v8/test/mjsunit/d8-worker-sharedarraybuffer.js

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// Flags: --harmony-sharedarraybuffer

if (this.Worker) {

  (function TestTransfer() {
    var workerScript =
      `onmessage = function(m) {
       var sab = m;
       var ta = new Uint32Array(sab);
       if (sab.byteLength !== 16) {
         throw new Error('SharedArrayBuffer transfer byteLength');
       }
       for (var i = 0; i < 4; ++i) {
         if (ta[i] !== i) {
           throw new Error('SharedArrayBuffer transfer value ' + i);
         }
       }
        // Atomically update ta[0]
        Atomics.store(ta, 0, 100);
      };`;

    var w = new Worker(workerScript);

    var sab = new SharedArrayBuffer(16);
    var ta = new Uint32Array(sab);
    for (var i = 0; i < 4; ++i) {
      ta[i] = i;
    }

    // Transfer SharedArrayBuffer
    w.postMessage(sab, [sab]);
    assertEquals(16, sab.byteLength);  // ArrayBuffer should not be neutered.

    // Spinwait for the worker to update ta[0]
    var ta0;
    while ((ta0 = Atomics.load(ta, 0)) == 0) {}

    assertEquals(100, ta0);

    w.terminate();

    assertEquals(16, sab.byteLength);  // Still not neutered.
  })();

  (function TestTransferMulti() {
    var workerScript =
      `onmessage = function(msg) {
       var sab = msg.sab;
       var id = msg.id;
       var ta = new Uint32Array(sab);
       Atomics.store(ta, id, 1);
       postMessage(id);
      };`;

    var sab = new SharedArrayBuffer(16);
    var ta = new Uint32Array(sab);

    var id;
    var workers = [];
    for (id = 0; id < 4; ++id) {
      workers[id] = new Worker(workerScript);
      workers[id].postMessage({sab: sab, id: id}, [sab]);
    }

    // Spinwait for each worker to update ta[id]
    var count = 0;
    while (count < 4) {
      for (id = 0; id < 4; ++id) {
        if (Atomics.compareExchange(ta, id, 1, -1) == 1) {
          // Worker is finished.
          assertEquals(id, workers[id].getMessage());
          workers[id].terminate();
          count++;
        }
      }
    }
  })();

}