1'\"
|
2'\" Copyright (c)1996-2002 by Hartmut Brandt
|
2'\" Copyright (c)1996-2006 by Hartmut Brandt |
3'\" All rights reserved. 4'\"
|
5'\" Author: Hartmut Brandt
|
5'\" Author: harti@freebsd.org <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 3 "21 Oct 1996" "BEGEMOT" "BEGEMOT Library"
|
31.TH rpoll 3 "8 Dec 2006" "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);"
|
38.BR "typedef void (*poll_f)(int " "fd" ", int " "mask" ", void *" "arg" ");" |
39.br
|
40.BR "typedef void (*timer_f)(int " "tid" ", void *" "arg);"
|
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,"
|
47.BR "int poll_start_timer(u_int " "msecs" ", int " "repeat" ", timer_f " "func" "," |
48.if n .ti +.5i
|
49.BR "void *" "arg);"
|
49.BR "void *" "arg" ");" |
50.LP 51.BR "void poll_stop_timer(int " "handle" ");" 52.LP
|
53.BR "int poll_start_utimer(unsigned long long " "usecs" ", int " "repeat" ", 54.if n .ti +.5i 55.BR "timer_f " "func" ", void *" "arg" ");" 56.LP |
57.BR "void poll_dispatch(int " "wait" ");" 58.SH DESCRIPTION 59Many programs need to read from several file descriptors at the same time. 60Typically in these programs one of 61.BR select (3c) 62or 63.BR poll (2) 64is used. 65These calls are however clumsy to use and the usage of one of these calls is 66probably not portable to other systems - not all systems support both calls. 67.LP 68The 69.BR rpoll (l) 70family of functions is designed to overcome these restrictions. 71They support the well known and understood technique of event driven 72programing and, in addition to 73.BR select (3c) 74and 75.BR poll (2) 76also support timers. 77.LP 78Each event on a file descriptor or each timer event is translated into a call to a user 79defined callback function. These functions need to be registered. 80A file descriptor is registered with 81.BR poll_register . 82.I fd 83is the file descriptor to watch, 84.I mask 85is an event mask. 86It may be any combination of 87.B POLL_IN 88to get informed when input on the file descriptor is possible, 89.B POLL_OUT 90to get informed when output is possible or 91.B POLL_EXCEPT 92to get informed when an exceptional condition occures. 93An example of an exceptional condition is the arrival of urgent data. 94(Note, that an end of file condition is signaled via POLL_IN). 95.I func 96is the user function to be called and 97.I arg 98is a user supplied argument for this function. 99The callback functions is called with the file descriptor, a mask 100describing the actual events (from the set supplied in the registration) and 101the user argument. 102.B poll_register 103returns a handle, which may be used later to de-register the file descriptor. 104A file descriptor may be registered more than once, if the function, the user arguments 105or both differ in the call to 106.BR poll_register . 107If 108.I func 109and 110.I arg 111are the same, then no new registration is done, instead the event mask of the registration 112is changed to reflect the new mask. 113.LP 114A registered file descriptor may be de-registered by calling 115.B poll_unregister 116with the handle returned by 117.BR poll_register . 118.LP 119A timer is created with
|
116.BR poll_start_timer .
|
120.BR poll_start_timer 121or 122.BR poll_start_utimer . |
123.I msecs
|
118is the number of milliseconds, after which the timer event will be generated.
|
124is the number of milliseconds in 125.BR poll_start_timer 126while 127.I usecs 128is the number of microseconds in 129.BR poll_start_utimer , 130after which the timer event will be generated. 131If the functions use the 132.BR poll (2) 133system call, then 134.I usecs 135is rounded to milliseconds and 136.BR poll_start_timer 137is called. |
138.I repeat 139selects one-short behavior (if 0) or a repeatable timer (if not 0). A one-short timer 140will automatically unregistered after expiry. 141.I func 142is the user function which will be called with a timer id and the user supplied 143.IR arg . 144.B poll_start_timer
|
126returnes a timer id, which may be used to cancel the timer with
|
145and 146.B poll_start_utimer 147return a timer id, which may be used to cancel the timer with |
148.BR poll_stop_timer . 149A one-short timer should be canceled only if it has not yet fired. 150.LP 151.B poll_dispatch 152must be called to actually dispatch events. 153.I wait 154is a flag, which should be 0, if only a poll should be done. In this case, the function returns, 155after polling the registered file descriptors and timers. If 156.I wait 157is not 0, 158.B poll_dispatch 159waits until an event occures. All events are dispatch (i.e. callback functions called) and 160.B poll_dispatch returns. 161.LP 162Typical use is: 163.LP 164.RS 165.nf 166.ft 3 167while(1) 168 poll_dispatch(1); 169.ft 1 170.fi 171.RE 172.SH "SEE ALSO" 173.BR poll (2), select (3C) 174.SH "RETURN VALUES"
|
154.B poll_register
155and
|
175.B poll_register , |
176.B poll_start_timer
|
157return a handle which may be used to unregister the file descriptor or cancel the timer.
|
177and 178.B poll_start_utimer 179return a handle which may be used to unregister the file descriptor or 180cancel the timer. |
181.LP 182Both functions and 183.B poll_dispatch 184call 185.BR xrealloc (l) 186and can end in 187.BR panic (l). 188.SH "ERRORS" 189System call or memory allocation errors are fatal and are handle by calling 190.BR panic (l). 191The one exception is a return of EINTR from 192.BR select (3c) 193or 194.BR poll (2) 195in 196.BR poll_dispatch . 197In this case 198.B poll_dispatch 199simply returns. 200.SH "BUGS" 201Obscure sequences of 202.B poll_start_timer 203and 204.B poll_stop_timer 205in callback functions may probably break the code. 206.LP 207The semantics of 208.B POLL_EXCEPT 209are not clear. 210.SH AUTHORS 211Hartmut Brandt, harti@freebsd.org
|