GCD底层源码十分难读，晦涩的原因在于，为了兼容，大范围的多层宏不断嵌套的方式，再加上没有较详细的注释辅助说明，导致阅读起来逻辑无法连贯。
本文针对于关键性的数据结构做了具体整理，辅助有兴趣探索底层的同学更好的阅读GCD源码
dispatch_xxx_t [dispatch_queue_t dispatch_lane_t dispatch_object_t]
struct dispatch_continuation_s *dispatch_continuation_t
struct dispatch_queue_s *dispatch_queue_t
struct dispatch_lane_s *dispatch_lane_t
typedef struct dispatch_object_s *dispatch_object_t
typedef union {
struct _os_object_s *_os_obj;
struct dispatch_object_s *_do;
struct dispatch_queue_s *_dq;
struct dispatch_queue_attr_s *_dqa;
struct dispatch_group_s *_dg;
struct dispatch_source_s *_ds;
struct dispatch_channel_s *_dch;
struct dispatch_mach_s *_dm;
struct dispatch_mach_msg_s *_dmsg;
struct dispatch_semaphore_s *_dsema;
struct dispatch_data_s *_ddata;
struct dispatch_io_s *_dchannel;
struct dispatch_continuation_s *_dc;
struct dispatch_sync_context_s *_dsc;
struct dispatch_operation_s *_doperation;
struct dispatch_disk_s *_ddisk;
struct dispatch_workloop_s *_dwl;
struct dispatch_lane_s *_dl;
struct dispatch_queue_static_s *_dsq;
struct dispatch_queue_global_s *_dgq;
struct dispatch_queue_pthread_root_s *_dpq;
dispatch_queue_class_t _dqu;
dispatch_lane_class_t _dlu;
uintptr_t _do_value;
} dispatch_object_t DISPATCH_TRANSPARENT_UNION;
typedef struct dispatch_lane_s *dispatch_queue_serial_t;
typedef struct dispatch_lane_s *dispatch_queue_concurrent_t;
复制代码dispatch_lane_class_t
typedef union {
struct dispatch_lane_s *_dl;
struct dispatch_queue_static_s *_dsq;
struct dispatch_queue_global_s *_dgq;
struct dispatch_queue_pthread_root_s *_dpq;
struct dispatch_source_s *_ds;
struct dispatch_channel_s *_dch;
struct dispatch_mach_s *_dm;
id<OS_dispatch_queue> _objc_dq; //unsafe cast for the sake of object.m
} dispatch_lane_class_t DISPATCH_TRANSPARENT_UNION;
复制代码dispatch_queue_class_t
typedef union {
struct dispatch_queue_s *_dq;
struct dispatch_workloop_s *_dwl;
struct dispatch_lane_s *_dl;
struct dispatch_queue_static_s *_dsq;
struct dispatch_queue_global_s *_dgq;
struct dispatch_queue_pthread_root_s *_dpq;
struct dispatch_source_s *_ds;
struct dispatch_channel_s *_dch;
struct dispatch_mach_s *_dm;
dispatch_lane_class_t _dlu;
id<OS_dispatch_queue> _objc_dq;
} dispatch_queue_class_t DISPATCH_TRANSPARENT_UNION;
复制代码struct dispatch_object_s
typedef struct dispatch_object_s *dispatch_object_t
struct dispatch_object_s {
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_object_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_object_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
};
}
复制代码_os_object_vtable_s
typedef struct _os_object_vtable_s {
const void *_os_obj_objc_isa;
} _os_object_vtable_s;
复制代码_os_object_s
typedef struct _os_object_s {
/* must be pointer-sized and use __ptrauth_objc_isa_pointer */ \
const _os_object_vtable_s *__ptrauth_objc_isa_pointer os_obj_isa; \
int volatile os_obj_ref_cnt; \
int volatile os_obj_xref_cnt;
} _os_object_s;
复制代码struct dispatch_lane_vtable_s
struct dispatch_lane_vtable_s {
const void *_os_obj_objc_isa;
struct dispatch_lane_extra_vtable_s _os_obj_vtable;
};
复制代码struct dispatch_queue_vtable_s
struct dispatch_queue_vtable_s {
const void *_os_obj_objc_isa;
struct dispatch_queue_extra_vtable_s _os_obj_vtable;
};
复制代码struct dispatch_object_vtable_s
struct dispatch_object_vtable_s {
const void *_os_obj_objc_isa;
