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<!-- $Id$ -->
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="GENERATOR" CONTENT="Mozilla/4.04 [en] (X11; I; Linux 2.0.32 i486) [Netscape]">
<META NAME="Author" CONTENT="James CE Johnson">
<META NAME="Description" CONTENT="A first step towards using ACE productively">
<TITLE>ACE Tutorial 002</TITLE>
</HEAD>
<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F">
<CENTER><B><FONT SIZE=+2>ACE Tutorial 002</FONT></B></CENTER>
<CENTER><B><FONT SIZE=+2>Creating a Better Server</FONT></B></CENTER>
<P>
<HR WIDTH="100%">
<P>Now lets take a look at the new <A HREF="handler.h">Logging_Handler</A>:
<P>
<HR WIDTH="100%">
<PRE>
<font color=red>// $Id$</font>
<font color=blue>#ifndef</font> <font color=purple>LOGGING_HANDLER_H</font>
<font color=blue>#define</font> <font color=purple>LOGGING_HANDLER_H</font>
<font color=blue>#include</font> "<A HREF="../../../ace/INET_Addr.h">ace/INET_Addr.h</A>"
<font color=blue>#if !defined</font> (<font color=purple>ACE_LACKS_PRAGMA_ONCE</font>)
<font color=blue># pragma</font> <font color=purple>once</font>
<font color=blue>#endif</font> <font color=red>/* ACE_LACKS_PRAGMA_ONCE */</font>
<font color=blue>#include</font> "<A HREF="../../../ace/SOCK_Stream.h">ace/SOCK_Stream.h</A>"
<font color=blue>#include</font> "<A HREF="../../../ace/Reactor.h">ace/Reactor.h</A>"
<font color=red>/* Since we used the template to create the acceptor, we don't know if
there is a way to get to the reactor it uses. We'll take the easy
way out and grab the global pointer. (There is a way to get back to
the acceptor's reactor that we'll see later on.) */</font>
extern ACE_Reactor *g_reactor;
<font color=red>/* This time we're deriving from ACE_Svc_Handler instead of
ACE_Event_Handler. The big reason for this is because it already
knows how to contain a SOCK_Stream and provides all of the method
calls needed by the reactor. The second template parameter is for
some advanced stuff we'll do with later servers. For now, just use
it as is... */</font>
class Logging_Handler : public ACE_Svc_Handler <ACE_SOCK_STREAM, ACE_NULL_SYNCH>
{
public:
<font color=red>/* The Acceptor<> template will open() us when there is a new client
connection. */</font>
virtual int open (void *)
{
ACE_INET_Addr addr;
<font color=red>/* Ask the peer() (held in our baseclass) to tell us the address
of the cient which has connected. There may be valid reasons
for this to fail where we wouldn't want to drop the connection
but I can't think of one. */</font>
if (this->peer ().get_remote_addr (addr) == -1)
return -1;
<font color=red>/* The Acceptor<> won't register us with it's reactor, so we have
to do so ourselves. This is where we have to grab that global
pointer. Notice that we again use the READ_MASK so that
handle_input() will be called when the client does something. */</font>
if (g_reactor->register_handler (this,
<font color=#008888>ACE_Event_Handler::READ_MASK</font>) == -1)
ACE_ERROR_RETURN ((LM_ERROR,
"<font color=green>(%P|%t) can't register with reactor\n</font>"),
-1);
<font color=red>/* Here's another new treat. We schedule a timer event. This
particular one will fire in two seconds and then every three
seconds after that. It doesn't serve any useful purpose in our
application other than to show you how it is done. */</font>
else if (g_reactor->schedule_timer (this,
0,
ACE_Time_Value (2),
ACE_Time_Value (3)) == -1)
ACE_ERROR_RETURN ((LM_ERROR,
"<font color=green>can'(%P|%t) t register with reactor\n</font>"),
-1);
ACE_DEBUG ((LM_DEBUG,
"<font color=green>(%P|%t) connected with %s\n</font>",
addr.get_host_name ()));
return 0;
}
<font color=red>/* This is a matter of style & maybe taste. Instead of putting all
of this stuff into a destructor, we put it here and request that
everyone call destroy() instead of 'delete'. */</font>
virtual void destroy (void)
{
<font color=red>/* Remove ourselves from the reactor */</font>
g_reactor->remove_handler
(this,
<font color=#008888>ACE_Event_Handler::READ_MASK</font> | ACE_Event_Handler::DONT_CALL);
<font color=red>/* Cancel that timer we scheduled in open() */</font>
g_reactor->cancel_timer (this);
<font color=red>/* Shut down the connection to the client. */</font>
this->peer ().close ();
<font color=red>/* Free our memory. */</font>
delete this;
}
<font color=red>/* If somebody doesn't like us, they will close() us. Actually, if
our open() method returns -1, the Acceptor<> will invoke close()
on us for cleanup. */</font>
virtual int close (u_long flags = 0)
{
<font color=red>/* The ACE_Svc_Handler baseclass requires the <flags> parameter.
We don't use it here though, so we mark it as UNUSED. You can
accomplish the same thing with a signature like handle_input's
below. */</font>
ACE_UNUSED_ARG (flags);
<font color=red>/*
Clean up and go away.
*/</font>
this->destroy ();
return 0;
}
protected:
<font color=red>/* Respond to input just like Tutorial 1. */</font>
virtual int handle_input (ACE_HANDLE)
{
char buf[128];
<font color=#008888>ACE_OS::memset</font> (buf, 0, sizeof (buf));
switch (this->peer ().recv (buf,
sizeof buf))
{
case -1:
ACE_ERROR_RETURN ((LM_ERROR,
"<font color=green>(%P|%t) %p bad read\n</font>",
"<font color=green>client logger</font>"),
-1);
case 0:
ACE_ERROR_RETURN ((LM_ERROR,
"<font color=green>(%P|%t) closing log daemon (fd = %d)\n</font>",
this->get_handle ()),
-1);
default:
ACE_DEBUG ((LM_DEBUG,
"<font color=green>(%P|%t) from client: %s</font>",
buf));
}
return 0;
}
<font color=red>/* When the timer expires, handle_timeout() will be called. The
'arg' is the value passed after 'this' in the schedule_timer()
call. You can pass in anything there that you can cast to a
void*. */</font>
virtual int handle_timeout (const ACE_Time_Value &tv,
const void *arg)
{
ACE_DEBUG ((LM_DEBUG,
"<font color=green>(%P|%t) handling timeout from this = %u\n</font>",
this));
return 0;
}
<font color=red>/*
Clean ourselves up when handle_input() (or handle_timer()) returns -1
*/</font>
virtual int handle_close (ACE_HANDLE,
ACE_Reactor_Mask)
{
this->destroy ();
return 0;
}
};
<font color=blue>#endif</font> <font color=red>/* LOGGING_HANDLER_H */</font>
</PRE>
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