mdbx: release v0.10.1

Acknowledgements:
-----------------
 - [Alexey Akhunov](https://github.com/AlexeyAkhunov) and [Alex Sharov](https://github.com/AskAlexSharov) for bug reporting and testing.

New features:
-------------
 - Added `-p` option to `mdbx_stat` utility for printing page operations statistic.
 - Added explicit checking for and warning about using unfit github's archives.

Fixes:
------
 - Fixed minor "foo not used" warnings from modern C++ compilers when building the C++ part of the library.
 - Fixed confusing/messy errors when build library from unfit github's archives (https://github.com/erthink/libmdbx/issues/197).
 - Fixed `#​e​l​s​i​f` typo.
 - Fixed rare unexpected `MDBX_PROBLEM` error during altering data in huge transactions due to wrong spilling/oust of dirty pages (https://github.com/erthink/libmdbx/issues/195).

mdbx: release v0.10.0

Acknowledgements:
-----------------
 - [Mahlon E. Smith](https://github.com/mahlonsmith) for [Ruby bindings](https://rubygems.org/gems/mdbx/).
 - [Alex Sharov](https://github.com/AskAlexSharov) for [mdbx-go](https://github.com/torquem-ch/mdbx-go), bug reporting and testing.
 - [Artem Vorotnikov](https://github.com/vorot93) for bug reporting and PR.
 - [Paolo Rebuffo](https://www.linkedin.com/in/paolo-rebuffo-8255766/), [Alexey Akhunov](https://github.com/AlexeyAkhunov) and Mark Grosberg for donations.
 - [Noel Kuntze](https://github.com/Thermi) for preliminary [Python bindings](https://github.com/Thermi/libmdbx/tree/python-bindings)

New features:
-------------
 - Added `mdbx_env_set_option()` and `mdbx_env_get_option()` for controls
   various runtime options for an environment (announce of this feature  was missed in a previous news).
 - Added `MDBX_DISABLE_PAGECHECKS` build option to disable some checks to reduce an overhead
   and detection probability of database corruption to a values closer to the LMDB.
   The `MDBX_DISABLE_PAGECHECKS=1` provides a performance boost of about 10% in CRUD scenarios,
   and conjointly with the `MDBX_ENV_CHECKPID=0` and `MDBX_TXN_CHECKOWNER=0` options can yield
   up to 30% more performance compared to LMDB.
 - Using float point (exponential quantized) representation for internal 16-bit values
   of grow step and shrink threshold when huge ones (https://github.com/erthink/libmdbx/issues/166).
   To minimize the impact on compatibility, only the odd values inside the upper half
   of the range (i.e. 32769..65533) are used for the new representation.
 - Added the `mdbx_drop` similar to LMDB command-line tool to purge or delete (sub)database(s).
 - [Ruby bindings](https://rubygems.org/gems/mdbx/) is available now by [Mahlon E. Smith](https://github.com/mahlonsmith).
 - Added `MDBX_ENABLE_MADVISE` build option which controls the use of POSIX `madvise()` hints and friends.
 - The internal node sizes were refined, resulting in a reduction in large/overflow pages in some use cases
   and a slight increase in limits for a keys size to ≈½ of page size.
 - Added to `mdbx_chk` output number of keys/items on pages.
 - Added explicit `install-strip` and `install-no-strip` targets to the `Makefile` (https://github.com/erthink/libmdbx/pull/180).
 - Major rework page splitting (af9b7b560505684249b76730997f9e00614b8113) for
     - An "auto-appending" feature upon insertion for both ascending and
       descending key sequences. As a result, the optimality of page filling
       increases significantly (more densely, less slackness) while
       inserting ordered sequences of keys,
     - A "splitting at middle" to make page tree more balanced on average.
 - Added `mdbx_get_sysraminfo()` to the API.
 - Added guessing a reasonable maximum DB size for the default upper limit of geometry (https://github.com/erthink/libmdbx/issues/183).
 - Major rework internal labeling of a dirty pages (958fd5b9479f52f2124ab7e83c6b18b04b0e7dda) for
   a "transparent spilling" feature with the gist to make a dirty pages
   be ready to spilling (writing to a disk) without further altering ones.
   Thus in the `MDBX_WRITEMAP` mode the OS kernel able to oust dirty pages
   to DB file without further penalty during transaction commit.
   As a result, page swapping and I/O could be significantly reduced during extra large transactions and/or lack of memory.
 - Minimized reading leaf-pages during dropping subDB(s) and nested trees.
 - Major rework a spilling of dirty pages to support [LRU](https://en.wikipedia.org/wiki/Cache_replacement_policies#Least_recently_used_(LRU))
   policy and prioritization for a large/overflow pages.
 - Statistics of page operations (split, merge, copy, spill, etc) now available through `mdbx_env_info_ex()`.
 - Auto-setup limit for length of dirty pages list (`MDBX_opt_txn_dp_limit` option).
 - Support `make options` to list available build options.
 - Support `make help` to list available make targets.
 - Silently `make`'s build by default.
 - Preliminary [Python bindings](https://github.com/Thermi/libmdbx/tree/python-bindings) is available now
   by [Noel Kuntze](https://github.com/Thermi) (https://github.com/erthink/libmdbx/issues/147).

