[svn-r23473] Update the VOL plugin callbacks with better async I/O support:

 - change hid_t req in callbacks to void **req
 - change all callbacks to accept dxpl_ids (except dataset write and read which already do)
 - update all the private and public VL routines to accept a dxpl_id and event queue id
 - Add an async class for the VOL plugin with cancel, test, and wait request operations
 - add the external VOL log plugin test to the examples directory

NOTE that async operations are still not provided by the HDF5 API, so
all event queue IDs and requests passed to all plugins are NULL for
now.

Tested on jam.

1 files changed, 239 insertions, 131 deletions

diff --git a/src/H5VLint.c b/src/H5VLint.c
index 25b6fd2..90ed9d6 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -387,7 +387,7 @@ H5VL_object_register(void *obj, H5I_type_t obj_type, H5VL_t *vol_plugin, hbool_t
             break;
 
         case H5I_DATATYPE:
-            if ((ret_value = H5VL_create_datatype(obj, vol_plugin, app_ref, H5_REQUEST_NULL)) < 0)
+            if ((ret_value = H5VL_create_datatype(obj, vol_plugin, app_ref)) < 0)
                 HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize datatype handle")
             break;
 
@@ -467,7 +467,7 @@ done:
  */
 void *
 H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                 hid_t acpl_id, hid_t aapl_id, hid_t req)
+                 hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value;  /* Return value */
 
@@ -476,8 +476,10 @@ H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, co
     /* check if the corresponding VOL create callback exists */
     if(NULL == vol_plugin->cls->attr_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `attr create' method")
+
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.create) (obj, loc_params, name, acpl_id, aapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.create) (obj, loc_params, name, acpl_id, 
+                                                                aapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
     vol_plugin->nrefs ++;
@@ -501,7 +503,8 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t req)
+H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+               hid_t aapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value;  /* Return value */
 
@@ -511,7 +514,7 @@ H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, cons
     if(NULL == vol_plugin->cls->attr_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `attr open' method")
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.open) (obj, loc_params, name, aapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.open) (obj, loc_params, name, aapl_id, dxpl_id, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "attribute open failed")
 
     vol_plugin->nrefs ++;
@@ -534,7 +537,8 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, hid_t req)
+herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, 
+                      hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -542,7 +546,7 @@ herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *b
 
     if(NULL == vol_plugin->cls->attr_cls.read)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr read' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.read)(attr, mem_type_id, buf, req)) < 0)
+    if((ret_value = (vol_plugin->cls->attr_cls.read)(attr, mem_type_id, buf, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "read failed")
 
 done:
@@ -564,7 +568,8 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, hid_t req)
+herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, 
+                       hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -572,7 +577,7 @@ herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const
 
     if(NULL == vol_plugin->cls->attr_cls.write)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr write' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.write)(attr, mem_type_id, buf, req)) < 0)
+    if((ret_value = (vol_plugin->cls->attr_cls.write)(attr, mem_type_id, buf, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "write failed")
 
 done:
@@ -595,7 +600,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req, ...)
+H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, 
+              hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -604,8 +610,8 @@ H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req
 
     if(NULL == vol_plugin->cls->attr_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr get' method")
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->attr_cls.get)(obj, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->attr_cls.get)(obj, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 #if 0
@@ -613,7 +619,7 @@ H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req
     if(H5VL_ATTR_GET_TYPE == get_type) {
         hid_t           *ret_id;
 
-        va_start (arguments, req);
+        va_start (arguments, event_q);
         ret_id = va_arg (arguments, hid_t *);
 
         if(H5Tcommitted(*ret_id)) {
@@ -645,7 +651,7 @@ done:
  */
 herr_t 
 H5VL_attr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
-                 const char *attr_name, hid_t req)
+                 const char *attr_name, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -653,7 +659,7 @@ H5VL_attr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
 
     if(NULL == vol_plugin->cls->attr_cls.remove)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr remove' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.remove)(obj, loc_params, attr_name, req)) < 0)
+    if((ret_value = (vol_plugin->cls->attr_cls.remove)(obj, loc_params, attr_name, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTDELETE, FAIL, "remove failed")
 
 done:
@@ -676,7 +682,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t req)
+H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -687,19 +693,18 @@ H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t req)
     if(NULL == vol_plugin->cls->attr_cls.close){
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr close' method")
         /*
-        if(H5VL_object_close(id, req) < 0)
+        if(H5VL_object_close(id, dxpl_id, event_q) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close object")
         */
     }
-    else if((ret_value = (vol_plugin->cls->attr_cls.close)(attr, req)) < 0)
+    else if((ret_value = (vol_plugin->cls->attr_cls.close)(attr, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
     vol_plugin->nrefs --;
+
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
 
 done:
@@ -723,7 +728,8 @@ done:
  */
 void *
 H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                     hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t req)
+                     hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, 
+                     hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value = NULL;              /* Return value */
 
