mdbx: рефакторинг txn_renew() транзакций с вычленением txn_basal_start().

src/proto.h

@@ -39,16 +39,6 @@ static inline void dxb_sanitize_tail(MDBX_env *env, MDBX_txn *txn) {
 #endif /* ENABLE_MEMCHECK || __SANITIZE_ADDRESS__ */
 
 /* txn.c */
-MDBX_INTERNAL bool txn_refund(MDBX_txn *txn);
-MDBX_INTERNAL txnid_t txn_snapshot_oldest(const MDBX_txn *const txn);
-MDBX_INTERNAL int txn_abort(MDBX_txn *txn);
-MDBX_INTERNAL int txn_renew(MDBX_txn *txn, unsigned flags);
-MDBX_INTERNAL int txn_ro_park(MDBX_txn *txn, bool autounpark);
-MDBX_INTERNAL int txn_ro_unpark(MDBX_txn *txn);
-MDBX_INTERNAL int txn_check_badbits_parked(const MDBX_txn *txn, int bad_bits);
-MDBX_INTERNAL void txn_done_cursors(MDBX_txn *txn);
-MDBX_INTERNAL int txn_shadow_cursors(const MDBX_txn *parent, const size_t dbi);
-
 #define TXN_END_NAMES                                                                                                  \
   {"committed", "pure-commit", "abort", "reset", "fail-begin", "fail-begin-nested", "ousted", nullptr}
 enum {
@@ -66,21 +56,36 @@ enum {
   TXN_END_FREE = 0x20 /* free txn unless it is env.basal_txn */,
   TXN_END_SLOT = 0x40 /* release any reader slot if NOSTICKYTHREADS */
 };
-MDBX_INTERNAL int txn_end(MDBX_txn *txn, unsigned mode);
-MDBX_INTERNAL MDBX_txn *txn_alloc(const MDBX_txn_flags_t flags, MDBX_env *env);
-MDBX_INTERNAL MDBX_txn *txn_basal_create(const size_t max_dbi);
-MDBX_INTERNAL void txn_basal_destroy(MDBX_txn *txn);
-MDBX_INTERNAL int txn_nested_create(MDBX_txn *parent, const MDBX_txn_flags_t flags);
-MDBX_INTERNAL void txn_nested_abort(MDBX_txn *nested);
 
 struct commit_timestamp {
   uint64_t start, prep, gc, audit, write, sync, gc_cpu;
 };
+
+MDBX_INTERNAL bool txn_refund(MDBX_txn *txn);
+MDBX_INTERNAL txnid_t txn_snapshot_oldest(const MDBX_txn *const txn);
+MDBX_INTERNAL int txn_check_badbits_parked(const MDBX_txn *txn, int bad_bits);
+MDBX_INTERNAL void txn_done_cursors(MDBX_txn *txn);
+MDBX_INTERNAL int txn_shadow_cursors(const MDBX_txn *parent, const size_t dbi);
+
+MDBX_INTERNAL MDBX_txn *txn_alloc(const MDBX_txn_flags_t flags, MDBX_env *env);
+MDBX_INTERNAL int txn_abort(MDBX_txn *txn);
+MDBX_INTERNAL int txn_renew(MDBX_txn *txn, unsigned flags);
+MDBX_INTERNAL int txn_end(MDBX_txn *txn, unsigned mode);
+
+MDBX_INTERNAL int txn_nested_create(MDBX_txn *parent, const MDBX_txn_flags_t flags);
+MDBX_INTERNAL void txn_nested_abort(MDBX_txn *nested);
 MDBX_INTERNAL int txn_nested_join(MDBX_txn *txn, struct commit_timestamp *ts);
+
+MDBX_INTERNAL MDBX_txn *txn_basal_create(const size_t max_dbi);
+MDBX_INTERNAL void txn_basal_destroy(MDBX_txn *txn);
+MDBX_INTERNAL int txn_basal_start(MDBX_txn *txn, unsigned flags);
 MDBX_INTERNAL int txn_basal_commit(MDBX_txn *txn, struct commit_timestamp *ts);
 MDBX_INTERNAL int txn_basal_end(MDBX_txn *txn, unsigned mode);
-MDBX_INTERNAL int txn_ro_end(MDBX_txn *txn, unsigned mode);
+
+MDBX_INTERNAL int txn_ro_park(MDBX_txn *txn, bool autounpark);
+MDBX_INTERNAL int txn_ro_unpark(MDBX_txn *txn);
 MDBX_INTERNAL int txn_ro_start(MDBX_txn *txn, unsigned flags);
+MDBX_INTERNAL int txn_ro_end(MDBX_txn *txn, unsigned mode);
 
