1'\"
2'\" Copyright (c)1996-2002 by Hartmut Brandt
3'\" All rights reserved.
4'\"
5'\" Author: Hartmut Brandt
6'\"
7'\" Redistribution of this software and documentation and use in source and
8'\" binary forms, with or without modification, are permitted provided that
9'\" the following conditions are met:
10'\"
11'\" 1. Redistributions of source code or documentation must retain the above
12'\" copyright notice, this list of conditions and the following disclaimer.
13'\" 2. Redistributions in binary form must reproduce the above copyright
14'\" notice, this list of conditions and the following disclaimer in the
15'\" documentation and/or other materials provided with the distribution.
16'\"
17'\" THIS SOFTWARE AND DOCUMENTATION IS PROVIDED BY THE AUTHOR
18'\" AND ITS CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
19'\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20'\" FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
21'\" THE AUTHOR OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22'\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23'\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
24'\" OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25'\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26'\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27'\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28'\"
29'\" $Begemot: libbegemot/rpoll.man,v 1.4 2004/09/21 15:59:00 brandt Exp $
30'\"
| 1'\"
2'\" Copyright (c)1996-2002 by Hartmut Brandt
3'\" All rights reserved.
4'\"
5'\" Author: Hartmut Brandt
6'\"
7'\" Redistribution of this software and documentation and use in source and
8'\" binary forms, with or without modification, are permitted provided that
9'\" the following conditions are met:
10'\"
11'\" 1. Redistributions of source code or documentation must retain the above
12'\" copyright notice, this list of conditions and the following disclaimer.
13'\" 2. Redistributions in binary form must reproduce the above copyright
14'\" notice, this list of conditions and the following disclaimer in the
15'\" documentation and/or other materials provided with the distribution.
16'\"
17'\" THIS SOFTWARE AND DOCUMENTATION IS PROVIDED BY THE AUTHOR
18'\" AND ITS CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
19'\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20'\" FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
21'\" THE AUTHOR OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22'\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23'\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
24'\" OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25'\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26'\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27'\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28'\"
29'\" $Begemot: libbegemot/rpoll.man,v 1.4 2004/09/21 15:59:00 brandt Exp $
30'\"
|
31.TH rpoll l "21 Oct 1996" "BEGEMOT" "BEGEMOT Library"
| 31.TH rpoll 3 "21 Oct 1996" "BEGEMOT" "BEGEMOT Library"
|
32.SH NAME
33rpoll - callback functions for file descriptors and timers
34.SH SYNOPSIS
35.LP
36.B "# include <rpoll.h>"
37.LP
38.BR "typedef void (*poll_f)(int " "fd" ", int " "mask" ", void *" "arg);"
39.br
40.BR "typedef void (*timer_f)(int " "tid" ", void *" "arg);"
41.LP
42.BR "int poll_register(int " "fd" ", poll_f "
43.RB "func" ", void *" "arg" ", int " "mask" ");"
44.LP
45.BR "void poll_unregister(int " "handle" ");"
46.LP
47.BR "int poll_start_timer(u_int " "msecs" ", int " "repeat" ", timer_f " "func,"
48.if n .ti +.5i
49.BR "void *" "arg);"
50.LP
51.BR "void poll_stop_timer(int " "handle" ");"
52.LP
53.BR "void poll_dispatch(int " "wait" ");"
54.SH DESCRIPTION
55Many programs need to read from several file descriptors at the same time.
56Typically in these programs one of
57.BR select (3c)
58or
59.BR poll (2)
60is used.
61These calls are however clumsy to use and the usage of one of these calls is
62probably not portable to other systems - not all systems support both calls.
63.LP
64The
65.BR rpoll (l)
66family of functions is designed to overcome these restrictions.
67They support the well known and understood technique of event driven
68programing and, in addition to
69.BR select (3c)
70and
71.BR poll (2)
72also support timers.
73.LP
74Each event on a file descriptor or each timer event is translated into a call to a user
75defined callback function. These functions need to be registered.
76A file descriptor is registered with
77.BR poll_register .
