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mdbx: re-verify atomic-ops and remove mo_SequentialConsistency.

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Леонид Юрьев (Leonid Yuriev) 2022-07-11 23:26:02 +03:00
parent 5e565433f7
commit 08e936a809
2 changed files with 7 additions and 8 deletions
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11
src/core.c
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@ -1099,16 +1099,16 @@ static __always_inline void safe64_reset(MDBX_atomic_uint64_t *p,
} else { } else {
#if MDBX_64BIT_CAS && MDBX_64BIT_ATOMIC #if MDBX_64BIT_CAS && MDBX_64BIT_ATOMIC
/* atomically make value >= SAFE64_INVALID_THRESHOLD by 64-bit operation */ /* atomically make value >= SAFE64_INVALID_THRESHOLD by 64-bit operation */
atomic_store64(p, UINT64_MAX, mo_SequentialConsistency); atomic_store64(p, UINT64_MAX, mo_AcquireRelease);
#elif MDBX_64BIT_CAS #elif MDBX_64BIT_CAS
/* atomically make value >= SAFE64_INVALID_THRESHOLD by 32-bit operation */ /* atomically make value >= SAFE64_INVALID_THRESHOLD by 32-bit operation */
atomic_store32(&p->high, UINT32_MAX, mo_SequentialConsistency); atomic_store32(&p->high, UINT32_MAX, mo_AcquireRelease);
#else #else
/* it is safe to increment low-part to avoid ABA, since xMDBX_TXNID_STEP > 1 /* it is safe to increment low-part to avoid ABA, since xMDBX_TXNID_STEP > 1
* and overflow was preserved in safe64_txnid_next() */ * and overflow was preserved in safe64_txnid_next() */
STATIC_ASSERT(xMDBX_TXNID_STEP > 1); STATIC_ASSERT(xMDBX_TXNID_STEP > 1);
atomic_add32(&p->low, 1) /* avoid ABA in safe64_reset_compare() */; atomic_add32(&p->low, 1) /* avoid ABA in safe64_reset_compare() */;
atomic_store32(&p->high, UINT32_MAX, mo_SequentialConsistency); atomic_store32(&p->high, UINT32_MAX, mo_AcquireRelease);
atomic_add32(&p->low, 1) /* avoid ABA in safe64_reset_compare() */; atomic_add32(&p->low, 1) /* avoid ABA in safe64_reset_compare() */;
#endif /* MDBX_64BIT_CAS && MDBX_64BIT_ATOMIC */ #endif /* MDBX_64BIT_CAS && MDBX_64BIT_ATOMIC */
} }
@ -1794,8 +1794,7 @@ static int uniq_poke(const mdbx_mmap_t *pending, mdbx_mmap_t *scan,
<< 24 | << 24 |
*abra >> 40; *abra >> 40;
MDBX_lockinfo *const scan_lck = scan->lck; MDBX_lockinfo *const scan_lck = scan->lck;
atomic_store64(&scan_lck->mti_bait_uniqueness, cadabra, atomic_store64(&scan_lck->mti_bait_uniqueness, cadabra, mo_AcquireRelease);
mo_SequentialConsistency);
*abra = *abra * UINT64_C(6364136223846793005) + 1; *abra = *abra * UINT64_C(6364136223846793005) + 1;
return uniq_peek(pending, scan); return uniq_peek(pending, scan);
} }
@ -7787,7 +7786,7 @@ static bind_rslot_result bind_rslot(MDBX_env *env, const uintptr_t tid) {
* slot, next publish it in lck->mti_numreaders. After * slot, next publish it in lck->mti_numreaders. After
* that, it is safe for mdbx_env_close() to touch it. * that, it is safe for mdbx_env_close() to touch it.
* When it will be closed, we can finally claim it. */ * When it will be closed, we can finally claim it. */
atomic_store32(&result.rslot->mr_pid, 0, mo_SequentialConsistency); atomic_store32(&result.rslot->mr_pid, 0, mo_AcquireRelease);
safe64_reset(&result.rslot->mr_txnid, true); safe64_reset(&result.rslot->mr_txnid, true);
if (slot == nreaders) if (slot == nreaders)
env->me_lck->mti_numreaders.weak = ++nreaders; env->me_lck->mti_numreaders.weak = ++nreaders;

4
src/internals.h
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@ -218,8 +218,8 @@ extern LIBMDBX_API const char *const mdbx_sourcery_anchor;
enum MDBX_memory_order { enum MDBX_memory_order {
mo_Relaxed, mo_Relaxed,
mo_AcquireRelease, mo_AcquireRelease
mo_SequentialConsistency /* , mo_SequentialConsistency */
}; };
typedef union { typedef union {