From 333069e7a875799fe63ecf46b67c049bdefa0081 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=9B=D0=B5=D0=BE=D0=BD=D0=B8=D0=B4=20=D0=AE=D1=80=D1=8C?=
 =?UTF-8?q?=D0=B5=D0=B2=20=28Leonid=20Yuriev=29?= <leo@yuriev.ru>
Date: Thu, 6 Mar 2025 10:29:57 +0300
Subject: [PATCH] =?UTF-8?q?mdbx:=20=D1=80=D0=B5=D1=84=D0=B0=D0=BA=D1=82?=
 =?UTF-8?q?=D0=BE=D1=80=D0=B8=D0=BD=D0=B3=20`cursor=5Feot()`=20=D0=B4?=
 =?UTF-8?q?=D0=BB=D1=8F=20=D1=83=D0=BF=D1=80=D0=BE=D1=89=D0=B5=D0=BD=D0=B8?=
 =?UTF-8?q?=D1=8F=20`txn=5Fdone=5Fcursors()`.?=
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---
 src/cursor.c | 26 ++++++++++++++------------
 src/cursor.h |  2 +-
 src/dbi.h    |  2 +-
 src/txn.c    |  8 +++-----
 4 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/src/cursor.c b/src/cursor.c
index b0857e73..1fd8cbc1 100644
--- a/src/cursor.c
+++ b/src/cursor.c
@@ -214,18 +214,21 @@ int cursor_shadow(MDBX_cursor *cursor, MDBX_txn *nested, const size_t dbi) {
   return MDBX_SUCCESS;
 }
 
-void cursor_eot(MDBX_cursor *cursor) {
+MDBX_cursor *cursor_eot(MDBX_cursor *cursor, MDBX_txn *txn) {
+  MDBX_cursor *const next = cursor->next;
+  cursor->next = cursor;
   const unsigned stage = cursor->signature;
   MDBX_cursor *const shadow = cursor->backup;
-  ENSURE(cursor->txn->env, stage == cur_signature_live || (stage == cur_signature_wait4eot && shadow));
+  ENSURE(txn->env, stage == cur_signature_live || (stage == cur_signature_wait4eot && shadow));
+  tASSERT(txn, cursor->txn == txn);
   if (shadow) {
     subcur_t *subcur = cursor->subcur;
-    cASSERT(cursor, cursor->txn->parent != nullptr);
-    /* Zap: Using uninitialized memory '*cursor->backup'. */
+    tASSERT(txn, txn->parent != nullptr && shadow->txn == txn->parent);
+    /* Zap: Using uninitialized memory '*mc->backup'. */
     MDBX_SUPPRESS_GOOFY_MSVC_ANALYZER(6001);
-    ENSURE(cursor->txn->env, shadow->signature == cur_signature_live);
-    cASSERT(cursor, subcur == shadow->subcur);
-    if (((cursor->txn->flags | cursor->txn->parent->flags) & MDBX_TXN_ERROR) == 0) {
+    ENSURE(txn->env, shadow->signature == cur_signature_live);
+    tASSERT(txn, subcur == shadow->subcur);
+    if ((txn->flags & MDBX_TXN_ERROR) == 0) {
       /* Update pointers to parent txn */
       cursor->next = shadow->next;
       cursor->backup = shadow->backup;
@@ -233,25 +236,24 @@ void cursor_eot(MDBX_cursor *cursor) {
       cursor->tree = shadow->tree;
       cursor->dbi_state = shadow->dbi_state;
       if (subcur) {
-        subcur->cursor.txn = cursor->txn;
-        subcur->cursor.dbi_state = cursor->dbi_state;
+        subcur->cursor.txn = shadow->txn;
+        subcur->cursor.dbi_state = shadow->dbi_state;
       }
     } else {
       /* Restore from backup, i.e. rollback/abort nested txn */
       *cursor = *shadow;
+      cursor->signature = stage /* Promote (cur_signature_wait4eot) state to parent txn */;
       if (subcur)
         *subcur = *(subcur_t *)(shadow + 1);
     }
-    if (stage == cur_signature_wait4eot /* Cursor was closed by user */)
-      cursor->signature = stage /* Promote closed state to parent txn */;
     shadow->signature = 0;
     osal_free(shadow);
   } else {
     ENSURE(cursor->txn->env, stage == cur_signature_live);
     be_poor(cursor);
     cursor->signature = cur_signature_ready4dispose /* Cursor may be reused */;
-    cursor->next = cursor;
   }
+  return next;
 }
 
 /*----------------------------------------------------------------------------*/
diff --git a/src/cursor.h b/src/cursor.h
index 8ca4ea72..e53e91db 100644
--- a/src/cursor.h
+++ b/src/cursor.h
@@ -292,7 +292,7 @@ MDBX_NOTHROW_PURE_FUNCTION static inline bool check_leaf_type(const MDBX_cursor
   return (((page_type(mp) ^ mc->checking) & (z_branch | z_leaf | z_largepage | z_dupfix)) == 0);
 }
 
-MDBX_INTERNAL void cursor_eot(MDBX_cursor *cursor);
+MDBX_INTERNAL MDBX_cursor *cursor_eot(MDBX_cursor *cursor, MDBX_txn *txn);
 MDBX_INTERNAL int cursor_shadow(MDBX_cursor *cursor, MDBX_txn *nested, const size_t dbi);
 
 MDBX_INTERNAL MDBX_cursor *cursor_cpstk(const MDBX_cursor *csrc, MDBX_cursor *cdst);
diff --git a/src/dbi.h b/src/dbi.h
index 36c7e8bb..f634ee19 100644
--- a/src/dbi.h
+++ b/src/dbi.h
@@ -101,7 +101,7 @@ static inline bool dbi_changed(const MDBX_txn *txn, const size_t dbi) {
   const MDBX_env *const env = txn->env;
   eASSERT(env, dbi_state(txn, dbi) & DBI_LINDO);
   const uint32_t snap_seq = atomic_load32(&env->dbi_seqs[dbi], mo_AcquireRelease);
-  return snap_seq != txn->dbi_seqs[dbi];
+  return unlikely(snap_seq != txn->dbi_seqs[dbi]);
 }
 
 static inline int dbi_check(const MDBX_txn *txn, const size_t dbi) {
diff --git a/src/txn.c b/src/txn.c
index 3d9c3aa3..09c4a3d0 100644
--- a/src/txn.c
+++ b/src/txn.c
@@ -15,11 +15,9 @@ void txn_done_cursors(MDBX_txn *txn) {
     MDBX_cursor *cursor = txn->cursors[i];
     if (cursor) {
       txn->cursors[i] = nullptr;
-      do {
-        MDBX_cursor *const next = cursor->next;
-        cursor_eot(cursor);
-        cursor = next;
-      } while (cursor);
+      do
+        cursor = cursor_eot(cursor, txn);
+      while (cursor);
     }
   }
   txn->flags &= ~txn_may_have_cursors;