threadsafe: Load preferences threadsafe

include/volk/volk_prefs.h

@@ -22,6 +22,12 @@ typedef struct volk_arch_pref {
     char impl_u[128]; // best unaligned impl
 } volk_arch_pref_t;
 
+
+VOLK_API void volk_initialize_preferences();
+VOLK_API void volk_free_preferences();
+VOLK_API const size_t volk_get_num_arch_prefs();
+VOLK_API const volk_arch_pref_t* volk_get_arch_prefs();
+
 ////////////////////////////////////////////////////////////////////////
 // get path to volk_config profiling info; second arguments specifies
 // if config file should be tested on existence for reading.

lib/CMakeLists.txt

@@ -560,6 +560,7 @@ if(ORC_FOUND)
 endif()
 if(NOT MSVC)
   target_link_libraries(volk PUBLIC m)
+  target_link_libraries(volk PRIVATE pthread)
 endif()
 set_target_properties(volk PROPERTIES VERSION ${VERSION})
 set_target_properties(volk PROPERTIES SOVERSION ${SOVERSION})

lib/volk_prefs.c

@@ -18,6 +18,9 @@
 #else
 #include <unistd.h>
 #endif
+#ifndef __STDC_NO_THREADS__
+#include <threads.h>
+#endif
 #include <volk/volk_prefs.h>
 
 void volk_get_config_path(char* path, bool read)
@@ -72,6 +75,76 @@ void volk_get_config_path(char* path, bool read)
     return;
 }
 
+
+static struct volk_preferences {
+    volk_arch_pref_t* volk_arch_prefs;
+    size_t n_arch_prefs;
+    int initialized;
+#ifndef __STDC_NO_THREADS__
+    mtx_t mutex;
+#endif
+} volk_preferences;
+
+#ifndef __STDC_NO_THREADS__
+void init_struct_mutex(void)
+{
+    if (mtx_init(&volk_preferences.mutex, mtx_plain) != thrd_success) {
+        printf("\n mutex init failed\n");
+    }
+}
+
+static once_flag mutex_init_once_flag = ONCE_FLAG_INIT;
+void initialize_mutex() { call_once(&mutex_init_once_flag, init_struct_mutex); }
+#endif
+
+void volk_initialize_preferences()
+{
+#ifndef __STDC_NO_THREADS__
+    initialize_mutex();
+    mtx_lock(&volk_preferences.mutex);
+#endif
+    if (!volk_preferences.initialized) {
+        volk_preferences.n_arch_prefs =
+            volk_load_preferences(&volk_preferences.volk_arch_prefs);
+        volk_preferences.initialized = 1;
+    }
+#ifndef __STDC_NO_THREADS__
+    mtx_unlock(&volk_preferences.mutex);
+#endif
+}
+
+
+void volk_free_preferences()
+{
+#ifndef __STDC_NO_THREADS__
+    initialize_mutex();
+    mtx_lock(&volk_preferences.mutex);
+#endif
+    if (volk_preferences.initialized) {
+        free(volk_preferences.volk_arch_prefs);
+        volk_preferences.n_arch_prefs = 0;
+        volk_preferences.initialized = 0;
+    }
+#ifndef __STDC_NO_THREADS__
+    mtx_unlock(&volk_preferences.mutex);
+#endif
+}
+
+
+const size_t volk_get_num_arch_prefs()
+{
+    volk_initialize_preferences();
+    return volk_preferences.n_arch_prefs;
+}
+
+
+const volk_arch_pref_t* volk_get_arch_prefs()
+{
+    volk_initialize_preferences();
+    return volk_preferences.volk_arch_prefs;
+}
+
+
 size_t volk_load_preferences(volk_arch_pref_t** prefs_res)
 {
     FILE* config_file;

lib/volk_rank_archs.c

@@ -41,13 +41,9 @@ int volk_rank_archs(const char* kern_name,    // name of the kernel to rank
 )
 {
     size_t i;
-    static volk_arch_pref_t* volk_arch_prefs;
-    static size_t n_arch_prefs = 0;
-    static int prefs_loaded = 0;
-    if (!prefs_loaded) {
-        n_arch_prefs = volk_load_preferences(&volk_arch_prefs);
-        prefs_loaded = 1;
-    }
+
+    const volk_arch_pref_t* volk_arch_prefs = volk_get_arch_prefs();
+    const size_t n_arch_prefs = volk_get_num_arch_prefs();
 
     // If we've defined VOLK_GENERIC to be anything, always return the
     // 'generic' kernel. Used in GR's QA code.