mdbx: new mdbx_get_cached() with separated tests (v0.14.1-234-g329ac7b7).

2026-01-04 mdbx: update ChangeLog.
2026-01-04 mdbx-docs: add BTC and SOL to donations.
2026-01-04 mdbx-docs: refine common/title doxygen descriptions.
2026-01-04 mdbx-cmake: add more docs files.
2026-01-04 mdbx-doc: doxygen comments for `mdbx_cache_get()`.
2026-01-04 mdbx-test: add multithread case into `extra/get_cached`.
2026-01-03 mdbx: fix ABA-like issue and add `MDBX_CACHE_UNABLE`.
2026-01-03 mdbx: merge branch 'get-cached' into `devel`.
\
 2025-12-06 mdbx-test: initial basic test for a multithreaded get-cached API.
 2025-12-02 mdbx-test: using randomly/generated path for walking deep-transition matrix inside `extra/get-cached`.
 2025-12-02 mdbx-test: add basic test for `get-cached` feature.
 2025-11-27 mdbx++: initial/minimal support for `get-cached` feature (draft).
 2025-12-01 mdbx: preview of `mdbx_get_cached()`.

CMakeLists.txt

@@ -1,7 +1,9 @@
 # Copyright (c) 2020-2026 Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> ###############################################
 # SPDX-License-Identifier: Apache-2.0
 #
-# Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`. Всё будет хорошо!
+# Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`,
+# BTC `bc1qzvl9uegf2ea6cwlytnanrscyv8snwsvrc0xfsu`, SOL `FTCTgbHajoLVZGr8aEFWMzx3NDMyS5wXJgfeMTmJznRi`.
+# Всё будет хорошо!
 
 # libmdbx = { Revised and extended descendant of Symas LMDB. }
 # Please see README.md at https://sourcecraft.dev/dqdkfa/libmdbx
@@ -573,6 +575,7 @@ else()
   endif()
   message(FATAL_ERROR "This \"${CMAKE_CURRENT_LIST_FILE}\" has been trimmed and is therefore intended only for build from an amalgamated form of the source code.")
 endif(MDBX_AMALGAMATED_SOURCE)
+
 if(MDBX_BUILD_CXX)
   message(STATUS "Use C${MDBX_C_STANDARD} and C++${MDBX_CXX_STANDARD} for libmdbx")
   list(APPEND LIBMDBX_PUBLIC_HEADERS mdbx.h++)

ChangeLog.md

@@ -5,7 +5,9 @@ English version [by liar Google](https://libmdbx-dqdkfa-ru.translate.goog/md__ch
 
 The source code is availale on [SourceCraft](https://sourcecraft.dev/dqdkfa/libmdbx) and mirrors on [abf.io](https://abf.io/erthink/libmdbx) and [GitFlic](https://gitflic.ru/project/erthink/libmdbx).
 Please use the `stable` branch or the latest release for production environment through stagging, but the `master` branch for development a derivative projects.
-Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`. Всё будет хорошо!
+Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`,
+BTC `bc1qzvl9uegf2ea6cwlytnanrscyv8snwsvrc0xfsu`, SOL `FTCTgbHajoLVZGr8aEFWMzx3NDMyS5wXJgfeMTmJznRi`.
+Всё будет хорошо!
 
 ## v0.14.2 в разработке без конкретизации даты выпуска
 
@@ -29,7 +31,13 @@ Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`. Вс
 
    Объём накладных расходов теперь более пропорционален объему совершаемых операций. Поэтому, в большинстве сценариев накладные расходы чуть меньше, но наоборот чуть больше при отмене вложенных транзакций.
 
- - В API копирования БД добавлена опция `MDBX_CP_OVERWRITE` (перезапись целевого файла), а в утилиту `mdbx_copy` аналогичная по смыслу опция командной строки `-f` .
+ - Расширение API:
+
+    - в функции копирования БД добавлена опция `MDBX_CP_OVERWRITE` (перезапись целевого файла), а в утилиту `mdbx_copy` аналогичная по смыслу опция командной строки `-f` .
+
+    - добавлена простая реализация функции `mdbx_cursor_bunch_delete()`, которая выполняет массивное удаление соседствующих элементов значительно быстрее, за счёт исключения из дерева целиком страниц и ветвей с удаляемыми элементами.
+
+    - добавлены функции получения/поиска данных с "кэшированием" `mdbx_cache_get()` и `mdbx_cache_get_SingleThreaded()`.
 
  - Поддержка Harmony OS (OHOS).
 
@@ -42,10 +50,8 @@ Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`. Вс
  - Основной репозиторий libmdbx перенесен с Gitflic на SourceCraft.
 
    Со своей стороны, я удручен необходимостью совершать такие манипуляции, ибо они создают существенные неудобства пользователям, но (к сожалению) для того есть достаточные причины:
-     - Вместо обещанной интернационализации на Gitflic осталась только русскоязычная локализация с массой технический особенностей, затрудняющих использование систем машинного перевода. Это сделало невозможным использование сервиса многими пользователями и породило ряд справедливых жалоб/упреков, в том числе от разработчиков из Китая, Бразилии, Кореи, Ирана и т.д.
-     - За три года, прошедшие с миграции на Gitflic, не исправлено несколько возмутительных ошибок в редакторе markdown, что превращало оформление релизов в раздражающую борьбу. Кроме этого из публичного пространства пропал roadmap развития. Суммарно это заставило меня отказаться от Gitflic.
-
- - В API добавлена простая реализация функции `mdbx_cursor_bunch_delete()`, которая выполняет массивное удаление соседствующих элементов знаничельно быстрее, за счёт исключения из дерева целиком страниц и ветвей с удаляемыми элементами.
+    - Вместо обещанной интернационализации на Gitflic осталась только русскоязычная локализация с массой технический особенностей, затрудняющих использование систем машинного перевода. Это сделало невозможным использование сервиса многими пользователями и породило ряд справедливых жалоб/упреков, в том числе от разработчиков из Китая, Бразилии, Кореи, Ирана и т.д.
+    - За три года, прошедшие с миграции на Gitflic, не исправлено несколько возмутительных ошибок в редакторе markdown, что превращало оформление релизов в раздражающую борьбу. Кроме этого из публичного пространства пропал roadmap развития. Суммарно это заставило меня отказаться от Gitflic.
 
