js/tests/js1_8/extensions/peterson.js

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  15  * The Original Code is JavaScript Engine testing utilities.
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  22  * Contributor(s): Guoxin Fan <gfan@sta.samsung.com>
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  37
  38 var gTestfile = 'peterson.js';
  39 //-----------------------------------------------------------------------
  40
  41 var summary = "Peterson's algorithm for mutual exclusion";
  42
  43 printStatus(summary);
  44
  45 var N = 500;  // number of iterations
  46
  47 // the mutex mechanism
  48 var f = [false, false];
  49 var turn = 0;
  50
  51 // the resource being protected
  52 var counter = 0;
  53
  54 function worker(me) {
  55   let him = 1 - me;
  56
  57   for (let i = 0; i < N; i++) {
  58     // enter the mutex
  59     f[me] = true;
  60     turn = him;
  61     while (f[him] && turn == him)
  62       ;  // busy wait
  63
  64     // critical section
  65     let x = counter;
  66     sleep(0.003);
  67     counter = x+1;
  68
  69     // leave the mutex
  70     f[me] = false;
  71   }
  72
  73   return 'ok';
  74 }
  75
  76 var expect;
  77 var actual;
  78
  79 if (typeof scatter == 'undefined' || typeof sleep == 'undefined') {
  80   print('Test skipped. scatter or sleep not defined.');
  81   expect = actual = 'Test skipped.';
  82 } else {
  83   var results = scatter ([function() { return worker(0); },
  84                           function() { return worker(1); }]);
  85   expect = "Thread status: [ok,ok], counter: " + (2 * N);
  86   actual = "Thread status: [" + results + "], counter: " + counter;
  87 }
  88
  89 reportCompare(expect, actual, summary);