struct dispatch_object_extra_vtable_s _os_obj_vtable;
};
复制代码dispatch_object_extra_vtable_s
struct dispatch_object_extra_vtable_s {
DISPATCH_OBJECT_VTABLE_HEADER(dispatch_object)
};
struct dispatch_object_extra_vtable_s {
unsigned long const do_type;
void *const (do_dispose)(struct dispatch_object_s *,
bool *allow_free);
size_t *const (do_debug)(struct dispatch_object_s *, \
char *, size_t);
void *const (do_invoke)(struct dispatch_object_s *, \
dispatch_invoke_context_t, dispatch_invoke_flags_t)
};
复制代码dispatch_source_extra_vtable_s
struct dispatch_source_extra_vtable_s {
DISPATCH_QUEUE_VTABLE_HEADER(dispatch_source)
};
struct dispatch_source_extra_vtable_s {
unsigned long const do_type;
void *const (do_dispose)(struct dispatch_source_s *,
bool *allow_free);
size_t *const (do_debug)(struct dispatch_source_s *, \
char *, size_t);
void *const (do_invoke)(struct dispatch_source_s *, \
dispatch_invoke_context_t, dispatch_invoke_flags_t)
void *const (dq_activate)(dispatch_queue_class_t); \
void *const (dq_wakeup)(dispatch_queue_class_t, \
dispatch_qos_t, dispatch_wakeup_flags_t); \
void *const (dq_push)(dispatch_queue_class_t, \
dispatch_object_t, dispatch_qos_t)
};
复制代码struct dispatch_lane_s
struct dispatch_lane_s *dispatch_lane_t
typedef struct dispatch_lane_s {
struct dispatch_queue_s _as_dq[0]; \
struct dispatch_object_s _as_do[0]; \
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_lane_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_lane_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
} \
struct dispatch_object_s *volatile dq_items_tail; \
DISPATCH_UNION_LE(uint64_t volatile dq_state, \
dispatch_lock dq_state_lock, \
uint32_t dq_state_bits \
) /* LP64 global queue cacheline boundary */ \
unsigned long dq_serialnum; \
const char *dq_label; \
DISPATCH_UNION_LE(uint32_t volatile dq_atomic_flags, \
const uint16_t dq_width, \
const uint16_t __dq_opaque2 \
); \
dispatch_priority_t dq_priority; \
union { \
struct dispatch_queue_specific_head_s *dq_specific_head; \
struct dispatch_source_refs_s *ds_refs; \
struct dispatch_timer_source_refs_s *ds_timer_refs; \
struct dispatch_mach_recv_refs_s *dm_recv_refs; \
struct dispatch_channel_callbacks_s const *dch_callbacks; \
}; \
int volatile dq_sref_cnt;
dispatch_unfair_lock_s dq_sidelock; \
struct dispatch_object_s *volatile dq_items_head; \
uint32_t dq_side_suspend_cnt
} DISPATCH_ATOMIC64_ALIGN *dispatch_lane_t;
复制代码struct dispatch_queue_s
struct dispatch_queue_s *dispatch_queue_t
struct dispatch_queue_s {
struct dispatch_object_s _as_do[0]; \
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_queue_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_queue_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
} \
void *__dq_opaque1; \
DISPATCH_UNION_LE(uint64_t volatile dq_state, \
dispatch_lock dq_state_lock, \
uint32_t dq_state_bits \
) /* LP64 global queue cacheline boundary */ \
unsigned long dq_serialnum; \
const char *dq_label; \
DISPATCH_UNION_LE(uint32_t volatile dq_atomic_flags, \
const uint16_t dq_width, \
const uint16_t __dq_opaque2 \
); \
dispatch_priority_t dq_priority; \
union { \
struct dispatch_queue_specific_head_s *dq_specific_head; \
struct dispatch_source_refs_s *ds_refs; \
struct dispatch_timer_source_refs_s *ds_timer_refs; \
struct dispatch_mach_recv_refs_s *dm_recv_refs; \
