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<HTML>
<HEAD>
<META NAME="GENERATOR" CONTENT="Adobe PageMill 3.0 Win">
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="Author" CONTENT="Magdalena Nieplocha">
<TITLE>sf gowno</TITLE>
</HEAD>
<BODY BGCOLOR="#f8f8eb" LINK="#0000ee" VLINK="#990099" TEXT="#000099"
ALINK="#00ffff" BACKGROUND="Image2.gif">
<H2><CENTER><A NAME="overview"></A></CENTER></H2>
<H2><CENTER>Shared Files Library</CENTER></H2>
<P>The Shared Files (SF) library implements logically-shared temporary
files for parallel SPMD (single-program-multiple-data) applications.
Any process can read and write at arbitrary location in a file
independently of other processes. Shared files must be created
and destroyed collectively. To optimize performance of the library,
user can provide hints on:</P>
<UL>
<LI>soft limit, and
<LI>hard limit for the file size.
</UL>
<P>The SF <I>read </I>and <I>write</I> operations are asynchronous/nonblocking
and require a <I>wait</I> operation to complete.</P>
<P>Due to the FORTRAN data type limitations, in order to facilitate
access to files >2GB the file size, request size and offset
arguments use double precision data types.</P>
<P>All SF routines return an error code. The "0" value
means success, other values correspond to error codes.</P>
<P><HR ALIGN=LEFT></P>
<H2><A NAME="sf_create"></A></H2>
<H2>sf_create</H2>
<PRE>integer sf_create(fname, size_hard_limit, size_soft_limit, req_size, handle)
fname -- meta-file name
size_hard_limit -- max file size in bytes not to be exceeded (a hint)
size_soft_limit -- estimated file size (a hint)
req_size -- size of a typical request (a hint)
handle -- returned handle to the created file</PRE>
<P>Creates shared file using name and path specified in <I>fname
</I>as a template. <BR>
<I>req_size</I> specifies size of a typical request (-1. means
"don't know").</P>
<P>Creates shared file using name and path specified in fname
as a template. <BR>
req_size specifies size of a typical request (-1. means "don't
know").</P>
<P>It is a collective operation.</P>
<P><HR ALIGN=LEFT></P>
<P><A NAME="sf_write"></A></P>
<H2>sf_write</H2>
<P> </P>
<PRE>integer sf_write(handle, offset, bytes, buffer, request_id)
handle -- file handle returned from sf_create [in]
offset -- location in file (from the beginning)
where data should be written to [in]
buffer -- local array to put the data [in]
bytes -- number of bytes to read [in]
request_id -- id identifying asynchronous operation [out]</PRE>
<P>Asynchronous write operation. Writes number of <I>bytes</I>
to the file identified by <I>handle</I> at location <I>offset</I>.Operation
is guaranteed to be complete when <I>sf_wait</I> called with <I>request_id
</I>argument returns. <BR>
<HR ALIGN=LEFT></P>
<H2><A NAME="sf_read"></A></H2>
<H2>sf_read</H2>
<PRE>integer sf_read(handle, offset, bytes, buffer, request_id)
handle -- file handle returned from sf_create [in]
offset -- location in file (from the beginning)
where data should be read from [in]
buffer -- local array to put the data [in]
bytes -- number of bytes to read [in]
request_id -- id identifying asynchronous operation [out]</PRE>
<P>Asynchronous read operation. Reads number of <I>bytes</I> to
the file identified by <I>handle</I> at location <I>offset</I>.Operation
is guaranteed to be complete when <I>sf_wait</I> called with <I>request_id
</I>argument returns.</P>
<P><HR ALIGN=LEFT></P>
<H2><A NAME="sf_wait"></A></H2>
<H2>sf_wait</H2>
<PRE>integer sf_wait(request_id)
request_id -- id identifying asynchronous operation [in/out]</PRE>
<P>Blocks the calling process until I/O operation associated with
<I>request</I>_<I>id</I> completes. <BR>
Invalidates <I>request_id.</I> <BR>
<BR>
<HR ALIGN=LEFT><BR>
<A NAME="sf_waitall"></A></P>
<H2>sf_waitall</H2>
<PRE>integer sf_waitall(list, num)
list(num) -- array of ids for asynchronous operations [in/out]
num -- number of entries in list [in]</PRE>
<P>Blocks the calling process until all of the <I>num</I> I/O
operations associated with <I>ids</I><BR>
specified in <I>list</I> complete. Invalidates (modifies) <I>ids</I>
on the <I>list.</I><BR>
<HR ALIGN=LEFT></P>
<H2><A NAME="sf_destroy"></A></H2>
<H2>sf_destroy</H2>
<PRE>
integer sf_destroy(handle)
handle -- file handle returned from sf_create [in]</PRE>
<P>Destroys the shared file associated with <I>handle</I>. It
is a collective operation.
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