 /* env.c */
 MDBX_INTERNAL int env_open(MDBX_env *env, mdbx_mode_t mode);

src/txn-basal.c

@@ -89,6 +89,47 @@ __cold void txn_basal_destroy(MDBX_txn *txn) {
   osal_free(txn);
 }
 
+int txn_basal_start(MDBX_txn *txn, unsigned flags) {
+  MDBX_env *const env = txn->env;
+
+  txn->wr.troika = meta_tap(env);
+  const meta_ptr_t head = meta_recent(env, &txn->wr.troika);
+  uint64_t timestamp = 0;
+  while ("workaround for https://libmdbx.dqdkfa.ru/dead-github/issues/269") {
+    int err = coherency_fetch_head(txn, head, &timestamp);
+    if (likely(err == MDBX_SUCCESS))
+      break;
+    if (unlikely(err != MDBX_RESULT_TRUE))
+      return err;
+  }
+  eASSERT(env, meta_txnid(head.ptr_v) == txn->txnid);
+  txn->txnid = safe64_txnid_next(txn->txnid);
+  if (unlikely(txn->txnid > MAX_TXNID)) {
+    ERROR("txnid overflow, raise %d", MDBX_TXN_FULL);
+    return MDBX_TXN_FULL;
+  }
+
+  tASSERT(txn, txn->dbs[FREE_DBI].flags == MDBX_INTEGERKEY);
+  tASSERT(txn, check_table_flags(txn->dbs[MAIN_DBI].flags));
+  txn->flags = flags;
+  txn->nested = nullptr;
+  txn->wr.loose_pages = nullptr;
+  txn->wr.loose_count = 0;
+#if MDBX_ENABLE_REFUND
+  txn->wr.loose_refund_wl = 0;
+#endif /* MDBX_ENABLE_REFUND */
+  MDBX_PNL_SETSIZE(txn->wr.retired_pages, 0);
+  txn->wr.spilled.list = nullptr;
+  txn->wr.spilled.least_removed = 0;
+  txn->wr.gc.time_acc = 0;
+  txn->wr.gc.last_reclaimed = 0;
+  if (txn->wr.gc.retxl)
+    MDBX_PNL_SETSIZE(txn->wr.gc.retxl, 0);
+  env->txn = txn;
+
+  return MDBX_SUCCESS;
+}
+
 int txn_basal_end(MDBX_txn *txn, unsigned mode) {
   MDBX_env *const env = txn->env;
   tASSERT(txn, (txn->flags & (MDBX_TXN_FINISHED | txn_may_have_cursors)) == 0 && txn->owner);

src/txn.c

@@ -70,6 +70,19 @@ int txn_abort(MDBX_txn *txn) {
   return txn_end(txn, TXN_END_ABORT | TXN_END_SLOT | TXN_END_FREE);
 }
 