Backward compatibility break:
-----------------------------
 - The `MDBX_AVOID_CRT` build option was renamed to `MDBX_WITHOUT_MSVC_CRT`.
   This option is only relevant when building for Windows.
 - The `mdbx_env_stat()` always, and `mdbx_env_stat_ex()` when called with the zeroed transaction parameter,
   now internally start temporary read transaction and thus may returns `MDBX_BAD_RSLOT` error.
   So, just never use deprecated `mdbx_env_stat()' and call `mdbx_env_stat_ex()` with transaction parameter.
 - The build option `MDBX_CONFIG_MANUAL_TLS_CALLBACK` was removed and now just a non-zero value of
   the `MDBX_MANUAL_MODULE_HANDLER` macro indicates the requirement to manually call `mdbx_module_handler()`
   when loading libraries and applications uses statically linked libmdbx on an obsolete Windows versions.

Fixes:
------
 - Fixed performance regression due non-optimal C11 atomics usage (https://github.com/erthink/libmdbx/issues/160).
 - Fixed "reincarnation" of subDB after it deletion (https://github.com/erthink/libmdbx/issues/168).
 - Fixed (disallowing) implicit subDB deletion via operations on `@MAIN`'s DBI-handle.
 - Fixed a crash of `mdbx_env_info_ex()` in case of a call for a non-open environment (https://github.com/erthink/libmdbx/issues/171).
 - Fixed the selecting/adjustment values inside `mdbx_env_set_geometry()` for implicit out-of-range cases (https://github.com/erthink/libmdbx/issues/170).
 - Fixed `mdbx_env_set_option()` for set initial and limit size of dirty page list ((https://github.com/erthink/libmdbx/issues/179).
 - Fixed an unreasonably huge default upper limit for DB geometry (https://github.com/erthink/libmdbx/issues/183).
 - Fixed `constexpr` specifier for the `slice::invalid()`.
 - Fixed (no)readahead auto-handling (https://github.com/erthink/libmdbx/issues/164).
 - Fixed non-alloy build for Windows.
 - Switched to using Heap-functions instead of LocalAlloc/LocalFree on Windows.
 - Fixed `mdbx_env_stat_ex()` to returning statistics of the whole environment instead of MainDB only (https://github.com/erthink/libmdbx/issues/190).
 - Fixed building by GCC 4.8.5 (added workaround for a preprocessor's bug).
 - Fixed building C++ part for iOS <= 13.0 (unavailability of  `std::filesystem::path`).
 - Fixed building for Windows target versions prior to Windows Vista (`WIN32_WINNT < 0x0600`).
 - Fixed building by MinGW for Windows (https://github.com/erthink/libmdbx/issues/155).

