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127 lines
3.7 KiB
JavaScript
127 lines
3.7 KiB
JavaScript
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is JavaScript Engine testing utilities.
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*
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* The Initial Developer of the Original Code is
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* Mozilla Foundation.
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* Portions created by the Initial Developer are Copyright (C) 2005
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s): Guoxin Fan <gfan@sta.samsung.com>
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* Jason Orendorff <jorendorff@mozilla.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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var gTestfile = 'lamport.js'
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//-----------------------------------------------------------------------
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var summary = "Lamport Bakery's algorithm for mutual exclusion";
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// Adapted from pseudocode in Wikipedia:
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// http://en.wikipedia.org/wiki/Lamport%27s_bakery_algorithm
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printStatus(summary);
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var N = 15; // Number of threads.
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var LOOP_COUNT = 10; // Number of times each thread should loop
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function range(n) {
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for (let i = 0; i < n; i++)
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yield i;
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}
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function max(a) {
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let x = Number.NEGATIVE_INFINITY;
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for each (let i in a)
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if (i > x)
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x = i;
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return x;
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}
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// the mutex mechanism
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var entering = [false for (i in range(N))];
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var ticket = [0 for (i in range(N))];
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// the object being protected
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var counter = 0;
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function lock(i)
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{
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entering[i] = true;
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ticket[i] = 1 + max(ticket);
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entering[i] = false;
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for (let j = 0; j < N; j++) {
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// If thread j is in the middle of getting a ticket, wait for that to
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// finish.
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while (entering[j])
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;
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// Wait until all threads with smaller ticket numbers or with the same
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// ticket number, but with higher priority, finish their work.
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while ((ticket[j] != 0) && ((ticket[j] < ticket[i]) ||
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((ticket[j] == ticket[i]) && (i < j))))
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;
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}
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}
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function unlock(i) {
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ticket[i] = 0;
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}
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function worker(i) {
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for (let k = 0; k < LOOP_COUNT; k++) {
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lock(i);
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// The critical section
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let x = counter;
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sleep(0.003);
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counter = x + 1;
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unlock(i);
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}
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return 'ok';
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}
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function makeWorker(id) {
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return function () { return worker(id); };
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}
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var expect;
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var actual;
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if (typeof scatter == 'undefined' || typeof sleep == 'undefined') {
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print('Test skipped. scatter or sleep not defined.');
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expect = actual = 'Test skipped.';
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} else {
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scatter([makeWorker(i) for (i in range(N))]);
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expect = "counter: " + (N * LOOP_COUNT);
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actual = "counter: " + counter;
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}
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reportCompare(expect, actual, summary);
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