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Add function _init_once for intrusive shared pointer

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Patrick Pelissier committed 2020-12-05 18:14:22 +01:00
1 parent 5f0b6b9f26
commit 34c990e259
2 files changed
+69 -10
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m-i-shared.h
+44 -7
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@@ -46,6 +46,11 @@ M_BEGIN_PROTECTED_CODE
atomic_int M_C(name, _cpt)
/* Value of the interface field for static intialization. */
#define ISHARED_PTR_STATIC_INIT(name, type) \
.M_C(name, _cpt) = ATOMIC_VAR_INIT(0)
/* Define the intrusive shared pointer type and its static inline functions.
USAGE: ISHARED_PTR_DEF(name, type, [, oplist]) */
#define ISHARED_PTR_DEF(name, ...) \
@@ -122,7 +127,7 @@ M_BEGIN_PROTECTED_CODE
{ \
/* Initialize the type referenced by the pointer */ \
if (M_LIKELY (ptr != NULL)) { \
atomic_init(&ptr->M_C(name, _cpt), 1); \
atomic_init(&ptr->M_C(name, _cpt), 2); \
} \
return ptr; \
} \
@@ -131,7 +136,7 @@ M_BEGIN_PROTECTED_CODE
M_C(name, _init_set)(shared_t shared) \
{ \
if (M_LIKELY (shared != NULL)) { \
int n = atomic_fetch_add(&(shared->M_C(name, _cpt)), 1); \
int n = atomic_fetch_add(&(shared->M_C(name, _cpt)), 2); \
(void) n; \
} \
return shared; \
@@ -144,9 +149,41 @@ M_BEGIN_PROTECTED_CODE
*ptr = M_C(name, _init_set)(shared); \
} \
\
M_IF_METHOD(INIT, oplist)( \
M_IF_DISABLED_METHOD(NEW, oplist) \
( /* Nothing to do */, M_IF_METHOD(INIT, oplist) \
( \
( \
/* This function is only for static object */ \
static inline shared_t \
M_C(name, _init_once)(type *shared) \
{ \
if (M_LIKELY (shared != NULL)) { \
/* Pretty much like atomic_add, except the first one increment by 1, others by 2 */ \
int o = atomic_load(&(shared->M_C(name, _cpt))); \
int n; \
do { \
n = o + 1 + (o != 0); \
} while (!atomic_compare_exchange_strong(&(shared->M_C(name, _cpt)), &o, n)); \
if (o == 0) { \
/* Partial initialization: _cpt is odd */ \
/* Call the INIT function once */ \
M_CALL_INIT(oplist, *shared); \
/* Finish initialization: _cpt is even */ \
atomic_fetch_add(&(shared->M_C(name, _cpt)), 1); \
} else if ( (o&1) != 0) { \
/* Not fully initialized yet: wait for initialization */ \
m_core_backoff_ct bkoff; \
m_core_backoff_init(bkoff); \
/* Wait for _cpt to be _even */ \
while ((atomic_load(&(shared->M_C(name, _cpt)))&1) != 0 ) { \
m_core_backoff_wait(bkoff); \
} \
} \
M_ASSERT( (atomic_load(&(shared->M_C(name, _cpt)))&1) == 0); \
} \
return shared; \
} \
, \
/* This function is only for dynamic object */ \
static inline shared_t \
M_C(name, _init_new)(void) \
{ \
@@ -156,17 +193,17 @@ M_BEGIN_PROTECTED_CODE
return NULL; \
} \
M_CALL_INIT(oplist, *ptr); \
atomic_init (&ptr->M_C(name, _cpt), 1); \
atomic_init (&ptr->M_C(name, _cpt), 2); \
return ptr; \
} \
, /* End of INIT */) \
/* End of NEW */) \
, /* End of INIT */) \
\
static inline void \
M_C(name, _clear)(shared_t shared) \
{ \
if (shared != NULL) { \
if (atomic_fetch_sub(&(shared->M_C(name, _cpt)), 1) == 1) { \
if (atomic_fetch_sub(&(shared->M_C(name, _cpt)), 2) == 2) { \
M_CALL_CLEAR(oplist, *shared); \
M_IF_DISABLED_METHOD(DEL, oplist)(, M_CALL_DEL(oplist, shared);) \
} \