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Use more markup. Use HTML escapes. Use .Rs/.Re for book citation.

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wiz 2006-12-04 13:16:59 +00:00
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65
share/man/man9/condvar.9
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@ -1,4 +1,4 @@
.\" $NetBSD: condvar.9,v 1.2 2006/11/13 18:28:15 ad Exp $
.\" $NetBSD: condvar.9,v 1.3 2006/12/04 13:16:59 wiz Exp $
.\"
.\" Copyright (c) 2006 The NetBSD Foundation, Inc.
.\" All rights reserved.
@ -90,7 +90,7 @@ argument specifies a string of no more than 8 characters that describes
the resource or condition associated with the CV.
The kernel does not use this argument directly but makes it available for
utilities such as
.Xr ps 1
.Xr ps 1
to display.
.It Fn cv_destroy "cv"
.Pp
@ -114,7 +114,7 @@ before
.Fn cv_wait
returns.
.Pp
A small window exists between testing for availability of a resource and
A small window exists between testing for availability of a resource and
waiting for the resource with
.Fn cv_wait ,
in which the resource may become available again.
@ -134,9 +134,15 @@ code returned.
.Pp
If
.Fn cv_wait_sig
returns as a result of a signal, the return value is ERESTART if the signal
has the SA_RESTART property.
If awoken normally, the value is zero, and EINTR under all other conditions.
returns as a result of a signal, the return value is
.Er ERESTART
if the signal
has the
.Dv SA_RESTART
property.
If awoken normally, the value is zero, and
.Er EINTR
under all other conditions.
.It Fn cv_timedwait "cv" "mtx" "ticks"
.Pp
As per
@ -158,14 +164,15 @@ one suitable for
.Fn cv_timedwait .
.Pp
If the timeout expires before the LWP is awoken, the return value is
EWOULDBLOCK.
.Er EWOULDBLOCK .
If awoken normally, the return value is zero.
.It Fn cv_timedwait_sig "cv" "mtx" "ticks"
.Pp
As per
.Fn cv_wait_sig ,
but also accepts a timeout value and will return EWOULDBLOCK if the
timeout expires.
but also accepts a timeout value and will return
.Er EWOULDBLOCK
if the timeout expires.
.It Fn cv_signal "cv"
.Pp
Awaken one LWP (potentially among many) that is waiting on the specified
@ -187,28 +194,28 @@ Consuming a resource:
* Lock the resource. Its mutex will also serve as the
* interlock.
*/
mutex_enter(&res->mutex);
mutex_enter(\*[Am]res-\*[Gt]mutex);
/*
* Wait for the resource to become available, and take
* ownership of it.
*/
while (res->state == BUSY)
cv_wait(&res->condvar, &res->mutex);
res->state = BUSY;
while (res-\*[Gt]state == BUSY)
cv_wait(\*[Am]res-\*[Gt]condvar, \*[Am]res-\*[Gt]mutex);
res-\*[Gt]state = BUSY;
/*
* It's now available to us.
*/
mutex_exit(&res->mutex);
mutex_exit(\*[Am]res-\*[Gt]mutex);
consume(res);
Releasing a resource for the next consumer to use:
mutex_enter(&res->mutex);
res->state = IDLE;
cv_signal(&res->condvar);
mutex_exit(&res->mutex);
mutex_enter(\*[Am]res-\*[Gt]mutex);
res-\*[Gt]state = IDLE;
cv_signal(\*[Am]res-\*[Gt]condvar);
mutex_exit(\*[Am]res-\*[Gt]mutex);
.Ed
.Sh CODE REFERENCES
This section describes places within the
@ -217,26 +224,30 @@ source tree where code implementing condition variables can be found.
All pathnames are relative to
.Pa /usr/src .
.Pp
The core of the CV implementation is in
The core of the CV implementation is in
.Pa sys/kern/kern_condvar.c .
.Pp
The header file
.Pa sys/sys/condvar.h
describes the public interface.
.Sh SEE ALSO
.Xr condvar 9 ,
.Xr sigaction 2 ,
.Xr errno 9 ,
.Xr mstohz 9 ,
.Xr mutex 9 ,
.Xr sigaction 2 ,
.Xr rwlock 9 .
.Xr rwlock 9
.Pp
Jim Mauro and Richard McDougall,
.Em Solaris Internals: Core Kernel Architecture ,
Prentice Hall, 2001.
ISBN 0-13-022496-0
.Rs
.%A Jim Mauro
.%A Richard McDougall
.%T Solaris Internals: Core Kernel Architecture
.%I Prentice Hall
.%D 2001
.%O ISBN 0-13-022496-0
.Re
.Sh HISTORY
The CV primatives first appeared in
.Nx 5.0 .
They are modelled after similar primatives implemented in
Sun Solaris, and have been extended for NetBSD.
Sun Solaris, and have been extended for
.Nx .