src/object_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_OBJECT_INTERNAL__
  28 #define __DISPATCH_OBJECT_INTERNAL__
  29
  30 enum {
  31         _DISPATCH_CONTINUATION_TYPE             =        0x00000, // meta-type for continuations
  32         _DISPATCH_QUEUE_TYPE                    =    0x10000, // meta-type for queues
  33         _DISPATCH_SOURCE_TYPE                   =    0x20000, // meta-type for sources
  34         _DISPATCH_SEMAPHORE_TYPE                =    0x30000, // meta-type for semaphores
  35         _DISPATCH_ATTR_TYPE                             = 0x10000000, // meta-type for attribute structures
  36
  37         DISPATCH_CONTINUATION_TYPE              = _DISPATCH_CONTINUATION_TYPE,
  38
  39         DISPATCH_QUEUE_ATTR_TYPE                = _DISPATCH_QUEUE_TYPE | _DISPATCH_ATTR_TYPE,
  40
  41         DISPATCH_QUEUE_TYPE                             = 1 | _DISPATCH_QUEUE_TYPE,
  42         DISPATCH_QUEUE_GLOBAL_TYPE              = 2 | _DISPATCH_QUEUE_TYPE,
  43         DISPATCH_QUEUE_MGR_TYPE                 = 3 | _DISPATCH_QUEUE_TYPE,
  44
  45         DISPATCH_SEMAPHORE_TYPE                 = _DISPATCH_SEMAPHORE_TYPE,
  46
  47         DISPATCH_SOURCE_ATTR_TYPE               = _DISPATCH_SOURCE_TYPE | _DISPATCH_ATTR_TYPE,
  48
  49         DISPATCH_SOURCE_KEVENT_TYPE             = 1 | _DISPATCH_SOURCE_TYPE,
  50 };
  51
  52 #define DISPATCH_VTABLE_HEADER(x)       \
  53         unsigned long const do_type;    \
  54         const char *const do_kind; \
  55         size_t (*const do_debug)(struct x *, char *, size_t);   \
  56         struct dispatch_queue_s *(*const do_invoke)(struct x *);        \
  57         bool (*const do_probe)(struct x *); \
  58         void (*const do_dispose)(struct x *)
  59
  60 #define dx_type(x) (x)->do_vtable->do_type
  61 #define dx_kind(x) (x)->do_vtable->do_kind
  62 #define dx_debug(x, y, z) (x)->do_vtable->do_debug((x), (y), (z))
  63 #define dx_dispose(x) (x)->do_vtable->do_dispose(x)
  64 #define dx_invoke(x) (x)->do_vtable->do_invoke(x)
  65 #define dx_probe(x) (x)->do_vtable->do_probe(x)
  66
  67 #define DISPATCH_STRUCT_HEADER(x, y)    \
  68         const struct y *do_vtable;      \
  69         struct x *volatile do_next;     \
  70         unsigned int do_ref_cnt;        \
  71         unsigned int do_xref_cnt;       \
  72         unsigned int do_suspend_cnt;    \
  73         struct dispatch_queue_s *do_targetq;    \
  74         void *do_ctxt; \
  75         void *do_finalizer
  76
  77 #define DISPATCH_OBJECT_GLOBAL_REFCNT   (~0u)
  78 #define DISPATCH_OBJECT_SUSPEND_LOCK            1u      // "word and bit" must be a power of two to be safely subtracted
  79 #define DISPATCH_OBJECT_SUSPEND_INTERVAL        2u
  80 #define DISPATCH_OBJECT_SUSPENDED(x)    ((x)->do_suspend_cnt >= DISPATCH_OBJECT_SUSPEND_INTERVAL)
  81 #ifdef __LP64__
  82 // the bottom nibble must not be zero, the rest of the bits should be random
  83 // we sign extend the 64-bit version so that a better instruction encoding is generated on Intel
  84 #define DISPATCH_OBJECT_LISTLESS        ((void *)0xffffffff89abcdef)
  85 #else
  86 #define DISPATCH_OBJECT_LISTLESS        ((void *)0x89abcdef)
  87 #endif
  88
  89 #define _dispatch_trysuspend(x) __sync_bool_compare_and_swap(&(x)->do_suspend_cnt, 0, DISPATCH_OBJECT_SUSPEND_INTERVAL)
  90 // _dispatch_source_invoke() relies on this testing the whole suspend count
  91 // word, not just the lock bit. In other words, no point taking the lock
  92 // if the source is suspended or canceled.
  93 #define _dispatch_trylock(x)    dispatch_atomic_cmpxchg(&(x)->do_suspend_cnt, 0, DISPATCH_OBJECT_SUSPEND_LOCK)
  94
  95 struct dispatch_object_vtable_s {
  96         DISPATCH_VTABLE_HEADER(dispatch_object_s);
  97 };
  98
  99 struct dispatch_object_s {
 100         DISPATCH_STRUCT_HEADER(dispatch_object_s, dispatch_object_vtable_s);
 101 };
 102
 103 size_t dispatch_object_debug_attr(dispatch_object_t dou, char* buf, size_t bufsiz);
 104
 105 void _dispatch_retain(dispatch_object_t dou);
 106 void _dispatch_release(dispatch_object_t dou);
 107 void _dispatch_dispose(dispatch_object_t dou);
 108 dispatch_queue_t _dispatch_wakeup(dispatch_object_t dou);
 109
 110 #endif