Use H5_ATOMIC macros in H5VL

src/H5VLdyn_ops.c

@@ -193,8 +193,11 @@ H5VL__term_opt_operation(void)
 herr_t
 H5VL__register_opt_operation(H5VL_subclass_t subcls, const char *op_name, int *op_val)
 {
-    H5VL_dyn_op_t *new_op;              /* Info about new operation */
-    herr_t         ret_value = SUCCEED; /* Return value */
+    H5VL_dyn_op_t *new_op            = NULL;    /* Info about new operation */
+    herr_t         ret_value         = SUCCEED; /* Return value */
+    H5SL_t        *new_op_list       = NULL;    /* Newly created skip list, if any */
+    H5SL_t        *op_list           = NULL;    /* Existing skip list */
+    bool           new_list_inserted = false;   /* Whether a new skip list was inserted into global array */
 
     FUNC_ENTER_PACKAGE
     H5_API_LOCK
@@ -204,25 +207,57 @@ H5VL__register_opt_operation(H5VL_subclass_t subcls, const char *op_name, int *o
     assert(op_name && *op_name);
 
     /* Check for duplicate operation */
-    if (H5VL_opt_ops_g[subcls]) {
+#ifdef H5_HAVE_MULTITHREAD
+    if ((op_list = atomic_load(&H5VL_opt_ops_g[subcls])) != NULL) {
+        if (NULL != H5SL_search(op_list, op_name))
+            HGOTO_ERROR(H5E_VOL, H5E_EXISTS, FAIL, "operation name already exists");
+    } /* end if */
+#else
+    if ((op_list = H5VL_opt_ops_g[subcls]) != NULL) {
         if (NULL != H5SL_search(H5VL_opt_ops_g[subcls], op_name))
             HGOTO_ERROR(H5E_VOL, H5E_EXISTS, FAIL, "operation name already exists");
     } /* end if */
+#endif
+
+    /* List does not exist: Create skip list for operations of this subclass */
     else {
-        /* Create skip list for operation of this subclass */
-        if (NULL == (H5VL_opt_ops_g[subcls] = H5SL_create(H5SL_TYPE_STR, NULL)))
+        if ((new_op_list = H5SL_create(H5SL_TYPE_STR, NULL)) == NULL)
             HGOTO_ERROR(H5E_VOL, H5E_CANTCREATE, FAIL, "can't create skip list for operations");
+
+#ifdef H5_HAVE_MULTITHREAD
+        H5SL_t *expected = NULL;
+
+        /* If another thread has concurrently set up this op list, abort and use that instead */
+        if ((new_list_inserted =
+                 atomic_compare_exchange_strong(&H5VL_opt_ops_g[subcls], &expected, new_op_list))) {
+            op_list = new_op_list;
+        }
+        else {
+            /* Another thread initialized the list */
+            if ((op_list = atomic_load(&H5VL_opt_ops_g[subcls])) == NULL)
+                HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "can't get skip list for operations");
+        }
+#else
+        H5VL_opt_ops_g[subcls] = new_op_list;
+        op_list                = new_op_list;
+        new_list_inserted      = true;
+#endif
     } /* end else */
 
     /* Register new operation */
     if (NULL == (new_op = H5FL_CALLOC(H5VL_dyn_op_t)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTALLOC, FAIL, "can't allocate memory for dynamic operation info");
     if (NULL == (new_op->op_name = H5MM_strdup(op_name)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTALLOC, FAIL, "can't allocate name for dynamic operation info");
+
+#ifdef H5_HAVE_MULTITHREAD
+    new_op->op_val = atomic_fetch_add(&H5VL_opt_vals_g[subcls], 1);
+#else
     new_op->op_val = H5VL_opt_vals_g[subcls]++;
+#endif
 
     /* Insert into subclass's skip list */
-    if (H5SL_insert(H5VL_opt_ops_g[subcls], new_op, new_op->op_name) < 0)
+    if (H5SL_insert(op_list, new_op, new_op->op_name) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINSERT, FAIL, "can't insert operation info into skip list");
 