 Исправления:
 

NOTICE

@@ -8,7 +8,8 @@ documentation, C++ API description and links to the original git repo
 with the source code. Questions, feedback and suggestions are welcome
 to the Telegram' group https://t.me/libmdbx.
 
-Donations are welcome to the Ethereum/ERC-20 `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`.
+Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`,
+BTC `bc1qzvl9uegf2ea6cwlytnanrscyv8snwsvrc0xfsu`, SOL `FTCTgbHajoLVZGr8aEFWMzx3NDMyS5wXJgfeMTmJznRi`.
 Всё будет хорошо!
 
 Copyright 2015-2026 Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru>

README.md

@@ -25,7 +25,8 @@ Historically, _libmdbx_ is a deeply revised and extended descendant of the legen
 
 [![Telergam: Support | Discussions | News](https://img.shields.io/endpoint?color=scarlet&logo=telegram&label=Support%20%7C%20Discussions%20%7C%20News&url=https%3A%2F%2Ftg.sumanjay.workers.dev%2Flibmdbx)](https://t.me/libmdbx)
 
-> Please refer to the online [official libmdbx documentation site](https://libmdbx.dqdkfa.ru) with [`C` API description](https://libmdbx.dqdkfa.ru/group__c__api.html) and pay attention to the [`C++` API](https://sourcecraft.dev/dqdkfa/libmdbx/blob?file=mdbx.h%2B%2B#line-num-1). Donations are welcome to the Ethereum/ERC-20 `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`.
+> Please refer to the online [official libmdbx documentation site](https://libmdbx.dqdkfa.ru) with [`C` API description](https://libmdbx.dqdkfa.ru/group__c__api.html) and pay attention to the [`C++` API](https://sourcecraft.dev/dqdkfa/libmdbx/blob?file=mdbx.h%2B%2B#line-num-1).Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`,
+BTC `bc1qzvl9uegf2ea6cwlytnanrscyv8snwsvrc0xfsu`, SOL `FTCTgbHajoLVZGr8aEFWMzx3NDMyS5wXJgfeMTmJznRi`.
 > Всё будет хорошо!
 
 Telegram Group archive: [1](https://libmdbx.dqdkfa.ru/tg-archive/messages1.html), [2](https://libmdbx.dqdkfa.ru/tg-archive/messages2.html), [3](https://libmdbx.dqdkfa.ru/tg-archive/messages3.html), [4](https://libmdbx.dqdkfa.ru/tg-archive/messages4.html), [5](https://libmdbx.dqdkfa.ru/tg-archive/messages5.html), [6](https://libmdbx.dqdkfa.ru/tg-archive/messages6.html), [7](https://libmdbx.dqdkfa.ru/tg-archive/messages7.html).

VERSION.json

@@ -1 +1 @@
-{ "git_describe": "v0.14.1-220-g0f8b288c", "git_timestamp": "2026-01-02T23:27:02+03:00", "git_tree": "d490bb4b78537c494ffecf7b31b961c48a715d94", "git_commit": "0f8b288ce9d1e1028f8bb760f5f87eafa8e94bfe", "semver": "0.14.1.220" }
+{ "git_describe": "v0.14.1-234-g329ac7b7", "git_timestamp": "2026-01-04T14:41:25+03:00", "git_tree": "26e213307787c195455ed09e75f197acc4c22d3d", "git_commit": "329ac7b72663cd5524733f61ce5a7cff9615f5bc", "semver": "0.14.1.234" }

