Bring async branch to develop (#166)

* Add H5Fwait, H5Dwait, and other changes for async vol connector

* Revert temporary testing changes

* Add H5Fwait to header file

* Add H5VLreset_lib_state() routine.

* Correct VOL wrap context when retrieving library state for file open & create.

* Manage the API context's VOL connector state as part of the library state.

* Set the 'VOL connector property valid' flag when restoring the library state.

* Don't push new API context on stack when retrieving "current" one.

* Check for NULL VOL wrap context before decrementing refcount on it, when
freeing the API context state.

* Manage recount of underlying connector for VOL wrap context.

* Add H5TSmutex_acquire() and H5TSmutex_release() routines to acquire and
release the global lock on the HDF5 library.

* Update library with new functions related to library global lock

* Add asynchronous token API

* Add new lightweight FUNC_ENTER / LEAVE macros for helping to structure the
threadsafety (H5TS*) routines.

* Sync w/develop

* Initial event set code framework.

* Elaborate on the H5ES routines, starting to add API routines.

Update the "close ID" callbacks to allow asynchronous request tokens to be
passed in from an asynchronous close API call.

Refactor current asynchronous API routines (H5Fopen/H5Fclose and
H5Dread/H5Dread) to use event sets instead of directly working with request
tokens from the application.

Clean up a few other minor warnings & code style issues.

* Implement H5EScreate, H5ESget_count, and H5ESclose.

It should be possible to write a simple application that creates an event
set and uses it with H5Fopen_async, H5Dread_async, H5Dwrite_async, and
H5Fclose_async, then calls H5ESclose (which waits for all async events to
complete).

* Add source file for event set test.

* Refactor sync & async API routines to call common routine.

Move dataset API read / write routines to src/H5D.c, along with all the other
API routines.

Progress on "fake" async VOL connector, for testing.

* Modify async implementation to wrap async requests in a H5VL_object_t
struct so the VOL layer can find the connector when accessing the
request at a later point.

* Free the requests is H5ESclose.  Remove comments implying that request
wait, notify, and cancel callbacks should free the request.

* Fix bug in error handling in H5Fclose.

* Fix bugs in async file routines.  Rename H5VL_create_object_generic to
H5VL_create_object.

* Add explicit async version of H5Fcreate.

* Add more _async routines

* Correct typo for return value from H5Awrite changes

* Add H5EStest and H5ESwait routines

* Updated with API tracing info

* Fix NULL pointer dereference in H5ES__wait

* Add H5is_library_terminating() routine, so that VOL connectors can detect
when the library is shutting down.

* Fix typo

* Remove event from event set's linked list

* Move block of code so that vol_obj is valid

* Avoid setting properties in the DXPL when reseting the library state (and in
the test code).

* Refactor argument tracing to implement new capability for tracing arguments
of non-API routines, with the H5ARG_TRACE macro.   This macro is updated
automatically with the bin/trace script that runs as part of the autogen.sh
process.   Major changes were in src/H5trace.c and bin/trace, with the other
changes being cleanups to the argument lists, to improve their presentation
in the tracing output.

Also - added the "managed string" routines, which can dynamically allocate
strings, appending printf-formatted output to the string efficiently.

* Release memory for managed strings

* Fix printf() formats.

* More printf() format fixes.

* Add H5Eappend_stack routine and regression tests

* Clean up a few missed merge conflicts and update the error stacks.

* Remove unnecessary fork() operations and ten second sleep().

* Restore commented out attribute out, to better enable tracking down the previous failure

* Allow multiple H5ARG_TRACE macros within a routine to be updated

* Switch to using "new" H5ES_insert (which takes the arguments for the caller routine) for all event set operations.  Renames H5ES_insert_new to H5ES_insert and removes the previous H5ES_insert.

* Merge "managed" string routines into "ref-counted" strings, and refactor code to use them.

* Add missing file.

* Add caller's name and arguments to event, for error reporting

* Refactor event set setup for "API common" internal routines

* Checkin async API routines for H5A* and H5G* modules as listed in ID-283.
Fix couple h5dump expected output files due to the changes.

* Add some of the error query routines needed for event sets.

* Refactor to make async setup / teardown and "common" routines cleaner

* (1) Add async APIs to H5L, H5F, and H5D modules
(2) Fix errors in previous checkins of async APIs in H5A and H5G modules
(3) h5dump expected output changes

* Enhance event info, for better error handling

* Change name of temporary vol_obj variable, to help reduce coding errors

* Fix oversight with vol_obj pointer

* Minor code cleanup

* Add missing \'valid\' flag for VOL wrapper context, when restoring the library\'s state

* Run source formatter

* Change H5TSmutex lock and release to include a lock count

* Update error reporting ideas

* Minor updates to improve sanity checking for retrieving / restoring library state

* Updated with feedback from h5py team members

* Refactor internal event set list and event handling, add implementation for H5ESget_err_info

* Change the VOL request subclass callbacks that switch from using "H5ES_status_t" to "H5VL_request_status_t", and also add a H5VL_request_status_t* parameter to the 'cancel' callback in the request subclass.  Also more code quality cleanups to add iterator callbacks to internal event set routines.