@@ -735,7 +741,7 @@ H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin
 
     /* call the corresponding VOL commit callback */
     if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.commit) 
-        (obj, loc_params, name, type_id, lcpl_id, tcpl_id, tapl_id, req)))
+        (obj, loc_params, name, type_id, lcpl_id, tcpl_id, tapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "commit failed")
     vol_plugin->nrefs ++;
 
@@ -760,7 +766,7 @@ done:
  */
 void *
 H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                   hid_t tapl_id, hid_t req)
+                   hid_t tapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value = NULL;              /* Return value */
 
@@ -777,11 +783,11 @@ H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
         loc_params.loc_data.loc_by_name.plist_id = tapl_id;
 
         /* Open the object class */
-        if((ret_value = H5VL_object_open(id, loc_params, H5_REQUEST_NULL)) < 0)
+        if((ret_value = H5VL_object_open(id, loc_params, dxpl_id, event_q)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "unable to open object")
 #endif
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.open)(obj, loc_params, name, tapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.open)(obj, loc_params, name, tapl_id, dxpl_id, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
     vol_plugin->nrefs ++;
 
@@ -805,7 +811,8 @@ done:
  *-------------------------------------------------------------------------
  */
 ssize_t 
-H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t req)
+H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, 
+                         hid_t dxpl_id, hid_t UNUSED event_q)
 {
     ssize_t ret_value = FAIL;
 
@@ -815,7 +822,7 @@ H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size
     if(NULL == vol_plugin->cls->datatype_cls.get_binary)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "no datatype get_binary callback");
     /* call the corresponding VOL open callback */
-    if((ret_value = (vol_plugin->cls->datatype_cls.get_binary)(obj, buf, size, req)) < 0)
+    if((ret_value = (vol_plugin->cls->datatype_cls.get_binary)(obj, buf, size, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "get binary failed")
 
 done:
@@ -837,7 +844,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t req)
+H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t		ret_value = SUCCEED;    /* Return value */
 
@@ -848,15 +855,13 @@ H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t req)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype close' method")
 
     /* call the corresponding VOL close callback */
-    if((ret_value = (vol_plugin->cls->datatype_cls.close)(dt, req)) < 0)
+    if((ret_value = (vol_plugin->cls->datatype_cls.close)(dt, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
 
 done:
@@ -880,7 +885,7 @@ done:
  */
 void *
 H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                    hid_t dcpl_id, hid_t dapl_id, hid_t req)
+                    hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value; /* Return value */
 
@@ -890,7 +895,7 @@ H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
     if(NULL == vol_plugin->cls->dataset_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `dataset create' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.create)(obj, loc_params, name, dcpl_id, dapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.create)(obj, loc_params, name, dcpl_id, dapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
     vol_plugin->nrefs ++;
 
@@ -915,7 +920,7 @@ done:
  */
 void *
 H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                  hid_t dapl_id, hid_t req)
+                  hid_t dapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value; /* Return value */
 
@@ -926,13 +931,13 @@ H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, c
         ;
 #if 0
         /* Open the object class */
-        if((ret_value = H5VL_object_open(id, loc_params, H5_REQUEST_NULL)) < 0)
+        if((ret_value = H5VL_object_open(id, loc_params, dxpl_id, event_q)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "unable to open object")
 #endif
     }
     else {
         /* call the corresponding VOL open callback */
-        if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.open)(obj, loc_params, name, dapl_id, req)))
+        if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.open)(obj, loc_params, name, dapl_id, dxpl_id, H5_REQUEST_NULL)))
             HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
         vol_plugin->nrefs ++;
 
