source: trunk/abcl/src/org/armedbear/lisp/threads.lisp @ 14215

Last change on this file since 14215 was 14106, checked in by ehuelsmann, 8 years ago

Move exports from the THREADS package to threads.lisp.
Move sockets related exports to socket.lisp, fixing symbol references

to refer to the EXTENSIONS package instead of SYSTEM.

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 4.5 KB
Line 
1;;; threads.lisp
2;;;
3;;; Copyright (C) 2009-2010 Erik Huelsmann <ehuelsmann@common-lisp.net>
4;;;
5;;; $Id: threads.lisp 14106 2012-08-17 10:45:00Z ehuelsmann $
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
36(export '(make-mailbox mailbox-send mailbox-empty-p
37          mailbox-read mailbox-peek
38          make-thread-lock with-thread-lock
39          make-mutex get-mutex release-mutex with-mutex))
40
41
42;;
43;; MAKE-THREAD helper to establish restarts
44;;
45
46(defun thread-function-wrapper (fun)
47  (restart-case
48      (funcall fun)
49    (abort () :report "Abort thread.")))
50
51;;
52;; Mailbox implementation
53;;
54
55;; this export statement is also in autoloads.lisp
56(export '(make-mailbox mailbox-send mailbox-empty-p mailbox-read mailbox-peek))
57
58(defstruct mailbox
59  queue)
60
61(defun mailbox-send (mailbox item)
62  "Sends an item into the mailbox, notifying 1 waiter
63to wake up for retrieval of that object."
64  (threads:synchronized-on mailbox
65     (push item (mailbox-queue mailbox))
66     (threads:object-notify mailbox)))
67
68(defun mailbox-empty-p (mailbox)
69  "Returns non-NIL if the mailbox can be read from, NIL otherwise."
70  ;; Because we're just checking the value of an object reference,
71  ;; (which are atomically gotten and set) we don't need to lock
72  ;; the mailbox before operating on it.
73  (null (mailbox-queue mailbox)))
74
75(defun mailbox-read (mailbox)
76  "Blocks on the mailbox until an item is available for reading.
77When an item is available, it is returned."
78  (threads:synchronized-on mailbox
79     (loop
80        (unless (mailbox-empty-p mailbox)
81          (return))
82        (object-wait mailbox))
83     (pop (mailbox-queue mailbox))))
84
85(defun mailbox-peek (mailbox)
86  "Returns two values. The second returns non-NIL when the mailbox
87is empty. The first is the next item to be read from the mailbox.
88
89Note that due to multi-threading, the first value returned upon
90peek, may be different from the one returned upon next read in the
91calling thread."
92  (threads:synchronized-on mailbox
93     (values (car (mailbox-queue mailbox))
94             (null (mailbox-queue mailbox)))))
95
96
97
98;;
99;; Mutex implementation
100;;
101
102
103;; this export statement is also in autoloads.lisp
104(export '(make-mutex get-mutex release-mutex))
105
106(defstruct mutex
107  in-use)
108
109(defun get-mutex (mutex)
110  "Acquires a lock on the `mutex'."
111  (synchronized-on mutex
112    (loop
113       while (mutex-in-use mutex)
114       do (object-wait mutex))
115    (setf (mutex-in-use mutex) T)))
116
117(defun release-mutex (mutex)
118  "Releases a lock on the `mutex'."
119  (synchronized-on mutex
120    (setf (mutex-in-use mutex) NIL)
121    (object-notify mutex)))
122
123(defmacro with-mutex ((mutex) &body body)
124  "Acquires a lock on `mutex', executes the body
125and releases the lock."
126  (let ((m (gensym)))
127    `(let ((,m ,mutex))
128       (when (get-mutex ,m)
129         (unwind-protect
130          (progn
131            ,@body)
132          (release-mutex ,m))))))
133
134
135;;
136;; Lock implementation
137;;
138
139(defun make-thread-lock ()
140  "Returns an object to be used with the `with-thread-lock' macro."
141  (gensym))
142
143(defmacro with-thread-lock ((lock) &body body)
144  "Acquires a lock on the `lock', executes `body' and releases the lock."
145  (let ((glock (gensym)))
146    `(let ((,glock ,lock))
147       (synchronized-on ,glock
148          ,@body))))
149
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