struct dispatch_channel_callbacks_s const *dch_callbacks; \
}; \
int volatile dq_sref_cnt;
} DISPATCH_ATOMIC64_ALIGN;
复制代码struct dispatch_continuation_s
typedef struct dispatch_continuation_s {
union { \
const void *__ptrauth_objc_isa_pointer do_vtable; \
uintptr_t dc_flags; \
}; \
union { \
pthread_priority_t dc_priority; \
int dc_cache_cnt; \
uintptr_t dc_pad; \
}; \
struct voucher_s *dc_voucher; \
struct dispatch_continuation_s *volatile do_next; \
dispatch_function_t dc_func; \
void *dc_ctxt; \
void *dc_data; \
void *dc_other
} *dispatch_continuation_t;
复制代码struct voucher_s
typedef struct voucher_s {
struct voucher_vtable_s *__ptrauth_objc_isa_pointer os_obj_isa; /* must be pointer-sized and use __ptrauth_objc_isa_pointer */ \
int volatile os_obj_ref_cnt; \
int volatile os_obj_xref_cnt;
struct voucher_hash_entry_s {
uintptr_t vhe_next;
uintptr_t vhe_prev_ptr;
} v_list;
mach_voucher_t v_kvoucher, v_ipc_kvoucher; // if equal, only one reference
voucher_t v_kvbase; // if non-NULL, v_kvoucher is a borrowed reference
firehose_activity_id_t v_activity;
uint64_t v_activity_creator;
firehose_activity_id_t v_parent_activity;
_voucher_priority_t v_priority;
unsigned int v_kv_has_importance:1;
#if VOUCHER_ENABLE_RECIPE_OBJECTS
size_t v_recipe_extra_offset;
mach_voucher_attr_recipe_size_t v_recipe_extra_size;
#endif
} voucher_s;
复制代码DISPATCH_VTABLE_INSTANCE workloop
DISPATCH_VTABLE_INSTANCE(workloop,
.do_type = DISPATCH_WORKLOOP_TYPE,
.do_dispose = _dispatch_workloop_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_workloop_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_workloop_wakeup,
.dq_push = _dispatch_workloop_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_workloop_extra_vtable_s _OS_dispatch_workloop_vtable
= {
.do_kind = workloop,
.do_type = DISPATCH_WORKLOOP_TYPE,
.do_dispose = _dispatch_workloop_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_workloop_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_workloop_wakeup,
.dq_push = _dispatch_workloop_push,
};
复制代码DISPATCH_VTABLE_INSTANCE queue
DISPATCH_VTABLE_INSTANCE(queue,
.do_type = _DISPATCH_QUEUE_CLUSTER,
.do_dispose = _dispatch_object_no_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_object_no_invoke,
.dq_activate = _dispatch_queue_no_activate,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_queue_extra_vtable_s _OS_dispatch_queue_vtable
= {
.do_kind = queue,
.do_type = _DISPATCH_QUEUE_CLUSTER,
.do_dispose = _dispatch_object_no_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_object_no_invoke,
.dq_activate = _dispatch_queue_no_activate
};
复制代码DISPATCH_VTABLE_SUBCLASS_INSTANCE - queue_serial
DISPATCH_VTABLE_SUBCLASS_INSTANCE(queue_serial, lane,
.do_type = DISPATCH_QUEUE_SERIAL_TYPE,
.do_dispose = _dispatch_lane_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
\
.dq_activate = _dispatch_lane_activate,
.dq_wakeup = _dispatch_lane_wakeup,
.dq_push = _dispatch_lane_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_lane_extra_vtable_s _OS_dispatch_queue_serial_vtable
= {
.do_kind = queue_serial,
.do_type = DISPATCH_QUEUE_SERIAL_TYPE,
.do_dispose = _dispatch_lane_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
.dq_activate = _dispatch_lane_activate,
.dq_wakeup = _dispatch_lane_wakeup,
.dq_push = _dispatch_lane_push
};