@@ -958,7 +963,7 @@ done:
  */
 herr_t 
 H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
-                  hid_t file_space_id, hid_t plist_id, void *buf, hid_t req)
+                  hid_t file_space_id, hid_t plist_id, void *buf, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -967,7 +972,7 @@ H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_s
     if(NULL == vol_plugin->cls->dataset_cls.read)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset read' method")
     if((ret_value = (vol_plugin->cls->dataset_cls.read)
-        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, req)) < 0)
+        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_READERROR, FAIL, "read failed")
 
 done:
@@ -991,7 +996,7 @@ done:
  */
 herr_t 
 H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
-                   hid_t file_space_id, hid_t plist_id, const void *buf, hid_t req)
+                   hid_t file_space_id, hid_t plist_id, const void *buf, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1000,7 +1005,7 @@ H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_
     if(NULL == vol_plugin->cls->dataset_cls.write)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset write' method")
     if((ret_value = (vol_plugin->cls->dataset_cls.write)
-        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, req)) < 0)
+        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_WRITEERROR, FAIL, "write failed")
 
 done:
@@ -1023,7 +1028,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t 
-H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t req)
+H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], 
+                        hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1031,7 +1037,7 @@ H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hi
 
     if(NULL == vol_plugin->cls->dataset_cls.set_extent)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset set_extent' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.set_extent)(dset, size, req)) < 0)
+    if((ret_value = (vol_plugin->cls->dataset_cls.set_extent)(dset, size, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "set_extent failed")
 
 done:
@@ -1054,7 +1060,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t req, ...)
+H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, 
+                 hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1064,8 +1071,8 @@ H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hi
     if(NULL == vol_plugin->cls->dataset_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset get' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->dataset_cls.get)(dset, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->dataset_cls.get)(dset, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 
@@ -1074,7 +1081,7 @@ H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hi
     if(H5VL_DATASET_GET_TYPE == get_type) {
         hid_t           *ret_id;
 
-        va_start (arguments, req);
+        va_start (arguments, event_q);
         ret_id = va_arg (arguments, hid_t *);
 
         if(H5Tcommitted(*ret_id)) {
@@ -1106,7 +1113,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t req)
+H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1117,22 +1124,21 @@ H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t req)
     if(NULL == vol_plugin->cls->dataset_cls.close){
         ;
 #if 0
-        if(H5VL_object_close(id, req) < 0)
+        if(H5VL_object_close(id, dxpl_id, dxpl_id, event_q) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close object")
 #endif
     }
     else {
-        if((ret_value = (vol_plugin->cls->dataset_cls.close)(dset, req)) < 0)
+        if((ret_value = (vol_plugin->cls->dataset_cls.close)(dset, dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
     }
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_dataset_close() */
@@ -1154,7 +1160,7 @@ done:
  */
 void *
 H5VL_file_create(H5VL_t **plugin, const char *name, unsigned flags, hid_t fcpl_id, 
-                 hid_t fapl_id, hid_t req)
+                 hid_t fapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     H5P_genplist_t     *plist;                 /* Property list pointer */
     H5VL_class_t       *vol_cls;               /* VOL class attached to fapl_id */
@@ -1173,7 +1179,7 @@ H5VL_file_create(H5VL_t **plugin, const char *name, unsigned flags, hid_t fcpl_i
     if(NULL == vol_cls->file_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `file create' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_cls->file_cls.create)(name, flags, fcpl_id, fapl_id, req)))
+    if(NULL == (ret_value = (vol_cls->file_cls.create)(name, flags, fcpl_id, fapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
     /* Build the vol plugin struct */
@@ -1206,7 +1212,8 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t req)
+H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id, 
+               hid_t dxpl_id, hid_t UNUSED event_q)
 {
     H5P_genplist_t     *plist;                 /* Property list pointer */
     H5VL_class_t       *vol_cls;               /* VOL class attached to fapl_id */
@@ -1225,7 +1232,7 @@ H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id,
     if(NULL == vol_cls->file_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `file open' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_cls->file_cls.open)(name, flags, fapl_id, req)))
+    if(NULL == (ret_value = (vol_cls->file_cls.open)(name, flags, fapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
 
     /* Build the vol plugin struct */
@@ -1258,7 +1265,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, hid_t req)
+H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, 
+                hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1266,7 +1274,7 @@ H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F
 
     if(NULL == vol_plugin->cls->file_cls.flush)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file flush' method")
-    if((ret_value = (vol_plugin->cls->file_cls.flush)(obj, loc_params, scope, req)) < 0)
+    if((ret_value = (vol_plugin->cls->file_cls.flush)(obj, loc_params, scope, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTFLUSH, FAIL, "flush failed")
 
 done:
@@ -1289,7 +1297,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req, ...)
+H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, 
+              hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1299,8 +1308,8 @@ H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t re
     if(NULL == vol_plugin->cls->file_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file get' method")
 