TODO for a next releases:
-------------------------
 - [Get rid of dirty-pages list in MDBX_WRITEMAP mode](https://github.com/erthink/libmdbx/issues/193).
 - [Large/Overflow pages accounting for dirty-room](https://github.com/erthink/libmdbx/issues/192).
 - [C++ Buffer issue](https://github.com/erthink/libmdbx/issues/191).
 - Finalize C++ API (few typos and trivia bugs are still likely for now).
 - [Support for RAW devices](https://github.com/erthink/libmdbx/issues/124).
 - [Test framework issue](https://github.com/erthink/libmdbx/issues/127).
 - [Support MessagePack for Keys & Values](https://github.com/erthink/libmdbx/issues/115).
 - [Engage new terminology](https://github.com/erthink/libmdbx/issues/137).
 - Packages for [Astra Linux](https://astralinux.ru/), [ALT Linux](https://www.altlinux.org/), [ROSA Linux](https://www.rosalinux.ru/), Fedora/RHEL, Debian/Ubuntu.

mdbx: release v0.9.3

Acknowledgements:
-----------------
 - [Mahlon E. Smith](http://www.martini.nu/) for [FreeBSD port of libmdbx](https://svnweb.freebsd.org/ports/head/databases/mdbx/).
 - [장세연](http://www.castis.com) for bug fixing and PR.
 - [Clément Renault](https://github.com/Kerollmops/heed) for [Heed](https://github.com/Kerollmops/heed) fully typed Rust wrapper.
 - [Alex Sharov](https://github.com/AskAlexSharov) for bug reporting.
 - [Noel Kuntze](https://github.com/Thermi) for bug reporting.

Removed options and features:
-----------------------------
 - Drop `MDBX_HUGE_TRANSACTIONS` build-option (now no longer required).

New features:
-------------
 - Package for FreeBSD is available now by Mahlon E. Smith.
 - New API functions to get/set various options (https://github.com/erthink/libmdbx/issues/128):
    - the maximum number of named databases for the environment;
    - the maximum number of threads/reader slots;
    - threshold (since the last unsteady commit) to force flush the data buffers to disk;
    - relative period (since the last unsteady commit) to force flush the data buffers to disk;
    - limit to grow a list of reclaimed/recycled page's numbers for finding a sequence of contiguous pages for large data items;
    - limit to grow a cache of dirty pages for reuse in the current transaction;
    - limit of a pre-allocated memory items for dirty pages;
    - limit of dirty pages for a write transaction;
    - initial allocation size for dirty pages list of a write transaction;
    - maximal part of the dirty pages may be spilled when necessary;
    - minimal part of the dirty pages should be spilled when necessary;
    - how much of the parent transaction dirty pages will be spilled while start each child transaction;
 - Unlimited/Dynamic size of retired and dirty page lists (https://github.com/erthink/libmdbx/issues/123).
 - Added `-p` option (purge subDB before loading) to `mdbx_load` tool.
 - Reworked spilling of large transaction and committing of nested transactions:
    - page spilling code reworked to avoid the flaws and bugs inherited from LMDB;
    - limit for number of dirty pages now is controllable at runtime;
    - a spilled pages, including overflow/large pages, now can be reused and refunded/compactified in nested transactions;
    - more effective refunding/compactification especially for the loosed page cache.
 - Added `MDBX_ENABLE_REFUND` and `MDBX_PNL_ASCENDING` internal/advanced build options.
 - Added `mdbx_default_pagesize()` function.
 - Better support architectures with a weak/relaxed memory consistency model (ARM, AARCH64, PPC, MIPS, RISC-V, etc) by means [C11 atomics](https://en.cppreference.com/w/c/atomic).
 - Speed up page number lists and dirty page lists (https://github.com/erthink/libmdbx/issues/132).
 - Added `LIBMDBX_NO_EXPORTS_LEGACY_API` build option.

Fixes:
------
 - Fixed missing cleanup (null assigned) in the C++ commit/abort (https://github.com/erthink/libmdbx/pull/143).
 - Fixed `mdbx_realloc()` for case of nullptr and `MDBX_AVOID_CRT=ON` for Windows.
 - Fixed the possibility to use invalid and renewed (closed & re-opened, dropped & re-created) DBI-handles (https://github.com/erthink/libmdbx/issues/146).
 - Fixed 4-byte aligned access to 64-bit integers, including access to the `bootid` meta-page's field (https://github.com/erthink/libmdbx/issues/153).
 - Fixed minor/potential memory leak during page flushing and unspilling.
 - Fixed handling states of cursors's and subDBs's for nested transactions.
 - Fixed page leak in extra rare case the list of retired pages changed during update GC on transaction commit.
 - Fixed assertions to avoid false-positive UB detection by CLANG/LLVM (https://github.com/erthink/libmdbx/issues/153).
 - Fixed `MDBX_TXN_FULL` and regressive `MDBX_KEYEXIST` during large transaction commit with `MDBX_LIFORECLAIM` (https://github.com/erthink/libmdbx/issues/123).
 - Fixed auto-recovery (`weak->steady` with the same boot-id) when Database size at last weak checkpoint is large than at last steady checkpoint.
 - Fixed operation on systems with unusual small/large page size, including PowerPC (https://github.com/erthink/libmdbx/issues/157).