复制代码DISPATCH_VTABLE_SUBCLASS_INSTANCE - queue_concurrent
DISPATCH_VTABLE_SUBCLASS_INSTANCE(queue_concurrent, lane,
.do_type = DISPATCH_QUEUE_CONCURRENT_TYPE,
.do_dispose = _dispatch_lane_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
.dq_activate = _dispatch_lane_activate,
.dq_wakeup = _dispatch_lane_wakeup,
.dq_push = _dispatch_lane_concurrent_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_lane_extra_vtable_s _OS_dispatch_queue_concurrent_vtable
= {
.do_kind = queue_concurrent,
.do_type = DISPATCH_QUEUE_CONCURRENT_TYPE,
.do_dispose = _dispatch_lane_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
.dq_activate = _dispatch_lane_activate,
.dq_wakeup = _dispatch_lane_wakeup,
.dq_push = _dispatch_lane_concurrent_push
};
复制代码DISPATCH_VTABLE_SUBCLASS_INSTANCE - queue_global
DISPATCH_VTABLE_SUBCLASS_INSTANCE(queue_global, lane,
.do_type = DISPATCH_QUEUE_GLOBAL_ROOT_TYPE,
.do_dispose = _dispatch_object_no_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_object_no_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_root_queue_wakeup,
.dq_push = _dispatch_root_queue_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_lane_extra_vtable_s _OS_dispatch_queue_global_vtable
= {
.do_kind = queue_concurrent,
.do_type = DISPATCH_QUEUE_GLOBAL_ROOT_TYPE,
.do_dispose = _dispatch_object_no_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_object_no_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_root_queue_wakeup,
.dq_push = _dispatch_root_queue_push
};
复制代码DISPATCH_VTABLE_SUBCLASS_INSTANCE - queue_pthread_root
DISPATCH_VTABLE_SUBCLASS_INSTANCE(queue_pthread_root, lane,
.do_type = DISPATCH_QUEUE_PTHREAD_ROOT_TYPE,
.do_dispose = _dispatch_pthread_root_queue_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_object_no_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_root_queue_wakeup,
.dq_push = _dispatch_root_queue_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_lane_extra_vtable_s _OS_dispatch_queue_pthread_root_vtable
= {
.do_kind = queue_pthread_root,
.do_type = DISPATCH_QUEUE_PTHREAD_ROOT_TYPE,
.do_dispose = _dispatch_pthread_root_queue_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_object_no_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_root_queue_wakeup,
.dq_push = _dispatch_root_queue_push
};
复制代码DISPATCH_VTABLE_SUBCLASS_INSTANCE - queue_mgr
DISPATCH_VTABLE_SUBCLASS_INSTANCE(queue_mgr, lane,
.do_type = DISPATCH_QUEUE_MGR_TYPE,
.do_dispose = _dispatch_object_no_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_mgr_thread,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_mgr_queue_wakeup,
.dq_push = _dispatch_mgr_queue_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_lane_extra_vtable_s _OS_dispatch_queue_mgr_vtable
= {
.do_kind = queue_mgr,
.do_type = DISPATCH_QUEUE_MGR_TYPE,
.do_dispose = _dispatch_object_no_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_mgr_thread,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_mgr_queue_wakeup,
.dq_push = _dispatch_mgr_queue_push
};
复制代码DISPATCH_VTABLE_SUBCLASS_INSTANCE - queue_main
DISPATCH_VTABLE_SUBCLASS_INSTANCE(queue_main, lane,
.do_type = DISPATCH_QUEUE_MAIN_TYPE,
.do_dispose = _dispatch_lane_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_main_queue_wakeup,
