H5P_SET_OBJECT_FLUSH_CB sets the callback function to invoke in the file access property list fapl_id whenever an object flush occurs in the file. Library objects are group, dataset, and committed datatype.

The callback function func must conform to the prototype defined below:

• typedef herr_t (*H5F_flush_cb_t)(hid_t object_id, void *user_data)

The parameters of the callback function, per the above prototyps, are defined as follows:

• object_id is the identifier of the object which has just been flushed.
• user_data is the user-defined input data for the callback function.

Returns a non-negative value if successful; otherwise returns a negative value.

The example below illustrates the usage of this routine to set the callback function to invoke when an object flush occurs.

hid_t file_id, fapl_id;
hid_t dataset_id, dapl_id;
unsigned counter;

/* Create a copy of the file access property list *
fapl_id = H5Pcreate(H5P_FILE_ACCESS);

/* Set up the object flush property values */
/* flush_cb: callback function to invoke when an object flushes (see below) */
/* counter: user data to pass along to the callback function */
H5Pset_object_flush_cb(fapl_id, flush_cb, &counter);

/* Open the file */
file_id = H5Fopen(FILE, H5F_ACC_RDWR, H5P_DEFAULT);

/* Create a group */
gid = H5Gcreate2(fid, “group”, H5P_DEFAULT, H5P_DEFAULT_H5P_DEFAULT);

/* Open a dataset */ 
dataset_id = H5Dopen2(file_id, DATASET, H5P_DEFAULT);

/* The flush will invoke flush_cb() with counter */
H5Dflush(dataset_id);
/* counter will be equal to 1 */
:
:
:
/* The flush will invoke flush_cb() with counter */
H5Gflush(gid);
/* counter will be equal to 2 */
:
:
:

/* The callback function for object flush property */
static herr_t
flush_cb(hid_t obj_id, void *_udata)
{
    unsigned *flush_ct = (unsigned*)_udata;
    ++(*flush_ct);
    return 0;
}