* Update API tracing for new H5VL_request_status_t typedef

* Finish converting internal event set operations to use list iterator callbacks, instead of directly accessing the list structure

* Add H5VL_REQUEST_GET_ERR_STACK operation to request subclass, for retrieving a copy of the error stack for a failed asynchronous operation

* Remove 'canceled' event status from Java constants

* Be safer about releasing resources when inserting a newly opened/created object or file into an event set

* Remove H5EStest, add H5ES_WAIT_NONE for 0 timeout, and revise parameters to H5ESwait, to make it more "aggregate".

* Remove H5ES_STATUS_CANCELED from Java wrappers also

* (a) Add async APIs for H5O module as listed in jira issue ID-283.
(b) Remove verification of name parameter in async related routines for H55A and H5L modules
    because it is checked in H5VL_setup* routine.
(c) Modify h5dump expected output due to the async changes.

* Corrections based on PR feedback.

* Further changes to make based on PR feedback.

* Fix missed merge marker, and reformatted line

* Clean up some warnings

* Correct level of indirection

* Relocate prototype (and doxygen info) for H5Aclose

* Change non-static function declarations to be static

* Ensure that H5TSpublic.h header gets installed (#129)

* Add 'wrapper' versions of async calls, to allow language wrappers and layers on top of HDF5 to pass in their application information.

* Switch H5Aexists\*_async and H5Lexists\*_async to use flag to return status, instead of return value.  Make the corresponding changes through most of the v1 and v2 B-tree code.  Clean up warnings in H5public.h and cmpd_dtransform.c.

* Add H5Iregister_future routine and tests.

* Correct return value for H5Lexists_async

* Add H5_DLL macro to public H5ES API routines

* Update supported -> flags parameter for introspect_query callback

* Remove my email address.  Update passthrough VOL connector ID.

* Fix comment for post_open_api_common

* Remove unused non-blocking VOL connector

* Minor cleanup in async branch in preparation for merge to develop

* Update CMake and the Autotools to use the new pass-through VOL ID

* Fix for SWMR daily test failures (#160)

The H5I_register_using_existing_id() call did not initialize the future
ID callbacks, causing the library to segfault when it tried to
resolve those function pointers.

* Added selective async APIs (#150)

* Added selective async APIs

Description:
    Added the following APIs:
        H5Ropen_attr_async
        H5Ropen_object_async
        H5Ropen_region_async

        H5Mcreate_async
        H5Mopen_async
        H5Mput_async
        H5Mget_async
        H5Mclose_async

        H5Tcommit_async
        H5Topen_async
        H5Tcopy_async
        H5Tclose_async
    - Updated an expected output file to include a new internal function
      in the error stack for the failure case.

* Updated async APIs per reviews, including removing async version of
H5Tcopy.

* Removed statements that were added by mistake in the previous commit.

* Fix compile issues in H5M and warnings elsewhere

* Reformat code

* Brings VOL_LIST changes from develop. (#163)

Co-authored-by: Houjun Tang <htang4@lbl.gov>
Co-authored-by: Neil Fortner <nfortne2@hdfgroup.org>
Co-authored-by: vchoi <vchoi@jelly.ad.hdfgroup.org>
Co-authored-by: vchoi-hdfgroup <55293060+vchoi-hdfgroup@users.noreply.github.com>
Co-authored-by: jhendersonHDF <jhenderson@hdfgroup.org>
Co-authored-by: Dana Robinson <derobins@hdfgroup.org>
Co-authored-by: Dana Robinson <43805+derobins@users.noreply.github.com>
Co-authored-by: bmribler <39579120+bmribler@users.noreply.github.com>

1 files changed, 524 insertions, 147 deletions

diff --git a/src/H5G.c b/src/H5G.c
index 7d8ed39..c59194d 100644
--- a/src/H5G.c
+++ b/src/H5G.c
@@ -83,6 +83,7 @@
 #include "H5private.h"   /* Generic Functions                        */
 #include "H5CXprivate.h" /* API Contexts                             */
 #include "H5Eprivate.h"  /* Error handling                           */
+#include "H5ESprivate.h" /* Event Sets                               */
 #include "H5Gpkg.h"      /* Groups                                   */
 #include "H5Iprivate.h"  /* IDs                                      */
 #include "H5Pprivate.h"  /* Property lists                           */
@@ -104,6 +105,20 @@
 /* Local Prototypes */
 /********************/
 
+/* Helper routines for sync/async API calls */
+static hid_t  H5G__create_api_common(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id,
+                                     hid_t gapl_id, void **token_ptr, H5VL_object_t **_vol_obj_ptr);
+static hid_t  H5G__open_api_common(hid_t loc_id, const char *name, hid_t gapl_id, void **token_ptr,
+                                   H5VL_object_t **_vol_obj_ptr);
+static herr_t H5G__get_info_api_common(hid_t loc_id, H5G_info_t *group_info /*out*/, void **token_ptr,
+                                       H5VL_object_t **_vol_obj_ptr);
+static herr_t H5G__get_info_by_name_api_common(hid_t loc_id, const char *name, H5G_info_t *group_info /*out*/,
+                                               hid_t lapl_id, void **token_ptr, H5VL_object_t **_vol_obj_ptr);
+static herr_t H5G__get_info_by_idx_api_common(hid_t loc_id, const char *group_name, H5_index_t idx_type,
+                                              H5_iter_order_t order, hsize_t n,
+                                              H5G_info_t *group_info /*out*/, hid_t lapl_id, void **token_ptr,
+                                              H5VL_object_t **_vol_obj_ptr);
+
 /*********************/
 /* Package Variables */
 /*********************/
@@ -117,38 +132,27 @@
 /*******************/
 