-    va_start(arguments, req);
-    if((ret_value = (vol_plugin->cls->file_cls.get)(file, get_type, req, arguments)) < 0)
+    va_start(arguments, event_q);
+    if((ret_value = (vol_plugin->cls->file_cls.get)(file, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end(arguments);
 
@@ -1323,7 +1332,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t req, ...)
+H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, 
+               hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1336,7 +1346,7 @@ H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
         va_list             tmp_args;       /* argument list passed from the API call */
         hid_t               fapl_id;
 
-        va_start (tmp_args, req);
+        va_start (tmp_args, event_q);
         fapl_id = va_arg (tmp_args, hid_t);
         va_end (tmp_args);
 
@@ -1346,8 +1356,8 @@ H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
         if(H5P_get(plist, H5F_ACS_VOL_NAME, &vol_cls) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get vol plugin")
 
-        va_start (arguments, req);
-        if((ret_value = (vol_cls->file_cls.misc)(file, misc_type, req, arguments)) < 0)
+        va_start (arguments, event_q);
+        if((ret_value = (vol_cls->file_cls.misc)(file, misc_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "misc failed")
         va_end (arguments);
     }
@@ -1355,8 +1365,8 @@ H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
         if(NULL == vol_plugin->cls->file_cls.misc)
             HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file misc' method")
 
-        va_start (arguments, req);
-        if((ret_value = (vol_plugin->cls->file_cls.misc)(file, misc_type, req, arguments)) < 0)
+        va_start (arguments, event_q);
+        if((ret_value = (vol_plugin->cls->file_cls.misc)(file, misc_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "misc failed")
         va_end (arguments);
     }
@@ -1380,7 +1390,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t req, ...)
+H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, 
+                   hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1390,8 +1401,8 @@ H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional
     if(NULL == vol_plugin->cls->file_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file optional' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->file_cls.optional)(file, optional_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->file_cls.optional)(file, optional_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "optional failed")
     va_end (arguments);
 
@@ -1420,7 +1431,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t req)
+H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1428,16 +1439,15 @@ H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t req)
 
     if(NULL == vol_plugin->cls->file_cls.close)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file close' method")
-    if((ret_value = (vol_plugin->cls->file_cls.close)(file, req)) < 0)
+    if((ret_value = (vol_plugin->cls->file_cls.close)(file, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTCLOSEFILE, FAIL, "close failed")
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_file_close() */
@@ -1459,7 +1469,7 @@ done:
  */
 void *
 H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                  hid_t gcpl_id, hid_t gapl_id, hid_t req)
+                  hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value = NULL; /* Return value */
 
@@ -1469,7 +1479,7 @@ H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, c
     if(NULL == vol_plugin->cls->group_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `group create' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->group_cls.create)(obj, loc_params, name, gcpl_id, gapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->group_cls.create)(obj, loc_params, name, gcpl_id, gapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
     vol_plugin->nrefs ++;
 
@@ -1494,7 +1504,7 @@ done:
  */
 void *
 H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                hid_t gapl_id, hid_t req)
+                hid_t gapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value; /* Return value */
 
@@ -1505,13 +1515,13 @@ H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, con
         ;
 #if 0
         /* Open the object class */
-        if((ret_value = H5VL_object_open(id, loc_params, H5_REQUEST_NULL)) < 0)
+        if((ret_value = H5VL_object_open(id, loc_params, dxpl_id, event_q)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "unable to open object")
 #endif
     }
     else {
         /* call the corresponding VOL open callback */
-        if(NULL == (ret_value = (vol_plugin->cls->group_cls.open)(obj, loc_params, name, gapl_id, req)))
+        if(NULL == (ret_value = (vol_plugin->cls->group_cls.open)(obj, loc_params, name, gapl_id, dxpl_id, H5_REQUEST_NULL)))
             HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
         vol_plugin->nrefs ++;
     }
@@ -1535,7 +1545,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t req, ...)
+H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, 
+               hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1544,8 +1555,8 @@ H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t r
 
