mpid_info.tex

来自「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」· TEX 代码 · 共 45 行

\startmanpage
\mantitle{MPID{\tt \char`\_}Info}{tex}{10/7/2002}
\manname{MPID{\tt \char`\_}Info}
--- Structure of an MPID info 
\subhead{Synopsis}
\startvb\begin{verbatim}
typedef struct MPID_Info_s {
    int                handle;
    struct MPID_Info_s *next;
    char               *key;
    char               *value;
} MPID_Info;

\end{verbatim}
\endvb

\subhead{Notes}
There is no reference count because {\tt MPI{\tt \char`\_}Info} values, unlike other MPI
objects, may be changed after they are passed to a routine without
changing the routine's behavior.  In other words, any routine that uses
an {\tt MPI{\tt \char`\_}Info} object must make a copy or otherwise act on any info value
that it needs.
\par
A linked list is used because the typical {\tt MPI{\tt \char`\_}Info} list will be short
and a simple linked list is easy to implement and to maintain.  Similarly,
a single structure rather than separate header and element structures are
defined for simplicity.  No separate thread lock is provided because
info routines are not performance critical; they use the {\tt common{\tt \char`\_}lock
}in the {\tt MPIR{\tt \char`\_}Process} structure when they need a thread lock.
\par
This particular form of linked list (in particular, with this particular
choice of the first two members) is used because it allows us to use
the same routines to manage this list as are used to manage the
list of free objects (in the file {\tt src/util/mem/handlemem.c}).  In
particular, if lock-free routines for updating a linked list are
provided, they can be used for managing the {\tt MPID{\tt \char`\_}Info} structure as well.
\par
The MPI standard requires that keys can be no less that 32 characters and
no more than 255 characters.  There is no mandated limit on the size
of values.
\par
\subhead{Module}
Info-DS
\endmanpage