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<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="Author" CONTENT="James CE Johnson">
<TITLE>ACE Tutorial 021</TITLE>
</HEAD>
<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F">
<CENTER><B><FONT SIZE=+2>ACE Tutorial 021</FONT></B></CENTER>
<CENTER><B><FONT SIZE=+2>Pooling your memories</FONT></B></CENTER>
<P>
<HR WIDTH="100%">
Everything common the server & client is kept here. In
particular, the Constants class where we keep the names &
semaphore keys.
<p>
The Allocator class is just a thin wrapper around
ACE_Malloc<> that moves some of the details out of the
application logic.
<hr><PRE>
<font color=red>// $Id$</font>
<font color=blue>#ifndef</font> <font color=purple>MPOOL_H</font>
<font color=blue>#define</font> <font color=purple>MPOOL_H</font>
<font color=red>// Everything else we need is in this one header</font>
<font color=blue>#include</font> "<font color=green>ace/Malloc.h</font>"
<font color=red>/*
With this we will abstract away some of the details of the memory
pool. Note that we don't treat this as a singleton because an
application may need more than one pool. Each would have a
different name and be used for different purposes.
*/</font>
class Allocator
{
public:
<font color=red>// The pool name will be used to create a unique semaphore to</font>
<font color=red>// keep this pool separate from others.</font>
Allocator( const char * _name = "<font color=green>MemoryPool</font>" );
~Allocator(void);
typedef ACE_Malloc<ACE_MMAP_Memory_Pool, ACE_SV_Semaphore_Simple> pool_t;
<font color=red>// Provide an accessor to the pool. This will also allocate the</font>
<font color=red>// pool when first invoked.</font>
pool_t & pool(void);
protected:
<font color=red>// The name we gave to the pool</font>
char * name_;
pool_t * pool_;
};
<font color=red>/*
The client and server need to agree on a certain set of values. By
placing them in the Constants class we can eliminate a bit of confusion.
*/</font>
class Constants
{
public:
<font color=red>// The semaphore keys are needed for the two semaphores that</font>
<font color=red>// synch access to the shared memory area.</font>
static const int SEM_KEY_1;
static const int SEM_KEY_2;
<font color=red>// How big the pool will be and what we'll put into it. A real</font>
<font color=red>// app wouldn't need SHMDATA of course.</font>
static const int SHMSZ;
static const char * SHMDATA;
<font color=red>// The name assigned to the memory pool by the server is needed</font>
<font color=red>// by the client. Without it, the pool cannot be found.</font>
<font color=red>// Likewise, the name the server will bind() to the region of the </font>
<font color=red>// pool must be available to the client.</font>
static const char * PoolName;
static const char * RegionName;
};
<font color=blue>#endif</font>
</PRE>
<P><HR WIDTH="100%">
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