TODO:
-----
 - Engage new terminology (https://github.com/erthink/libmdbx/issues/137).
 - Resolve few TODOs (https://github.com/erthink/libmdbx/issues/124, https://github.com/erthink/libmdbx/issues/127,    https://github.com/erthink/libmdbx/issues/115).
 - Finalize C++ API.
 - Packages for [ROSA Linux](https://www.rosalinux.ru/), [ALT Linux](https://www.altlinux.org/), Fedora/RHEL, Debian/Ubuntu.

Release v0.9.2 2020-11-27

Acknowledgements:
-----------------

 - Jens Alfke (Mobile Architect at [Couchbase](https://www.couchbase.com/)) for [NimDBX](https://github.com/snej/nimdbx).
 - Clément Renault (CTO at [MeiliSearch](https://www.meilisearch.com/)) for [mdbx-rs](https://github.com/Kerollmops/mdbx-rs).
 - Alex Sharov (Go-Lang Teach Lead at [TurboGeth/Ethereum](https://ethereum.org/)) for an extreme test cases and bug reporting.
 - George Hazan (CTO at [Miranda NG](https://www.miranda-ng.org/)) for bug reporting.
 - [Positive Technologies](https://www.ptsecurity.com/) for funding and [The Standoff](https://standoff365.com/).

Added features:
---------------

 - Provided package for [buildroot](https://buildroot.org/).
 - Binding for Nim is [available](https://github.com/snej/nimdbx) now by Jens Alfke.
 - Added `mdbx_env_delete()` for deletion an environment files in a proper and multiprocess-safe way.
 - Added `mdbx_txn_commit_ex()` with collecting latency information.
 - Fast completion pure nested transactions.
 - Added `LIBMDBX_INLINE_API` macro and inline versions of some API functions.
 - Added `mdbx_cursor_copy()` function.
 - Extended tests for checking cursor tracking.
 - Added `MDBX_SET_LOWERBOUND` operation for `mdbx_cursor_get()`.

Fixes:
------

 - Fixed missing installation of `mdbx.h++`.
 - Fixed use of obsolete `__noreturn`.
 - Fixed use of `yield` instruction on ARM if unsupported.
 - Added pthread workaround for buggy toolchain/cmake/buildroot.
 - Fixed use of `pthread_yield()` for non-GLIBC.
 - Fixed use of `RegGetValueA()` on Windows 2000/XP.
 - Fixed use of `GetTickCount64()` on Windows 2000/XP.
 - Fixed opening DB on a network shares (in the exclusive mode).
 - Fixed copy&paste typos.
 - Fixed minor false-positive GCC warning.
 - Added workaround for broken `DEFINE_ENUM_FLAG_OPERATORS` from Windows SDK.
 - Fixed cursor state after multimap/dupsort repeated deletes (https://github.com/erthink/libmdbx/issues/121).
 - Added `SIGPIPE` suppression for internal thread during `mdbx_env_copy()`.
 - Fixed extra-rare `MDBX_KEY_EXIST` error during `mdbx_commit()` (https://github.com/erthink/libmdbx/issues/131).
 - Fixed spilled pages checking (https://github.com/erthink/libmdbx/issues/126).
 - Fixed `mdbx_load` for 'plain text' and without `-s name` cases (https://github.com/erthink/libmdbx/issues/136).
 - Fixed save/restore/commit of cursors for nested transactions.
 - Fixed cursors state in rare/special cases (move next beyond end-of-data, after deletion and so on).
 - Added workaround for MSVC 19.28 (Visual Studio 16.8) (but may still hang during compilation).
 - Fixed paranoidal Clang C++ UB for bitwise operations with flags defined by enums.
 - Fixed large pages checking (for compatibility and to avoid false-positive errors from `mdbx_chk`).
 - Added workaround for Wine (https://github.com/miranda-ng/miranda-ng/issues/1209).
 - Fixed `ERROR_NOT_SUPPORTED` while opening DB by UNC pathnames (https://github.com/miranda-ng/miranda-ng/issues/2627).
 - Added handling `EXCEPTION_POSSIBLE_DEADLOCK` condition for Windows.