     /* Return the next operation value to the caller */

src/H5VLint.c

@@ -57,11 +57,7 @@
 
 /* Object wrapping context info */
 typedef struct H5VL_wrap_ctx_t {
-#ifdef H5_HAVE_MULTITHREAD
-    _Atomic unsigned rc;
-#else
-    unsigned rc;           /* Ref. count for the # of times the context was set / reset */
-#endif
+    H5_ATOMIC(unsigned) rc; /* Ref. count for the # of times the context was set / reset */
     H5VL_t  *connector;    /* VOL connector for "outermost" class to start wrap */
     void    *obj_wrap_ctx; /* "wrap context" for outermost connector */
 } H5VL_wrap_ctx_t;

src/H5VLpassthru.c

@@ -35,12 +35,13 @@
 #include <stdlib.h>
 #include <string.h>
 
-/* TODO: H5_HAVE_MULTITHREAD seems not to be exposed to this module, always import */
-#include <stdatomic.h>
-
 /* Public HDF5 file */
 #include "hdf5.h"
 
+#ifdef H5_HAVE_MULTITHREAD
+#include <stdatomic.h>
+#endif
+
 /* This connector's header */
 #include "H5VLpassthru.h"
 
@@ -368,12 +369,7 @@ static const H5VL_class_t H5VL_pass_through_g = {
 };
 
 /* The connector identification number, initialized at runtime */
-#ifdef H5_HAVE_MULTITHREAD
-static _Atomic(hid_t) H5VL_PASSTHRU_ID_g = ATOMIC_VAR_INIT(H5I_INVALID_HID);
-#else
-static hid_t H5VL_PASSTHRU_ID_g = H5I_INVALID_HID;
-#endif
-
+static H5_ATOMIC_SPECIFIER(hid_t) H5VL_PASSTHRU_ID_g = H5_ATOMIC_VAR_INIT(H5I_INVALID_HID);
 /*-------------------------------------------------------------------------
  * Function:    H5VL__pass_through_new_obj
  *

src/H5VLpkg.h

@@ -26,6 +26,10 @@
 /* Get package's private header */
 #include "H5VLprivate.h" /* Generic Functions                    */
 
+#ifdef H5_HAVE_MULTITHREAD
+#include <stdatomic.h>
+#endif
+
 /* Other private headers needed by this file */
 
 /**************************/
@@ -63,6 +67,7 @@ H5_DLL size_t  H5VL__num_opt_operation(void);
 H5_DLL herr_t  H5VL__find_opt_operation(H5VL_subclass_t subcls, const char *op_name, int *op_val);
 H5_DLL herr_t  H5VL__unregister_opt_operation(H5VL_subclass_t subcls, const char *op_name);
 H5_DLL herr_t  H5VL__term_opt_operation(void);
+H5_DLL void H5VL__init_opt_operation_table(void);
 
 /* Testing functions */
 #ifdef H5VL_TESTING

src/H5VLprivate.h

@@ -34,23 +34,15 @@
 /* Internal struct to track VOL connector information for objects */
 typedef struct H5VL_t {
     const H5VL_class_t *cls; /* Pointer to connector class struct                    */
-#ifdef H5_HAVE_MULTITHREAD
-    _Atomic int64_t nrefs; /* Number of references by objects using this struct    */
-#else
-    int64_t nrefs; /* Number of references by objects using this struct    */
-#endif
+    H5_ATOMIC(int64_t) nrefs; /* Number of references by objects using this struct    */
     hid_t id; /* Identifier for the VOL connector                     */
 } H5VL_t;
 
 /* Internal vol object structure returned to the API */
 typedef struct H5VL_object_t {
     void   *data;      /* Pointer to connector-managed data for this object    */
     H5VL_t *connector; /* Pointer to VOL connector struct                      */
-#ifdef H5_HAVE_MULTITHREAD
-    _Atomic size_t rc; /* Reference count                                      */
-#else
-    size_t  rc;        /* Reference count                                      */
-#endif
+    H5_ATOMIC(size_t) rc; /* Reference count                                      */
 
 } H5VL_object_t;