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MPI_Grequest_start(3)		      MPI		 MPI_Grequest_start(3)

NAME
       MPI_Grequest_start -  Create and	return a user-defined request

SYNOPSIS
       int MPI_Grequest_start( MPI_Grequest_query_function *query_fn,
			     MPI_Grequest_free_function	*free_fn,
			     MPI_Grequest_cancel_function *cancel_fn,
			     void *extra_state,	MPI_Request *request )

INPUT PARAMETERS
       query_fn
	      -	 callback  function  invoked  when  request  status is queried
	      (function)
       free_fn
	      -	callback function invoked when request is freed	(function)
       cancel_fn
	      -	callback function invoked when request is cancelled (function)
       extra_state
	      -	Extra state passed to the above	functions.

OUTPUT PARAMETER
       request
	      -	Generalized request (handle)

NOTES ON THE CALLBACK FUNCTIONS
       The return values from the callback functions must be a valid MPI error
       code  or	class.	This value may either be the return value from any MPI
       routine (with one exception noted  below)  or  any  of  the  MPI	 error
       classes.	  For portable programs, MPI_ERR_OTHER may be used; to provide
       more specific information, create a new MPI error class	or  code  with
       MPI_Add_error_class or MPI_Add_error_code and return that value.

       The  MPI	 standard  is not clear	on the return values from the callback
       routines.  However, there are notes in the  standard  that  imply  that
       these are MPI error codes.  For example,	pages 169 line 46 through page
       170, line 1 require that	the free_fn return an MPI error	code that  may
       be   used   in	the   MPI   completion	 functions  when  they	return
       MPI_ERR_IN_STATUS .

       The one special case is the error value returned	by  MPI_Comm_dup  when
       the  attribute callback routine returns a failure.  The MPI standard is
       not clear on what values	may be used to indicate	an error return.  Fur-
       ther,  the Intel	MPI test suite made use	of non-zero values to indicate
       failure,	and expected these values to be	returned by  the  MPI_Comm_dup
       when  the  attribute  routines encountered an error.  Such error	values
       may not be valid	MPI error codes	or classes.  Because of	 this,	it  is
       the user's responsibility to either use valid MPI error codes in	return
       from the	attribute callbacks, if	those error codes are to  be  returned
       by a generalized	request	callback, or to	detect and convert those error
       codes to	valid MPI error	codes (recall that MPI error classes are valid
       error codes).

THREAD AND INTERRUPT SAFETY
       This  routine  is  thread-safe.	 This  means  that this	routine	may be
       safely used by multiple threads without the need	for any	 user-provided
       thread  locks.  However,	the routine is not interrupt safe.  Typically,
       this is due to the use of memory	allocation routines such as malloc  or
       other  non-MPICH	 runtime  routines  that are themselves	not interrupt-
       safe.

NOTES FOR FORTRAN
       All MPI routines	in Fortran (except for MPI_WTIME and MPI_WTICK )  have
       an  additional  argument	ierr at	the end	of the argument	list.  ierr is
       an integer and has the same meaning as the return value of the  routine
       in  C.	In Fortran, MPI	routines are subroutines, and are invoked with
       the call	statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm )	are of type INTEGER in
       Fortran.

ERRORS
       All  MPI	 routines  (except  MPI_Wtime  and MPI_Wtick ) return an error
       value; C	routines as the	value of the function and Fortran routines  in
       the last	argument.  Before the value is returned, the current MPI error
       handler is called.  By default, this error handler aborts the MPI  job.
       The error handler may be	changed	with MPI_Comm_set_errhandler (for com-
       municators), MPI_File_set_errhandler (for files),  and  MPI_Win_set_er-
       rhandler	 (for  RMA windows).  The MPI-1	routine	MPI_Errhandler_set may
       be used but its	use  is	 deprecated.   The  predefined	error  handler
       MPI_ERRORS_RETURN  may  be  used	 to cause error	values to be returned.
       Note that MPI does not guarentee	that an	MPI program can	continue  past
       an  error;  however, MPI	implementations	will attempt to	continue when-
       ever possible.

       MPI_SUCCESS
	      -	No error; MPI routine completed	successfully.
       MPI_ERR_ARG
	      -	Invalid	argument.  Some	argument is invalid and	is not identi-
	      fied by a	specific error class (e.g., MPI_ERR_RANK ).

LOCATION
       src/mpi/pt2pt/greq_start.c

				   9/20/2012		 MPI_Grequest_start(3)

NAME | SYNOPSIS | INPUT PARAMETERS | OUTPUT PARAMETER | NOTES ON THE CALLBACK FUNCTIONS | THREAD AND INTERRUPT SAFETY | NOTES FOR FORTRAN | ERRORS | LOCATION

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