mdbx: добавление mdbx_txn_release_all_cursors() в API.

mdbx.h

@@ -4803,6 +4803,27 @@ LIBMDBX_API int mdbx_cursor_open(MDBX_txn *txn, MDBX_dbi dbi,
  *                     or \ref mdbx_cursor_create(). */
 LIBMDBX_API void mdbx_cursor_close(MDBX_cursor *cursor);
 
+/** \brief Unbind or closes all cursors of a given transaction.
+ * \ingroup c_cursors
+ *
+ * Unbinds either closes all cursors associated (opened or renewed) with
+ * a given transaction in a bulk with minimal overhead.
+ *
+ * \see mdbx_cursor_unbind()
+ * \see mdbx_cursor_close()
+ *
+ * \param [in] txn      A transaction handle returned by \ref mdbx_txn_begin().
+ * \param [in] unbind   If non-zero, unbinds cursors and leaves ones reusable.
+ *                      Otherwise close and dispose cursors.
+ *
+ * \returns A negative error value on failure or the number of closed cursors
+ *          on success, some possible errors are:
+ * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
+ *                               by current thread.
+ * \retval MDBX_BAD_TXN          Given transaction is invalid or has
+ *                               a child/nested transaction transaction. */
+LIBMDBX_API int mdbx_txn_release_all_cursors(const MDBX_txn *txn, bool unbind);
+
 /** \brief Renew a cursor handle for use within the given transaction.
  * \ingroup c_cursors
  *

mdbx.h++

@@ -3841,6 +3841,15 @@ public:
   /// \brief Opens cursor for specified key-value map handle.
   inline cursor_managed open_cursor(map_handle map);
 
+  /// \brief Unbind or close all cursors.
+  inline size_t release_all_cursors(bool unbind) const;
+
+  /// \brief Close all cursors.
+  inline size_t close_all_cursors() const { return release_all_cursors(false); }
+
+  /// \brief Unbind all cursors.
+  inline size_t unbind_all_cursors() const { return release_all_cursors(true); }
+
   /// \brief Open existing key-value map.
   inline map_handle open_map(
       const char *name,
@@ -5466,6 +5475,13 @@ inline cursor_managed txn::open_cursor(map_handle map) {
   return cursor_managed(ptr);
 }
 
+inline size_t txn::release_all_cursors(bool unbind) const {
+  int err = ::mdbx_txn_release_all_cursors(handle_, unbind);
+  if (MDBX_UNLIKELY(err < 0))
+    MDBX_CXX20_UNLIKELY error::throw_exception(err);
+  return size_t(err);
+}
+
 inline ::mdbx::map_handle
 txn::open_map(const char *name, const ::mdbx::key_mode key_mode,
               const ::mdbx::value_mode value_mode) const {

src/core.c

@@ -19019,6 +19019,32 @@ void mdbx_cursor_close(MDBX_cursor *mc) {
   }
 }
 
+int mdbx_txn_release_all_cursors(const MDBX_txn *txn, bool unbind) {
+  int rc = check_txn(txn, MDBX_TXN_FINISHED | MDBX_TXN_HAS_CHILD);
+  if (likely(rc == MDBX_SUCCESS)) {
+    for (size_t i = FREE_DBI; i < txn->mt_numdbs; ++i) {
+      while (txn->mt_cursors[i]) {
+        MDBX_cursor *mc = txn->mt_cursors[i];
+        ENSURE(NULL, mc->mc_signature == MDBX_MC_LIVE &&
+                         (mc->mc_flags & C_UNTRACK) && !mc->mc_backup);
+        rc = likely(rc < INT_MAX) ? rc + 1 : rc;
+        txn->mt_cursors[i] = mc->mc_next;
+        if (unbind) {
+          mc->mc_signature = MDBX_MC_READY4CLOSE;
+          mc->mc_flags = 0;
+        } else {
+          mc->mc_signature = 0;
+          mc->mc_next = mc;
+          osal_free(mc);
+        }
+      }
+    }
+  } else {
+    eASSERT(nullptr, rc < 0);
+  }
+  return rc;
+}
+
 MDBX_txn *mdbx_cursor_txn(const MDBX_cursor *mc) {
   if (unlikely(!mc || mc->mc_signature != MDBX_MC_LIVE))
     return NULL;