUE_PRIORITY_COUNT 3
 107
 108 #if DISPATCH_DEBUG
 109 void dispatch_debug_queue(dispatch_queue_t dq, const char* str);
 110 #else
 111 static inline void dispatch_debug_queue(dispatch_queue_t dq __attribute__((unused)), const char* str __attribute__((unused))) {}
 112 #endif
 113
 114 size_t dispatch_queue_debug(dispatch_queue_t dq, char* buf, size_t bufsiz);
 115 size_t dispatch_queue_debug_attr(dispatch_queue_t dq, char* buf, size_t bufsiz);
 116
 117 static inline dispatch_queue_t
 118 _dispatch_queue_get_current(void)
 119 {
 120         return _dispatch_thread_getspecific(dispatch_queue_key);
 121 }
 122
 123 __private_extern__ malloc_zone_t *_dispatch_ccache_zone;
 124 dispatch_continuation_t _dispatch_continuation_alloc_from_heap(void);
 125
 126 static inline dispatch_continuation_t
 127 _dispatch_continuation_alloc_cacheonly(void)
 128 {
 129         dispatch_continuation_t dc = fastpath(_dispatch_thread_getspecific(dispatch_cache_key));
 130         if (dc) {
 131                 _dispatch_thread_setspecific(dispatch_cache_key, dc->do_next);
 132         }
 133         return dc;
 134 }
 135
 136 #endif