 /*-------------------------------------------------------------------------
- * Function:    H5Gcreate2
- *
- * Purpose:     Creates a new group relative to LOC_ID, giving it the
- *              specified creation property list GCPL_ID and access
- *              property list GAPL_ID.  The link to the new group is
- *              created with the LCPL_ID.
- *
- * Usage:       H5Gcreate2(loc_id, char *name, lcpl_id, gcpl_id, gapl_id)
- *                  hid_t loc_id;	  IN: File or group identifier
- *                  const char *name; IN: Absolute or relative name of the new group
- *                  hid_t lcpl_id;	  IN: Property list for link creation
- *                  hid_t gcpl_id;	  IN: Property list for group creation
- *                  hid_t gapl_id;	  IN: Property list for group access
+ * Function:    H5G__create_api_common
  *
- * Return:      Success:    The object ID of a new, empty group open for
- *                          writing.  Call H5Gclose() when finished with
- *                          the group.
+ * Purpose:     This is the common function for creating HDF5 groups.
  *
+ * Return:      Success:    A group ID
  *              Failure:    H5I_INVALID_HID
  *
  *-------------------------------------------------------------------------
  */
-hid_t
-H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t gapl_id)
+static hid_t
+H5G__create_api_common(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t gapl_id,
+                       void **token_ptr, H5VL_object_t **_vol_obj_ptr)
 {
-    void *            grp     = NULL; /* Structure for new group */
-    H5VL_object_t *   vol_obj = NULL; /* object of loc_id */
-    H5VL_loc_params_t loc_params;
-    hid_t             ret_value = H5I_INVALID_HID; /* Return value */
+    void *          grp         = NULL; /* Structure for new group */
+    H5VL_object_t * tmp_vol_obj = NULL; /* Object for loc_id */
+    H5VL_object_t **vol_obj_ptr =
+        (_vol_obj_ptr ? _vol_obj_ptr : &tmp_vol_obj); /* Ptr to object ptr for loc_id */
+    H5VL_loc_params_t loc_params;                     /* Location parameters for object access */
+    hid_t             ret_value = H5I_INVALID_HID;    /* Return value */
 
-    FUNC_ENTER_API(H5I_INVALID_HID)
-    H5TRACE5("i", "i*siii", loc_id, name, lcpl_id, gcpl_id, gapl_id);
+    FUNC_ENTER_STATIC
 
     /* Check arguments */
     if (!name)
@@ -156,6 +160,10 @@ H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t g
     if (!*name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "name parameter cannot be an empty string")
 
+    /* Set up object access arguments */
+    if (H5VL_setup_acc_args(loc_id, H5P_CLS_GACC, TRUE, &gapl_id, vol_obj_ptr, &loc_params) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, H5I_INVALID_HID, "can't set object access arguments")
+
     /* Check link creation property list */
     if (H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
@@ -171,36 +179,109 @@ H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t g
     /* Set the LCPL for the API context */
     H5CX_set_lcpl(lcpl_id);
 
-    /* Verify access property list and set up collective metadata if appropriate */
-    if (H5CX_set_apl(&gapl_id, H5P_CLS_GACC, loc_id, TRUE) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
-
-    /* Get the location object */
-    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
-
-    /* Set the location parameters */
-    loc_params.type     = H5VL_OBJECT_BY_SELF;
-    loc_params.obj_type = H5I_get_type(loc_id);
-
     /* Create the group */
-    if (NULL == (grp = H5VL_group_create(vol_obj, &loc_params, name, lcpl_id, gcpl_id, gapl_id,
-                                         H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL)))
+    if (NULL == (grp = H5VL_group_create(*vol_obj_ptr, &loc_params, name, lcpl_id, gcpl_id, gapl_id,
+                                         H5P_DATASET_XFER_DEFAULT, token_ptr)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, H5I_INVALID_HID, "unable to create group")
 
     /* Get an ID for the group */
-    if ((ret_value = H5VL_register(H5I_GROUP, grp, vol_obj->connector, TRUE)) < 0)
+    if ((ret_value = H5VL_register(H5I_GROUP, grp, (*vol_obj_ptr)->connector, TRUE)) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to get ID for group handle")
 
 done:
     if (H5I_INVALID_HID == ret_value)
-        if (grp && H5VL_group_close(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL) < 0)
+        if (grp && H5VL_group_close(*vol_obj_ptr, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, H5I_INVALID_HID, "unable to release group")
 
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5G__create_api_common() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Gcreate2
+ *
+ * Purpose:     Creates a new group relative to LOC_ID, giving it the
+ *              specified creation property list GCPL_ID and access
+ *              property list GAPL_ID.  The link to the new group is
+ *              created with the LCPL_ID.
+ *
+ * Usage:       H5Gcreate2(loc_id, char *name, lcpl_id, gcpl_id, gapl_id)
+ *                  hid_t loc_id;	  IN: File or group identifier
+ *                  const char *name; IN: Absolute or relative name of the new group
+ *                  hid_t lcpl_id;	  IN: Property list for link creation
+ *                  hid_t gcpl_id;	  IN: Property list for group creation
+ *                  hid_t gapl_id;	  IN: Property list for group access
+ *
+ * Return:      Success:    The object ID of a new, empty group open for
+ *                          writing.  Call H5Gclose() when finished with
+ *                          the group.
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t gapl_id)
+{
+    hid_t ret_value = H5I_INVALID_HID; /* Return value */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE5("i", "i*siii", loc_id, name, lcpl_id, gcpl_id, gapl_id);
+
+    /* Create the group synchronously */
+    if ((ret_value = H5G__create_api_common(loc_id, name, lcpl_id, gcpl_id, gapl_id, NULL, NULL)) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTCREATE, H5I_INVALID_HID, "unable to synchronously create group")
+
+done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gcreate2() */
 