78.I fd
79is the file descriptor to watch,
80.I mask
81is an event mask.
82It may be any combination of
83.B POLL_IN
| 32.SH NAME
33rpoll - callback functions for file descriptors and timers
34.SH SYNOPSIS
35.LP
36.B "# include <rpoll.h>"
37.LP
38.BR "typedef void (*poll_f)(int " "fd" ", int " "mask" ", void *" "arg);"
39.br
40.BR "typedef void (*timer_f)(int " "tid" ", void *" "arg);"
41.LP
42.BR "int poll_register(int " "fd" ", poll_f "
43.RB "func" ", void *" "arg" ", int " "mask" ");"
44.LP
45.BR "void poll_unregister(int " "handle" ");"
46.LP
47.BR "int poll_start_timer(u_int " "msecs" ", int " "repeat" ", timer_f " "func,"
48.if n .ti +.5i
49.BR "void *" "arg);"
50.LP
51.BR "void poll_stop_timer(int " "handle" ");"
52.LP
53.BR "void poll_dispatch(int " "wait" ");"
54.SH DESCRIPTION
55Many programs need to read from several file descriptors at the same time.
56Typically in these programs one of
57.BR select (3c)
58or
59.BR poll (2)
60is used.
61These calls are however clumsy to use and the usage of one of these calls is
62probably not portable to other systems - not all systems support both calls.
63.LP
64The
65.BR rpoll (l)
66family of functions is designed to overcome these restrictions.
67They support the well known and understood technique of event driven
68programing and, in addition to
69.BR select (3c)
70and
71.BR poll (2)
72also support timers.
73.LP
74Each event on a file descriptor or each timer event is translated into a call to a user
75defined callback function. These functions need to be registered.
76A file descriptor is registered with
77.BR poll_register .
78.I fd
79is the file descriptor to watch,
80.I mask
81is an event mask.
82It may be any combination of
83.B POLL_IN
|
84to get informed, when input on the file descriptor is possible,
| 84to get informed when input on the file descriptor is possible,
|
85.B POLL_OUT
| 85.B POLL_OUT
|
86to get informed, when output is possible or
| 86to get informed when output is possible or
|
87.B POLL_EXCEPT
| 87.B POLL_EXCEPT
|
88to get informed, when an exceptional condition occures.
| 88to get informed when an exceptional condition occures.
|
89An example of an exceptional condition is the arrival of urgent data.
90(Note, that an end of file condition is signaled via POLL_IN).
91.I func
92is the user function to be called and
93.I arg
94is a user supplied argument for this function.
95The callback functions is called with the file descriptor, a mask
96describing the actual events (from the set supplied in the registration) and
97the user argument.
98.B poll_register
99returns a handle, which may be used later to de-register the file descriptor.
100A file descriptor may be registered more than once, if the function, the user arguments
101or both differ in the call to
102.BR poll_register .
103If
104.I func
105and
106.I arg
107are the same, then no new registration is done, instead the event mask of the registration
108is changed to reflect the new mask.
109.LP
110A registered file descriptor may be de-registered by calling
111.B poll_unregister
112with the handle returned by
113.BR poll_register .
114.LP
115A timer is created with
116.BR poll_start_timer .
117.I msecs
118is the number of milliseconds, after which the timer event will be generated.
119.I repeat
120selects one-short behavior (if 0) or a repeatable timer (if not 0). A one-short timer
121will automatically unregistered after expiry.
122.I func
123is the user function which will be called with a timer id and the user supplied
124.IR arg .
125.B poll_start_timer
126returnes a timer id, which may be used to cancel the timer with
127.BR poll_stop_timer .
128A one-short timer should be canceled only if it has not yet fired.
129.LP
130.B poll_dispatch
131must be called to actually dispatch events.
132.I wait
133is a flag, which should be 0, if only a poll should be done. In this case, the function returns,
134after polling the registered file descriptors and timers. If
135.I wait
136is not 0,
137.B poll_dispatch
138waits until an event occures. All events are dispatch (i.e. callback functions called) and
139.B poll_dispatch returns.
