From d21ae28bb9a13cb18a13bc7c27d629f13a0cea17 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: Fri, 2 Aug 2024 19:03:34 +0300
Subject: [PATCH] =?UTF-8?q?mdbx++:=20=D0=B4=D0=BE=D0=B1=D0=B0=D0=B2=D0=BB?=
 =?UTF-8?q?=D0=B5=D0=BD=D0=B8=D0=B5=20=D0=BE=D0=B1=D1=80=D0=B0=D0=B1=D0=BE?=
 =?UTF-8?q?=D1=82=D0=BA=D0=B8=20`MDBX=5FMVCC=5FRETARDED`=20=D0=B2=20C++=20?=
 =?UTF-8?q?API.?=
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---
 mdbx.h++     | 1 +
 src/mdbx.c++ | 2 ++
 src/misc.c   | 4 ++++
 3 files changed, 7 insertions(+)

diff --git a/mdbx.h++ b/mdbx.h++
index 7ef55c18..0d2e8d09 100644
--- a/mdbx.h++
+++ b/mdbx.h++
@@ -583,6 +583,7 @@ MDBX_DECLARE_EXCEPTION(transaction_overlapping);
 MDBX_DECLARE_EXCEPTION(duplicated_lck_file);
 MDBX_DECLARE_EXCEPTION(dangling_map_id);
 MDBX_DECLARE_EXCEPTION(transaction_ousted);
+MDBX_DECLARE_EXCEPTION(mvcc_retarded);
 #undef MDBX_DECLARE_EXCEPTION
 
 [[noreturn]] LIBMDBX_API void throw_too_small_target_buffer();
diff --git a/src/mdbx.c++ b/src/mdbx.c++
index adef7c34..d6ca4c11 100644
--- a/src/mdbx.c++
+++ b/src/mdbx.c++
@@ -340,6 +340,7 @@ DEFINE_EXCEPTION(transaction_overlapping)
 DEFINE_EXCEPTION(duplicated_lck_file)
 DEFINE_EXCEPTION(dangling_map_id)
 DEFINE_EXCEPTION(transaction_ousted)
+DEFINE_EXCEPTION(mvcc_retarded)
 #undef DEFINE_EXCEPTION
 
 __cold const char *error::what() const noexcept {
@@ -429,6 +430,7 @@ __cold void error::throw_exception() const {
     CASE_EXCEPTION(duplicated_lck_file, MDBX_DUPLICATED_CLK);
     CASE_EXCEPTION(dangling_map_id, MDBX_DANGLING_DBI);
     CASE_EXCEPTION(transaction_ousted, MDBX_OUSTED);
+    CASE_EXCEPTION(mvcc_retarded, MDBX_MVCC_RETARDED);
 #undef CASE_EXCEPTION
   default:
     if (is_mdbx_error())
diff --git a/src/misc.c b/src/misc.c
index 415eee1c..bf8246ab 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -210,6 +210,10 @@ __cold const char *mdbx_liberr2str(int errnum) {
   case MDBX_OUSTED:
     return "MDBX_OUSTED: The parked read transaction was outed for the sake"
            " of recycling old MVCC snapshots";
+  case MDBX_MVCC_RETARDED:
+    return "MDBX_MVCC_RETARDED: MVCC snapshot used by read transaction"
+           " is outdated and could not be copied"
+           " since corresponding meta-pages was overwritten";
   default:
     return nullptr;
   }