Atomics Futex API

test/mjsunit/harmony/futex.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-atomics --harmony-sharedarraybuffer
+
+(function TestFailsWithNonSharedArray() {
+  var ab = new ArrayBuffer(16);
+
+  var i8a = new Int8Array(ab);
+  var i16a = new Int16Array(ab);
+  var i32a = new Int32Array(ab);
+  var ui8a = new Uint8Array(ab);
+  var ui8ca = new Uint8ClampedArray(ab);
+  var ui16a = new Uint16Array(ab);
+  var ui32a = new Uint32Array(ab);
+  var f32a = new Float32Array(ab);
+  var f64a = new Float64Array(ab);
+
+  [i8a, i16a, i32a, ui8a, ui8ca, ui16a, ui32a, f32a, f64a].forEach(function(
+      ta) {
+    assertThrows(function() { Atomics.futexWait(ta, 0, 0); });
+    assertThrows(function() { Atomics.futexWake(ta, 0, 1); });
+    assertThrows(function() { Atomics.futexWakeOrRequeue(ta, 0, 1, 0, 0); });
+  });
+})();
+
+(function TestFailsWithNonSharedInt32Array() {
+  var sab = new SharedArrayBuffer(16);
+
+  var i8a = new Int8Array(sab);
+  var i16a = new Int16Array(sab);
+  var ui8a = new Uint8Array(sab);
+  var ui8ca = new Uint8ClampedArray(sab);
+  var ui16a = new Uint16Array(sab);
+  var ui32a = new Uint32Array(sab);
+  var f32a = new Float32Array(sab);
+  var f64a = new Float64Array(sab);
+
+  [i8a, i16a, ui8a, ui8ca, ui16a, ui32a, f32a, f64a].forEach(function(
+      ta) {
+    assertThrows(function() { Atomics.futexWait(ta, 0, 0); });
+    assertThrows(function() { Atomics.futexWake(ta, 0, 1); });
+    assertThrows(function() { Atomics.futexWakeOrRequeue(ta, 0, 1, 0, 0); });
+  });
+})();
+
+(function TestInvalidIndex() {
+  var i32a = new Int32Array(new SharedArrayBuffer(16));
+
+  // Valid indexes are 0-3.
+  [-1, 4, 100].forEach(function(invalidIndex) {
+    assertEquals(undefined, Atomics.futexWait(i32a, invalidIndex, 0));
+    assertEquals(undefined, Atomics.futexWake(i32a, invalidIndex, 0));
+    var validIndex = 0;
+    assertEquals(undefined, Atomics.futexWakeOrRequeue(i32a, invalidIndex, 0, 0,
+                                                       validIndex));
+    assertEquals(undefined, Atomics.futexWakeOrRequeue(i32a, validIndex, 0, 0,
+                                                       invalidIndex));
+  });
+
+})();
+
+(function TestWaitTimeout() {
+  var i32a = new Int32Array(new SharedArrayBuffer(16));
+  var waitMs = 100;
+  var startTime = new Date();
+  assertEquals(Atomics.TIMEDOUT, Atomics.futexWait(i32a, 0, 0, waitMs));
+  var endTime = new Date();
+  assertTrue(endTime - startTime >= waitMs);
+})();
+
+(function TestWaitNotEqual() {
+  var i32a = new Int32Array(new SharedArrayBuffer(16));
+  assertEquals(Atomics.NOTEQUAL, Atomics.futexWait(i32a, 0, 42));
+})();
+
+(function TestWaitNegativeTimeout() {
+  var i32a = new Int32Array(new SharedArrayBuffer(16));
+  assertEquals(Atomics.TIMEDOUT, Atomics.futexWait(i32a, 0, 0, -1));
+  assertEquals(Atomics.TIMEDOUT, Atomics.futexWait(i32a, 0, 0, -Infinity));
+})();
+
+//// WORKER ONLY TESTS
+
+if (this.Worker) {
+
+  var TestWaitWithTimeout = function(timeout) {
+    var sab = new SharedArrayBuffer(16);
+    var i32a = new Int32Array(sab);
+
+    var workerScript =
+      `onmessage = function(sab) {
+         var i32a = new Int32Array(sab);
+         var result = Atomics.futexWait(i32a, 0, 0, ${timeout});
+         postMessage(result);
+       };`;
+
+    var worker = new Worker(workerScript);
+    worker.postMessage(sab, [sab]);
+
+    // Spin until the worker is waiting on the futex.
+    while (%AtomicsFutexNumWaitersForTesting(i32a, 0) != 1) {}
+
+    Atomics.futexWake(i32a, 0, 1);
+    assertEquals(Atomics.OK, worker.getMessage());
+    worker.terminate();
+  };
+
+  // Test various infinite timeouts
+  TestWaitWithTimeout(undefined);
+  TestWaitWithTimeout(NaN);
+  TestWaitWithTimeout(Infinity);
+
+
+  (function TestWakeMulti() {
+    var sab = new SharedArrayBuffer(20);
+    var i32a = new Int32Array(sab);
+
+    // SAB values:
+    // i32a[id], where id in range [0, 3]:
+    //   0 => Worker |id| is still waiting on the futex
+    //   1 => Worker |id| is not waiting on futex, but has not be reaped by the
+    //        main thread.
+    //   2 => Worker |id| has been reaped.
+    //
+    // i32a[4]:
+    //   always 0. Each worker is waiting on this index.
