The Tor Browser / file comparison
comparison: js/src/tests/js1_8/extensions/lamport.js
js/src/tests/js1_8/extensions/lamport.js
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
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| -1:000000000000 | 0:2deaf2b8bdaa |
|---|---|
| 1 // |reftest| skip | |
| 2 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 3 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 4 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 //----------------------------------------------------------------------- | |
| 8 | |
| 9 var summary = "Lamport Bakery's algorithm for mutual exclusion"; | |
| 10 // Adapted from pseudocode in Wikipedia: | |
| 11 // http://en.wikipedia.org/wiki/Lamport%27s_bakery_algorithm | |
| 12 | |
| 13 printStatus(summary); | |
| 14 | |
| 15 var N = 15; // Number of threads. | |
| 16 var LOOP_COUNT = 10; // Number of times each thread should loop | |
| 17 | |
| 18 function range(n) { | |
| 19 for (let i = 0; i < n; i++) | |
| 20 yield i; | |
| 21 } | |
| 22 | |
| 23 function max(a) { | |
| 24 let x = Number.NEGATIVE_INFINITY; | |
| 25 for each (let i in a) | |
| 26 if (i > x) | |
| 27 x = i; | |
| 28 return x; | |
| 29 } | |
| 30 | |
| 31 // the mutex mechanism | |
| 32 var entering = [false for (i in range(N))]; | |
| 33 var ticket = [0 for (i in range(N))]; | |
| 34 | |
| 35 // the object being protected | |
| 36 var counter = 0; | |
| 37 | |
| 38 function lock(i) | |
| 39 { | |
| 40 entering[i] = true; | |
| 41 ticket[i] = 1 + max(ticket); | |
| 42 entering[i] = false; | |
| 43 | |
| 44 for (let j = 0; j < N; j++) { | |
| 45 // If thread j is in the middle of getting a ticket, wait for that to | |
| 46 // finish. | |
| 47 while (entering[j]) | |
| 48 ; | |
| 49 | |
| 50 // Wait until all threads with smaller ticket numbers or with the same | |
| 51 // ticket number, but with higher priority, finish their work. | |
| 52 while ((ticket[j] != 0) && ((ticket[j] < ticket[i]) || | |
| 53 ((ticket[j] == ticket[i]) && (i < j)))) | |
| 54 ; | |
| 55 } | |
| 56 } | |
| 57 | |
| 58 function unlock(i) { | |
| 59 ticket[i] = 0; | |
| 60 } | |
| 61 | |
| 62 function worker(i) { | |
| 63 for (let k = 0; k < LOOP_COUNT; k++) { | |
| 64 lock(i); | |
| 65 | |
| 66 // The critical section | |
| 67 let x = counter; | |
| 68 sleep(0.003); | |
| 69 counter = x + 1; | |
| 70 | |
| 71 unlock(i); | |
| 72 } | |
| 73 return 'ok'; | |
| 74 } | |
| 75 | |
| 76 function makeWorker(id) { | |
| 77 return function () { return worker(id); }; | |
| 78 } | |
| 79 | |
| 80 var expect; | |
| 81 var actual; | |
| 82 | |
| 83 if (typeof scatter == 'undefined' || typeof sleep == 'undefined') { | |
| 84 print('Test skipped. scatter or sleep not defined.'); | |
| 85 expect = actual = 'Test skipped.'; | |
| 86 } else { | |
| 87 scatter([makeWorker(i) for (i in range(N))]); | |
| 88 | |
| 89 expect = "counter: " + (N * LOOP_COUNT); | |
| 90 actual = "counter: " + counter; | |
| 91 } | |
| 92 | |
| 93 reportCompare(expect, actual, summary); |
