# Name

`MPI_Grequest_complete` - Reports that a generalized request is
complete.

# Syntax

## C Syntax

```c
#include <mpi.h>

int MPI_Grequest_complete(MPI_Request request)
```

## Fortran Syntax

```fortran
USE MPI
! or the older form: INCLUDE 'mpif.h'

MPI_GREQUEST_COMPLETE(REQUEST, IERROR)
    INTEGER	REQUEST, IERROR
```

## Fortran 2008 Syntax

```fortran
USE mpi_f08

MPI_Grequest_complete(request, ierror)
    TYPE(MPI_Request), INTENT(IN) :: request
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror
```

# Input/Output Parameter

* `request` : Generalized request (handle).

# Output Parameter

* `IERROR` : Fortran only: Error status (integer).

# Description

`MPI_Grequest_complete` informs MPI that the operations represented by the
generalized request `request` are complete. A call to `MPI_Wait(request, status)`
will return, and a call to `MPI_Test(request, flag, status)` will return
flag=true only after a call to `MPI_Grequest_complete` has
declared that these operations are complete.

MPI imposes no restrictions on the code executed by the callback
functions. However, new nonblocking operations should be defined so that
the general semantic rules about MPI calls such as `MPI_Test`,
`MPI_Request_free`, or `MPI_Cancel` still hold. For example, all these calls
are supposed to be local and nonblocking. Therefore, the callback
functions `query_fn`, `free_fn`, or `cancel_fn` should invoke blocking
MPI communication calls only if the context is such that these calls are
guaranteed to return in finite time. Once `MPI_Cancel` has been invoked,
the canceled operation should complete in finite time, regardless of the
state of other processes (the operation has acquired "local"
semantics). It should either succeed or fail without side-effects. The
user should guarantee these same properties for newly defined
operations.

# Errors

Almost all MPI routines return an error value; C routines as the value
of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for
I/O function errors. The error handler may be changed with
`MPI_Comm_set_errhandler`; the predefined error handler `MPI_ERRORS_RETURN`
may be used to cause error values to be returned. Note that MPI does not
guarantee that an MPI program can continue past an error.