mdbx++: добавление обработки MDBX_MVCC_RETARDED в C++ API.

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();

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())

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+ " is outdated and could not be copied"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;
  }