From 5fd319bbc2913b452b48ce5dc06958694044e46c 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, 20 Mar 2025 01:42:50 +0300
Subject: [PATCH] =?UTF-8?q?mdbx:=20=D0=BF=D0=B5=D1=80=D0=B5=D1=80=D0=B0?=
 =?UTF-8?q?=D0=B1=D0=BE=D1=82=D0=BA=D0=B0=20`mdbx=5Ftxn=5Frelease=5Fall=5F?=
 =?UTF-8?q?cursors=5Fex()`=20(backport).?=
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---
 mdbx.h           | 26 ++++++++++--------------
 src/api-cursor.c | 51 +++++++++++++++++++++++++++++++-----------------
 2 files changed, 43 insertions(+), 34 deletions(-)

diff --git a/mdbx.h b/mdbx.h
index 0ae5921a..ae2af5ad 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -5261,15 +5261,12 @@ LIBMDBX_API void mdbx_cursor_close(MDBX_cursor *cursor);
  * \retval MDBX_EINVAL  An invalid parameter was specified. */
 LIBMDBX_API int mdbx_cursor_close2(MDBX_cursor *cursor);
 
-/** \brief Unbind or closes all cursors of a given transaction.
+/** \brief Unbind or closes all cursors of a given transaction and of all
+ * its parent transactions if ones are.
  * \ingroup c_cursors
  *
- * Unbinds either closes all cursors associated (opened or renewed) with
- * a given transaction in a bulk with minimal overhead.
- *
- * A transaction should not be nested, since in this case no way to restore
- * state if this nested transaction will be aborted, nor impossible to define
- * the expected behavior.
+ * Unbinds either closes all cursors associated (opened, renewed or binded) with
+ * the given transaction in a bulk with minimal overhead.
  *
  * \see mdbx_cursor_unbind()
  * \see mdbx_cursor_close()
@@ -5284,19 +5281,16 @@ LIBMDBX_API int mdbx_cursor_close2(MDBX_cursor *cursor);
  *          some possible errors are:
  * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
  *                               by current thread.
- * \retval MDBX_BAD_TXN          Given transaction is invalid, nested or has
+ * \retval MDBX_BAD_TXN          Given transaction is invalid or has
  *                               a child/nested transaction transaction. */
 LIBMDBX_API int mdbx_txn_release_all_cursors_ex(const MDBX_txn *txn, bool unbind, size_t *count);
 
-/** \brief Unbind or closes all cursors of a given transaction.
+/** \brief Unbind or closes all cursors of a given transaction and of all
+ * its parent transactions if ones are.
  * \ingroup c_cursors
  *
- * Unbinds either closes all cursors associated (opened or renewed) with
- * a given transaction in a bulk with minimal overhead.
- *
- * A transaction should not be nested, since in this case no way to restore
- * state if this nested transaction will be aborted, nor impossible to define
- * the expected behavior.
+ * Unbinds either closes all cursors associated (opened, renewed or binded) with
+ * the given transaction in a bulk with minimal overhead.
  *
  * \see mdbx_cursor_unbind()
  * \see mdbx_cursor_close()
@@ -5309,7 +5303,7 @@ LIBMDBX_API int mdbx_txn_release_all_cursors_ex(const MDBX_txn *txn, bool unbind
  *          some possible errors are:
  * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
  *                               by current thread.
- * \retval MDBX_BAD_TXN          Given transaction is invalid, nested or has
+ * \retval MDBX_BAD_TXN          Given transaction is invalid or has
  *                               a child/nested transaction transaction. */
 LIBMDBX_INLINE_API(int, mdbx_txn_release_all_cursors, (const MDBX_txn *txn, bool unbind)) {
   return mdbx_txn_release_all_cursors_ex(txn, unbind, NULL);
diff --git a/src/api-cursor.c b/src/api-cursor.c
index d86bc34e..24288fb5 100644
--- a/src/api-cursor.c
+++ b/src/api-cursor.c
@@ -233,28 +233,43 @@ int mdbx_txn_release_all_cursors_ex(const MDBX_txn *txn, bool unbind, size_t *co
   int rc = check_txn(txn, MDBX_TXN_FINISHED | MDBX_TXN_HAS_CHILD);
   if (unlikely(rc != MDBX_SUCCESS))
     return LOG_IFERR(rc);
-  if (unlikely(txn->parent)) {
-    rc = MDBX_BAD_TXN;
-    ERROR("%s, err %d", "must not unbind or close cursors for a nested txn", rc);
-    return rc;
-  }
 
   size_t n = 0;
-  TXN_FOREACH_DBI_FROM(txn, i, MAIN_DBI) {
-    while (txn->cursors[i]) {
-      ++n;
-      MDBX_cursor *mc = txn->cursors[i];
-      ENSURE(nullptr, mc->signature == cur_signature_live && (mc->next != mc) && !mc->backup);
-      txn->cursors[i] = mc->next;
-      mc->next = mc;
-      mc->signature = cur_signature_ready4dispose;
-      cursor_drown((cursor_couple_t *)mc);
-      if (!unbind) {
-        mc->signature = 0;
-        osal_free(mc);
+  do {
+    TXN_FOREACH_DBI_FROM(txn, i, MAIN_DBI) {
+      MDBX_cursor *mc = txn->cursors[i], *next = nullptr;
+      if (mc) {
+        txn->cursors[i] = nullptr;
+        do {
+          next = mc->next;
+          if (mc->signature == cur_signature_live) {
+            mc->signature = cur_signature_wait4eot;
+            cursor_drown((cursor_couple_t *)mc);
+          } else
+            ENSURE(nullptr, mc->signature == cur_signature_wait4eot);
+          if (mc->backup) {
+            MDBX_cursor *bk = mc->backup;
+            mc->next = bk->next;
+            mc->backup = bk->backup;
+            mc->backup = nullptr;
+            bk->signature = 0;
+            bk = bk->next;
+            osal_free(bk);
+          } else {
+            mc->signature = cur_signature_ready4dispose;
+            mc->next = mc;
+            ++n;
+            if (!unbind) {
+              mc->signature = 0;
+              osal_free(mc);
+            }
+          }
+        } while ((mc = next) != nullptr);
       }
     }
-  }
+    txn = txn->parent;
+  } while (txn);
+
   if (count)
     *count = n;
   return MDBX_SUCCESS;