TODO for v0.9.3:
----------------

 - Engage new terminology (https://github.com/erthink/libmdbx/issues/137).
 - Rework/speedup the implementation of the dirty page list (lazy compactification, lazy sorting via merge).
 - Resolve few TODOs (https://github.com/erthink/libmdbx/issues/123, https://github.com/erthink/libmdbx/issues/124, https://github.com/erthink/libmdbx/issues/127, https://github.com/erthink/libmdbx/issues/128, https://github.com/erthink/libmdbx/issues/132, https://github.com/erthink/libmdbx/issues/115).
 - Finalize C++ API (few typos and trivia bugs are still likely for now).
 - Packages for ROSA Linux, ALT Linux, Fedora/RHEL, Debian/Ubuntu.

Release v0.9.1 2020-09-30

Added features:
---------------

 - Preliminary C++ API with support for C++17 polymorphic allocators.
 - [Online C++ API reference](https://erthink.github.io/libmdbx/) by Doxygen.
 - Quick reference for Insert/Update/Delete operations.
 - Explicit `MDBX_SYNC_DURABLE` to sync modes for API clarity.
 - Explicit `MDBX_ALLDUPS` and `MDBX_UPSERT` for API clarity.
 - Support for read transactions preparation (`MDBX_TXN_RDONLY_PREPARE` flag).
 - Support for cursor preparation/(pre)allocation and reusing (`mdbx_cursor_create()` and `mdbx_cursor_bind()` functions).
 - Support for checking database using specified meta-page (see `mdbx_chk -h`).
 - Support for turn to the specific meta-page after checking (see `mdbx_chk -h`).
 - Support for explicit reader threads (de)registration.
 - The `mdbx_txn_break()` function to explicitly mark a transaction as broken.
 - Improved handling of corrupted databases by `mdbx_chk` utility and `mdbx_walk_tree()` function.
 - Improved DB corruption detection by checking parent-page-txnid.
 - Improved opening large DB (> 4Gb) from 32-bit code.
 - Provided `pure-function` and `const-function` attributes to C API.
 - Support for user-settable context for transactions & cursors.
 - Revised API and documentation related to Handle-Slow-Readers callback feature.

Deprecated functions and flags:
-------------------------------

 - For clarity and API simplification the `MDBX_MAPASYNC` flag is deprecated.
   Just use `MDBX_SAFE_NOSYNC` or `MDBX_UTTERLY_NOSYNC` instead of it.
 - `MDBX_oom_func`, `mdbx_env_set_oomfunc()` and `mdbx_env_get_oomfunc()`
   replaced with `MDBX_hsr_func`, `mdbx_env_get_hsr` and `mdbx_env_get_hsr()`.

Fixes:
------

 - Fix `mdbx_strerror()` for `MDBX_BUSY` error (no error description is returned).
 - Fix update internal meta-geo information in read-only mode (`EACCESS` or `EBADFD` error).
 - Fix `mdbx_page_get()` null-defer when DB corrupted (crash by `SIGSEGV`).
 - Fix `mdbx_env_open()` for re-opening after non-fatal errors (`mdbx_chk` unexpected failures).
 - Workaround for MSVC 19.27 `static_assert()` bug.
 - Doxygen descriptions and refinement.
 - Update Valgrind's suppressions.
 - Workaround to avoid infinite loop of 'nested' testcase on MIPS under QEMU.
 - Fix a lot of typos & spelling (Thanks to Josh Soref for PR).
 - Fix `getopt()` messages for Windows (Thanks to Andrey Sporaw for reporting).
 - Fix MSVC compiler version requirements (Thanks to Andrey Sporaw for reporting).
 - Workarounds for QEMU's bugs to run tests for cross-builded library under QEMU.
 - Now C++ compiler optional for building by CMake.

TODO for next version(s):
-------------------------

 - Rework/speedup the implementation of the dirty page list (lazy compactification, lazy sorting via merge).
 - Finalize C++ API (few typos and trivia bugs are likely for now).
 - Packages for ROSA Linux, ALT Linux, Fedora/RHEL, Debian/Ubuntu.