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<META NAME="Author" CONTENT="James CE Johnson">
<META NAME="Description" CONTENT="A first step towards using ACE productively">
<TITLE>ACE Tutorial 002</TITLE>
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<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%">
<BR>
<PRE>#ifndef LOGGING_HANDLER_H
#define LOGGING_HANDLER_H
/*
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.)
*/
extern ACE_Reactor * g_reactor;
/*
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...
*/
class Logging_Handler : public ACE_Svc_Handler < ACE_SOCK_STREAM, ACE_NULL_SYNCH >
{
public:
/*
The Acceptor<> template will open() us when there is a new client connection.
*/
int open (void *)
{
ACE_INET_Addr addr;
/*
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.
*/
if (this->peer ().get_remote_addr (addr) == -1)
return -1;
/*
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.
*/
if (g_reactor->register_handler (this, ACE_Event_Handler::READ_MASK) == -1)
ACE_ERROR_RETURN ((LM_ERROR, "(%P|%t) can't register with reactor\n"), -1);
/*
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.
*/
else if (g_reactor->schedule_timer (this, 0, ACE_Time_Value (2), ACE_Time_Value (3)) == -1)
ACE_ERROR_RETURN ((LM_ERROR, "can'(%P|%t) t register with reactor\n"), -1);
ACE_DEBUG ((LM_DEBUG, "(%P|%t) connected with %s\n", addr.get_host_name() ));
return 0;
}
/*
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'.
*/
void destroy (void)
{
/*
Cancel that timer we scheduled in open()
*/
g_reactor->cancel_timer (this);
/*
Shut down the connection to the client.
*/
this->peer ().close ();
/*
Free our memory.
*/
delete this;
}
/*
If somebody doesn't like us, the will close() us. Actually, if our open() method
returns -1, the Acceptor<> will invoke close() on us for cleanup.
*/
int close (u_long)
{
/*
Clean up and go away.
*/
this->destroy ();
return 0;
}
protected:
/*
Respond to input just like Tutorial 1.
*/
int handle_input (ACE_HANDLE)
{
char buf[128];
memset (buf, 0, sizeof (buf));
switch (this->peer ().recv (buf, sizeof buf))
{
case -1:
ACE_ERROR_RETURN ((LM_ERROR, "(%P|%t) %p bad read\n", "client logger"), -1);
case 0:
ACE_ERROR_RETURN ((LM_ERROR, "(%P|%t) closing log daemon (fd = %d)\n", this->get_handle ()), -1);
default:
ACE_DEBUG ((LM_DEBUG, "(%P|%t) from client: %s", buf));
}
return 0;
}
/*
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*.
*/
int handle_timeout (const ACE_Time_Value & tv, const void *arg)
{
ACE_DEBUG ((LM_DEBUG, "(%P|%t) handling timeout from this = %u\n", this));
return 0;
}
};
#endif // LOGGING_HANDLER_H</PRE>
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