versions prior to 3.78 will not work correctly with this runtime.
The aim of these changes is to provide a central mechanism to detect
input on all input channels, and thus to prevent a single thread from
performing a blocking input operation that locks out other threads
that can do useful work. Now, in places where a thread would block on
an input device, it instead registers its interest in the device
with a centralized registry, and suspends. If all threads in the
system are suspended, then Scheme blocks by calling `select' and
waiting for something interesting to happen.
* Introduce new procedures that use the `select' system call to
provide a mechanism to monitor input availability on many input
devices simultaneously:
ADD-TO-SELECT-REGISTRY!
CHANNEL-DESCRIPTOR-FOR-SELECT
DEREGISTER-INPUT-THREAD-EVENT
MAKE-SELECT-REGISTRY
PERMANENTLY-REGISTER-INPUT-THREAD-EVENT
REGISTER-INPUT-THREAD-EVENT
REMOVE-FROM-SELECT-REGISTRY!
SELECT-DESCRIPTOR
SELECT-REGISTRY-TEST
TEST-FOR-INPUT-ON-CHANNEL
TEST-FOR-INPUT-ON-DESCRIPTOR
These procedures require the operating system to support `select' or
some equivalent. Calling them in another operating system, e.g.
DOS, will cause an error to be signalled.
* Delete old `select' mechanism procedures which are no longer used or
supported (these will be deleted from the microcode in the future):
CHANNEL-REGISTER
CHANNEL-UNREGISTER
CHANNEL-REGISTERED?
CHANNEL-SELECT-THEN-READ
* Modify CHANNEL-READ to automatically call TEST-FOR-INPUT-ON-CHANNEL
if the `select' system call is supported by the operating system.
One consequence of this is that CHANNEL-READ can return #F for
channels that are in "blocking" mode; if you don't want #F you must
call CHANNEL-READ-BLOCK instead (this was always a good idea
anyway).
* Change X graphics devices to use the new select machinery to preview
the event stream from the X server.
--------------------
The following changes are not part of the general aim stated above,
although most of them either derive from it or support it:
* Add new procedures to the "threads" package: (THREADS-LIST) returns
a list of all thread objects, including dead threads, that haven't
yet been garbage collected. (THREAD-EXECUTION-STATE thread) returns
the "execution state" of a thread, a symbol.
* Add code to the threads package that attempts to clean up all
attachments of the thread when it is exited. This is a
generalization of previous patches generated by GJR and GJS for
6.001.
* Plug several holes in the thread event delivery mechanism which
allowed the threads package to get into states where events were not
delivered to their threads.
* SUSPEND-CURRENT-THREAD now returns the event that caused the thread
the be resumed; previously it had an unspecified value. If several
events are delivered before resumption, the event returned is the
first one that is not #F, or #F if all of the events were #F.
* Fix several typos that caused errors when generating reports for
conditions in the threads package.
#| -*-Scheme-*-
-$Id: version.scm,v 14.160 1993/01/12 23:08:40 gjr Exp $
+$Id: version.scm,v 14.161 1993/04/27 09:44:01 cph Exp $
Copyright (c) 1988-1993 Massachusetts Institute of Technology
'()))
(add-system! microcode-system)
(add-event-receiver! event:after-restore snarf-microcode-version!)
- (add-identification! "Runtime" 14 160))
+ (add-identification! "Runtime" 14 161))
(define microcode-system)
projects / mit-scheme.git / commitdiff