Method run

src/test/java/net/starlark/java/eval/Benchmarks.java:250–280

(Benchmark b, long budgetNanos, int iterations)

  // (which we may exceed by a factor of two) or number of iterations,
  // exactly one of which must be nonnegative. Reports success.
  private static boolean run(Benchmark b, long budgetNanos, int iterations) {
    // Exactly one of the parameters must be specified.
    Preconditions.checkState((budgetNanos >= 0) != (iterations >= 0));

    Mutability mu = Mutability.create("test");
    StarlarkThread thread = StarlarkThread.createTransient(mu, semantics);

    // Run for a fixed number of iterations?
    if (iterations >= 0) {
      return b.runIterations(thread, iterations);
    }

    // Run for a fixed amount of time (default behavior).
    iterations = 1;
    while (b.time < budgetNanos) {
      if (!b.runIterations(thread, iterations)) {
        return false;
      }

      // Keep doubling the number of iterations until we exceed the deadline.
      // TODO(adonovan): opt: extrapolate and predict the number of iterations
      // in the remaining time budget, being wary of extrapolation error.
      iterations <<= 1;
      if (iterations <= 0) { // overflow
        System.err.printf(
            "In %s: function is too fast; likely a loop over `range(b.n)` is missing\n", b.name);
        return false;
      }
    }
    return true;
  }

  // The type of the parameter to each bench(b) function.
  // Provides n, the number of iterations.