140.LP
141Typical use is:
142.LP
143.RS
144.nf
145.ft 3
146while(1)
147 poll_dispatch(1);
148.ft 1
149.fi
150.RE
151.SH "SEE ALSO"
152.BR poll (2), select (3C)
153.SH "RETURN VALUES"
154.B poll_register
155and
156.B poll_start_timer
157return a handle which may be used to unregister the file descriptor or cancel the timer.
158.LP
159Both functions and
160.B poll_dispatch
161call
162.BR xrealloc (l)
163and can end in
164.BR panic (l).
165.SH "ERRORS"
166System call or memory allocation errors are fatal and are handle by calling
167.BR panic (l).
168The one exception is a return of EINTR from
169.BR select (3c)
170or
171.BR poll (2)
172in
173.BR poll_dispatch .
174In this case
175.B poll_dispatch
176simply returns.
177.SH "BUGS"
178Obscure sequences of
179.B poll_start_timer
180and
181.B poll_stop_timer
182in callback functions may probably break the code.
183.LP
184The semantics of
185.B POLL_EXCEPT
186are not clear.
187.SH AUTHORS
188Hartmut Brandt, harti@freebsd.org
| 89An example of an exceptional condition is the arrival of urgent data.
90(Note, that an end of file condition is signaled via POLL_IN).
91.I func
92is the user function to be called and
93.I arg
94is a user supplied argument for this function.
95The callback functions is called with the file descriptor, a mask
96describing the actual events (from the set supplied in the registration) and
97the user argument.
98.B poll_register
99returns a handle, which may be used later to de-register the file descriptor.
100A file descriptor may be registered more than once, if the function, the user arguments
101or both differ in the call to
102.BR poll_register .
103If
104.I func
105and
106.I arg
107are the same, then no new registration is done, instead the event mask of the registration
108is changed to reflect the new mask.
109.LP
110A registered file descriptor may be de-registered by calling
111.B poll_unregister
112with the handle returned by
113.BR poll_register .
114.LP
115A timer is created with
116.BR poll_start_timer .
117.I msecs
118is the number of milliseconds, after which the timer event will be generated.
119.I repeat
120selects one-short behavior (if 0) or a repeatable timer (if not 0). A one-short timer
121will automatically unregistered after expiry.
122.I func
123is the user function which will be called with a timer id and the user supplied
124.IR arg .
125.B poll_start_timer
126returnes a timer id, which may be used to cancel the timer with
127.BR poll_stop_timer .
128A one-short timer should be canceled only if it has not yet fired.
129.LP
130.B poll_dispatch
131must be called to actually dispatch events.
132.I wait
133is a flag, which should be 0, if only a poll should be done. In this case, the function returns,
134after polling the registered file descriptors and timers. If
135.I wait
136is not 0,
137.B poll_dispatch
138waits until an event occures. All events are dispatch (i.e. callback functions called) and
139.B poll_dispatch returns.
140.LP
141Typical use is:
142.LP
143.RS
144.nf
145.ft 3
146while(1)
147 poll_dispatch(1);
148.ft 1
149.fi
150.RE
151.SH "SEE ALSO"
152.BR poll (2), select (3C)
153.SH "RETURN VALUES"
154.B poll_register
155and
156.B poll_start_timer
157return a handle which may be used to unregister the file descriptor or cancel the timer.
158.LP
159Both functions and
160.B poll_dispatch
161call
162.BR xrealloc (l)
163and can end in
164.BR panic (l).
165.SH "ERRORS"
166System call or memory allocation errors are fatal and are handle by calling
167.BR panic (l).
168The one exception is a return of EINTR from
169.BR select (3c)
170or
171.BR poll (2)
172in
173.BR poll_dispatch .
174In this case
175.B poll_dispatch
176simply returns.
177.SH "BUGS"
178Obscure sequences of
179.B poll_start_timer
180and
181.B poll_stop_timer
182in callback functions may probably break the code.
183.LP
184The semantics of
185.B POLL_EXCEPT
186are not clear.
187.SH AUTHORS
188Hartmut Brandt, harti@freebsd.org
|