1.\" 2.\" Copyright (c) 1996 Joerg Wunsch 3.\" 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.\" $Id$ 27.\" " 28.Dd April 3, 1996 29.Os 30.Dt SLEEP 9 31.Sh NAME 32.Nm sleep , 33.Nm tsleep , 34.Nm wakeup 35.Nd wait for events 36.Sh SYNOPSIS 37.Fd #include <sys/param.h> 38.Fd #include <sys/systm.h> 39.Fd #include <sys/proc.h> 40.Fd #include <sys/errno.h> 41.Ft int 42.Fn tsleep "void *ident" "int priority" "char *wmesg" "int timo" 43.Ft void 44.Fn wakeup "void *ident" 45.Ft int 46.Fn sleep "void *ident" "int priority" 47.Sh DESCRIPTION 48The functions 49.Fn tsleep 50and 51.Fn wakeup 52handle event-based process blocking. If a process must wait for an 53external event, it is put on sleep by 54.Nm tsleep . 55The parameter 56.Ar ident 57is an arbitrary address that uniquely identifies the event on which 58the process is being asleep. All processes sleeping on a single 59.Ar ident 60are woken up later by 61.Nm wakeup , 62often called from inside an interrupt routine, to indicate that the 63resource the process was blocking on is available now. 64.Pp 65The parameter 66.Ar wmesg 67is a string describing the sleep condition for tools like 68.Xr ps 1 . 69Due to the limited space of those programs to display arbitrary strings, 70this message should not be longer than 6 characters. 71.Pp 72.Nm Tsleep 73is the general sleep call. Suspends the current process until a wakeup is 74performed on the specified identifier. The process will then be made 75runnable with the specified 76.Ar priority . 77Sleeps at most 78.Ar timo 79\&/ hz seconds (0 means no timeout). If 80.Ar pri 81includes the 82.Dv PCATCH 83flag, signals are checked before and after sleeping, else signals are 84not checked. Returns 0 if awakened, 85.Dv EWOULDBLOCK 86if the timeout expires. If 87.Dv PCATCH 88is set and a signal needs to be delivered, 89.Dv ERESTART 90is returned if the current system call should be restarted if 91possible, and 92.Dv EINTR 93is returned if the system call should be interrupted by the signal 94.Pq return Dv EINTR . 95.Pp 96.Nm Sleep 97is the traditional form. It doesn't let you specify a timeout nor a 98.Ar wmesg , 99hence its use is deprecated. 100.Sh RETURN VALUES 101See above. 102.Sh SEE ALSO 103.Xr ps 1 104.Sh HISTORY 105The sleep/wakeup process synchronization mechanism is very old. It 106appeared in a very early version of Unix. 107.Pp 108.Nm Tsleep 109appeared in 110.Bx 4.4 . 111.Sh AUTHORS 112This man page has been written by 113.ie t J\(:org Wunsch. 114.el Joerg Wunsch. 115