| Allegro CL version 8.2 New since 8.2 release. |
Arguments: (mode lock &key recursive-p yield-rate timeout timeout-body) &body body
Evaluate a body of code in the context of a sharable-lock
acquired in the
specified mode. This macro allows more control
of the behavior than with-shared-lock or with-exclusive-lock and the values returned by
this macro (the value of the last body form when the lock is
successfully acquired) is consistent with other with-XXX macros
in Common Lisp, unlike with-shared-lock or with-exclusive-lock which
return t
.
This macro is in
the smputil
module and may not be included in the
image util (require :smputil)
is evaluated.
The mode argument must evaluate to one of
the keywords :exclusive
or :shared
.
The lock argument must evaluate to an
instance of sharable-lock
.
The yield-rate argument, if specified,
must evaluate to a positive integer, or the
keyword :never
. The specified value overrides the
value in the lock instance. If the argument is omitted, or specified
as nil
, than the value in the lock instance
is used.
The timeout argument, if specified, must
evaluate to nil
or a number of seconds. The
value determines how long the program will wait if the lock is not
immediately available. A timeout value of zero (or a negative value)
specifies that the lock must be available immediately.
The recursive-p argument can be used to
override the recursive-p specification in the
sharable-lock
instance.
See make-sharable-lock.
The body expressions are evaluated as a progn body and the returned values are the values of the progn when the lock is successfully acquired. (The return values when the lock is not acquired are described below.)
The timeout-body argument specified the
behavior when a timout is requested.
The timeout-body argument must be a list of
expressions beginning with nil
or a bound
variable list. The default timeout behavior is ((x) (values
nil x))
If a timeout occurs, or when timout is zero or negative and the lock is not available immediately, the first variable in the list of bound variables is bound to the reason for the timeout and the remainder of the timout-body is evaluated as a let body. The values returned by the timeout-body forms are the values returned from the with-sharable-lock form. In the event of a true timeout, the reason is always :timeout, but when timout is zero or negative, the reason may be one of the keywords returned by sharable-lock-lock.
If the timeout does not occur, the timeout-body argument is never evaluated, and the values of the body forms are returned.
See Sharable locks in smp.htm.
See multiprocessing.htm for general information on multiprocessing in Allegro CL.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page is new in the 8.2 release.
Created 2016.6.21.
| Allegro CL version 8.2 New since 8.2 release. |