Annotation of libwww/Library/src/HTEvent.html, revision 2.16
2.1 eric 1: <HTML>
2: <HEAD>
2.13 frystyk 3: <TITLE>W3C Sample Code Library libwww Event Class</TITLE>
2.1 eric 4: </HEAD>
5: <BODY>
2.4 frystyk 6: <H1>
7: The Event Class
2.3 frystyk 8: </H1>
2.1 eric 9: <PRE>
10: /*
11: ** (c) COPYRIGHT MIT 1995.
12: ** Please first read the full copyright statement in the file COPYRIGH.
13: */
2.4 frystyk 14: </PRE>
15: <P>
16: The Event Class defines any event manager to be used by libwww for handling
17: events. An <I>event</I> is not strictly defined as it is highly platform
18: dependent and hence out of scope for the Library. If you are using the libwww
19: pseudo threads on Unix then an event is when the <I>select()</I> system
20: call returns a notification on a socket descriptor, but it may as well
21: be an asynchronous event from the windows manager etc. If your application
22: is not using anything but traditional blocking sockets then you do not need
23: an event manager at all. In that case, libwww will block on any socket or
24: system call until the process can proceed.
25: <P>
26: The libwww interface to an event manager is very simple as it consists of
27: <B>registering</B> a <I>socket descriptor</I>, the <I>location</I> in the
28: program, and the <I>current state</I> when an operation (for example
29: <CODE>read</CODE>) would block. When the event manager at a later point in
30: time gets a notification that the socket has become ready, it can then call
31: libwww with the state saved from the registration and libwww can continue.
32: Second, libwww must be able to <B>unregister</B> a socket when it is not
33: anymore in a state where it can block. <I>Only</I> in case the application
34: wishes to use <I>non-blocking</I> sockets it should register methods for
35: handling the <B>registration</B> process as described below.
36: <P>
37: <B>Note</B>: The library <B>core</B> does <I>not</I> define any event manager
38: - it is considered part of the application. The library comes with a
39: <A HREF="HTEvntrg.html">default event manager</A> which can be initiated
2.6 frystyk 40: using the function <CODE>HTEventInit()</CODE> in <A HREF="HTInit.html">HTInit
41: module</A>
2.4 frystyk 42: <P>
43: This module is implemented by <A HREF="HTEvent.c">HTEvent.c</A>, and it is
2.16 ! frystyk 44: a part of the <A HREF="http://www.w3.org/Library/">W3C Sample Code Library</A>.
2.4 frystyk 45: <PRE>
2.1 eric 46: #ifndef HTEVENT_H
47: #define HTEVENT_H
2.14 frystyk 48: #include "wwwsys.h"
2.11 eric 49: #ifdef IN_EVENT
50: typedef struct _HTTimer HTTimer;
51: #endif
2.2 frystyk 52:
2.8 frystyk 53: #if 0
2.4 frystyk 54: #define FD_NONE 0
55: #define FD_ALL (FD_READ | FD_WRITE | FD_OOB | FD_ACCEPT | FD_CONNECT |FD_CLOSE)
56: #define FD_UNREGISTER (((FD_ALL) << 1) & (~(FD_ALL)))
2.8 frystyk 57: #endif
2.4 frystyk 58:
2.2 frystyk 59: typedef enum _HTPriority {
60: HT_PRIORITY_INV = -1,
61: HT_PRIORITY_OFF = 0,
62: HT_PRIORITY_MIN = 1,
63: HT_PRIORITY_MAX = 20
64: } HTPriority;
65:
2.10 eric 66: #define HTEVENT_INDEX 0x10
2.8 frystyk 67: typedef enum {
2.9 eric 68: #ifdef WWW_WIN_ASYNC
2.10 eric 69: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
70: HTEvent_WRITE = (0x002 | 1 << HTEVENT_INDEX),
71: HTEvent_OOB = (0x004 | 2 << HTEVENT_INDEX),
72: HTEvent_ACCEPT = (0x008 | 3 << HTEVENT_INDEX),
73: HTEvent_CONNECT = (0x010 | 4 << HTEVENT_INDEX),