mdbx.c

@@ -4,7 +4,7 @@
 
 #define xMDBX_ALLOY 1  /* alloyed build */
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED
@@ -11358,6 +11358,387 @@ __cold const char *mdbx_ratio2percents(uint64_t value, uint64_t whole, char *buf
   else
     return ratio2percent(value, whole, (ratio2digits_buffer_t *)buffer);
 }
+/// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2025-2026
+
+static MDBX_cache_result_t cache_get(const MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key, MDBX_val *data,
+                                     MDBX_cache_entry_t *entry);
+
+static inline bool is_outside_dxb(const MDBX_txn *txn, const void *ptr) {
+  const MDBX_env *env = txn->env;
+  const ptrdiff_t offset = ptr_dist(ptr, env->dxb_mmap.base);
+  return offset < 0 || (size_t)offset >= pgno2bytes(env, txn->geo.first_unallocated);
+}
+
+static inline bool is_not_commited(const MDBX_txn *txn, const page_t *mp) {
+  tASSERT(txn, mp >= (const page_t *)txn->env->dxb_mmap.base &&
+                   mp < (const page_t *)(ptr_disp(txn->env->dxb_mmap.base,
+                                                  pgno2bytes(txn->env, txn->geo.first_unallocated))));
+  return mp->txnid > txn_basis_snapshot(txn);
+}
+
+MDBX_MAYBE_UNUSED static inline bool is_inside_dxb_and_commited(const MDBX_txn *txn, const void *ptr) {
+  return !is_outside_dxb(txn, ptr) && !is_not_commited(txn, ptr2page(txn->env, ptr));
+}
+
+static inline MDBX_cache_result_t cache_result(int err, MDBX_cache_status_t status) {
+  MDBX_cache_result_t result = {.errcode = err, .status = status};
+  return result;
+}
+
+static inline MDBX_cache_result_t cache_error(int err) {
+  assert(err != MDBX_SUCCESS && err != MDBX_RESULT_TRUE);
+  return cache_result(err, MDBX_CACHE_ERROR);
+}
+
+static inline MDBX_cache_result_t cache_fallback(const MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key, MDBX_val *data,
+                                                 MDBX_cache_status_t status) {
+  MDBX_cache_entry_t stub = {.last_confirmed_txnid = 0, .trunk_txnid = 0};
+  MDBX_cache_result_t result = cache_get(txn, dbi, key, data, &stub);
+  if (result.status > MDBX_CACHE_DIRTY)
+    result.status = status;
+  return result;
+}
+
+static inline bool is_afterlast(MDBX_cursor *mc, const page_t *mp, const MDBX_val *key) {
+  MDBX_val last = get_key(page_node(mp, page_numkeys(mp) - 1));
+  return mc->clc->k.cmp(key, &last) > 0;
+}
+
+__hot static MDBX_cache_result_t cache_get(const MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key, MDBX_val *data,
+                                           MDBX_cache_entry_t *entry) {
+  DKBUF_DEBUG;
+  DEBUG("===> cached-get dbi %u, key [%s], entry %p (trunk %" PRIaTXN ", last_confirmed %" PRIaTXN
+        ", data offset %zu, len %u)",
+        dbi, DKEY_DEBUG(key), __Wpedantic_format_voidptr(entry), entry->trunk_txnid, entry->last_confirmed_txnid,
+        entry->offset, entry->length);
+
+  if (unlikely(entry->trunk_txnid > entry->last_confirmed_txnid))
+    return cache_error(LOG_IFERR(MDBX_INVALID));
+
+  int err = check_txn(txn, MDBX_TXN_BLOCKED);
+  if (unlikely(err != MDBX_SUCCESS))
+    return cache_error(LOG_IFERR(err));
+
+  tASSERT(txn, entry->offset || entry->length == 0);
+  tASSERT(txn, entry->last_confirmed_txnid <= MAX_TXNID);
+  if (unlikely(txn->txnid < entry->trunk_txnid))
+    /* the used/read MVCC-snapshot is behind the accessible MVCC-range */
+    return cache_fallback(txn, dbi, key, data, MDBX_CACHE_BEHIND);
+
+  if (likely(txn->txnid <= entry->last_confirmed_txnid)) {
+    if (entry->offset) {
+      /* cache hit fast-path */
+      data->iov_base = ptr_disp(txn->env->dxb_mmap.base, entry->offset);
+      data->iov_len = entry->length;
+      tASSERT(txn, (!entry->offset && !entry->length) || is_inside_dxb_and_commited(txn, data->iov_base));
+      return cache_result(MDBX_SUCCESS, MDBX_CACHE_HIT);
+    }
+
+    if (txn->txnid == entry->last_confirmed_txnid || txn->txnid == entry->trunk_txnid) {
+      data->iov_base = nullptr;
+      data->iov_len = 0;
+      tASSERT(txn, (!entry->offset && !entry->length) || is_inside_dxb_and_commited(txn, data->iov_base));
+      return cache_result(MDBX_NOTFOUND, MDBX_CACHE_HIT);
+    }
+
+    /* Здесь ABA-подобная проблема:
+     *
+     * В случае когда txn->txnid > entry->trunk_txnid и txn->txnid < entry->last_confirmed_txnid
+     * возможна ситуация, когда в истории транзакции целевой ключ (и значение) отсутствовали
+     * в версии entry->trunk_txnid и entry->last_confirmed_txnid, но присутствовали в MVCC-снимке txn->txnid.
+     *
+     * Теоретически можно подумать о том, чтобы обработать такие случаи без полного поиска. Но сначала требуется
+     * понять как часто будут возникать такие ситуации на практике и стоит-ли с этим заморачиваться. */
+    return cache_fallback(txn, dbi, key, data, MDBX_CACHE_UNABLE);
+  }
+
+  err = dbi_check(txn, dbi);
+  if (unlikely(err != MDBX_SUCCESS))
+    return cache_error(LOG_IFERR(err));
+
+  const uint64_t committed_snapshot_txnid = txn_basis_snapshot(txn);
+  txnid_t trunk_txnid = txn->front_txnid;
+  if (unlikely(txn->dbi_state[dbi] & DBI_STALE)) {
+    err = tbl_refresh((MDBX_txn *)txn, dbi);
+    if (unlikely(err != MDBX_SUCCESS)) {
+      if (err == MDBX_NOTFOUND) {
+        /* the corresponding table has been deleted */
+        tASSERT(txn, !entry->offset || trunk_txnid > entry->trunk_txnid);
+      not_found:
+        data->iov_base = nullptr;
+        data->iov_len = 0;
+        MDBX_cache_status_t status = MDBX_CACHE_DIRTY;
+        if (trunk_txnid <= committed_snapshot_txnid) {
+          status = MDBX_CACHE_CONFIRMED;
+          if (entry->offset || !entry->trunk_txnid) {
+            status = MDBX_CACHE_REFRESHED;
+            tASSERT(txn, (!entry->offset && !entry->trunk_txnid) || trunk_txnid > entry->trunk_txnid);
+            entry->offset = 0;
+            entry->length = 0;
+            entry->trunk_txnid = trunk_txnid;
+          }
+          entry->last_confirmed_txnid = committed_snapshot_txnid;
+        }
+        return cache_result(MDBX_NOTFOUND, status);
+      }
+      return cache_error(LOG_IFERR(err));
+    }
+  }
+
+  /* lookup the trunk mvcc/txn-id thru nested transactions stack. */
+  if (txn->dbs[dbi].mod_txnid /* tree->mod_txnid maybe zero in a legacy DB */)
+    trunk_txnid = txn->dbs[dbi].mod_txnid;
+  if ((txn->flags & MDBX_TXN_RDONLY) == 0) {
+    const MDBX_txn *scan = txn;
+    do
+      if ((scan->flags & MDBX_TXN_DIRTY) && (dbi == MAIN_DBI || (scan->dbi_state[dbi] & DBI_DIRTY))) {
+        /* После коммита вложенных тразакций может быть mod_txnid > front */
+        trunk_txnid = scan->front_txnid;
+        break;
+      }
+    while (unlikely((scan = scan->parent) != nullptr));
+  }
+
+  if (trunk_txnid <= entry->last_confirmed_txnid) {
+    /* the corresponding table has not been changed since the last check. */
+    tASSERT(txn, (txn->dbi_state[dbi] & DBI_DIRTY) == 0);
+    tASSERT(txn, trunk_txnid == entry->trunk_txnid);
+  confirmed:
+    tASSERT(txn, trunk_txnid <= committed_snapshot_txnid && trunk_txnid <= entry->last_confirmed_txnid);
+    data->iov_base = entry->offset ? ptr_disp(txn->env->dxb_mmap.base, entry->offset) : 0;
+    data->iov_len = entry->length;
+    tASSERT(txn, (!entry->offset && !entry->length) || is_inside_dxb_and_commited(txn, data->iov_base));
+    if (entry->last_confirmed_txnid == committed_snapshot_txnid)
+      return cache_result(data->iov_base ? MDBX_SUCCESS : MDBX_NOTFOUND, MDBX_CACHE_HIT);
+    entry->last_confirmed_txnid = committed_snapshot_txnid;
+    return cache_result(data->iov_base ? MDBX_SUCCESS : MDBX_NOTFOUND, MDBX_CACHE_CONFIRMED);
+  }
+
+  if (unlikely(txn->dbs[dbi].root == P_INVALID)) {
+    /* the corresponding table is empty now */
+    tASSERT(txn, !entry->offset || trunk_txnid > entry->trunk_txnid);
+    goto not_found;
+  }
+
+  cursor_couple_t cx;
+  err = cursor_init(&cx.outer, txn, dbi);
+  if (unlikely(err != MDBX_SUCCESS))
+    return cache_error(LOG_IFERR(err));
+
+  alignkey_t aligned;
+  err = check_key(&cx.outer, key, &aligned);
+  if (unlikely(err != MDBX_SUCCESS))
+    return cache_error(LOG_IFERR(err));
+
+  page_t *mp = nullptr;
+  err = page_get(&cx.outer, txn->dbs[dbi].root, &mp, trunk_txnid);
+  if (unlikely(err != MDBX_SUCCESS))
+    return cache_error(LOG_IFERR(err));
+
+  cx.outer.pg[cx.outer.top = 0] = mp;
+  /* walking along the branches of the tree to the leaves */
+  while (is_branch(mp)) {
+    if (mp->txnid <= entry->last_confirmed_txnid) {
+      /* Страница НЕ была обновлена после последней проверки,
+       * проверяем остальные условия для раннего завершения поиска. */
+      if (!entry->offset) {
+        /* Ключа не было и он не мог быть добавлен без изменения страницы. */
+      notfound_elevate_trunk:
+        if (trunk_txnid > entry->trunk_txnid)
+          goto not_found;
+        for (intptr_t i = cx.outer.top - 1; i >= 0; --i) {