+static bool txn_check_overlapped(lck_t *const lck, const uint32_t pid, const uintptr_t tid) {
+  const size_t snap_nreaders = atomic_load32(&lck->rdt_length, mo_AcquireRelease);
+  for (size_t i = 0; i < snap_nreaders; ++i) {
+    if (atomic_load32(&lck->rdt[i].pid, mo_Relaxed) == pid &&
+        unlikely(atomic_load64(&lck->rdt[i].tid, mo_Relaxed) == tid)) {
+      const txnid_t txnid = safe64_read(&lck->rdt[i].txnid);
+      if (txnid >= MIN_TXNID && txnid <= MAX_TXNID)
+        return true;
+    }
+  }
+  return false;
+}
+
 int txn_renew(MDBX_txn *txn, unsigned flags) {
   MDBX_env *const env = txn->env;
   int rc;
@@ -90,17 +103,9 @@ int txn_renew(MDBX_txn *txn, unsigned flags) {
                  /* not recovery mode */ env->stuck_meta >= 0))
       return MDBX_BUSY;
     lck_t *const lck = env->lck_mmap.lck;
-    if (lck && (env->flags & MDBX_NOSTICKYTHREADS) == 0 && (globals.runtime_flags & MDBX_DBG_LEGACY_OVERLAP) == 0) {
+    if (lck && !(env->flags & MDBX_NOSTICKYTHREADS) && !(globals.runtime_flags & MDBX_DBG_LEGACY_OVERLAP) &&
-      const size_t snap_nreaders = atomic_load32(&lck->rdt_length, mo_AcquireRelease);
+        txn_check_overlapped(lck, env->pid, tid))
-      for (size_t i = 0; i < snap_nreaders; ++i) {
+      return MDBX_TXN_OVERLAPPING;
-        if (atomic_load32(&lck->rdt[i].pid, mo_Relaxed) == env->pid &&
-            unlikely(atomic_load64(&lck->rdt[i].tid, mo_Relaxed) == tid)) {
-          const txnid_t txnid = safe64_read(&lck->rdt[i].txnid);
-          if (txnid >= MIN_TXNID && txnid <= MAX_TXNID)
-            return MDBX_TXN_OVERLAPPING;
-        }
-      }
-    }
 
     /* Not yet touching txn == env->basal_txn, it may be active */
     jitter4testing(false);
@@ -118,41 +123,9 @@ int txn_renew(MDBX_txn *txn, unsigned flags) {
     }
 #endif /* Windows */
 
-    txn->wr.troika = meta_tap(env);
+    rc = txn_basal_start(txn, flags);
-    const meta_ptr_t head = meta_recent(env, &txn->wr.troika);
+    if (unlikely(rc != MDBX_SUCCESS))
-    uint64_t timestamp = 0;
-    while ("workaround for https://libmdbx.dqdkfa.ru/dead-github/issues/269") {
-      rc = coherency_fetch_head(txn, head, &timestamp);
-      if (likely(rc == MDBX_SUCCESS))
-        break;
-      if (unlikely(rc != MDBX_RESULT_TRUE))
-        goto bailout;
-    }
-    eASSERT(env, meta_txnid(head.ptr_v) == txn->txnid);
-    txn->txnid = safe64_txnid_next(txn->txnid);
-    if (unlikely(txn->txnid > MAX_TXNID)) {
-      rc = MDBX_TXN_FULL;
-      ERROR("txnid overflow, raise %d", rc);
       goto bailout;
-    }
-
-    tASSERT(txn, txn->dbs[FREE_DBI].flags == MDBX_INTEGERKEY);
-    tASSERT(txn, check_table_flags(txn->dbs[MAIN_DBI].flags));
-    txn->flags = flags;
-    txn->nested = nullptr;
-    txn->wr.loose_pages = nullptr;
-    txn->wr.loose_count = 0;
-#if MDBX_ENABLE_REFUND
-    txn->wr.loose_refund_wl = 0;
-#endif /* MDBX_ENABLE_REFUND */
-    MDBX_PNL_SETSIZE(txn->wr.retired_pages, 0);
-    txn->wr.spilled.list = nullptr;
-    txn->wr.spilled.least_removed = 0;
-    txn->wr.gc.time_acc = 0;
-    txn->wr.gc.last_reclaimed = 0;
-    if (txn->wr.gc.retxl)
-      MDBX_PNL_SETSIZE(txn->wr.gc.retxl, 0);
-    env->txn = txn;
   }
 
   txn->front_txnid = txn->txnid + ((flags & (MDBX_WRITEMAP | MDBX_RDONLY)) == 0);