 /*-------------------------------------------------------------------------
+ * Function:    H5Gcreate_async
+ *
+ * Purpose:     Asynchronous version of H5Gcreate
+ *
+ * Return:      Success:    A group ID
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Gcreate_async(const char *app_file, const char *app_func, unsigned app_line, hid_t loc_id, const char *name,
+                hid_t lcpl_id, hid_t gcpl_id, hid_t gapl_id, hid_t es_id)
+{
+    H5VL_object_t *vol_obj   = NULL;            /* Object for loc_id */
+    void *         token     = NULL;            /* Request token for async operation        */
+    void **        token_ptr = H5_REQUEST_NULL; /* Pointer to request token for async operation        */
+    hid_t          ret_value = H5I_INVALID_HID; /* Return value */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE9("i", "*s*sIui*siiii", app_file, app_func, app_line, loc_id, name, lcpl_id, gcpl_id, gapl_id,
+             es_id);
+
+    /* Set up request token pointer for asynchronous operation */
+    if (H5ES_NONE != es_id)
+        token_ptr = &token; /* Point at token for VOL connector to set up */
+
+    /* Create the group asynchronously */
+    if ((ret_value = H5G__create_api_common(loc_id, name, lcpl_id, gcpl_id, gapl_id, token_ptr, &vol_obj)) <
+        0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTCREATE, H5I_INVALID_HID, "unable to asynchronously create group")
+
+    /* If a token was created, add the token to the event set */
+    if (NULL != token)
+        if (H5ES_insert(es_id, vol_obj->connector, token,
+                        H5ARG_TRACE9(FUNC, "*s*sIui*siiii", app_file, app_func, app_line, loc_id, name,
+                                     lcpl_id, gcpl_id, gapl_id, es_id)) < 0) {
+            if (H5I_dec_app_ref_always_close(ret_value) < 0)
+                HDONE_ERROR(H5E_SYM, H5E_CANTDEC, H5I_INVALID_HID, "can't decrement count on group ID")
+            HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, H5I_INVALID_HID, "can't insert token into event set")
+        } /* end if */
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Gcreate_async() */
+
+/*-------------------------------------------------------------------------
  * Function:    H5Gcreate_anon
  *
  * Purpose:     Creates a new group relative to LOC_ID, giving it the
@@ -280,30 +361,27 @@ done:
 } /* end H5Gcreate_anon() */
 
 /*-------------------------------------------------------------------------
- * Function:    H5Gopen2
+ * Function:    H5G__open_api_common
  *
- * Purpose:     Opens an existing group for modification.  When finished,
- *              call H5Gclose() to close it and release resources.
- *
- *              This function allows the user the pass in a Group Access
- *              Property List, which H5Gopen1() does not.
- *
- * Return:      Success:    Object ID of the group
+ * Purpose:     This is the common function for opening HDF5 groups.
  *
+ * Return:      Success:    A group ID
  *              Failure:    H5I_INVALID_HID
  *
  *-------------------------------------------------------------------------
  */
-hid_t
-H5Gopen2(hid_t loc_id, const char *name, hid_t gapl_id)
+static hid_t
+H5G__open_api_common(hid_t loc_id, const char *name, hid_t gapl_id, void **token_ptr,
+                     H5VL_object_t **_vol_obj_ptr)
 {
-    void *            grp     = NULL; /* Group opened */
-    H5VL_object_t *   vol_obj = NULL; /* object of loc_id */
-    H5VL_loc_params_t loc_params;
-    hid_t             ret_value = H5I_INVALID_HID; /* Return value */
+    void *          grp         = NULL; /* Group opened */
+    H5VL_object_t * tmp_vol_obj = NULL; /* Object for loc_id */
+    H5VL_object_t **vol_obj_ptr =
+        (_vol_obj_ptr ? _vol_obj_ptr : &tmp_vol_obj); /* Ptr to object ptr for loc_id */
+    H5VL_loc_params_t loc_params;                     /* Location parameters for object access */
+    hid_t             ret_value = H5I_INVALID_HID;    /* Return value */
 
-    FUNC_ENTER_API(H5I_INVALID_HID)
-    H5TRACE3("i", "i*si", loc_id, name, gapl_id);
+    FUNC_ENTER_STATIC
 
     /* Check args */
     if (!name)
@@ -311,35 +389,102 @@ H5Gopen2(hid_t loc_id, const char *name, hid_t gapl_id)
     if (!*name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "name parameter cannot be an empty string")
 
-    /* Verify access property list and set up collective metadata if appropriate */
-    if (H5CX_set_apl(&gapl_id, H5P_CLS_GACC, loc_id, FALSE) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
-
-    /* Get the location object */
-    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
+    /* Set up object access arguments */
+    if (H5VL_setup_acc_args(loc_id, H5P_CLS_GACC, FALSE, &gapl_id, vol_obj_ptr, &loc_params) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, H5I_INVALID_HID, "can't set object access arguments")
 
