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>

1 files changed, 13 insertions, 5 deletions

diff --git a/src/H5private.h b/src/H5private.h
index 7f77c9a..6b29a44 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -1976,9 +1976,13 @@ extern char H5_lib_vers_info_g[];
 
 /* replacement structure for original global variable */
 typedef struct H5_api_struct {
-    H5TS_mutex_t init_lock;    /* API entrance mutex */
-    hbool_t      H5_libinit_g; /* Has the library been initialized? */
-    hbool_t      H5_libterm_g; /* Is the library being shutdown? */
+#ifdef H5_USE_RECURSIVE_WRITER_LOCKS
+    H5TS_rw_lock_t init_rw_lock; /* API entrance RW lock */
+#else
+    H5TS_mutex_t init_lock; /* API entrance mutex */
+#endif
+    hbool_t H5_libinit_g; /* Has the library been initialized? */
+    hbool_t H5_libterm_g; /* Is the library being shutdown? */
 } H5_api_t;
 
 /* Macros for accessing the global variables */
@@ -1993,13 +1997,17 @@ typedef struct H5_api_struct {
 #endif
 
 /* Macros for threadsafe HDF-5 Phase I locks */
+#ifdef H5_USE_RECURSIVE_WRITER_LOCKS
+#define H5_API_LOCK   H5TS_rw_wrlock(&H5_g.init_rw_lock);
+#define H5_API_UNLOCK H5TS_rw_unlock(&H5_g.init_rw_lock);
+#else
 #define H5_API_LOCK   H5TS_mutex_lock(&H5_g.init_lock);
 #define H5_API_UNLOCK H5TS_mutex_unlock(&H5_g.init_lock);
+#endif
 
 /* Macros for thread cancellation-safe mechanism */
 #define H5_API_UNSET_CANCEL H5TS_cancel_count_inc();
-
-#define H5_API_SET_CANCEL H5TS_cancel_count_dec();
+#define H5_API_SET_CANCEL   H5TS_cancel_count_dec();
 
 extern H5_api_t H5_g;