+          trunk_txnid = cx.outer.pg[i]->txnid;
+          if (trunk_txnid > entry->trunk_txnid)
+            goto not_found;
+        }
+        trunk_txnid = txn->dbs[dbi].mod_txnid ? txn->dbs[dbi].mod_txnid : txn->front_txnid;
+        tASSERT(txn, trunk_txnid > entry->trunk_txnid);
+        goto not_found;
+      }
+      if (mp->txnid < entry->trunk_txnid) {
+        /* Попали на более старую страницу, такое может быть только при "схлопывании" b-tree,
+         * когда целевой ключ был удален вместе с ведущими к нему branch-страницами. */
+        goto notfound_elevate_trunk;
+      }
+
+      /* Искомый ключ больше или равен первому на этой странице и меньше следующего с родительской,
+       * но может быть больше последнего ключа на этой странице. */
+      if (!is_afterlast(&cx.outer, mp, &aligned.key)) {
+        /* Следовательно, если ключ не-больше последнего на этой страницы,
+         * то он не мог быть изменен или удалён. */
+        trunk_txnid = mp->txnid;
+        goto confirmed;
+      }
+
+      /* Но если искомый ключ больше последнего на этой страницы, то он мог быть удалён вместе со всеми
+       * страницами расположенными дальше/после текущей и до следующего узла родительской страницы.
+       * Следует продолжить поиск. */
+    }
+
+    trunk_txnid = mp->txnid;
+    const size_t ki = tree_search_branch(&cx.outer, key);
+    cx.outer.ki[cx.outer.top] = (indx_t)ki;
+    err = page_get(&cx.outer, node_pgno(page_node(mp, ki)), &mp, trunk_txnid);
+    if (unlikely(err != MDBX_SUCCESS))
+      return cache_error(LOG_IFERR(err));
+
+    err = cursor_push(&cx.outer, mp, 0);
+    if (unlikely(err != MDBX_SUCCESS))
+      return cache_error(LOG_IFERR(err));
+  }
+
+  if (!MDBX_DISABLE_VALIDATION && unlikely(!check_leaf_type(&cx.outer, mp))) {
+    ERROR("unexpected leaf-page #%" PRIaPGNO " type 0x%x seen by cursor", mp->pgno, mp->flags);
+    err = MDBX_CORRUPTED;
+    return cache_error(LOG_IFERR(err));
+  }
+
+  if (mp->txnid <= entry->last_confirmed_txnid) {
+    if (!entry->offset) {
+      /* Ключа не было и он не мог быть добавлен без изменения страницы. */
+      goto notfound_elevate_trunk;
+    }
+    if (mp->txnid < entry->trunk_txnid) {
+      /* Попали на более старую страницу, такое может быть только при "схлопывании" b-tree,
+       * когда целевой ключ был удален вместе с ведущими к нему branch-страницами. */
+      tASSERT(txn, !node_search(&cx.outer, &aligned.key).exact);
+      goto notfound_elevate_trunk;
+    }
+
+    /* Искомый ключ больше или равен первому на этой странице и меньше следующего с родительской,
+     * но может быть больше последнего ключа на этой странице. Страница не была обновлена после
+     * последней проверки наличия ключа. */
+    if (!is_afterlast(&cx.outer, mp, &aligned.key)) {
+      /* Следовательно, если ключ не-больше последнего на этой страницы,
+       * то он не мог быть изменен или удалён. */
+      trunk_txnid = mp->txnid;
+      goto confirmed;
+    }
+
+    /* Но если искомый ключ больше последнего на этой страницы, то он мог быть удалён вместе со всеми
+     * страницами расположенными дальше/после текущей и до следующего узла родительской страницы.
+     *
+     * В зоне branch-страниц дерева следовало-бы продолжить поиск, но в случае листовой страницы можно
+     * быть уверенным что ключ отсутствует, так он больше последнего ключа на этой странице и меньше
+     * первого на следующей, а таких ключей нет физически. */
+    tASSERT(txn, !node_search(&cx.outer, &aligned.key).exact);
+    goto notfound_elevate_trunk;
+  }
+
+  trunk_txnid = mp->txnid;
+  struct node_search_result nsr = node_search(&cx.outer, &aligned.key);
+  if (!nsr.exact) {
+    tASSERT(txn, !entry->offset || trunk_txnid > entry->trunk_txnid);
+    goto not_found;
+  }
+
+  if (unlikely(node_flags(nsr.node) & N_DUP)) {
+    /* TODO: It is possible to implement support for multivalues, but need to think through the usage scenarios. */
+    err = MDBX_EMULTIVAL;
+    return cache_error(LOG_IFERR(err));
+  }
+
+  err = node_read(&cx.outer, nsr.node, data, mp);
+  if (unlikely(err != MDBX_SUCCESS))
+    return cache_error(LOG_IFERR(err));
+
+  if (trunk_txnid > committed_snapshot_txnid) {
+    tASSERT(txn, trunk_txnid > entry->last_confirmed_txnid && trunk_txnid > entry->trunk_txnid);
+    return cache_result(MDBX_SUCCESS, MDBX_CACHE_DIRTY);
+  }
+
+  tASSERT(txn, is_inside_dxb_and_commited(txn, data->iov_base));
+  tASSERT(txn, trunk_txnid <= committed_snapshot_txnid && trunk_txnid > entry->last_confirmed_txnid &&
+                   trunk_txnid > entry->trunk_txnid);
+  entry->offset = ptr_dist(data->iov_base, txn->env->dxb_mmap.base);
+  entry->length = (uint32_t)data->iov_len;
+  entry->trunk_txnid = trunk_txnid;
+  entry->last_confirmed_txnid = committed_snapshot_txnid;
+  return cache_result(MDBX_SUCCESS, MDBX_CACHE_REFRESHED);
+}
+
+/*----------------------------------------------------------------------------*/
+
+__hot MDBX_cache_result_t mdbx_cache_get(const MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key, MDBX_val *data,
+                                         volatile MDBX_cache_entry_t *entry) {
+
+  if (unlikely(!key || !data || !entry))
+    return cache_error(LOG_IFERR(MDBX_EINVAL));
+
+  MDBX_cache_entry_t local = *entry;
+  while (true) {
+    MDBX_cache_entry_t again;
+    again.last_confirmed_txnid = safe64_read((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid);
+    if (unlikely(again.last_confirmed_txnid > MAX_TXNID)) {
+#if MDBX_DEBUG
+      return cache_fallback(txn, dbi, key, data, MDBX_CACHE_RACE);
+#else
+      atomic_yield();
+      again.last_confirmed_txnid = safe64_read((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid);
+      if (unlikely(again.last_confirmed_txnid > MAX_TXNID)) {
+        atomic_yield();
+        atomic_yield();
+        again.last_confirmed_txnid = safe64_read((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid);
+        if (unlikely(again.last_confirmed_txnid > MAX_TXNID)) {
+          atomic_yield();
+          atomic_yield();
+          atomic_yield();
+          again.last_confirmed_txnid = safe64_read((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid);
+          if (unlikely(again.last_confirmed_txnid > MAX_TXNID))
+            return cache_fallback(txn, dbi, key, data, MDBX_CACHE_RACE);
+        }
+      }
+#endif /* MDBX_DEBUG */
+    }
+
+    again.trunk_txnid = entry->trunk_txnid;
+    again.offset = entry->offset;
+    again.length = entry->length;
+    if (likely(local.last_confirmed_txnid == again.last_confirmed_txnid && local.trunk_txnid == again.trunk_txnid &&
+               local.offset == again.offset && local.length == again.length &&
+               local.last_confirmed_txnid == safe64_read((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid)))
+      break;
+
+    local = again;
+    atomic_yield();
+  }
+
+  MDBX_cache_result_t result = cache_get(txn, dbi, key, data, &local);
+  if (result.status > MDBX_CACHE_HIT) {
+    tASSERT(txn, local.last_confirmed_txnid < MAX_TXNID && local.trunk_txnid <= local.last_confirmed_txnid &&
+                     local.trunk_txnid > 0);
+    while (true) {
+      const txnid_t snap = safe64_read((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid);
+      if (snap >= local.last_confirmed_txnid) {
+        result.status = MDBX_CACHE_RACE;
+        break;
+      }
+
+      if (likely(safe64_reset_compare((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid, snap))) {
+        entry->trunk_txnid = 0;
+        osal_compiler_barrier();
+        entry->offset = local.offset;
+        entry->length = local.length;
+        entry->trunk_txnid = local.trunk_txnid;
+        safe64_write((mdbx_atomic_uint64_t *)&entry->last_confirmed_txnid, local.last_confirmed_txnid);
+        break;
+      }
+
+      atomic_yield();
+    }
+  }
+  return result;
+}
+
+__hot MDBX_cache_result_t mdbx_cache_get_SingleThreaded(const MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key,
+                                                        MDBX_val *data, MDBX_cache_entry_t *entry) {
+  if (unlikely(!key || !data || !entry))
+    return cache_error(LOG_IFERR(MDBX_EINVAL));
+
+  return cache_get(txn, dbi, key, data, entry);
+}
+
+LIBMDBX_API void mdbx_cache_init(MDBX_cache_entry_t *entry) { __inline_mdbx_cache_init(entry); }
 /// \copyright SPDX-License-Identifier: Apache-2.0
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
@@ -37921,7 +38302,7 @@ int txn_basal_commit(MDBX_txn *txn, struct commit_timestamp *ts) {
   if (commit_txnid > txn->txnid)
     VERBOSE("use @%" PRIaTXN " (+%zu) for committing bigfoot-txn", commit_txnid, (size_t)(commit_txnid - txn->txnid));
   else
-    VERBOSE("committing @%" PRIaTXN "txn", commit_txnid);
+    VERBOSE("committing @%" PRIaTXN " txn", commit_txnid);
   gc_put_destroy(&gcu_ctx);
 
