SelectListener

1 // A shared resource, owned by the server. A reference is passed to each
2 // connection handler.
3 class SomeSharedResource
4 {
5 }
6 
7 // The connection handler class. The server owns a select listener instance.
8 // The select listener owns a pool of connection handlers. When a new
9 // connection is accepted by the select listener, a connection handler is
10 // taken from the pool (or allocated, if there are no free items in the
11 // pool) and set to handle the incoming connection.
12 // (Connection handler classes must not be nested, in order for the pool to
13 // be able to automatically allocate instances. In this case, it must be
14 // declared static, as the class definition is "nested" inside a unittest.)
15 static class MyConnectionHandler : IConnectionHandler
16 {
17     import ocean.net.server.connection.IConnectionHandlerInfo;
18     import ocean.sys.socket.AddressIPSocket;
19 
20     /// Reference to the global shared resource (passed to the ctor).
21     private SomeSharedResource shared_resource;
22 
23     /// Flag set when an IO error occurs (see error()).
24     private bool error_occurred;
25 
26     /***********************************************************************
27 
28         Constructs a connection handler.
29 
30         Params:
31             finalize_dg = delegate required by the super class.
32                 Automatically set by SelectListenerPool to be
33                 SelectListener.returnToPool. Called by the super class when
34                 finalize() is called
35             shared_resource = reference to a global shared resource
36 
37     ***********************************************************************/
38 
39     public this ( scope FinalizeDg finalize_dg, SomeSharedResource shared_resource )
40     {
41         this.shared_resource = shared_resource;
42 
43         super(new AddressIPSocket!(), finalize_dg, &this.error);
44     }
45 
46     /// The actual logic for handling a connection.
47     override public void handleConnection ( )
48     {
49         // Do something in here.
50 
51         // When you're finished, call finalize(), which recycles this
52         // connection into the pool owned by the select listener.
53         this.finalize();
54     }
55 
56     /// Tells the super class whether an I/O error occurred.
57     override protected bool io_error ( )
58     {
59         return this.error_occurred;
60     }
61 
62     /// Called by epoll when an I/O error occurs.
63     private void error ( Exception exception, Event event,
64         IConnectionHandlerInfo info )
65     {
66         this.error_occurred = true;
67     }
68 
69     /// Unregisters the socket from the epoll before closing it. Called by
70     /// finalize.
71     override protected void unregisterSocket ()
72     {
73     }
74 }
75 
76 // Top-level server class which owns the select listener and all global
77 // resources.
78 class MyServer
79 {
80     import ocean.sys.socket.AddressIPSocket;
81     import ocean.sys.socket.InetAddress;
82     import ocean.io.select.EpollSelectDispatcher;
83 
84     /// Select listener alias.
85     private alias SelectListener!(MyConnectionHandler, SomeSharedResource)
86         MySelectListener;
87 
88     /// Select listener instance.
89     private MySelectListener listener;
90 
91     /// Epoll instance.
92     private EpollSelectDispatcher epoll;
93 
94     /// Constructs a server.
95     public this ( )
96     {
97         InetAddress!(false) addr;
98         auto socket = new AddressIPSocket!();
99         auto shared_resource = new SomeSharedResource;
100 
101         this.listener = new MySelectListener(addr("127.0.0.1", 2009),
102             socket, shared_resource);
103 
104         this.epoll = new EpollSelectDispatcher;
105     }
106 
107     /// Starts the server.
108     public void start ( )
109     {
110         // The listener is an ISelectClient, so must be registered with
111         // epoll in order to do anything.
112         this.epoll.register(this.listener);
113 
114         // The event loop must also be running.
115         this.epoll.eventLoop();
116     }
117 
118     /// Stops the server.
119     public void stop ( )
120     {
121         this.listener.shutdown();
122     }
123 }