mpid_dev_comm_attr_set_hook.tex

刚才是说明 现在是安装程序在 LINUX环境下进行编程的MPICH安装文件

\startmanpage
\mantitle{MPID{\tt \char`\_}Dev{\tt \char`\_}comm{\tt \char`\_}attr{\tt \char`\_}set{\tt \char`\_}hook}{tex}{10/7/2002}
\manname{MPID{\tt \char`\_}Dev{\tt \char`\_}comm{\tt \char`\_}attr{\tt \char`\_}set{\tt \char`\_}hook}
--- Inform the device about a change to an attribute value for a particular communicator. 
\subhead{Synopsis}
\startvb\begin{verbatim}
void MPID_Dev_comm_attr_set_hook( MPID_Comm *comm, int keyval, void *attr_val, 
                                  MPID_Lang_t lang, int was_set )

\end{verbatim}
\endvb

\subhead{Input Parameters}
\startarg{comm  }{Communicator with attribute
}
\startarg{keyval }{Key value for attribute
}
\startarg{attr{\tt \char`\_}val }{Value of attribute
}
\startarg{lang }{Language that attribute was set from (see notes).
}
\startarg{was{\tt \char`\_}set }{Indicates whether the attribute was set (1) or deleted (0)
}
\par
\subhead{Notes}
This routine allows the device to find out when an attribute value changes.
This can be used by a device that defines its own keyvals (see
{\tt MPID{\tt \char`\_}Init}) to allow the MPI user to communicate preferences to
the device.  This has already been used in MPICH-G2 to pass
quality-of-service information to the device.
\par
The language value is necessary because Fortran 77 attributes are integers,
while C, C++, and Fortran 90 attributes are pointers (addresses).  These
may not be the same length, so the address {\tt attr{\tt \char`\_}val} must be interpreted
differently.  Note that MPI uses 4 separate routines since each language
has its own binding (the Fortran 90 one is {\tt MPI{\tt \char`\_}Comm{\tt \char`\_}attr{\tt \char`\_}set}; the
Fortran 77 one is {\tt MPI{\tt \char`\_}Attr{\tt \char`\_}set}).
\par
By default, this is {\tt {\tt \char`\#}define}d as empty in {\tt mpiimpl.h}.  A device that
wishes to use
this function should {\tt {\tt \char`\#}undef} it in the device include file ({\tt mpidevpost.h}).
\par
\subhead{Module}
Attribute
\par
\subhead{Question}
We may want to register keyvals with the device so that only attributes
associated with the device call into it.  (e.g.,
{\tt MPID{\tt \char`\_}Create{\tt \char`\_}keyval( ... )}).
That also allows us to define
"enhanced" keyvals that contain functions that validate any changes to the
attribute values (e.g. an
\begin{verbatim}
  MPID_Attr_validate_function( int keyval, void *attr_val, 
                               MPID_Lang_t lang )
\end{verbatim}

). This also argues that {\tt MPID{\tt \char`\_}Dev{\tt \char`\_}comm{\tt \char`\_}attr{\tt \char`\_}set{\tt \char`\_}hook} routine should
return an MPI error code, allowing the device to cleanly signal an error
to the user.
\endmanpage