   if (ts)
@@ -39904,10 +40285,10 @@ __dll_export
         0,
         14,
         1,
-        220,
+        234,
         "", /* pre-release suffix of SemVer
-                                        0.14.1.220 */
-        {"2026-01-02T23:27:02+03:00", "d490bb4b78537c494ffecf7b31b961c48a715d94", "0f8b288ce9d1e1028f8bb760f5f87eafa8e94bfe", "v0.14.1-220-g0f8b288c"},
+                                        0.14.1.234 */
+        {"2026-01-04T14:41:25+03:00", "26e213307787c195455ed09e75f197acc4c22d3d", "329ac7b72663cd5524733f61ce5a7cff9615f5bc", "v0.14.1-234-g329ac7b7"},
         sourcery};
 
 __dll_export

mdbx.c++

@@ -2,7 +2,7 @@
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 /* clang-format off */
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED

mdbx.h

@@ -1,6 +1,9 @@
 /**
 
-_libmdbx_ (aka MDBX) is an extremely fast, compact, powerful, embeddable,
+\file mdbx.h
+\brief The libmdbx C API header file.
+
+\details _libmdbx_ (aka MDBX) is an extremely fast, compact, powerful, embeddable,
 transactional [key-value
 store](https://en.wikipedia.org/wiki/Key-value_database), with [Apache 2.0
 license](./LICENSE). _MDBX_ has a specific set of properties and capabilities,
@@ -18,21 +21,36 @@ C++ API description and links to the origin git repo with the source code.
 Questions, feedback and suggestions are welcome to the Telegram' group
 https://t.me/libmdbx.
 
-Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`.
+Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`,
+BTC `bc1qzvl9uegf2ea6cwlytnanrscyv8snwsvrc0xfsu`, SOL `FTCTgbHajoLVZGr8aEFWMzx3NDMyS5wXJgfeMTmJznRi`.
 Всё будет хорошо!
 
-\note The libmdbx project has been completely relocated to the jurisdiction of the Russian Federation.
-It is still open and provided with first-class free support. Please refer to https://libmdbx.dqdkfa.ru for documentation
-and https://sourcecraft.dev/dqdkfa/libmdbx for the source code.
+The _libmdbx_ project has been completely relocated to the jurisdiction of the Russian Federation.
+\note _libmdbx_ is still open and provided with first-class free support.
 
 \section copyright LICENSE & COPYRIGHT
 \copyright SPDX-License-Identifier: Apache-2.0
-\note Please refer to the COPYRIGHT file for explanations license change, credits and acknowledgments.
+Please refer to the COPYRIGHT file for explanations license change, credits and acknowledgments.
 \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
 *******************************************************************************/
 
 #pragma once
+/*
+ * Tested with, since 2026:
+ *  - Elbrus LCC >= 1.28 (http://www.mcst.ru/lcc);
+ *  - GNU C >= 11.3;
+ *  - CLANG >= 14.0;
+ *  - MSVC >= 19.44 (Visual Studio 2022 toolchain v143),
+ * before 2026:
+ *  - Elbrus LCC >= 1.23 (http://www.mcst.ru/lcc);
+ *  - GNU C >= 4.8;
+ *  - CLANG >= 3.9;
+ *  - MSVC >= 14.0 (Visual Studio 2015),
+ *    but 19.2x could hang due optimizer bug;
+ *  - AppleClang.
+ */
+
 #ifndef LIBMDBX_H
 #define LIBMDBX_H
 
@@ -4858,6 +4876,8 @@ LIBMDBX_API int mdbx_drop(MDBX_txn *txn, MDBX_dbi dbi, bool del);
  * \note Values returned from the table are valid only until a
  * subsequent update operation, or the end of the transaction.
  *
+ * \see mdbx_cache_get()
+ *
  * \param [in] txn       A transaction handle returned by \ref mdbx_txn_begin().
  * \param [in] dbi       A table handle returned by \ref mdbx_dbi_open().
  * \param [in] key       The key to search for in the table.
@@ -4933,6 +4953,180 @@ LIBMDBX_API int mdbx_get_ex(const MDBX_txn *txn, MDBX_dbi dbi, MDBX_val *key, MD
  * \retval MDBX_EINVAL        An invalid parameter was specified. */
 LIBMDBX_API int mdbx_get_equal_or_great(const MDBX_txn *txn, MDBX_dbi dbi, MDBX_val *key, MDBX_val *data);
 
