1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
<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> "<font color=green>ace/INET_Addr.h</font>"
<font color=blue>#if !defined</font> (<font color=purple>ACE_LACKS_PRAGMA_ONCE</font>)
# pragma once
<font color=blue>#endif</font> <font color=red>/* ACE_LACKS_PRAGMA_ONCE */</font>
<font color=blue>#include</font> "<font color=green>ace/SOCK_Stream.h</font>"
<font color=blue>#include</font> "<font color=green>ace/Reactor.h</font>"
<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];
memset (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 _mask)
{
this->destroy();
return 0;
}
};
<font color=blue>#endif</font> <font color=red>// LOGGING_HANDLER_H</font>
</PRE>
<P><HR WIDTH="100%">
<CENTER>[<A HREF="../online-tutorials.html">Tutorial Index</A>] [<A HREF="page04.html">Continue This Tutorial</A>]</CENTER>
|
