Brings the thread-safety recursive writer locks to 1.12 (#466)

* First cut at replaceing the existing mutex with a recursive R/W lock.

This implementation has the following issues:

    1) pthreads implementation only -- we still need a windows version.

    2) must investigate thread cancelation issues

    3) Error reporting is very poor.  I followed the error reporting on
       the existing thread safe code, but this should be re-visited and
       improved.

Code is currently setup to use the new recursive R/W lock instead of
the global mutex to control entry to the library in threadsafe builds.
To revert to the global mutex, set H5TS__USE_REC_RW_LOCK_FOR_GLOBAL_MUTEX
in H5TSprivate.h to FALSE.

Added a reasonably robust regression test for the reursive R/W lock
in test/ttsafe_rec_rw_lock.c

Note that the change to hl/src/H5LTanalyse.c is an artifact of clang-format.

Tested serial threadsafe debug and production on jelly, and also regular
serial / debug.

On Windows builds, the new recursive R/W lock should not be built and
we should use the existing global mutex -- however this is not tested
at this time.

* Updates CMake to build recursive RW lock test

* Updates to allow building on Windows

* Moves #if statements to better protect non-RW lock code

* Adds configure and CMake options for the recursive RW locks

* Committing clang-format changes

* Updates RELEASE.txt and the build options

* Renames H5TS RW lock things

* Makes struct members platform independent

Also removes _ptr from identifiers

* Partial thread-safety RW locks platform independence

* Committing clang-format changes

* Pthreads side of things is platform-independent now

* Formatted source

* Added Windows equivalents for some Pthreads calls

* Rename H5TS takedown call to destroy

* Reorg of RW lock code

* Committing clang-format changes

* Changes to Pthreads code after development on Visual Studio

* Moves stats macros to static inline functions and tidies memory allocs

* Converts RW lock print stats call to use C99 formatting

* Fixes typos

* Formatted source

* Updates the RELEASE.txt note to indicate no Win32 threads support

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

3 files changed, 16 insertions, 1 deletions

diff --git a/config/cmake/ConfigureChecks.cmake b/config/cmake/ConfigureChecks.cmake
index 0d82668..9fc4680 100644
--- a/config/cmake/ConfigureChecks.cmake
+++ b/config/cmake/ConfigureChecks.cmake
@@ -28,6 +28,18 @@ if (HDF5_STRICT_FORMAT_CHECKS)
 endif ()
 MARK_AS_ADVANCED (HDF5_STRICT_FORMAT_CHECKS)
 
+#-----------------------------------------------------------------------------
+# Option for --enable-threadsafe
+#-----------------------------------------------------------------------------
+# Recursive RW locks are not supported on Windows (yet)
+if (NOT WINDOWS)
+  option (HDF5_USE_RECURSIVE_RW_LOCKS "Whether to use recursive RW locks for thread-safety" OFF)
+  if (HDF5_USE_RECURSIVE_RW_LOCKS)
+    set (${HDF_PREFIX}_USE_RECURSIVE_RW_LOCKS 1)
+  endif ()
+  MARK_AS_ADVANCED (HDF5_USE_RECURSIVE_RW_LOCKS)
+endif ()
+
 # ----------------------------------------------------------------------
 # Decide whether the data accuracy has higher priority during data
 # conversions.  If not, some hard conversions will still be prefered even
diff --git a/config/cmake/H5pubconf.h.in b/config/cmake/H5pubconf.h.in
index 69c2d4a..97731f1 100644
--- a/config/cmake/H5pubconf.h.in
+++ b/config/cmake/H5pubconf.h.in
@@ -744,6 +744,9 @@
 /* Define if the library will use file locking */
 #cmakedefine H5_USE_FILE_LOCKING @H5_USE_FILE_LOCKING@
 
+/* Define if the library will use recursive RW locks for thread safety */
+#cmakedefine H5_USE_RECURSIVE_RW_LOCKS @H5_USE_RECURSIVE_RW_LOCKS@
+
 /* Define if a memory checking tool will be used on the library, to cause
    library to be very picky about memory operations and also disable the
    internal free list manager code. */
diff --git a/config/cmake/libhdf5.settings.cmake.in b/config/cmake/libhdf5.settings.cmake.in
index ebcbd61..dd345b4 100644
--- a/config/cmake/libhdf5.settings.cmake.in
+++ b/config/cmake/libhdf5.settings.cmake.in
@@ -70,7 +70,7 @@ Parallel Filtered Dataset Writes: @PARALLEL_FILTERED_WRITES@
               High-level library: @HDF5_BUILD_HL_LIB@
                 Build HDF5 Tests: @BUILD_TESTING@
                 Build HDF5 Tools: @HDF5_BUILD_TOOLS@
-                    Threadsafety: @HDF5_ENABLE_THREADSAFE@
+                    Threadsafety: @HDF5_ENABLE_THREADSAFE@ (recursive RW locks: @HDF5_USE_RECURSIVE_RW_LOCKS@) 
              Default API mapping: @DEFAULT_API_VERSION@
   With deprecated public symbols: @HDF5_ENABLE_DEPRECATED_SYMBOLS@
           I/O filters (external): @EXTERNAL_FILTERS@