-    /* Open the group */
-    loc_params.type     = H5VL_OBJECT_BY_SELF;
-    loc_params.obj_type = H5I_get_type(loc_id);
-
-    if (NULL == (grp = H5VL_group_open(vol_obj, &loc_params, name, gapl_id, H5P_DATASET_XFER_DEFAULT,
-                                       H5_REQUEST_NULL)))
+    if (NULL == (grp = H5VL_group_open(*vol_obj_ptr, &loc_params, name, gapl_id, H5P_DATASET_XFER_DEFAULT,
+                                       token_ptr)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open group")
 
     /* Register an ID for the group */
-    if ((ret_value = H5VL_register(H5I_GROUP, grp, vol_obj->connector, TRUE)) < 0)
+    if ((ret_value = H5VL_register(H5I_GROUP, grp, (*vol_obj_ptr)->connector, TRUE)) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register group")
 
 done:
     if (H5I_INVALID_HID == ret_value)
-        if (grp && H5VL_group_close(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL) < 0)
+        if (grp && H5VL_group_close(*vol_obj_ptr, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, H5I_INVALID_HID, "unable to release group")
 
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5G__open_api_common() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Gopen2
+ *
+ * Purpose:     Opens an existing group for modification.  When finished,
+ *              call H5Gclose() to close it and release resources.
+ *
+ *              This function allows the user the pass in a Group Access
+ *              Property List, which H5Gopen1() does not.
+ *
+ * Return:      Success:    Object ID of the group
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Gopen2(hid_t loc_id, const char *name, hid_t gapl_id)
+{
+    hid_t ret_value = H5I_INVALID_HID; /* Return value */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE3("i", "i*si", loc_id, name, gapl_id);
+
+    /* Open the group synchronously */
+    if ((ret_value = H5G__open_api_common(loc_id, name, gapl_id, NULL, NULL)) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTCREATE, H5I_INVALID_HID, "unable to synchronously open group")
+
+done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gopen2() */
 
 /*-------------------------------------------------------------------------
+ * Function:    H5Gopen_async
+ *
+ * Purpose:     Asynchronous version of H5Gopen2
+ *
+ * Return:      Success:    A group ID
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Gopen_async(const char *app_file, const char *app_func, unsigned app_line, hid_t loc_id, const char *name,
+              hid_t gapl_id, hid_t es_id)
+{
+    H5VL_object_t *vol_obj   = NULL;            /* Object for loc_id */
+    void *         token     = NULL;            /* Request token for async operation        */
+    void **        token_ptr = H5_REQUEST_NULL; /* Pointer to request token for async operation        */
+    hid_t          ret_value = H5I_INVALID_HID; /* Return value */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE7("i", "*s*sIui*sii", app_file, app_func, app_line, loc_id, name, gapl_id, es_id);
+
+    /* Set up request token pointer for asynchronous operation */
+    if (H5ES_NONE != es_id)
+        token_ptr = &token; /* Point at token for VOL connector to set up */
+
+    /* Open the group asynchronously */
+    if ((ret_value = H5G__open_api_common(loc_id, name, gapl_id, token_ptr, &vol_obj)) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTCREATE, H5I_INVALID_HID, "unable to asynchronously open group")
+
+    /* If a token was created, add the token to the event set */
+    if (NULL != token)
+        if (H5ES_insert(es_id, vol_obj->connector, token,
+                        H5ARG_TRACE7(FUNC, "*s*sIui*sii", app_file, app_func, app_line, loc_id, name, gapl_id,
+                                     es_id)) < 0) {
+            if (H5I_dec_app_ref_always_close(ret_value) < 0)
+                HDONE_ERROR(H5E_SYM, H5E_CANTDEC, H5I_INVALID_HID, "can't decrement count on group ID")
+            HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, H5I_INVALID_HID, "can't insert token into event set")
+        } /* end if */
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Gopen_async() */
+
+/*-------------------------------------------------------------------------
  * Function:    H5Gget_create_plist
  *
  * Purpose:     Returns a copy of the group creation property list.
@@ -375,6 +520,49 @@ done:
 } /* end H5Gget_create_plist() */
 
 /*-------------------------------------------------------------------------
+ * Function:    H5G__get_info_api_common
+ *
+ * Purpose:     This is the common function for retrieving information
+ *              about a group.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5G__get_info_api_common(hid_t loc_id, H5G_info_t *group_info /*out*/, void **token_ptr,
+                         H5VL_object_t **_vol_obj_ptr)
+{
+    H5VL_object_t * tmp_vol_obj = NULL; /* Object for loc_id */
+    H5VL_object_t **vol_obj_ptr =
+        (_vol_obj_ptr ? _vol_obj_ptr : &tmp_vol_obj); /* Ptr to object ptr for loc_id */
+    H5VL_loc_params_t loc_params;                     /* Location parameters for object access */
+    H5I_type_t        id_type;                        /* Type of ID */
+    herr_t            ret_value = SUCCEED;            /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Check args */
+    id_type = H5I_get_type(loc_id);
+    if (!(H5I_GROUP == id_type || H5I_FILE == id_type))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid group (or file) ID")
+    if (!group_info)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "group_info parameter cannot be NULL")
+
+    /* Set up object access arguments */
+    if (H5VL_setup_self_args(loc_id, vol_obj_ptr, &loc_params) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, FAIL, "can't set object access arguments")
+
+    /* Retrieve group information */
+    if (H5VL_group_get(*vol_obj_ptr, H5VL_GROUP_GET_INFO, H5P_DATASET_XFER_DEFAULT, token_ptr, &loc_params,
+                       group_info) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "unable to get group info")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5G__get_info_api_common() */
+
+/*-------------------------------------------------------------------------
  * Function:    H5Gget_info
  *
  * Purpose:     Retrieve information about a group.
@@ -386,35 +574,97 @@ done:
 herr_t
 H5Gget_info(hid_t loc_id, H5G_info_t *group_info /*out*/)
 {
-    H5VL_object_t *   vol_obj;
-    H5I_type_t        id_type; /* Type of ID */
-    H5VL_loc_params_t loc_params;
-    herr_t            ret_value = SUCCEED; /* Return value */
+    herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE2("e", "ix", loc_id, group_info);
 