     if(NULL == vol_plugin->cls->group_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group get' method")
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->group_cls.get)(obj, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->group_cls.get)(obj, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 
@@ -1569,7 +1580,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t req)
+H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1580,21 +1591,19 @@ H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t req)
     if(NULL == vol_plugin->cls->group_cls.close) {
         ;
 #if 0
-        if(H5VL_object_close(id, req) < 0)
+        if(H5VL_object_close(id, dxpl_id, event_q) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close object")
 #endif
     }
     else {
-        if((ret_value = (vol_plugin->cls->group_cls.close)(grp, req)) < 0)
+        if((ret_value = (vol_plugin->cls->group_cls.close)(grp, dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
    }
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
 
 done:
@@ -1616,7 +1625,7 @@ done:
  */
 herr_t
 H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, 
-                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t req)
+                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
 
@@ -1627,7 +1636,7 @@ H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link create' method")
     /* call the corresponding VOL create callback */
     if((ret_value = (vol_plugin->cls->link_cls.create)
-        (create_type, obj, loc_params, lcpl_id, lapl_id, req)) < 0)
+        (create_type, obj, loc_params, lcpl_id, lapl_id, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link create failed")
 
 done:
@@ -1647,9 +1656,10 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5_DLL herr_t H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj, 
-                             H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin, 
-                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t req)
+herr_t 
+H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj,
+               H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin, hbool_t copy_flag, 
+               hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
 
@@ -1660,7 +1670,7 @@ H5_DLL herr_t H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link move' method")
     /* call the corresponding VOL move callback */
     if((ret_value = (vol_plugin->cls->link_cls.move)
-        (src_obj, loc_params1, dst_obj, loc_params2, copy_flag, lcpl_id, lapl_id, req)) < 0)
+        (src_obj, loc_params1, dst_obj, loc_params2, copy_flag, lcpl_id, lapl_id, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link move failed")
 
 done:
@@ -1681,9 +1691,10 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_link_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
-                         hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, 
-                         H5L_iterate_t op, void *op_data, hid_t req)
+herr_t 
+H5VL_link_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                  hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, 
+                  H5L_iterate_t op, void *op_data, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1692,7 +1703,7 @@ herr_t H5VL_link_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_pl
     if(NULL == vol_plugin->cls->link_cls.iterate)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link iterate' method")
     if((ret_value = (vol_plugin->cls->link_cls.iterate)(obj, loc_params, recursive, idx_type,
-                                                        order, idx, op, op_data, req)) < 0)
+                                                        order, idx, op, op_data, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_BADITER, FAIL, "iteration failed")
 
 done:
@@ -1716,7 +1727,7 @@ done:
  */
 herr_t
 H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, 
-              hid_t req, ...)
+              hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1725,8 +1736,8 @@ H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_
 
     if(NULL == vol_plugin->cls->link_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link get' method")
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->link_cls.get)(obj, loc_params, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->link_cls.get)(obj, loc_params, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 
@@ -1747,7 +1758,9 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5_DLL herr_t H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req)
+herr_t 
+H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                 hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t             ret_value = SUCCEED;    /* Return value */
 
@@ -1757,7 +1770,7 @@ H5_DLL herr_t H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *
     if(NULL == vol_plugin->cls->link_cls.remove)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link remove' method")
     /* call the corresponding VOL remove callback */
-    if((ret_value = (vol_plugin->cls->link_cls.remove)(obj, loc_params, req)) < 0)
+    if((ret_value = (vol_plugin->cls->link_cls.remove)(obj, loc_params, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link remove failed")
 
 done:
@@ -1781,7 +1794,7 @@ done:
  */
 void *
 H5VL_object_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_type_t *opened_type,
-                 hid_t req)
+                 hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value;              /* Return value */
 
@@ -1791,7 +1804,7 @@ H5VL_object_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_ty
     if(NULL == vol_plugin->cls->object_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `object open' method")
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->object_cls.open)(obj, params, opened_type, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->object_cls.open)(obj, params, opened_type, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
     vol_plugin->nrefs++;
 
