Annotation of libwww/Library/src/HTEvent.html, revision 2.11
2.1 eric 1: <HTML>
2: <HEAD>
2.4 frystyk 3: <TITLE>W3C Reference 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
44: a part of the <A HREF="http://www.w3.org/pub/WWW/Library/">W3C Reference
45: Library</A>.
46: <PRE>
2.1 eric 47: #ifndef HTEVENT_H
48: #define HTEVENT_H
2.2 frystyk 49: #include "sysdep.h"
2.11 ! eric 50: #ifdef IN_EVENT
! 51: typedef struct _HTTimer HTTimer;
! 52: #endif
2.2 frystyk 53:
2.8 frystyk 54: #if 0
2.4 frystyk 55: #define FD_NONE 0
56: #define FD_ALL (FD_READ | FD_WRITE | FD_OOB | FD_ACCEPT | FD_CONNECT |FD_CLOSE)
57: #define FD_UNREGISTER (((FD_ALL) << 1) & (~(FD_ALL)))
2.8 frystyk 58: #endif
2.4 frystyk 59:
2.2 frystyk 60: typedef enum _HTPriority {
61: HT_PRIORITY_INV = -1,
62: HT_PRIORITY_OFF = 0,
63: HT_PRIORITY_MIN = 1,
64: HT_PRIORITY_MAX = 20
65: } HTPriority;
66:
2.10 eric 67: #define HTEVENT_INDEX 0x10
2.8 frystyk 68: typedef enum {
2.9 eric 69: #ifdef WWW_WIN_ASYNC
2.10 eric 70: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
71: HTEvent_WRITE = (0x002 | 1 << HTEVENT_INDEX),
72: HTEvent_OOB = (0x004 | 2 << HTEVENT_INDEX),
73: HTEvent_ACCEPT = (0x008 | 3 << HTEVENT_INDEX),
74: HTEvent_CONNECT = (0x010 | 4 << HTEVENT_INDEX),
75: HTEvent_CLOSE = (0x020 | 5 << HTEVENT_INDEX),
2.9 eric 76: HTEvent_TYPES = 6, /* winsock has seperate events for all of these */
2.10 eric 77: #define HTEVENT_TYPES 6 /* use in constructing the fake event below */
2.9 eric 78: #else /* WWW_WIN_ASYNC */
2.10 eric 79: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
80: HTEvent_ACCEPT = (0x002 | 0 << HTEVENT_INDEX),
81: HTEvent_CLOSE = (0x004 | 0 << HTEVENT_INDEX),
82: HTEvent_WRITE = (0x008 | 1 << HTEVENT_INDEX),
83: HTEvent_CONNECT = (0x010 | 1 << HTEVENT_INDEX),
84: HTEvent_OOB = (0x020 | 2 << HTEVENT_INDEX),
2.9 eric 85: HTEvent_TYPES = 3, /* only READ, WRITE, and OOB are real types */
2.10 eric 86: #define HTEVENT_TYPES 3 /* use in constructing the fake event below */
2.9 eric 87: #endif /* !WWW_WIN_ASYNC */
2.10 eric 88: /*
89: ** fake events - these don't correspond to event manager events, but they
90: ** are usefull for communicating with the protocol modules
91: */
92: HTEvent_TIMEOUT = (0x040 | HTEVENT_TYPES << HTEVENT_INDEX),
93: HTEvent_BEGIN = (0x000 | HTEVENT_TYPES << HTEVENT_INDEX),
94: HTEvent_END = (0x080 | HTEVENT_TYPES << HTEVENT_INDEX),
95: HTEvent_FLUSH = (0x100 | HTEVENT_TYPES << HTEVENT_INDEX),
96: HTEvent_RESET = (0x200 | HTEVENT_TYPES << HTEVENT_INDEX),
2.9 eric 97: HTEvent_ALL = 0xFFFF
2.8 frystyk 98: } HTEventType;
2.1 eric 99:
2.8 frystyk 100: #define HTEvent_BITS(type) (type & 0xFFFF)
2.10 eric 101: #define HTEvent_INDEX(type) (type >> HTEVENT_INDEX)
2.8 frystyk 102:
2.11 ! eric 103: #define HT_EVENT_INITIALIZER \
! 104: {HTEvent_READ, "HTEvent_READ"}, \
! 105: {HTEvent_ACCEPT, "HTEvent_ACCEPT"}, \
! 106: {HTEvent_CLOSE, "HTEvent_CLOSE"}, \
! 107: {HTEvent_WRITE, "HTEvent_WRITE"}, \
! 108: {HTEvent_CONNECT, "HTEvent_CONNECT"}, \
! 109: {HTEvent_OOB, "HTEvent_OOB"}, \
! 110: {HTEvent_TIMEOUT, "HTEvent_TIMEOUT"}, \
! 111: {HTEvent_BEGIN, "HTEvent_BEGIN"}, \
! 112: {HTEvent_END, "HTEvent_END"}, \
! 113: {HTEvent_FLUSH, "HTEvent_FLUSH"}, \
! 114: {HTEvent_RESET, "HTEvent_RESET"}
! 115:
! 116: extern char * HTEvent_type2str(HTEventType type);
! 117:
2.8 frystyk 118: /* Avoid circular include for HTReq->HTNet->HTHost: HTEvent blah */
119: typedef struct _HTEvent HTEvent;
2.1 eric 120: #include "HTReq.h"
121: </PRE>
2.3 frystyk 122: <H2>
2.7 eric 123: <A NAME="eventHandlers">Event Handlers</A>
2.3 frystyk 124: </H2>
125: <P>
2.4 frystyk 126: A <I>location</I> is a function that can be registered by the event manager
127: and called at a later point in time in order to continue an operation. All
128: locations must be of type <CODE>HTEventCallback</CODE> as defined here:
2.2 frystyk 129: <PRE>
2.8 frystyk 130: typedef int HTEventCallback (SOCKET, void *, HTEventType);
2.2 frystyk 131: </PRE>
