Event Set Interface (H5ES)

Detailed Description

Event Set Interface.

Todo:

Add the event set life cycle.

This interface can only be used with the HDF5 VOL connectors that enable the asynchronous feature in HDF5. The native HDF5 library has only synchronous operations.

HDF5 VOL connectors with support for asynchronous operations:

• ASYNC
• DAOS

Example:

fid = H5Fopen(..);
gid = H5Gopen(fid, ..);  //Starts when H5Fopen completes
did = H5Dopen(gid, ..);  //Starts when H5Gopen completes
 
es_id = H5EScreate();  // Create event set for tracking async operations
status = H5Dwrite_async(did, .., es_id);  //Asynchronous, starts when H5Dopen completes,
                                          // may run concurrently with other H5Dwrite_async
                                          // in event set.
status = H5Dwrite_async(did, .., es_id);  //Asynchronous, starts when H5Dopen completes,
                                          // may run concurrently with other H5Dwrite_async
                                          // in event set....
<other user code>
...
H5ESwait(es_id); // Wait for operations in event set to complete, buffers
                 // used for H5Dwrite_async must only be changed after wait
                 // returns.

Functions
hid_t	H5EScreate (void)
	Creates an event set.
herr_t	H5ESwait (hid_t es_id, uint64_t timeout, size_t *num_in_progress, hbool_t *err_occurred)
	Waits for operations in event set to complete.
herr_t	H5EScancel (hid_t es_id, size_t *num_not_canceled, hbool_t *err_occurred)
	Attempt to cancel operations in an event set.
herr_t	H5ESget_count (hid_t es_id, size_t *count)
	Retrieves number of events in an event set.
herr_t	H5ESget_op_counter (hid_t es_id, uint64_t *counter)
	Retrieves the accumulative operation counter for an event set.
herr_t	H5ESget_err_status (hid_t es_id, hbool_t *err_occurred)
	Checks for failed operations.
herr_t	H5ESget_err_count (hid_t es_id, size_t *num_errs)
	Retrieves the number of failed operations.
herr_t	H5ESget_err_info (hid_t es_id, size_t num_err_info, H5ES_err_info_t err_info[], size_t *err_cleared)
	Retrieves information about failed operations.
herr_t	H5ESfree_err_info (size_t num_err_info, H5ES_err_info_t err_info[])
	Convenience routine to free an array of H5ES_err_info_t structs.
herr_t	H5ESregister_insert_func (hid_t es_id, H5ES_event_insert_func_t func, void *ctx)
	Registers a callback to invoke when a new operation is inserted into an event set.
herr_t	H5ESregister_complete_func (hid_t es_id, H5ES_event_complete_func_t func, void *ctx)
	Registers a callback to invoke when an operation completes within an event set.
herr_t	H5ESclose (hid_t es_id)
	Terminates access to an event set.

Function Documentation

H5EScancel()

herr_t H5EScancel	(	hid_t	es_id,
		size_t *	num_not_canceled,
		hbool_t *	err_occurred
	)

Attempt to cancel operations in an event set.

Parameters

[in]	es_id	Event set identifier
[out]	num_not_canceled	The number of events not canceled
[out]	err_occurred	Status indicating if error is present in the event set

Returns

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

H5EScancel() attempts to cancel operations in an event set specified by es_id. H5ES_NONE is a valid value for es_id, but functions as a no-op.

Since

1.14.0

H5ESclose()

herr_t H5ESclose

(

hid_t

es_id

)

Terminates access to an event set.

Parameters

[in]

es_id

Event set identifier

Returns

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

H5ESclose() terminates access to an event set specified by es_id.

Since

1.14.0

H5EScreate()

hid_t H5EScreate

(

void

)

Creates an event set.

Returns

Returns a event set identifier if successful; otherwise returns H5I_INVALID_HID.

H5EScreate() creates a new event set and returns a corresponding event set identifier.

Since

1.14.0

H5ESfree_err_info()

herr_t H5ESfree_err_info	(	size_t	num_err_info,
		H5ES_err_info_t	err_info[]
	)

Convenience routine to free an array of H5ES_err_info_t structs.

Parameters

[in]	num_err_info	The number of elements in err_info array
[in]	err_info	Array of structures

Returns

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

Since

1.14.0

H5ESget_count()

herr_t H5ESget_count	(	hid_t	es_id,
		size_t *	count
	)

Retrieves number of events in an event set.

Parameters

[in]	es_id	Event set identifier
[out]	count	The number of events in the event set

Returns

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

H5ESget_count() retrieves number of events in an event set specified by es_id.

Since

1.14.0

H5ESget_err_count()

herr_t H5ESget_err_count	(	hid_t	es_id,
		size_t *	num_errs
	)

Retrieves the number of failed operations.