+
+    var workerScript =
+      `onmessage = function(msg) {
+         var id = msg.id;
+         var i32a = new Int32Array(msg.sab);
+
+         // Wait on i32a[4] (should be zero).
+         var result = Atomics.futexWait(i32a, 4, 0);
+         // Set i32a[id] to 1 to notify the main thread which workers were
+         // woken up.
+         Atomics.store(i32a, id, 1);
+         postMessage(result);
+       };`;
+
+    var id;
+    var workers = [];
+    for (id = 0; id < 4; id++) {
+      workers[id] = new Worker(workerScript);
+      workers[id].postMessage({sab: sab, id: id}, [sab]);
+    }
+
+    // Spin until all workers are waiting on the futex.
+    while (%AtomicsFutexNumWaitersForTesting(i32a, 4) != 4) {}
+
+    // Wake up three waiters.
+    assertEquals(3, Atomics.futexWake(i32a, 4, 3));
+
+    var wokenCount = 0;
+    var waitingId = 0 + 1 + 2 + 3;
+    while (wokenCount < 3) {
+      for (id = 0; id < 4; id++) {
+        // Look for workers that have not yet been reaped. Set i32a[id] to 2
+        // when they've been processed so we don't look at them again.
+        if (Atomics.compareExchange(i32a, id, 1, 2) == 1) {
+          assertEquals(Atomics.OK, workers[id].getMessage());
+          workers[id].terminate();
+          waitingId -= id;
+          wokenCount++;
+        }
+      }
+    }
+
+    assertEquals(3, wokenCount);
+    assertEquals(0, Atomics.load(i32a, waitingId));
+    assertEquals(1, %AtomicsFutexNumWaitersForTesting(i32a, 4));
+
+    // Finally wake the last waiter.
+    assertEquals(1, Atomics.futexWake(i32a, 4, 1));
+    assertEquals(Atomics.OK, workers[waitingId].getMessage());
+    workers[waitingId].terminate();
+
+    assertEquals(0, %AtomicsFutexNumWaitersForTesting(i32a, 4));
+
+  })();
+
+  (function TestWakeOrRequeue() {
+    var sab = new SharedArrayBuffer(24);
+    var i32a = new Int32Array(sab);
+
+    // SAB values:
+    // i32a[id], where id in range [0, 3]:
+    //   0 => Worker |id| is still waiting on the futex
+    //   1 => Worker |id| is not waiting on futex, but has not be reaped by the
+    //        main thread.
+    //   2 => Worker |id| has been reaped.
+    //
+    // i32a[4]:
+    //   always 0. Each worker will initially wait on this index.
+    //
+    // i32a[5]:
+    //   always 0. Requeued workers will wait on this index.
+
+    var workerScript =
+      `onmessage = function(msg) {
+         var id = msg.id;
+         var i32a = new Int32Array(msg.sab);
+
+         var result = Atomics.futexWait(i32a, 4, 0, Infinity);
+         Atomics.store(i32a, id, 1);
+         postMessage(result);
+       };`;
+
+    var workers = [];
+    for (id = 0; id < 4; id++) {
+      workers[id] = new Worker(workerScript);
+      workers[id].postMessage({sab: sab, id: id}, [sab]);
+    }
+
+    // Spin until all workers are waiting on the futex.
+    while (%AtomicsFutexNumWaitersForTesting(i32a, 4) != 4) {}
+
+    var index1 = 4;
+    var index2 = 5;
+
+    // If futexWakeOrRequeue is called with the incorrect value, it shouldn't
+    // wake any waiters.
+    assertEquals(Atomics.NOTEQUAL,
+                 Atomics.futexWakeOrRequeue(i32a, index1, 1, 42, index2));
+
+    assertEquals(4, %AtomicsFutexNumWaitersForTesting(i32a, index1));
+    assertEquals(0, %AtomicsFutexNumWaitersForTesting(i32a, index2));
+
+    // Now wake with the correct value.
+    assertEquals(1, Atomics.futexWakeOrRequeue(i32a, index1, 1, 0, index2));
+
+    // The workers that are still waiting should atomically be transferred to
+    // the new index.
+    assertEquals(3, %AtomicsFutexNumWaitersForTesting(i32a, index2));
+
+    // The woken worker may not have been scheduled yet. Look for which thread
+    // has set its i32a value to 1.
+    var wokenCount = 0;
+    while (wokenCount < 1) {
+      for (id = 0; id < 4; id++) {
+        if (Atomics.compareExchange(i32a, id, 1, 2) == 1) {
+          wokenCount++;
+        }
+      }
+    }
+
+    assertEquals(0, %AtomicsFutexNumWaitersForTesting(i32a, index1));
+
+    // Wake the remaining waiters.
+    assertEquals(3, Atomics.futexWake(i32a, index2, 3));
+
+    // As above, wait until the workers have been scheduled.
+    wokenCount = 0;
+    while (wokenCount < 3) {
+      for (id = 0; id < 4; id++) {
+        if (Atomics.compareExchange(i32a, id, 1, 2) == 1) {
+          wokenCount++;
+        }
+      }
+    }
+
+    assertEquals(0, %AtomicsFutexNumWaitersForTesting(i32a, index1));
+    assertEquals(0, %AtomicsFutexNumWaitersForTesting(i32a, index2));
+
+    for (id = 0; id < 4; ++id) {
+      assertEquals(Atomics.OK, workers[id].getMessage());
+      workers[id].terminate();
+    }
+
+  })();
+
+}