11622 clean up rarer mandoc lint warnings
1 '\" te 2 .\" Copyright (c) 2014, Joyent, Inc. All Rights Reserved. 3 .\" This file and its contents are supplied under the terms of the 4 .\" Common Development and Distribution License ("CDDL"), version 1.0. 5 .\" You may only use this file in accordance with the terms of version 6 .\" 1.0 of the CDDL. 7 .\" 8 .\" A full copy of the text of the CDDL should have accompanied this 9 .\" source. A copy of the CDDL is also available via the Internet at 10 .\" http://www.illumos.org/license/CDDL. 11 .TH EPOLL 5 "Apr 17, 2014" 12 .SH NAME 13 epoll \- Linux-compatible I/O event notification facility 14 .SH SYNOPSIS 15 .nf 16 #include <sys/epoll.h> 17 .fi 18 19 .SH DESCRIPTION 20 \fBepoll\fR is a facility for efficient event-oriented I/O that has a 21 similar model to \fBpoll\fR(2), but does not necessitate rescanning a 22 set of file descriptors to wait for an event. \fBepoll\fR is of Linux 23 origins, and this facility is designed to be binary-compatible with 24 the Linux facility, including the following interfaces: 25 26 .RS +4 27 .TP 28 .ie t \(bu 29 .el o 30 \fBepoll_create\fR(3C) creates an \fBepoll\fR instance, returning a file 31 descriptor. It contains a size arugment which is meaningful only in as 32 much as it cannot be 0. 33 .RE 34 .RS +4 35 .TP 36 .ie t \(bu 37 .el o 38 \fBepoll_create1\fR(3C) also creates an \fBepoll\fR instance, but eliminates 39 the meaningless size argument -- replacing it instead with a flags 40 argument. 41 .RE 42 .RS +4 43 .TP 44 .ie t \(bu 45 .el o 46 \fBepoll_ctl\fR(3C) allows file descriptors to be added 47 (via \fBEPOLL_CTL_ADD\fR), deleted (via \fBEPOLL_CTL_DEL\fR) or 48 modified (via \fBEPOLL_CTL_MOD\fR) with respect to the \fBepoll\fR'd set 49 of file descriptors. 50 .RE 51 .RS +4 52 .TP 53 .ie t \(bu 54 .el o 55 \fBepoll_wait\fR(3C) fetches pending events for file descriptors added 56 via \fBepoll_ctl\fR(3C), blocking the caller if no such events are pending. 57 .RE 58 .RS +4 59 .TP 60 .ie t \(bu 61 .el o 62 \fBepoll_pwait\fR(3C) opeates in a similar manner to \fBepoll_wait\fR(3C), but 63 allows the caller to specify a signal mask to be set atomically with respect 64 to waiting for events. 65 .RE 66 67 .sp 68 .SH NOTES 69 The \fBepoll\fR facility is implemented 70 for purposes of offering compatibility to and portability of Linux-borne 71 applications; native applications should continue to prefer using event ports 72 via the \fBport_create\fR(3C), 73 \fBport_associate\fR(3C) and \fBport_getn\fR(3C) interfaces. 74 In particular, use of \fBepoll\fR in a multithreaded environment is fraught 75 with peril; even when using \fBEPOLLONESHOT\fR for one-shot events, 76 there are race conditions with respect to \fBclose\fR(2) that are unresolvable. 77 (For more details, see the aborted effort in Linux to resolve this via the 78 proposed 79 \fBEPOLL_CTL_DISABLE\fR operation.) 80 The event port facility -- like the BSD kqueue facility that inspired it -- 81 is designed to deal with such issues via explicit event source dissociation. 82 83 While a best effort has been made to mimic the Linux semantics, there 84 are some semantics that are too peculiar or ill-conceived to merit 85 accommodation. In particular, the Linux \fBepoll\fR facility will -- by 86 design -- continue to generate events for closed file descriptors where/when 87 the underlying file description remains open. For example, if one were 88 to \fBfork\fR(2) and subsequently close an actively \fBepoll\fR'd file 89 descriptor in the parent, 90 any events generated in the child on the implicitly duplicated file descriptor 91 will continue to be delivered to the parent -- despite the fact that the 92 parent itself no longer has any notion of the file description! 93 This \fBepoll\fR facility refuses to honor 94 these semantics; closing the \fBEPOLL_CTL_ADD\fR'd file descriptor 95 will always result in no further 96 events being generated for that event description. 97 98 .SH SEE ALSO 99 \fBepoll_create\fR(3C), \fBepoll_create1\fR(3C), \fBepoll_ctl\fR(3C), 100 \fBepoll_wait\fR(3C), \fBepoll_pwait\fR(3C), 101 \fBport_create\fR(3C), \fBport_associate\fR(3C), \fBport_dissociate\fR(3C), 102 \fBport_get\fR(3C), 103 \fBpselect\fR(3C) --- EOF ---