+/** \brief Lightweight transparent cache entry structure used by \ref mdbx_cache_get().
+ * \ingroup c_crud
+ *
+ * The approach of these caching is to preserve address of a value retrieved from the database with an extremely fast
+ * check of relevance it based on a transaction ID within an internal b-tree structures. Event a b-tree was modified
+ * then the search for the corresponding key from the root of the b-tree to leaf pages stops as soon as reaches a page
+ * that has not been modified after the last check of given cache entry. This way, the minimum actions is performed,
+ * which is no slower than a usual key search in the worst case, and at best, only a few lightweight checks will be do.
+ *
+ * \note The cache structure allows it to be placed in shared memory and used by multiple processes.
+ * However, such interaction and management are not provided by libmdbx in any way yet now.
+ *
+ * \note An each cache entry must be initialized by \ref mdbx_cache_init() before first use. */
+typedef struct MDBX_cache_entry {
+  uint64_t trunk_txnid;          /**< The transaction/MVCC-snapshot ID of a page or other internal DB structure
+                                  *   that hold the cached data or reflect it state. */
+  uint64_t last_confirmed_txnid; /**< The recent transaction/MVCC-snapshot ID wherein the cache entry
+                                  *   was checked and confirmed. */
+  size_t offset;                 /**< The offset of cached data value for a corresponding key.
+                                  *   The zero value means \ref MDBX_NOTFOUND. */
+  uint32_t length;               /**< The length of cached data value for a corresponding key. */
+} MDBX_cache_entry_t;
+
+/** \brief Initializes the cache entry before the first use.
+ * \ingroup c_crud
+ * \see MDBX_cache_entry
+ * \see mdbx_cache_get() */
+LIBMDBX_INLINE_API(void, mdbx_cache_init, (MDBX_cache_entry_t * entry)) {
+  entry->offset = 0;
+  entry->length = 0;
+  entry->trunk_txnid = 0;
+  entry->last_confirmed_txnid = 0;
+}
+
+/** \brief Cache entry status returned by \ref mdbx_cache_get().
+ * \ingroup c_crud
+ * \see MDBX_cache_entry
+ * \see mdbx_cache_init() */
+typedef enum MDBX_cache_status {
+  /** \brief The error other than \ref MDBX_NOTFOUND has occurred.
+   *  \details There is no correct result since an error has occurred that is not related
+   *  to the absence of the desired key-value pair.
+   *  The given cache entry has not been changed. */
+  MDBX_CACHE_ERROR = -3,
+
+  /** \brief The result was obtained by bypassing the cache, because
+   *  the transaction is too old to using the cache entry.
+   *  \details The cache entry reflects a newer version of the data that is unavailable within
+   *  an MVCC-snapshot used by current transaction.
+   *  The given cache entry has not been changed.
+   *  The result of getting a value is correct until the transaction end. */
+  MDBX_CACHE_BEHIND = -2,
+
+  /** \brief The result of getting a value is correct, but it cannot be cached since there
+   *  the ABA-like issue is in the data history, either other similar reason.
+   *  \details When a cache entry is used by different threads reading different MVCC snapshots,
+   *  there may be a situation in which the key and associated value are missing from the old
+   *  and new MVCC snapshots, but are present in one of the MVCC snapshots between ones.
+   *  In such circumstances the result from the cache may be false negative, therefore,
+   *  in order to avoid an incorrect result, a search is performed bypassing cache.
+   *  The given cache entry has not been changed.
+   *  The result of getting a value is correct until the transaction end. */
+  MDBX_CACHE_UNABLE = -1,
+
+  /** \brief The result was obtained by bypassing the cache, because
+   *  the given cache entry being updated by another thread.
+   *  \details When accessing the cache entry, a race condition was detected with its update by another thread.
+   *  Therefore, the result was obtained without using the cache entry and without affecting an operation of other
+   *  threads using it, including the ones performing an update. For a read transaction, the result is correct until
+   *  the transaction end. For a write transactions, the result is correct until the value is explicitly changed or
+   *  the transaction is completed. */
+  MDBX_CACHE_RACE = 0,
+
+  /** \brief The result of getting a value is correct, but it cannot be cached since
+   *  the changes have not been committed.
+   *  \details The requested value of a pair is in a dirty state itself or on a dirty page with other updated items.
+   *  This cache entry has not been changed because the corresponding data changes have not yet been committed
+   *  and could be aborted.
+   *  The result of the get operation and data value are valid within the current write transaction
+   *  until any next modification. */
+  MDBX_CACHE_DIRTY = 1,
+
+  /** \brief The result of getting a value is correct and was retrieved from the cache entry which is untouched.
+   *  \details There were no changes in the cached data after the last check.
+   *  The given cache entry was not altered as it is complete up-to-date.
+   *  For a read transaction, the result is correct until the transaction end.
+   *  For a write transactions, the result is correct until the value is explicitly changed
+   *  or the transaction is completed. */
+  MDBX_CACHE_HIT = 2,
+
+  /** \brief The result of getting a value is correct and has been retrieved from the cache, which has been
+   *  altered to reflect recently committed transactions.
+   *  \details There were no changes in the cached data after the last check.
+   *  The given cache entry has been slightly updated to reflect the relevance of the data for recent committed
+   * transaction(s). For a read transaction, the result is correct until the transaction end. For a write transactions,
+   * the result is correct until the value is explicitly changed or the transaction is completed. */
+  MDBX_CACHE_CONFIRMED = 3,
+
+  /** \brief The result of getting a value is correct and corresponds to the fresh data readed from the database,
+   *  which also putted into the cache entry.
+   *  \details After the last check, either the value of the requested pair itself changed,
+   *  or it was moved to a new page due to the updating of neighboring items.
+   *  The given cache entry has been completely updated to reflect the actual data.
+   *  For a read transaction, the result is correct until the transaction end.
+   *  For a write transactions, the result is correct until the value is explicitly changed
+   *  or the transaction is completed. */
+  MDBX_CACHE_REFRESHED = 4
+} MDBX_cache_status_t;
+
+/** \brief Pair of error code and cache status as a result of \ref mdbx_cache_get().
+ * \ingroup c_crud
+ * \see mdbx_cache_get()
+ * \see mdbx_cache_get_SingleThreaded() */
+typedef struct MDBX_cache_result {
+  /** The error code of getting data same as from \ref mdbx_get(). */
+  MDBX_error_t errcode;
+  /** The result of cache operation as the value of \ref MDBX_cache_status_t. */
+  MDBX_cache_status_t status;
+} MDBX_cache_result_t;
+
+/** \brief Gets items from a table using cache including multithreaded cases.
+ * \ingroup c_crud
+ * \details The essence of this "caching" is using a cached information to check as quickly as possible whether the data
+ * has changed or not, with early exit when searching though a DB. For this a petty version information is stored in
+ * a \ref MDBX_cache_entry_t structure, along with the offset to the "cached" data inside the memory-mapped database
+ * file. Instead of a full B-tree search it stops when reaches a DB page that has not been modified after the last
+ * check. Thus a minimum number of steps are performed which provides dramatic acceleration in many cases.
+ *
+ * \note This function is supports multi-threaded cases and automatically resolves collisions using lockfree approach,
+ * nonetheless \ref MDBX_NOSTICKYTHREADS mode is required to use it within a different threads.
+ *
+ * \see mdbx_cache_get_SingleThreaded()
+ * \see MDBX_cache_entry_t
+ * \see mdbx_cache_init()
+ * \see mdbx_get()
+ *
+ * \param [in] txn        A transaction handle returned by \ref mdbx_txn_begin().
+ * \param [in] dbi        A table handle returned by \ref mdbx_dbi_open().
+ * \param [in] key        The key to search for in the table.
+ * \param [in,out] data   The data corresponding to the key.
+ * \param [in,out] entry  The cache entry corresponding to the key.
+ *
+ * \returns The \ref MDBX_cache_result_t with a pair of the error codes for getting a data
+ * and the cache entry processing both. */
+LIBMDBX_API MDBX_cache_result_t mdbx_cache_get(const MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key, MDBX_val *data,
+                                               volatile MDBX_cache_entry_t *entry);
+
+/** \brief Gets items from a table using cache within single-thread cases only.
+ * \ingroup c_crud
+ * \details The essence of this "caching" is using a cached information to check as quickly as possible whether the data
+ * has changed or not, with early exit when searching though a DB. For this a petty version information is stored in
+ * a \ref MDBX_cache_entry_t structure, along with the offset to the "cached" data inside the memory-mapped database
+ * file. Instead of a full B-tree search it stops when reaches a DB page that has not been modified after the last
+ * check. Thus a minimum number of steps are performed which provides dramatic acceleration in many cases.
+ *
+ * \note This function is intended to be used with a given cache entry only in single-threaded cases, otherwise
+ * behaviour is undefined.
+ *
+ * \see mdbx_cache_get()
+ * \see MDBX_cache_entry_t
+ * \see mdbx_cache_init()
+ * \see mdbx_get()
+ *
+ * \param [in] txn        A transaction handle returned by \ref mdbx_txn_begin().
+ * \param [in] dbi        A table handle returned by \ref mdbx_dbi_open().
+ * \param [in] key        The key to search for in the table.
+ * \param [in,out] data   The data corresponding to the key.
+ * \param [in,out] entry  The cache entry corresponding to the key.
+ *
+ * \returns The \ref MDBX_cache_result_t with a pair of the error codes for getting a data
+ * and the cache entry processing both. */
+LIBMDBX_API MDBX_cache_result_t mdbx_cache_get_SingleThreaded(const MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key,
+                                                              MDBX_val *data, MDBX_cache_entry_t *entry);
+
 /** \brief Store items into a table.
  * \ingroup c_crud
  *