@@ -1816,7 +1829,7 @@ done:
 herr_t 
 H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
                  void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
-                 hid_t ocpypl_id, hid_t lcpl_id, hid_t req)
+                 hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1829,7 +1842,7 @@ H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugi
     if(NULL == vol_plugin1->cls->object_cls.copy)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object copy' method")
     if((ret_value = (vol_plugin1->cls->object_cls.copy)
-        (src_obj, loc_params1, src_name, dst_obj, loc_params2, dst_name, ocpypl_id, lcpl_id, req)) < 0)
+        (src_obj, loc_params1, src_name, dst_obj, loc_params2, dst_name, ocpypl_id, lcpl_id, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "copy failed")
 
 done:
@@ -1850,8 +1863,9 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5_index_t idx_type,
-                         H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t req)
+herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                         H5_index_t idx_type, H5_iter_order_t order, H5O_iterate_t op, 
+                         void *op_data, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1861,7 +1875,7 @@ herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_pl
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object visit' method")
 
     if((ret_value = (vol_plugin->cls->object_cls.visit)(obj, loc_params, idx_type, order, op, 
-                                                        op_data, req)) < 0)
+                                                        op_data, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_BADITER, FAIL, "object visitation failed")
 
 done:
@@ -1885,7 +1899,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_lookup(hid_t id, H5VL_loc_type_t lookup_type, void **location, hid_t req, ...)
+H5VL_object_lookup(hid_t id, H5VL_loc_type_t lookup_type, void **location, 
+                   hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     H5VL_class_t      *vol_plugin;            /* VOL structure attached to id */
@@ -1899,8 +1914,8 @@ H5VL_object_lookup(hid_t id, H5VL_loc_type_t lookup_type, void **location, hid_t
     if(NULL == vol_plugin->object_cls.lookup)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object lookup' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->object_cls.lookup)(id, lookup_type, location, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->object_cls.lookup)(id, lookup_type, location, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "lookup of object location failed")
     va_end (arguments);
 done:
@@ -1922,7 +1937,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_free_loc(hid_t id, void *location, hid_t req)
+H5VL_object_free_loc(hid_t id, void *location, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     H5VL_class_t       *vol_plugin;            /* VOL structure attached to id */
     herr_t            ret_value = SUCCEED;
@@ -1935,7 +1950,7 @@ H5VL_object_free_loc(hid_t id, void *location, hid_t req)
     if(NULL == vol_plugin->object_cls.free_loc)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object free_loc' method")
 
-    if((ret_value = (vol_plugin->object_cls.free_loc)(location, req)) < 0)
+    if((ret_value = (vol_plugin->object_cls.free_loc)(location, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "freeing location token of object location failed")
 
 done:
@@ -1959,7 +1974,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t req, ...)
+H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, 
+                hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1969,8 +1985,8 @@ H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5V
     if(NULL == vol_plugin->cls->object_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object get' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->object_cls.get)(obj, loc_params, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->object_cls.get)(obj, loc_params, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 done:
@@ -1992,7 +2008,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, hid_t req, ...)
+H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, 
+                 hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -2002,8 +2019,8 @@ H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5
     if(NULL == vol_plugin->cls->object_cls.misc)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object misc' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->object_cls.misc)(obj, loc_params, misc_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->object_cls.misc)(obj, loc_params, misc_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "misc failed")
     va_end (arguments);
 
@@ -2027,7 +2044,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req)
+H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                  hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -2035,9 +2053,99 @@ H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, h
 
     if(NULL == vol_plugin->cls->object_cls.close)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object close' method")
-    if((ret_value = (vol_plugin->cls->object_cls.close)(obj, loc_params, req)) < 0)
+    if((ret_value = (vol_plugin->cls->object_cls.close)(obj, loc_params, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_object_close() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_request_cancel
+ *
+ * Purpose:	Cancels a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_request_cancel(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t              ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if(NULL == vol_plugin->cls->async_cls.cancel)
+	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async cancel' method");
+    if((ret_value = (vol_plugin->cls->async_cls.cancel)(req, status)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request cancel failed")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_request_cancel() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_request_test
+ *
+ * Purpose:	Tests a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_request_test(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t              ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if(NULL == vol_plugin->cls->async_cls.test)
+	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async test' method");
+    if((ret_value = (vol_plugin->cls->async_cls.test)(req, status)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request test failed")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_request_test() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_request_wait
+ *
+ * Purpose:	Waits a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_request_wait(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t              ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if(NULL == vol_plugin->cls->async_cls.wait)
+	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async wait' method");
+    if((ret_value = (vol_plugin->cls->async_cls.wait)(req, status)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request wait failed")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_request_wait() */