2.4 frystyk 132: <P>
133: There are many default event handlers provided with the Library. For example,
134: all the protocol modules such as the <A HREF="HTTP.html">HTTP client module</A>
135: are implemented as event handlers. In stead of using blocking sockets, this
136: allows a protocol module to register itself when performing an operation
137: that would block. When the sockets becomes ready the handler is called with
138: th socket in question, the request object, and the socket operation
2.3 frystyk 139: <H2>
2.4 frystyk 140: Registering and Unregistering Event Handlers
2.3 frystyk 141: </H2>
142: <P>
2.4 frystyk 143: As mentioned above, the only interface libwww requires from an event manager
144: is a method to <I>register</I> an event handler when an operation would block
145: and <I>unregister</I> it when the operation has completed The library registers
146: and unregisters event handlers by calling the following two functions:
2.8 frystyk 147: <PRE>
148: extern int HTEvent_register (SOCKET, HTEventType, HTEvent *);
149: extern int HTEvent_unregister (SOCKET, HTEventType);
2.4 frystyk 150: </PRE>
151: <P>
152: The register function contains information about which socket we are waiting
153: on to get ready and which operation we are waiting for (read, write, etc.),
154: the request object containing the current request, the event handler that
155: we want to be called when the socket becomes reasy, and finally the priority
156: by which we want the thread to be processed by the event manager. Likewise,
157: libwww can unregister a operation on a socket which means that libwww is
158: no longer waiting for this actiion to become ready.
159: <H2>
160: Registering an Event Manager
161: </H2>
162: <P>
163: The Library core does not contain any event manager as it depends on whether
164: you want to use pseudo threads no threads, or real threads. Instead, libwww
165: comes with a <A HREF="HTEvntrg.html">default implementation</A> that you
166: may register, but you may as well implement and register your own. The register
167: and unregister functions above actually does nothing than looking for a
168: registered event manager and then passes the call on to that. You register
169: your own event manager by using the methods below:
2.1 eric 170: <PRE>
2.8 frystyk 171: struct _HTEvent {
172: HTPriority priority; /* Priority of this request (event) */
173: int millis; /* Timeout in ms for this event */
2.11 ! eric 174: #ifdef IN_EVENT
! 175: HTTimer * timer;
! 176: #endif
2.8 frystyk 177: HTEventCallback * cbf; /* Protocol state machine */
178: void * param; /* HTEvent_register parameter */
179: HTRequest * request;
180: };
181:
182: typedef int HTEvent_registerCallback(SOCKET, HTEventType, HTEvent *);
183: typedef int HTEvent_unregisterCallback(SOCKET, HTEventType);
2.1 eric 184:
185: extern void HTEvent_setRegisterCallback(HTEvent_registerCallback *);
186: extern void HTEvent_setUnregisterCallback(HTEvent_unregisterCallback *);
2.8 frystyk 187: extern BOOL HTEvent_setCallback(HTEvent * event, HTEventCallback * cbf);
188:
189: extern HTEvent * HTEvent_new (HTEventCallback * cbf, void * context,
190: HTPriority pritority, int timeoutInMillis);
191: extern BOOL HTEvent_delete (HTEvent * event);
192:
193: extern BOOL HTEvent_setParam(HTEvent * event, void * param);
194: extern BOOL HTEvent_setPriority(HTEvent * event, HTPriority priority);
195: extern BOOL HTEvent_setTimeout(HTEvent * event, int timeoutInMillis);
2.1 eric 196: </PRE>
2.3 frystyk 197: <P>
2.4 frystyk 198: You can register the event manager provided together with libwww by using
2.6 frystyk 199: the <CODE>HTEventInit()</CODE> in the <A HREF="HTInit.html">HTInit module</A>
2.1 eric 200: <PRE>
201: #endif /* HTEVENT_H */
202: </PRE>
2.3 frystyk 203: <P>
204: <HR>
2.1 eric 205: <ADDRESS>
2.11 ! eric 206: @(#) $Id: HTEvent.html,v 2.10 1996/12/07 00:06:16 eric Exp $
2.1 eric 207: </ADDRESS>
2.3 frystyk 208: </BODY></HTML>
Webmaster