mdbx.h++

@@ -1,30 +1,45 @@
-/// \copyright SPDX-License-Identifier: Apache-2.0
-/// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2020-2026
-///
-/// Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`.
-/// Всё будет хорошо!
-///
-/// \file mdbx.h++
+/// \file mdbx.h++
 /// \brief The libmdbx C++ API header file.
 ///
-/// Tested with:
-///  - Elbrus LCC >= 1.23 (http://www.mcst.ru/lcc);
-///  - GNU C++ >= 4.8;
-///  - clang >= 3.9;
-///  - MSVC >= 14.0 (Visual Studio 2015),
-///    but 19.2x could hang due optimizer bug;
-///  - AppleClang, but without C++20 concepts.
+/// \details _libmdbx_ (aka MDBX) is an extremely fast, compact, powerful, embeddable,
+/// transactional [key-value
+/// store](https://en.wikipedia.org/wiki/Key-value_database), with [Apache 2.0
+/// license](./LICENSE). _MDBX_ has a specific set of properties and capabilities,
+/// focused on creating unique lightweight solutions with extraordinary performance.
 ///
-
+/// Please visit https://libmdbx.dqdkfa.ru for more information, documentation,
+/// C++ API description and links to the origin git repo with the source code.
+/// Questions, feedback and suggestions are welcome to the Telegram' group
+/// https://t.me/libmdbx.
+///
+/// Donations are welcome to ETH `0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A`,
+/// BTC `bc1qzvl9uegf2ea6cwlytnanrscyv8snwsvrc0xfsu`, SOL `FTCTgbHajoLVZGr8aEFWMzx3NDMyS5wXJgfeMTmJznRi`.
+/// Всё будет хорошо!
 ///
 /// The libmdbx project has been completely relocated to the jurisdiction of the Russian Federation.
-/// It is still open and provided with first-class free support.
-/// Please refer to https://libmdbx.dqdkfa.ru for documentation
-/// and https://sourcecraft.dev/dqdkfa/libmdbx for the source code.
+/// \note _libmdbx_ is still open and provided with first-class free support.
+///
+/// \copyright SPDX-License-Identifier: Apache-2.0
+/// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2020-2026
 ///
 
 #pragma once
 
+//
+// Tested with, since 2026:
+//  - Elbrus LCC >= 1.28 (http://www.mcst.ru/lcc);
+//  - GNU C++ >= 11.3;
+//  - CLANG >= 14.0;
+//  - MSVC >= 19.44 (Visual Studio 2022 toolchain v143),
+// before 2026:
+//  - Elbrus LCC >= 1.23 (http://www.mcst.ru/lcc);
+//  - GNU C++ >= 4.8;
+//  - CLANG >= 3.9;
+//  - MSVC >= 14.0 (Visual Studio 2015),
+//    but 19.2x could hang due optimizer bug;
+//  - AppleClang, but without C++20 concepts.
+//
+
 /* Workaround for modern libstdc++ with CLANG < 4.x */
 #if defined(__SIZEOF_INT128__) && !defined(__GLIBCXX_TYPE_INT_N_0) && defined(__clang__) && __clang_major__ < 4
 #define __GLIBCXX_BITSIZE_INT_N_0 128
@@ -1058,6 +1073,19 @@ protected:
   MDBX_CXX11_CONSTEXPR slice(size_t invalid_length) noexcept : ::MDBX_val({nullptr, invalid_length}) {}
 };
 
+/// \brief Cache entry for get-cached API (initial draft).
+class cache_entry : public MDBX_cache_entry_t {
+public:
+  cache_entry() noexcept { reset(); }
+  cache_entry(const cache_entry &) noexcept = default;
+  cache_entry &operator=(const cache_entry &) noexcept = default;
+  cache_entry(cache_entry &&other) noexcept {
+    *this = other;
+    other.reset();
+  }
+  void reset() noexcept { mdbx_cache_init(this); }
+};
+
 //------------------------------------------------------------------------------
 
 namespace allocation_aware_details {

mdbx_chk.c

@@ -18,7 +18,7 @@
 /// \copyright SPDX-License-Identifier: Apache-2.0
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED

mdbx_copy.c

@@ -18,7 +18,7 @@
 /// \copyright SPDX-License-Identifier: Apache-2.0
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED

mdbx_drop.c

@@ -18,7 +18,7 @@
 /// \copyright SPDX-License-Identifier: Apache-2.0
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED

mdbx_dump.c

@@ -18,7 +18,7 @@
 /// \copyright SPDX-License-Identifier: Apache-2.0
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED

mdbx_load.c

@@ -18,7 +18,7 @@
 /// \copyright SPDX-License-Identifier: Apache-2.0
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED

mdbx_stat.c

@@ -18,7 +18,7 @@
 /// \copyright SPDX-License-Identifier: Apache-2.0
 /// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2026
 
-#define MDBX_BUILD_SOURCERY e30d838fb2509384f10339f050c97b34b790926488f78b959203d21608b421aa_v0_14_1_220_g0f8b288c
+#define MDBX_BUILD_SOURCERY 225dda0a47ebc6c40e06f1d7820ff41263a6b47263cc0ea1832d12f5e38319c8_v0_14_1_234_g329ac7b7
 
 #define LIBMDBX_INTERNALS
 #define MDBX_DEPRECATED