.dq_push = _dispatch_main_queue_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_lane_extra_vtable_s _OS_dispatch_queue_main_vtable
= {
.do_kind = queue_main,
.do_type = DISPATCH_QUEUE_MAIN_TYPE,
.do_dispose = _dispatch_lane_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_main_queue_wakeup,
.dq_push = _dispatch_main_queue_push
};
复制代码DISPATCH_VTABLE_SUBCLASS_INSTANCE - queue_runloop
DISPATCH_VTABLE_SUBCLASS_INSTANCE(queue_runloop, lane,
.do_type = DISPATCH_QUEUE_RUNLOOP_TYPE,
.do_dispose = _dispatch_runloop_queue_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_runloop_queue_wakeup,
.dq_push = _dispatch_lane_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_lane_extra_vtable_s _OS_dispatch_queue_runloop_vtable
= {
.do_kind = queue_runloop,
.do_type = DISPATCH_QUEUE_RUNLOOP_TYPE,
.do_dispose = _dispatch_runloop_queue_dispose,
.do_debug = _dispatch_queue_debug,
.do_invoke = _dispatch_lane_invoke,
.dq_activate = _dispatch_queue_no_activate,
.dq_wakeup = _dispatch_runloop_queue_wakeup,
.dq_push = _dispatch_lane_push
};
复制代码DISPATCH_VTABLE_INSTANCE source
DISPATCH_VTABLE_INSTANCE(source,
.do_type = DISPATCH_SOURCE_KEVENT_TYPE,
.do_dispose = _dispatch_source_dispose,
.do_debug = _dispatch_source_debug,
.do_invoke = _dispatch_source_invoke,
.dq_activate = _dispatch_source_activate,
.dq_wakeup = _dispatch_source_wakeup,
.dq_push = _dispatch_lane_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_source_extra_vtable_s _OS_dispatch_source_vtable
= {
.do_kind = source,
.do_type = DISPATCH_SOURCE_KEVENT_TYPE,
.do_dispose = _dispatch_source_dispose,
.do_debug = _dispatch_source_debug,
.do_invoke = _dispatch_source_invoke,
.dq_activate = _dispatch_source_activate,
.dq_wakeup = _dispatch_source_wakeup,
.dq_push = _dispatch_lane_push
};
复制代码DISPATCH_VTABLE_INSTANCE channel
DISPATCH_VTABLE_INSTANCE(channel,
.do_type = DISPATCH_CHANNEL_TYPE,
.do_dispose = _dispatch_channel_dispose,
.do_debug = _dispatch_channel_debug,
.do_invoke = _dispatch_channel_invoke,
.dq_activate = _dispatch_lane_activate,
.dq_wakeup = _dispatch_channel_wakeup,
.dq_push = _dispatch_lane_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_channel_extra_vtable_s _OS_dispatch_channel_vtable
= {
.do_kind = channel,
.do_type = DISPATCH_CHANNEL_TYPE,
.do_dispose = _dispatch_channel_dispose,
.do_debug = _dispatch_channel_debug,
.do_invoke = _dispatch_channel_invoke,
.dq_activate = _dispatch_lane_activate,
.dq_wakeup = _dispatch_channel_wakeup,
.dq_push = _dispatch_lane_push
};
复制代码DISPATCH_VTABLE_INSTANCE mach
DISPATCH_VTABLE_INSTANCE(mach,
.do_type = DISPATCH_MACH_CHANNEL_TYPE,
.do_dispose = _dispatch_mach_dispose,
.do_debug = _dispatch_mach_debug,
.do_invoke = _dispatch_mach_invoke,
.dq_activate = _dispatch_mach_activate,
.dq_wakeup = _dispatch_mach_wakeup,
.dq_push = _dispatch_lane_push,
);
__attribute__((section("__DATA,__objc_data"), used)) \
const struct dispatch_mach_extra_vtable_s _OS_dispatch_mach_vtable
= {
.do_kind = mach,
.do_type = DISPATCH_MACH_CHANNEL_TYPE,
.do_dispose = _dispatch_mach_dispose,
.do_debug = _dispatch_mach_debug,
.do_invoke = _dispatch_mach_invoke,
.dq_activate = _dispatch_mach_activate,
.dq_wakeup = _dispatch_mach_wakeup,
.dq_push = _dispatch_lane_push
};
复制代码struct dispatch_queue_static_s
struct dispatch_queue_static_s {
struct dispatch_lane_s _as_dl[0]; \
struct dispatch_queue_s _as_dq[0]; \
