The stable release with the hotfix/workaround for a flaw of Linux 4.19 (at least) unified page/buffer cache.
See [issue#269](https://github.com/erthink/libmdbx/issues/269) for more information.
Acknowledgements:
-----------------
- [Simon Leier](https://github.com/leisim) for reporting and testing.
- [Kai Wetlesen](https://github.com/kaiwetlesen) for [RPMs](http://copr.fedorainfracloud.org/coprs/kwetlesen/libmdbx/).
- [Tullio Canepa](https://github.com/canepat) for reporting C++ API issue and contributing.
Fixes:
------
- [Added workaround](https://github.com/erthink/libmdbx/issues/269) for a flaw of Linux 4.19 (at least) unified page/buffer cache.
- [Fixed/Reworked](https://github.com/erthink/libmdbx/pull/270) move-assignment operators for "managed" classes of C++ API.
- Fixed potential `SIGSEGV` while open DB with overrided non-default page size.
- [Made](https://github.com/erthink/libmdbx/issues/267) `mdbx_env_open()` idempotence in failure cases.
- Refined/Fixed pages reservation inside `mdbx_update_gc()` to avoid non-reclamation in a rare cases.
- Fixed typo in a retained space calculation for the hsr-callback.
Minors:
-------
- Reworked functions for meta-pages, split-off non-volatile.
- Disentangled C11-atomic fences/barriers and pure-functions (with `__attribute__((__pure__))`) to avoid compiler misoptimization.
- Fixed hypotetic unaligned access to 64-bit dwords on ARM with `__ARM_FEATURE_UNALIGNED` defined.
- Reasonable paranoia that makes clarity for code readers.
- Minor fixes Doxygen references, comments, descriptions, etc.
Signed-off-by: Леонид Юрьев (Leonid Yuriev) <leo@yuriev.ru>
Backward compatibility break:
-----------------------------
The database format signature has been changed to prevent
forward-interoperability with an previous releases, which may lead to a
[false positive diagnosis of database corruption](https://github.com/erthink/libmdbx/issues/238)
due to flaws of an old library versions.
This change is mostly invisible:
- previously versions are unable to read/write a new DBs;
- but the new release is able to handle an old DBs and will silently upgrade ones.
Acknowledgements:
-----------------
- [Alex Sharov](https://github.com/AskAlexSharov) for reporting and testing.
Signed-off-by: Leonid Yuriev <leo@yuriev.ru>
