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// |reftest| skip
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* Any copyright is dedicated to the Public Domain.
* http://creativecommons.org/licenses/publicdomain/
* Contributor: Jason Orendorff
*/
//-----------------------------------------------------------------------------
var summary = "Dekker's algorithm for mutual exclusion";
// Adapted from pseudocode in Wikipedia:
// http://en.wikipedia.org/wiki/Dekker%27s_algorithm
printStatus (summary);
var N = 500; // number of iterations
// the mutex mechanism
var f = [false, false];
var turn = 0;
// resource being protected
var counter = 0;
function worker(me) {
let him = 1 - me;
for (let i = 0; i < N; i++) {
// enter the mutex
f[me] = true;
while (f[him]) {
if (turn != me) {
f[me] = false;
while (turn != me)
; // busy wait
f[me] = true;
}
}
// critical section
let x = counter;
sleep(0.003);
counter = x + 1;
// leave the mutex
turn = him;
f[me] = false;
}
return 'ok';
}
var expect;
var actual;
if (typeof scatter == 'undefined' || typeof sleep == 'undefined') {
print('Test skipped. scatter or sleep not defined.');
expect = actual = 'Test skipped.';
} else {
var results = scatter([function () { return worker(0); },
function () { return worker(1); }]);
expect = "Thread status: [ok,ok], counter: " + (2 * N);
actual = "Thread status: [" + results + "], counter: " + counter;
}
reportCompare(expect, actual, summary);
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