| Allegro CL version 10.1 New since the initial 10.1 release. | ||||||||||
Arguments: input-streams output-streams &key input-wait-function output-wait-function whostate timeout
This function was added by a patch in May, 2019. It is for version 10.1 and later.
This function is similar to wait-for-input-available but allows an application to wait for output possible on one set of streams as well as for input availble on another set.
The function returns nil or a list of items
of the form (stream . status)
where stream is a stream from one of the lists in
the first two arguments and status is one of the
following keywords:
:in: the associated stream is
one of the
input-streams and
the input-wait-function returned a
non-nil value.
:in-error: the associated stream
is one of the
input-streams and
the input-wait-function signaled an error.
:out: the associated stream is
one of the
output-streams and
the output-wait-function returned a
non-nil value.
:out-error: the
associated stream is one of the
output-streams and
the output-wait-function signaled an error.
The input-streams
and output-streams arguments must be lists
of streams or file descriptor integers or a single stream or file
descriptor integer or nil. If both
are nil, wait-for-io-available
returns nil immediately.
The input-wait-function argument, if supplied, must be name a function which accepts one argument, which is applied to each item in the input-streams list before a system wait is initiated, and after a system wait returns. The default function is stream-listen.
The output-wait-function argument, if supplied, must name a function which accepts one argument, which is applied to each item in the output-streams list before a system wait is initiated, and after a system wait returns. The default function is an internal function that attempts to write an empty array of octets to the stream.
The whostate argument is used as the whostate during a system wait. The default value is "waiting for i/o".
The timeout argument must
be nil or a
number. nil specifies an indefinite wait, a
number specifies a number of seconds.
When called, this function applies
input-wait-function to every element of
input-streams
and output-wait-function to every element of
output-streams. If any application errors or
returns non-nil, then a list of all cases of
erroring or returning non-nil is collected
and returned, the list being as described above. (Of course, the
information is based on when the functions are applied to the streams
and the state may changed even before wait-for-io-available returns.)
If all applications of the functions
return nil, a system wait is called that
monitors all the specified I/O devices. When the system wait returns,
the wait functions are again applied as above with a result being
returned if any function call errors or returns
non-nil. If timeout is a
number, wait-for-io-available
returns nil after that number of seconds. If
timeout is nil, wait-for-io-available returns only when some
application of a wait function errors or returns
non-nil.
Copyright (c) 1998-2022, Franz Inc. Lafayette, CA., USA. All rights reserved.
This page is new in the 10.1 release.
Created 2019.8.20.
| Allegro CL version 10.1 New since the initial 10.1 release. | ||||||||||