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.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc. All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" Copyright 2015-2016 Research Organization for Information Science
.\" and Technology (RIST). All rights reserved.
.\" $COPYRIGHT$
.TH MPI_File_read_at_all_begin 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_File_read_at_all_begin\fP \- Reads a file at explicitly specified offsets; beginning part of a split collective routine (nonblocking).
.SH SYNTAX
.ft R
.nf
.SH C Syntax
.nf
#include <mpi.h>
int MPI_File_read_at_all_begin(MPI_File \fIfh\fP, MPI_Offset
\fIoffset\fP, void \fI*buf\fP, int \fIcount\fP, MPI_Datatype
\fIdatatype\fP)
.fi
.SH Fortran Syntax (see FORTRAN 77 NOTES)
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_READ_AT_ALL_BEGIN(\fIFH\fP, \fIOFFSET\fP, \fIBUF\fP,
\fICOUNT\fP, \fIDATATYPE\fP, \fIIERROR\fP)
<type> \fIBUF\fP(*)
INTEGER \fIFH, COUNT, DATATYPE, IERROR\fP
INTEGER(KIND=MPI_OFFSET_KIND) \fIOFFSET\fP
.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_File_read_at_all_begin(\fIfh\fP, \fIoffset\fP, \fIbuf\fP, \fIcount\fP, \fIdatatype\fP, \fIierror\fP)
TYPE(MPI_File), INTENT(IN) :: \fIfh\fP
INTEGER(KIND=MPI_OFFSET_KIND), INTENT(IN) :: \fIoffset\fP
TYPE(*), DIMENSION(..), ASYNCHRONOUS :: \fIbuf\fP
INTEGER, INTENT(IN) :: \fIcount\fP
TYPE(MPI_Datatype), INTENT(IN) :: \fIdatatype\fP
INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP
.fi
.SH C++ Syntax
.nf
#include <mpi.h>
void MPI::File::Read_at_all_begin(MPI::Offset \fIoffset\fP, void* \fIbuf\fP,
int \fIcount\fP, const MPI::Datatype& \fIdatatype\fP)
.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
fh
File handle (handle).
.ft R
.TP 1i
offset
File offset (integer).
.ft R
.TP 1i
count
Number of elements in buffer (integer).
.ft R
.TP 1i
datatype
Data type of each buffer element.
.SH OUTPUT PARAMETERS
.ft R
.TP 1i
buf
Initial address of buffer (choice).
.TP 1i
IERROR
Fortran only: Error status (integer).
.SH DESCRIPTION
.ft R
MPI_File_read_at_all_begin is the beginning part of a split collective routine that attempts to read from the file associated with
.I fh
(at the
.I offset
position) a total number of
.I count
data items having
.I datatype
type into the user's buffer
.I buf.
The
.I offset
is in etype units relative to the current view. That is, holes are not counted
when locating an offset. The data is taken out of those parts of the
file specified by the current view.
.SH FORTRAN 77 NOTES
.ft R
The MPI standard prescribes portable Fortran syntax for
the \fIOFFSET\fP argument only for Fortran 90. FORTRAN 77
users may use the non-portable syntax
.sp
.nf
INTEGER*MPI_OFFSET_KIND \fIOFFSET\fP
.fi
.sp
where MPI_OFFSET_KIND is a constant defined in mpif.h
and gives the length of the declared integer in bytes.
.SH NOTES
.ft R
All the nonblocking collective routines for data access are "split" into two routines, each with _begin or _end as a suffix. These split collective routines are subject to the semantic rules described in Section 9.4.5 of the MPI-2 standard.
.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.
.sp
Before the error value is returned, the current MPI error handler is
called. For MPI I/O function errors, the default error handler is set to MPI_ERRORS_RETURN. The error handler may be changed with MPI_File_set_errhandler; the predefined error handler MPI_ERRORS_ARE_FATAL may be used to make I/O errors fatal. Note that MPI does not guarantee that an MPI program can continue past an error.
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