struct dispatch_object_s _as_do[0]; \
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_lane_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_lane_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
} \
struct dispatch_object_s *volatile dq_items_tail; \
DISPATCH_UNION_LE(uint64_t volatile dq_state, \
dispatch_lock dq_state_lock, \ uint32_t dq_state_bits \
)
/* LP64 global queue cacheline boundary */ \
unsigned long dq_serialnum; \
const char *dq_label; \
DISPATCH_UNION_LE(uint32_t volatile dq_atomic_flags, \
const uint16_t dq_width, \
const uint16_t __dq_opaque2 \
); \
dispatch_priority_t dq_priority; \
union { \
struct dispatch_queue_specific_head_s *dq_specific_head; \
struct dispatch_source_refs_s *ds_refs; \
struct dispatch_timer_source_refs_s *ds_timer_refs; \
struct dispatch_mach_recv_refs_s *dm_recv_refs; \
struct dispatch_channel_callbacks_s const *dch_callbacks; \
}; \
int volatile dq_sref_cnt;
dispatch_unfair_lock_s dq_sidelock; \
struct dispatch_object_s *volatile dq_items_head; \
uint32_t dq_side_suspend_cnt;
} DISPATCH_CACHELINE_ALIGN;
复制代码宏 - _DISPATCH_OBJECT_HEADER
#define _DISPATCH_OBJECT_HEADER(lane) \
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_lane_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_lane_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
}
复制代码宏 - DISPATCH_OBJECT_HEADER
#define DISPATCH_OBJECT_HEADER(x) \ x: lane / queue
struct dispatch_object_s _as_do[0]; \
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_lane_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_lane_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
}
复制代码宏 - _DISPATCH_QUEUE_CLASS_HEADER
#define _DISPATCH_QUEUE_CLASS_HEADER(x,__pointer_sized_field__)\
struct dispatch_object_s _as_do[0]; \
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_lane_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_lane_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
} \
__pointer_sized_field__; \
DISPATCH_UNION_LE(uint64_t volatile dq_state, \
dispatch_lock dq_state_lock, \ uint32_t dq_state_bits \ )
复制代码宏 - DISPATCH_QUEUE_CLASS_HEADER
#define DISPATCH_QUEUE_CLASS_HEADER(x, __pointer_sized_field__) \
struct dispatch_object_s _as_do[0]; \
struct _os_object_s _as_os_obj[0]; \
const struct dispatch_lane_vtable_s \
*__ptrauth_objc_isa_pointer do_vtable; \
int volatile do_ref_cnt; \
int volatile do_xref_cnt) \
struct dispatch_lane_s *volatile do_next; \
struct dispatch_queue_s *do_targetq; \
void *do_ctxt; \
union { \
void *do_finalizer; \
void *do_introspection_ctxt; \
} \
__pointer_sized_field__; \
DISPATCH_UNION_LE(uint64_t volatile dq_state, \
dispatch_lock dq_state_lock, \ uint32_t dq_state_bits \
)
/* LP64 global queue cacheline boundary */ \
unsigned long dq_serialnum; \
const char *dq_label; \
DISPATCH_UNION_LE(uint32_t volatile dq_atomic_flags, \
const uint16_t dq_width, \
const uint16_t __dq_opaque2 \
); \
dispatch_priority_t dq_priority; \
union { \
struct dispatch_queue_specific_head_s *dq_specific_head; \
struct dispatch_source_refs_s *ds_refs; \
struct dispatch_timer_source_refs_s *ds_timer_refs; \
struct dispatch_mach_recv_refs_s *dm_recv_refs; \
struct dispatch_channel_callbacks_s const *dch_callbacks; \
}; \
int volatile dq_sref_cnt
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