74: HTEvent_CLOSE = (0x020 | 5 << HTEVENT_INDEX),
2.9 eric 75: HTEvent_TYPES = 6, /* winsock has seperate events for all of these */
2.10 eric 76: #define HTEVENT_TYPES 6 /* use in constructing the fake event below */
2.9 eric 77: #else /* WWW_WIN_ASYNC */
2.10 eric 78: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
79: HTEvent_ACCEPT = (0x002 | 0 << HTEVENT_INDEX),
80: HTEvent_CLOSE = (0x004 | 0 << HTEVENT_INDEX),
81: HTEvent_WRITE = (0x008 | 1 << HTEVENT_INDEX),
82: HTEvent_CONNECT = (0x010 | 1 << HTEVENT_INDEX),
83: HTEvent_OOB = (0x020 | 2 << HTEVENT_INDEX),
2.9 eric 84: HTEvent_TYPES = 3, /* only READ, WRITE, and OOB are real types */
2.10 eric 85: #define HTEVENT_TYPES 3 /* use in constructing the fake event below */
2.9 eric 86: #endif /* !WWW_WIN_ASYNC */
2.10 eric 87: /*
88: ** fake events - these don't correspond to event manager events, but they
89: ** are usefull for communicating with the protocol modules
90: */
91: HTEvent_TIMEOUT = (0x040 | HTEVENT_TYPES << HTEVENT_INDEX),
92: HTEvent_BEGIN = (0x000 | HTEVENT_TYPES << HTEVENT_INDEX),
93: HTEvent_END = (0x080 | HTEVENT_TYPES << HTEVENT_INDEX),
94: HTEvent_FLUSH = (0x100 | HTEVENT_TYPES << HTEVENT_INDEX),
95: HTEvent_RESET = (0x200 | HTEVENT_TYPES << HTEVENT_INDEX),
2.9 eric 96: HTEvent_ALL = 0xFFFF
2.8 frystyk 97: } HTEventType;
2.1 eric 98:
2.16 ! frystyk 99: #define HTEvent_BITS(type) (type & 0xFFFF)
! 100: #define HTEvent_INDEX(type) (type >> HTEVENT_INDEX)
2.8 frystyk 101:
2.11 eric 102: #define HT_EVENT_INITIALIZER \
103: {HTEvent_READ, "HTEvent_READ"}, \
104: {HTEvent_ACCEPT, "HTEvent_ACCEPT"}, \
105: {HTEvent_CLOSE, "HTEvent_CLOSE"}, \
106: {HTEvent_WRITE, "HTEvent_WRITE"}, \
107: {HTEvent_CONNECT, "HTEvent_CONNECT"}, \
108: {HTEvent_OOB, "HTEvent_OOB"}, \
109: {HTEvent_TIMEOUT, "HTEvent_TIMEOUT"}, \
110: {HTEvent_BEGIN, "HTEvent_BEGIN"}, \
111: {HTEvent_END, "HTEvent_END"}, \
112: {HTEvent_FLUSH, "HTEvent_FLUSH"}, \
113: {HTEvent_RESET, "HTEvent_RESET"}
114:
115: extern char * HTEvent_type2str(HTEventType type);
2.12 frystyk 116: </PRE>
2.3 frystyk 117: <H2>
2.7 eric 118: <A NAME="eventHandlers">Event Handlers</A>
2.3 frystyk 119: </H2>
120: <P>
2.4 frystyk 121: A <I>location</I> is a function that can be registered by the event manager
122: and called at a later point in time in order to continue an operation. All
123: locations must be of type <CODE>HTEventCallback</CODE> as defined here:
2.2 frystyk 124: <PRE>
2.8 frystyk 125: typedef int HTEventCallback (SOCKET, void *, HTEventType);
2.12 frystyk 126: typedef struct _HTEvent HTEvent;
127:
2.16 ! frystyk 128: /* Avoid circular include for HTReq->HTNet->HTHost: HTEvent blah */
2.12 frystyk 129: #include "HTReq.h"
2.2 frystyk 130: </PRE>
2.4 frystyk 131: <P>
132: There are many default event handlers provided with the Library. For example,
133: all the protocol modules such as the <A HREF="HTTP.html">HTTP client module</A>
134: are implemented as event handlers. In stead of using blocking sockets, this
135: allows a protocol module to register itself when performing an operation
136: that would block. When the sockets becomes ready the handler is called with
137: th socket in question, the request object, and the socket operation
2.3 frystyk 138: <H2>
2.4 frystyk 139: Registering and Unregistering Event Handlers
2.3 frystyk 140: </H2>
141: <P>
