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mdbx: refine visibility of internal mdbx_osal_jitter().

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This commit is contained in:
Leonid Yuriev
2021-11-07 19:48:14 +03:00
parent c456625ef2
commit 0c3a5da3cb
3 changed files with 75 additions and 78 deletions
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64
src/core.c
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@@ -823,6 +823,70 @@ size_t __hot mdbx_e2k_strnlen_bug_workaround(const char *s, size_t maxlen) {
/*------------------------------------------------------------------------------
* safe read/write volatile 64-bit fields on 32-bit architectures. */
MDBX_MAYBE_UNUSED static __always_inline uint64_t
atomic_store64(MDBX_atomic_uint64_t *p, const uint64_t value,
enum MDBX_memory_order order) {
STATIC_ASSERT(sizeof(MDBX_atomic_uint64_t) == 8);
#if MDBX_64BIT_ATOMIC
#ifdef MDBX_HAVE_C11ATOMICS
assert(atomic_is_lock_free(MDBX_c11a_rw(uint64_t, p)));
atomic_store_explicit(MDBX_c11a_rw(uint64_t, p), value, mo_c11_store(order));
#else /* MDBX_HAVE_C11ATOMICS */
if (order != mo_Relaxed)
mdbx_compiler_barrier();
p->weak = value;
mdbx_memory_fence(order, true);
#endif /* MDBX_HAVE_C11ATOMICS */
#else /* !MDBX_64BIT_ATOMIC */
mdbx_compiler_barrier();
atomic_store32(&p->low, (uint32_t)value, mo_Relaxed);
mdbx_jitter4testing(true);
atomic_store32(&p->high, (uint32_t)(value >> 32), order);
mdbx_jitter4testing(true);
#endif /* !MDBX_64BIT_ATOMIC */
return value;
}
MDBX_MAYBE_UNUSED static
#if MDBX_64BIT_ATOMIC
__always_inline
#endif /* MDBX_64BIT_ATOMIC */
uint64_t
atomic_load64(const MDBX_atomic_uint64_t *p,
enum MDBX_memory_order order) {
STATIC_ASSERT(sizeof(MDBX_atomic_uint64_t) == 8);
#if MDBX_64BIT_ATOMIC
#ifdef MDBX_HAVE_C11ATOMICS
assert(atomic_is_lock_free(MDBX_c11a_ro(uint64_t, p)));
return atomic_load_explicit(MDBX_c11a_ro(uint64_t, p), mo_c11_load(order));
#else /* MDBX_HAVE_C11ATOMICS */
mdbx_memory_fence(order, false);
const uint64_t value = p->weak;
if (order != mo_Relaxed)
mdbx_compiler_barrier();
return value;
#endif /* MDBX_HAVE_C11ATOMICS */
#else /* !MDBX_64BIT_ATOMIC */
mdbx_compiler_barrier();
uint64_t value = (uint64_t)atomic_load32(&p->high, order) << 32;
mdbx_jitter4testing(true);
value |= atomic_load32(&p->low, (order == mo_Relaxed) ? mo_Relaxed
: mo_AcquireRelease);
mdbx_jitter4testing(true);
for (;;) {
mdbx_compiler_barrier();
uint64_t again = (uint64_t)atomic_load32(&p->high, order) << 32;
mdbx_jitter4testing(true);
again |= atomic_load32(&p->low, (order == mo_Relaxed) ? mo_Relaxed
: mo_AcquireRelease);
mdbx_jitter4testing(true);
if (likely(value == again))
return value;
value = again;
}
#endif /* !MDBX_64BIT_ATOMIC */
}
static __always_inline void atomic_yield(void) {
#if defined(_WIN32) || defined(_WIN64)
YieldProcessor();