source: branches/streams/abcl/src/org/armedbear/lisp/threads.lisp

Last change on this file was 14690, checked in by Mark Evenson, 11 years ago

THREADS:YIELD implements java.lang.Thread.yield().

Improved documenation strings in threads package.

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 4.8 KB
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1;;; threads.lisp
2;;;
3;;; Copyright (C) 2009-2010 Erik Huelsmann <ehuelsmann@common-lisp.net>
4;;;
5;;; $Id: threads.lisp 14690 2014-04-22 11:24:50Z mevenson $
6;;;
7;;; This program is free software; you can redistribute it and/or
8;;; modify it under the terms of the GNU General Public License
9;;; as published by the Free Software Foundation; either version 2
10;;; of the License, or (at your option) any later version.
11;;;
12;;; This program is distributed in the hope that it will be useful,
13;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
14;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15;;; GNU General Public License for more details.
16;;;
17;;; You should have received a copy of the GNU General Public License
18;;; along with this program; if not, write to the Free Software
19;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
20;;;
21;;; As a special exception, the copyright holders of this library give you
22;;; permission to link this library with independent modules to produce an
23;;; executable, regardless of the license terms of these independent
24;;; modules, and to copy and distribute the resulting executable under
25;;; terms of your choice, provided that you also meet, for each linked
26;;; independent module, the terms and conditions of the license of that
27;;; module.  An independent module is a module which is not derived from
28;;; or based on this library.  If you modify this library, you may extend
29;;; this exception to your version of the library, but you are not
30;;; obligated to do so.  If you do not wish to do so, delete this
31;;; exception statement from your version.
32
33(in-package #:threads)
34
35(export '(make-mailbox mailbox-send mailbox-empty-p
36          mailbox-read mailbox-peek
37          make-thread-lock with-thread-lock
38          current-thread yield
39          make-mutex get-mutex release-mutex with-mutex))
40;;
41;; MAKE-THREAD helper to establish restarts
42;;
43
44(defun thread-function-wrapper (fun)
45  (restart-case
46      (funcall fun)
47    (abort () :report "Abort thread.")))
48
49;;
50;; Mailbox implementation
51;;
52
53;; this export statement is also in autoloads.lisp
54(export '(make-mailbox mailbox-send mailbox-empty-p mailbox-read mailbox-peek))
55
56(defstruct mailbox
57  queue)
58
59(defun mailbox-send (mailbox item)
60  "Sends an item into the mailbox, notifying 1 waiter
61to wake up for retrieval of that object."
62  (threads:synchronized-on mailbox
63     (push item (mailbox-queue mailbox))
64     (threads:object-notify mailbox)))
65
66(defun mailbox-empty-p (mailbox)
67  "Returns non-NIL if the mailbox can be read from, NIL otherwise."
68  ;; Because we're just checking the value of an object reference,
69  ;; (which are atomically gotten and set) we don't need to lock
70  ;; the mailbox before operating on it.
71  (null (mailbox-queue mailbox)))
72
73(defun mailbox-read (mailbox)
74  "Blocks on the mailbox until an item is available for reading.
75When an item is available, it is returned."
76  (threads:synchronized-on mailbox
77     (loop
78        (unless (mailbox-empty-p mailbox)
79          (return))
80        (object-wait mailbox))
81     (pop (mailbox-queue mailbox))))
82
83(defun mailbox-peek (mailbox)
84  "Returns two values. The second returns non-NIL when the mailbox
85is empty. The first is the next item to be read from the mailbox.
86
87Note that due to multi-threading, the first value returned upon
88peek, may be different from the one returned upon next read in the
89calling thread."
90  (threads:synchronized-on mailbox
91     (values (car (mailbox-queue mailbox))
92             (null (mailbox-queue mailbox)))))
93
94
95
96;;
97;; Mutex implementation
98;;
99
100
101;; this export statement is also in autoloads.lisp
102(export '(make-mutex get-mutex release-mutex))
103
104(defstruct mutex
105  in-use)
106
107(defun get-mutex (mutex)
108  "Acquires a lock on the `mutex'."
109  (synchronized-on mutex
110    (loop
111       while (mutex-in-use mutex)
112       do (object-wait mutex))
113    (setf (mutex-in-use mutex) T)))
114
115(defun release-mutex (mutex)
116  "Releases a lock on the `mutex'."
117  (synchronized-on mutex
118    (setf (mutex-in-use mutex) NIL)
119    (object-notify mutex)))
120
121(defmacro with-mutex ((mutex) &body body)
122  "Acquires a lock on `mutex', executes the body
123and releases the lock."
124  (let ((m (gensym)))
125    `(let ((,m ,mutex))
126       (when (get-mutex ,m)
127         (unwind-protect
128          (progn
129            ,@body)
130          (release-mutex ,m))))))
131
132
133;;
134;; Lock implementation
135;;
136
137(defun make-thread-lock ()
138  "Returns an object to be used with the `with-thread-lock' macro."
139  (gensym))
140
141(defmacro with-thread-lock ((lock) &body body)
142  "Acquires a lock on the `lock', executes `body' and releases the lock."
143  (let ((glock (gensym)))
144    `(let ((,glock ,lock))
145       (synchronized-on ,glock
146          ,@body))))
147
148(defun yield ()
149  "A hint to the scheduler that the current thread is willing to yield its current use of a processor. The scheduler is free to ignore this hint.
150
151See java.lang.Thread.yield()."
152  (java:jcall "yield" (JAVA:jstatic "currentThread" "java.lang.Thread")))
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