+    /* Retrieve group information synchronously */
+    if (H5G__get_info_api_common(loc_id, group_info, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "unable to synchronously get group info")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Gget_info() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Gget_info_async
+ *
+ * Purpose:     Asynchronous version of H5Gget_info
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Gget_info_async(const char *app_file, const char *app_func, unsigned app_line, hid_t loc_id,
+                  H5G_info_t *group_info /*out*/, hid_t es_id)
+{
+    H5VL_object_t *vol_obj   = NULL;            /* Object for loc_id */
+    void *         token     = NULL;            /* Request token for async operation        */
+    void **        token_ptr = H5_REQUEST_NULL; /* Pointer to request token for async operation        */
+    herr_t         ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE6("e", "*s*sIuixi", app_file, app_func, app_line, loc_id, group_info, es_id);
+
+    /* Set up request token pointer for asynchronous operation */
+    if (H5ES_NONE != es_id)
+        token_ptr = &token; /* Point at token for VOL connector to set up */
+
+    /* Retrieve group information asynchronously */
+    if (H5G__get_info_api_common(loc_id, group_info, token_ptr, &vol_obj) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "unable to asynchronously get group info")
+
+    /* If a token was created, add the token to the event set */
+    if (NULL != token)
+        if (H5ES_insert(
+                es_id, vol_obj->connector, token,
+                H5ARG_TRACE6(FUNC, "*s*sIuixi", app_file, app_func, app_line, loc_id, group_info, es_id)) < 0)
+            HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "can't insert token into event set")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5Gget_info_async() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5G__get_info_by_name_api_common
+ *
+ * Purpose:     This is the common function for retrieving information
+ *              about a group.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5G__get_info_by_name_api_common(hid_t loc_id, const char *name, H5G_info_t *group_info /*out*/,
+                                 hid_t lapl_id, void **token_ptr, H5VL_object_t **_vol_obj_ptr)
+{
+    H5VL_object_t * tmp_vol_obj = NULL; /* Object for loc_id */
+    H5VL_object_t **vol_obj_ptr =
+        (_vol_obj_ptr ? _vol_obj_ptr : &tmp_vol_obj); /* Ptr to object ptr for loc_id */
+    H5VL_loc_params_t loc_params;                     /* Location parameters for object access */
+    herr_t            ret_value = SUCCEED;            /* Return value */
+
+    FUNC_ENTER_STATIC
+
     /* Check args */
-    id_type = H5I_get_type(loc_id);
-    if (!(H5I_GROUP == id_type || H5I_FILE == id_type))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid group (or file) ID")
     if (!group_info)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "group_info parameter cannot be NULL")
 
-    /* Get group location */
-    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
+    /* Set up object access arguments */
+    if (H5VL_setup_name_args(loc_id, name, H5P_CLS_LACC, FALSE, lapl_id, vol_obj_ptr, &loc_params) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, FAIL, "can't set object access arguments")
 
-    /* Retrieve the group's information */
-    loc_params.type     = H5VL_OBJECT_BY_SELF;
-    loc_params.obj_type = id_type;
-    if (H5VL_group_get(vol_obj, H5VL_GROUP_GET_INFO, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, &loc_params,
+    /* Retrieve group information */
+    if (H5VL_group_get(*vol_obj_ptr, H5VL_GROUP_GET_INFO, H5P_DATASET_XFER_DEFAULT, token_ptr, &loc_params,
                        group_info) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "unable to get group info")
 
 done:
-    FUNC_LEAVE_API(ret_value)
-} /* end H5Gget_info() */
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5G__get_info_by_name_api_common() */
 
 /*-------------------------------------------------------------------------
  * Function:    H5Gget_info_by_name
@@ -429,43 +679,99 @@ done:
 herr_t
 H5Gget_info_by_name(hid_t loc_id, const char *name, H5G_info_t *group_info /*out*/, hid_t lapl_id)
 {
-    H5VL_object_t *   vol_obj;
-    H5VL_loc_params_t loc_params;
-    herr_t            ret_value = SUCCEED; /* Return value */
+    herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE4("e", "i*sxi", loc_id, name, group_info, lapl_id);
 
