wake-in-order-standalone.js

// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
esid: sec-atomics.wake
description: >
  Test that Atomics.wake wakes agents in the order they are waiting.
features: [Atomics, SharedArrayBuffer, TypedArray]
---*/

const assert = {
  sameValue(actual, expected, message) {
    if (actual !== expected) {
      throw new Error(`${actual} !== ${expected}; ${message}`);
    }
  }
};

var NUMAGENT = 3;

var WAKEUP = 0;                 // Waiters on this will be woken
var SPIN = 1;                   // Worker i (zero-based) spins on location SPIN+i
var RUNNING = SPIN + NUMAGENT;  // Accounting of live agents
var NUMELEM = RUNNING + 1;

// Create workers and start them all spinning.  We set atomic slots to make
// them go into a wait, thus controlling the waiting order.  Then we wake them
// one by one and observe the wakeup order.

for (var i = 0; i < NUMAGENT; i++) {
$262.agent.start(`
$262.agent.receiveBroadcast(function(sab) {
  var i32a = new Int32Array(sab);
  Atomics.add(i32a, ${RUNNING}, 1);
  while (Atomics.load(i32a, ${SPIN + i}) === 0)
      /* nothing */ ;
  $262.agent.report(${i} + Atomics.wait(i32a, ${WAKEUP}, 0));
  $262.agent.leaving();
});
`);
}

var i32a = new Int32Array(new SharedArrayBuffer(NUMELEM * Int32Array.BYTES_PER_ELEMENT));
$262.agent.broadcast(i32a.buffer);

// Wait for agents to be running.
waitUntil(i32a, RUNNING, NUMAGENT);

// Then wait some more to give the agents a fair chance to wait.  If we don't,
// we risk sending the wakeup before agents are sleeping, and we hang.
$262.agent.sleep(50);

// Make them sleep in order 0 1 2 on i32a[0]
for (var i = 0; i < NUMAGENT; i++) {
  Atomics.store(i32a, SPIN + i, 1);
  $262.agent.sleep(50);
}

// Wake them up one at a time and check the order is 0 1 2
for (var i = 0; i < NUMAGENT; i++) {
  assert.sameValue(Atomics.wake(i32a, WAKEUP, 1), 1);
  assert.sameValue(getReport(), i + "ok");
}

function getReport() {
  var r;
  while ((r = $262.agent.getReport()) == null) {
    $262.agent.sleep(10);
  }
  return r;
}

function waitUntil(i32a, k, value) {
  var i = 0;
  while (Atomics.load(i32a, k) !== value && i < 15) {
    $262.agent.sleep(10);
    i++;
  }
  assert.sameValue(Atomics.load(i32a, k), value, 'All agents are running');
}