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<!-- $Id$ -->
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="Author" CONTENT="James CE Johnson">
<TITLE>ACE Tutorial 020</TITLE>
</HEAD>
<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F">
<CENTER><B><FONT SIZE=+2>ACE Tutorial 020</FONT></B></CENTER>
<CENTER><B><FONT SIZE=+2>Sharing your Memories with persistence</FONT></B></CENTER>
<P>
<HR WIDTH="100%">
Here's our new server using a memory mapped file instead of Unix
System V shared memory. Print out both servers and hold 'em up
to a strong light. I think you'll see there isn't much
difference.
<p>
The filename is defined in mmap.h as <i>mmapfile</i>. You can
<i>cat</i> it any time to see what's in there. If you're
feeling brave, try writting some data into it. On my system it
causes unpleasant things to happen. I'd recommend that you
don't do that!
<hr>
<PRE>
<font color=red>// $Id$</font>
<font color=blue>#include</font> "<font color=green>mmap.h</font>"
int
main (int, char *[])
{
<font color=red>/*
The default behavior of the memory map wrapper is to create
the file if it doesn't exist. This is a minor change from
the SV shared memory wrapper.
*/</font>
ACE_Shared_Memory_MM shm_server (SHM_KEY, SHMSZ);
char *shm = (char *) shm_server.malloc ();
char *s = shm;
ACE_DEBUG ((LM_INFO, "<font color=green>(%P|%t) Memory Mapped file is at 0x%x\n</font>",
shm ));
for (char c = 'a'; c <= 'z'; c++)
*s++ = c;
*s = '\0';
while (*shm != '*')
<font color=#008888>ACE_OS::sleep</font> (1);
for (s = shm; *s != '\0'; s++)
{
putchar (*s);
}
putchar ('\n');
if (shm_server.remove () < 0)
ACE_ERROR ((LM_ERROR, "<font color=green>%p\n</font>", "<font color=green>remove</font>"));
return 0;
}
</PRE>
<HR>
BTW: In ACE 4.6.7 and prior there is a bug that prevents the remove()
method from actually removing the physical file.
<P><HR WIDTH="100%">
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