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
|
// $Id$
#ifndef CLIENT_ACCEPTOR_H
#define CLIENT_ACCEPTOR_H
/* The ACE_Acceptor<> template lives in the ace/Acceptor.h header
file. You'll find a very consitent naming convention between the
ACE objects and the headers where they can be found. In general,
the ACE object ACE_Foobar will be found in ace/Foobar.h. */
#include "ace/Acceptor.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
/* Since we want to work with sockets, we'll need a SOCK_Acceptor to
allow the clients to connect to us. */
#include "ace/SOCK_Acceptor.h"
/* The Client_Handler object we develop will be used to handle clients
once they're connected. The ACE_Acceptor<> template's first
parameter requires such an object. In some cases, you can get by
with just a forward declaration on the class, in others you have to
have the whole thing. */
#include "client_handler.h"
/* Parameterize the ACE_Acceptor<> such that it will listen for socket
connection attempts and create Client_Handler objects when they
happen. In Tutorial 001, we wrote the basic acceptor logic on our
own before we realized that ACE_Acceptor<> was available. You'll
get spoiled using the ACE templates because they take away a lot of
the tedious details! */
typedef ACE_Acceptor <Client_Handler, ACE_SOCK_ACCEPTOR> Client_Acceptor_Base;
#include "thread_pool.h"
/* This time we've added quite a bit more to our acceptor. In
addition to providing a choice of concurrency strategies, we also
maintain a Thread_Pool object in case that strategy is chosen. The
object still isn't very complex but it's come a long way from the
simple typedef we had in Tutorial 5.
Why keep the thread pool as a member? If we go back to the inetd
concept you'll recall that we need several acceptors to make that
work. We may have a situation in which our different client types
requre different resources. That is, we may need a large thread
pool for some client types and a smaller one for others. We could
share a pool but then the client types may have undesirable impact
on one another.
Just in case you do want to share a single thread pool, there is a
constructor below that will let you do that. */
class Client_Acceptor : public Client_Acceptor_Base
{
public:
typedef Client_Acceptor_Base inherited;
/* Now that we have more than two strategies, we need more than a
boolean to tell us what we're using. A set of enums is a good
choice because it allows us to use named values. Another option
would be a set of static const integers. */
enum concurrency_t
{
single_threaded_,
thread_per_connection_,
thread_pool_
};
/* The default constructor allows the programmer to choose the
concurrency strategy. Since we want to focus on thread-pool,
that's what we'll use if nothing is specified. */
Client_Acceptor (int concurrency = thread_pool_);
/* Another option is to construct the object with an existing thread
pool. The concurrency strategy is pretty obvious at that point. */
Client_Acceptor (Thread_Pool &thread_pool);
/* Our destructor will take care of shutting down the thread-pool if
applicable. */
~Client_Acceptor (void);
/* Open ourselves and register with the given reactor. The thread
pool size can be specified here if you want to use that
concurrency strategy. */
int open (const ACE_INET_Addr &addr,
ACE_Reactor *reactor,
int pool_size = Thread_Pool::default_pool_size_);
/* Close ourselves and our thread pool if applicable */
int close (void);
/* What is our concurrency strategy? */
int concurrency (void)
{
return this->concurrency_;
}
/* Give back a pointer to our thread pool. Our Client_Handler
objects will need this so that their handle_input() methods can
put themselves into the pool. Another alternative would be a
globally accessible thread pool. ACE_Singleton<> is a way to
achieve that. */
Thread_Pool *thread_pool (void)
{
return &this->the_thread_pool_;
}
/* Since we can be constructed with a Thread_Pool reference, there
are times when we need to know if the thread pool we're using is
ours or if we're just borrowing it from somebody else. */
int thread_pool_is_private (void)
{
return &the_thread_pool_ == &private_thread_pool_;
}
protected:
int concurrency_;
Thread_Pool private_thread_pool_;
Thread_Pool &the_thread_pool_;
};
#endif /* CLIENT_ACCEPTOR_H */
|