2.4 frystyk 142: As mentioned above, the only interface libwww requires from an event manager
143: is a method to <I>register</I> an event handler when an operation would block
144: and <I>unregister</I> it when the operation has completed The library registers
145: and unregisters event handlers by calling the following two functions:
2.8 frystyk 146: <PRE>
147: extern int HTEvent_register (SOCKET, HTEventType, HTEvent *);
148: extern int HTEvent_unregister (SOCKET, HTEventType);
2.4 frystyk 149: </PRE>
150: <P>
151: The register function contains information about which socket we are waiting
152: on to get ready and which operation we are waiting for (read, write, etc.),
153: the request object containing the current request, the event handler that
154: we want to be called when the socket becomes reasy, and finally the priority
155: by which we want the thread to be processed by the event manager. Likewise,
156: libwww can unregister a operation on a socket which means that libwww is
157: no longer waiting for this actiion to become ready.
158: <H2>
159: Registering an Event Manager
160: </H2>
161: <P>
162: The Library core does not contain any event manager as it depends on whether
163: you want to use pseudo threads no threads, or real threads. Instead, libwww
164: comes with a <A HREF="HTEvntrg.html">default implementation</A> that you
165: may register, but you may as well implement and register your own. The register
166: and unregister functions above actually does nothing than looking for a
167: registered event manager and then passes the call on to that. You register
168: your own event manager by using the methods below:
2.1 eric 169: <PRE>
2.8 frystyk 170: struct _HTEvent {
171: HTPriority priority; /* Priority of this request (event) */
172: int millis; /* Timeout in ms for this event */
2.11 eric 173: #ifdef IN_EVENT
174: HTTimer * timer;
175: #endif
2.8 frystyk 176: HTEventCallback * cbf; /* Protocol state machine */
177: void * param; /* HTEvent_register parameter */
178: HTRequest * request;
179: };
180:
181: typedef int HTEvent_registerCallback(SOCKET, HTEventType, HTEvent *);
182: typedef int HTEvent_unregisterCallback(SOCKET, HTEventType);
2.1 eric 183:
184: extern void HTEvent_setRegisterCallback(HTEvent_registerCallback *);
185: extern void HTEvent_setUnregisterCallback(HTEvent_unregisterCallback *);
2.8 frystyk 186: extern BOOL HTEvent_setCallback(HTEvent * event, HTEventCallback * cbf);
187:
188: extern HTEvent * HTEvent_new (HTEventCallback * cbf, void * context,
189: HTPriority pritority, int timeoutInMillis);
190: extern BOOL HTEvent_delete (HTEvent * event);
191:
192: extern BOOL HTEvent_setParam(HTEvent * event, void * param);
193: extern BOOL HTEvent_setPriority(HTEvent * event, HTPriority priority);
194: extern BOOL HTEvent_setTimeout(HTEvent * event, int timeoutInMillis);
2.1 eric 195: </PRE>
2.3 frystyk 196: <P>
2.4 frystyk 197: You can register the event manager provided together with libwww by using
2.6 frystyk 198: the <CODE>HTEventInit()</CODE> in the <A HREF="HTInit.html">HTInit module</A>
2.1 eric 199: <PRE>
200: #endif /* HTEVENT_H */
201: </PRE>
2.3 frystyk 202: <P>
203: <HR>
2.1 eric 204: <ADDRESS>
2.16 ! frystyk 205: @(#) $Id: HTEvent.html,v 2.15 1998/05/14 02:10:25 frystyk Exp $
2.1 eric 206: </ADDRESS>
2.3 frystyk 207: </BODY></HTML>
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