tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

waiterlist-order-of-operations-is-fifo.js (2957B)

      1 // |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
      2 // Copyright (C) 2018 Amal Hussein.  All rights reserved.
      3 // This code is governed by the BSD license found in the LICENSE file.
      4 
      5 /*---
      6 esid: sec-atomics.wait
      7 description: >
      8  New waiters should be applied to the end of the list and woken by order they entered the list (FIFO)
      9 info: |
     10  Atomics.wait( typedArray, index, value, timeout )
     11 
     12  16.Perform AddWaiter(WL, W).
     13    ...
     14    3.Add W to the end of the list of waiters in WL.
     15 
     16 includes: [atomicsHelper.js]
     17 features: [Atomics, SharedArrayBuffer, TypedArray]
     18 ---*/
     19 
     20 var NUMAGENT = 3;
     21 
     22 var WAIT_INDEX = 0;
     23 var RUNNING = 1;
     24 var LOCK_INDEX = 2;
     25 
     26 for (var i = 0; i < NUMAGENT; i++) {
     27  var agentNum = i;
     28 
     29  $262.agent.start(`
     30    $262.agent.receiveBroadcast(function(sab) {
     31      const i32a = new Int32Array(sab);
     32      Atomics.add(i32a, ${RUNNING}, 1);
     33 
     34      // Synchronize workers before reporting the initial report.
     35      while (Atomics.compareExchange(i32a, ${LOCK_INDEX}, 0, 1) !== 0) ;
     36 
     37      // Report the agent number before waiting.
     38      $262.agent.report(${agentNum});
     39 
     40      // Wait until restarted by main thread.
     41      var status = Atomics.wait(i32a, ${WAIT_INDEX}, 0);
     42 
     43      // Report wait status.
     44      $262.agent.report(status);
     45 
     46      // Report the agent number after waiting.
     47      $262.agent.report(${agentNum});
     48 
     49      $262.agent.leaving();
     50    });
     51  `);
     52 }
     53 
     54 const i32a = new Int32Array(
     55  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
     56 );
     57 
     58 $262.agent.safeBroadcast(i32a);
     59 
     60 // Wait until all agents started.
     61 $262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
     62 
     63 // Agents may be started in any order.
     64 const started = [];
     65 for (var i = 0; i < NUMAGENT; i++) {
     66  // Wait until an agent entered its critical section.
     67  $262.agent.waitUntil(i32a, LOCK_INDEX, 1);
     68 
     69  // Record the agent number.
     70  started.push($262.agent.getReport());
     71 
     72  // The agent may have been interrupted between reporting its initial report
     73  // and the `Atomics.wait` call. Try to yield control to ensure the agent
     74  // actually started to wait.
     75  $262.agent.tryYield();
     76 
     77  // Now continue with the next agent.
     78  Atomics.store(i32a, LOCK_INDEX, 0);
     79 }
     80 
     81 // Agents must notify in the order they waited.
     82 for (var i = 0; i < NUMAGENT; i++) {
     83  var woken = 0;
     84  while ((woken = Atomics.notify(i32a, WAIT_INDEX, 1)) === 0) ;
     85 
     86  assert.sameValue(woken, 1,
     87                   'Atomics.notify(i32a, WAIT_INDEX, 1) returns 1, at index = ' + i);
     88 
     89  assert.sameValue($262.agent.getReport(), 'ok',
     90                   '$262.agent.getReport() returns "ok", at index = ' + i);
     91 
     92  assert.sameValue($262.agent.getReport(), started[i],
     93                   '$262.agent.getReport() returns the value of `started[' + i + ']`');
     94 }
     95 
     96 reportCompare(0, 0);