+    /* Retrieve group information synchronously */
+    if (H5G__get_info_by_name_api_common(loc_id, name, group_info, lapl_id, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't synchronously retrieve group info")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Gget_info_by_name() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Gget_info_by_name_async
+ *
+ * Purpose:     Asynchronous version of H5Gget_info_by_name
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Gget_info_by_name_async(const char *app_file, const char *app_func, unsigned app_line, hid_t loc_id,
+                          const char *name, H5G_info_t *group_info /*out*/, hid_t lapl_id, hid_t es_id)
+{
+    H5VL_object_t *vol_obj   = NULL;            /* Object for loc_id */
+    void *         token     = NULL;            /* Request token for async operation        */
+    void **        token_ptr = H5_REQUEST_NULL; /* Pointer to request token for async operation        */
+    herr_t         ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE8("e", "*s*sIui*sxii", app_file, app_func, app_line, loc_id, name, group_info, lapl_id, es_id);
+
+    /* Set up request token pointer for asynchronous operation */
+    if (H5ES_NONE != es_id)
+        token_ptr = &token; /* Point at token for VOL connector to set up */
+
+    /* Retrieve group information asynchronously */
+    if (H5G__get_info_by_name_api_common(loc_id, name, group_info, lapl_id, token_ptr, &vol_obj) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't asynchronously retrieve group info")
+
+    /* If a token was created, add the token to the event set */
+    if (NULL != token)
+        if (H5ES_insert(es_id, vol_obj->connector, token,
+                        H5ARG_TRACE8(FUNC, "*s*sIui*sxii", app_file, app_func, app_line, loc_id, name,
+                                     group_info, lapl_id, es_id)) < 0)
+            HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "can't insert token into event set")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5Gget_info_by_name_async() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5G__get_info_by_idx_api_common
+ *
+ * Purpose:     This is the common function for retrieving information
+ *              about a group.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5G__get_info_by_idx_api_common(hid_t loc_id, const char *group_name, H5_index_t idx_type,
+                                H5_iter_order_t order, hsize_t n, H5G_info_t *group_info /*out*/,
+                                hid_t lapl_id, void **token_ptr, H5VL_object_t **_vol_obj_ptr)
+{
+    H5VL_object_t * tmp_vol_obj = NULL; /* Object for loc_id */
+    H5VL_object_t **vol_obj_ptr =
+        (_vol_obj_ptr ? _vol_obj_ptr : &tmp_vol_obj); /* Ptr to object ptr for loc_id */
+    H5VL_loc_params_t loc_params;                     /* Location parameters for object access */
+    herr_t            ret_value = SUCCEED;            /* Return value */
+
+    FUNC_ENTER_STATIC
+
     /* Check args */
-    if (!name)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "name parameter cannot be NULL")
-    if (!*name)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "name parameter cannot be an empty string")
     if (!group_info)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "group_info parameter cannot be NULL")
 
-    /* Verify access property list and set up collective metadata if appropriate */
-    if (H5CX_set_apl(&lapl_id, H5P_CLS_LACC, loc_id, FALSE) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, FAIL, "can't set access property list info")
-
-    /* Get the location object */
-    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
-
-    /* Set up location parameters */
-    loc_params.type                         = H5VL_OBJECT_BY_NAME;
-    loc_params.loc_data.loc_by_name.name    = name;
-    loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
-    loc_params.obj_type                     = H5I_get_type(loc_id);
+    /* Set up object access arguments */
+    if (H5VL_setup_idx_args(loc_id, group_name, idx_type, order, n, H5P_CLS_LACC, FALSE, lapl_id, vol_obj_ptr,
+                            &loc_params) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, FAIL, "can't set object access arguments")
 
-    /* Retrieve the group's information */
-    if (H5VL_group_get(vol_obj, H5VL_GROUP_GET_INFO, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, &loc_params,
+    /* Retrieve group information */
+    if (H5VL_group_get(*vol_obj_ptr, H5VL_GROUP_GET_INFO, H5P_DATASET_XFER_DEFAULT, token_ptr, &loc_params,
                        group_info) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't retrieve group info")
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "unable to get group info")
 
 done:
-    FUNC_LEAVE_API(ret_value)
-} /* end H5Gget_info_by_name() */
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5G__get_info_by_idx_api_common() */
 
 /*-------------------------------------------------------------------------
  * Function:    H5Gget_info_by_idx
@@ -481,50 +787,62 @@ herr_t
 H5Gget_info_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type, H5_iter_order_t order,
                    hsize_t n, H5G_info_t *group_info /*out*/, hid_t lapl_id)
 {
-    H5VL_object_t *   vol_obj;
-    H5VL_loc_params_t loc_params;
-    herr_t            ret_value = SUCCEED; /* Return value */
+    herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE7("e", "i*sIiIohxi", loc_id, group_name, idx_type, order, n, group_info, lapl_id);
 
-    /* Check args */
-    if (!group_name)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "group_name parameter cannot be NULL")
-    if (!*group_name)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "group_name parameter cannot be an empty string")
-    if (idx_type <= H5_INDEX_UNKNOWN || idx_type >= H5_INDEX_N)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid index type specified")
-    if (order <= H5_ITER_UNKNOWN || order >= H5_ITER_N)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid iteration order specified")
-    if (!group_info)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "group_info parameter cannot be NULL")
+    /* Retrieve group information synchronously */
+    if (H5G__get_info_by_idx_api_common(loc_id, group_name, idx_type, order, n, group_info, lapl_id, NULL,
+                                        NULL) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't synchronously retrieve group info")
 
