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mdbx: drop mdbx_recent_steady_txnid() and fix extra search for steady meta-page.

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Леонид Юрьев (Leonid Yuriev) 2022-07-02 19:28:55 +03:00
parent b9835389f4
commit d61c096313
1 changed files with 10 additions and 20 deletions
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30
src/core.c
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@ -5917,17 +5917,6 @@ static txnid_t mdbx_recent_committed_txnid(const MDBX_env *env) {
} }
} }
static txnid_t mdbx_recent_steady_txnid(const MDBX_env *env) {
while (true) {
volatile const MDBX_meta *head = meta_prefer_steady(env);
const txnid_t recent = meta_txnid(env, head);
mdbx_compiler_barrier();
if (likely(head == meta_prefer_steady(env) &&
recent == meta_txnid(env, head)))
return recent;
}
}
static const char *mdbx_durable_str(volatile const MDBX_meta *const meta) { static const char *mdbx_durable_str(volatile const MDBX_meta *const meta) {
if (META_IS_STEADY(meta)) if (META_IS_STEADY(meta))
return (unaligned_peek_u64_volatile(4, meta->mm_datasync_sign) == return (unaligned_peek_u64_volatile(4, meta->mm_datasync_sign) ==
@ -5941,20 +5930,21 @@ static const char *mdbx_durable_str(volatile const MDBX_meta *const meta) {
/* Find oldest txnid still referenced. */ /* Find oldest txnid still referenced. */
static txnid_t find_oldest_reader(const MDBX_env *env) { static txnid_t find_oldest_reader(const MDBX_env *env) {
const txnid_t edge = mdbx_recent_steady_txnid(env); const txnid_t steady_edge =
mdbx_assert(env, edge <= env->me_txn0->mt_txnid); constmeta_txnid(env, constmeta_prefer_steady(env));
mdbx_assert(env, steady_edge <= env->me_txn0->mt_txnid);
MDBX_lockinfo *const lck = env->me_lck_mmap.lck; MDBX_lockinfo *const lck = env->me_lck_mmap.lck;
if (unlikely(lck == NULL /* exclusive without-lck mode */)) { if (unlikely(lck == NULL /* exclusive without-lck mode */)) {
mdbx_assert(env, env->me_lck == (void *)&env->x_lckless_stub); mdbx_assert(env, env->me_lck == (void *)&env->x_lckless_stub);
return env->me_lck->mti_oldest_reader.weak = edge; return env->me_lck->mti_oldest_reader.weak = steady_edge;
} }
const txnid_t last_oldest = const txnid_t last_oldest =
atomic_load64(&lck->mti_oldest_reader, mo_AcquireRelease); atomic_load64(&lck->mti_oldest_reader, mo_AcquireRelease);
mdbx_assert(env, edge >= last_oldest); mdbx_assert(env, steady_edge >= last_oldest);
if (likely(last_oldest == edge)) if (likely(last_oldest == steady_edge))
return edge; return steady_edge;
const uint32_t nothing_changed = MDBX_STRING_TETRAD("None"); const uint32_t nothing_changed = MDBX_STRING_TETRAD("None");
const uint32_t snap_readers_refresh_flag = const uint32_t snap_readers_refresh_flag =
@ -5966,12 +5956,12 @@ static txnid_t find_oldest_reader(const MDBX_env *env) {
atomic_store32(&lck->mti_readers_refresh_flag, nothing_changed, mo_Relaxed); atomic_store32(&lck->mti_readers_refresh_flag, nothing_changed, mo_Relaxed);
const unsigned snap_nreaders = const unsigned snap_nreaders =
atomic_load32(&lck->mti_numreaders, mo_AcquireRelease); atomic_load32(&lck->mti_numreaders, mo_AcquireRelease);
txnid_t oldest = edge; txnid_t oldest = steady_edge;
for (unsigned i = 0; i < snap_nreaders; ++i) { for (unsigned i = 0; i < snap_nreaders; ++i) {
if (atomic_load32(&lck->mti_readers[i].mr_pid, mo_AcquireRelease)) { if (atomic_load32(&lck->mti_readers[i].mr_pid, mo_AcquireRelease)) {
/* mdbx_jitter4testing(true); */ /* mdbx_jitter4testing(true); */
const txnid_t snap = safe64_read(&lck->mti_readers[i].mr_txnid); const txnid_t snap = safe64_read(&lck->mti_readers[i].mr_txnid);
if (oldest > snap && /* ignore pending updates */ snap <= edge) { if (oldest > snap && /* ignore pending updates */ snap <= steady_edge) {
oldest = snap; oldest = snap;
if (oldest == last_oldest) if (oldest == last_oldest)
return oldest; return oldest;
@ -21442,7 +21432,7 @@ __cold static txnid_t mdbx_kick_longlived_readers(MDBX_env *env,
int retry; int retry;
for (retry = 0; retry < INT_MAX; ++retry) { for (retry = 0; retry < INT_MAX; ++retry) {
txnid_t oldest = mdbx_recent_steady_txnid(env); txnid_t oldest = constmeta_txnid(env, constmeta_prefer_steady(env));
mdbx_assert(env, oldest < env->me_txn0->mt_txnid); mdbx_assert(env, oldest < env->me_txn0->mt_txnid);
mdbx_assert(env, oldest >= laggard); mdbx_assert(env, oldest >= laggard);
mdbx_assert(env, oldest >= env->me_lck->mti_oldest_reader.weak); mdbx_assert(env, oldest >= env->me_lck->mti_oldest_reader.weak);