test/mjsunit/d8-performance-now.js

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// Flags: --allow-natives-syntax

// Test the performance.now() function of d8.  This test only makes sense with
// d8.

if (this.performance && performance.now) {
  (function run() {
    var start_test = performance.now();
    // Let the retry run for maximum 100ms to reduce flakiness.
    for (var start = performance.now();
        start - start_test < 100;
        start = performance.now()) {
      var end = performance.now();
      assertTrue(start >= start_test);
      assertTrue(end >= start);
      while (end - start == 0) {
        var next = performance.now();
        assertTrue(next >= end);
        end = next;
      }
      if (end - start <= 1) {
        // Found (sub-)millisecond granularity.
        return;
      } else {
        print("Timer difference too big: " + (end - start) + "ms");
      }
    }
    assertTrue(false);
  })()
}