-    /* Verify access property list and set up collective metadata if appropriate */
-    if (H5CX_set_apl(&lapl_id, H5P_CLS_LACC, loc_id, FALSE) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTSET, FAIL, "can't set access property list info")
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Gget_info_by_idx() */
 
-    /* Get the location object */
-    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
-
-    /* Set location parameters */
-    loc_params.type                         = H5VL_OBJECT_BY_IDX;
-    loc_params.loc_data.loc_by_idx.name     = group_name;
-    loc_params.loc_data.loc_by_idx.idx_type = idx_type;
-    loc_params.loc_data.loc_by_idx.order    = order;
-    loc_params.loc_data.loc_by_idx.n        = n;
-    loc_params.loc_data.loc_by_idx.lapl_id  = lapl_id;
-    loc_params.obj_type                     = H5I_get_type(loc_id);
-
-    /* Retrieve the group's information */
-    if (H5VL_group_get(vol_obj, H5VL_GROUP_GET_INFO, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, &loc_params,
-                       group_info) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't retrieve group info")
+/*-------------------------------------------------------------------------
+ * Function:    H5Gget_info_by_idx_async
+ *
+ * Purpose:     Asynchronous version of H5Gget_info_by_idx
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Gget_info_by_idx_async(const char *app_file, const char *app_func, unsigned app_line, hid_t loc_id,
+                         const char *group_name, H5_index_t idx_type, H5_iter_order_t order, hsize_t n,
+                         H5G_info_t *group_info /*out*/, hid_t lapl_id, hid_t es_id)
+{
+    H5VL_object_t *vol_obj   = NULL;            /* Object for loc_id */
+    void *         token     = NULL;            /* Request token for async operation        */
+    void **        token_ptr = H5_REQUEST_NULL; /* Pointer to request token for async operation        */
+    herr_t         ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE11("e", "*s*sIui*sIiIohxii", app_file, app_func, app_line, loc_id, group_name, idx_type, order, n,
+              group_info, lapl_id, es_id);
+
+    /* Set up request token pointer for asynchronous operation */
+    if (H5ES_NONE != es_id)
+        token_ptr = &token; /* Point at token for VOL connector to set up */
+
+    /* Retrieve group information asynchronously */
+    if (H5G__get_info_by_idx_api_common(loc_id, group_name, idx_type, order, n, group_info, lapl_id,
+                                        token_ptr, &vol_obj) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't asynchronously retrieve group info")
+
+    /* If a token was created, add the token to the event set */
+    if (NULL != token)
+        if (H5ES_insert(es_id, vol_obj->connector, token,
+                        H5ARG_TRACE11(FUNC, "*s*sIui*sIiIohxii", app_file, app_func, app_line, loc_id,
+                                      group_name, idx_type, order, n, group_info, lapl_id, es_id)) < 0)
+            HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "can't insert token into event set")
 
 done:
     FUNC_LEAVE_API(ret_value)
-} /* end H5Gget_info_by_idx() */
+} /* H5Gget_info_by_idx_async() */
 
 /*-------------------------------------------------------------------------
  * Function:    H5Gclose
@@ -559,6 +877,65 @@ done:
 } /* end H5Gclose() */
 
 /*-------------------------------------------------------------------------
+ * Function:    H5Gclose_async
+ *
+ * Purpose:     Asynchronous version of H5Gclose
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Gclose_async(const char *app_file, const char *app_func, unsigned app_line, hid_t group_id, hid_t es_id)
+{
+    H5VL_object_t *vol_obj   = NULL;            /* Object for loc_id */
+    H5VL_t *       connector = NULL;            /* VOL connector */
+    void *         token     = NULL;            /* Request token for async operation        */
+    void **        token_ptr = H5_REQUEST_NULL; /* Pointer to request token for async operation        */
+    herr_t         ret_value = SUCCEED;         /* Return value                     */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE5("e", "*s*sIuii", app_file, app_func, app_line, group_id, es_id);
+
+    /* Check arguments */
+    if (H5I_GROUP != H5I_get_type(group_id))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a group ID")
+
+    /* Prepare for possible asynchronous operation */
+    if (H5ES_NONE != es_id) {
+        /* Get group object's connector */
+        if (NULL == (vol_obj = H5VL_vol_object(group_id)))
+            HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't get VOL object for group")
+
+        /* Increase connector's refcount, so it doesn't get closed if closing
+         * the group closes the file */
+        connector = vol_obj->connector;
+        H5VL_conn_inc_rc(connector);
+
+        /* Point at token for operation to set up */
+        token_ptr = &token;
+    } /* end if */
+
+    /* Decrement the counter on the group ID. It will be freed if the count
+     * reaches zero.
+     */
+    if (H5I_dec_app_ref_async(group_id, token_ptr) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTDEC, FAIL, "decrementing group ID failed")
+
+    /* If a token was created, add the token to the event set */
+    if (NULL != token)
+        if (H5ES_insert(es_id, vol_obj->connector, token,
+                        H5ARG_TRACE5(FUNC, "*s*sIuii", app_file, app_func, app_line, group_id, es_id)) < 0)
+            HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "can't insert token into event set")
+
+done:
+    if (connector && H5VL_conn_dec_rc(connector) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_CANTDEC, FAIL, "can't decrement ref count on connector")
+
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Gclose_async() */
+
+/*-------------------------------------------------------------------------
  * Function:    H5Gflush
  *
  * Purpose:     Flushes all buffers associated with a group to disk.