Parameters

[in]	es_id	Event set identifier
[out]	num_errs	Number of errors

Returns

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

H5ESget_err_count() retrieves the number of failed operations in an event set specified by es_id.

The function does not wait for active operations to complete, so count may not include all failures.

Since

1.14.0

H5ESget_err_info()

herr_t H5ESget_err_info	(	hid_t	es_id,
		size_t	num_err_info,
		H5ES_err_info_t	err_info[],
		size_t *	err_cleared
	)

Retrieves information about failed operations.

Parameters

[in]	es_id	Event set identifier
[in]	num_err_info	The number of elements in err_info array
[out]	err_info	Array of structures
[out]	err_cleared	Number of cleared errors

Returns

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

H5ESget_err_info() retrieves information about failed operations in an event set specified by es_id. The strings retrieved for each error info must be released by calling H5free_memory().

Below is the description of the H5ES_err_info_t structure:

 
typedef struct H5ES_err_info_t {
    /* API call info */
    char *api_name; 
    char *api_args; 
    /* Application info */
    char    *app_file_name; 
    char    *app_func_name; 
    unsigned app_line_num;  
    /* Operation info */
    uint64_t op_ins_count; 
    uint64_t op_ins_ts;    
    uint64_t op_exec_ts;   
    uint64_t op_exec_time; 
    /* Error info */
    hid_t err_stack_id; 
} H5ES_err_info_t;

(Click on a enumerator, field, or type for more information.)

Since

1.14.0

H5ESget_err_status()

herr_t H5ESget_err_status	(	hid_t	es_id,
		hbool_t *	err_occurred
	)

Checks for failed operations.

Parameters

[in]	es_id	Event set identifier
[out]	err_occurred	Status indicating if error is present in the event set

Returns

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

H5ESget_err_status() checks if event set specified by es_id has failed operations.

Since

1.14.0

H5ESget_op_counter()

herr_t H5ESget_op_counter	(	hid_t	es_id,
		uint64_t *	counter
	)

Retrieves the accumulative operation counter for an event set.

Parameters

[in]	es_id	Event set identifier
[out]	counter	The accumulative counter value for an event set

Returns

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

H5ESget_op_counter() retrieves the current accumulative count of event set operations since the event set creation of es_id.

Note

This is designed for wrapper libraries mainly, to use as a mechanism for matching operations inserted into the event set with possible errors that occur.

Since

1.14.0

H5ESregister_complete_func()

herr_t H5ESregister_complete_func	(	hid_t	es_id,
		H5ES_event_complete_func_t	func,
		void *	ctx
	)

Registers a callback to invoke when an operation completes within an event set.

Parameters

[in]	es_id	Event set identifier
[in]	func	The completion function to register
[in]	ctx	User-specified information (context) to pass to func

Returns

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

Only one complete callback can be registered for each event set. Registering a new callback will replace the existing one. H5ES_NONE is a valid value for 'es_id', but functions as a no-op

Since

1.14.0

H5ESregister_insert_func()

herr_t H5ESregister_insert_func	(	hid_t	es_id,
		H5ES_event_insert_func_t	func,
		void *	ctx
	)

Registers a callback to invoke when a new operation is inserted into an event set.

Parameters

[in]	es_id	Event set identifier
[in]	func	The insert function to register
[in]	ctx	User-specified information (context) to pass to func

Returns

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

Only one insert callback can be registered for each event set. Registering a new callback will replace the existing one. H5ES_NONE is a valid value for 'es_id', but functions as a no-op

Since

1.14.0

H5ESwait()

herr_t H5ESwait	(	hid_t	es_id,
		uint64_t	timeout,
		size_t *	num_in_progress,
		hbool_t *	err_occurred
	)

Waits for operations in event set to complete.

Parameters

[in]	es_id	Event set identifier
[in]	timeout	Total time in nanoseconds to wait for all operations in the event set to complete
[out]	num_in_progress	The number of operations still in progress
[out]	err_occurred	Flag if an operation in the event set failed

Returns

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

H5ESwait() waits for operations in an event set es_id to wait with timeout.

Timeout value is in nanoseconds, and is for the H5ESwait() call and not for each individual operation in the event set. For example, if "10" is passed as a timeout value and the event set waited 4 nanoseconds for the first operation to complete, the remaining operations would be allowed to wait for at most 6 nanoseconds more, i.e., the timeout value used across all operations in the event set until it reaches 0, then any remaining operations are only checked for completion, not waited on.

This call will stop waiting on operations and will return immediately if an operation fails. If a failure occurs, the value returned for the number of operations in progress may be inaccurate.

Since

1.14.0