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Make stdlib.getloadavg more resiliant.

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Using rint(3) gave us a step where if one side was 1.4 and the other
was 1.5, that would be 1 and 2 respectively. So instead use a simple
difference. Also log more detail in case this doesn't fix the flakiness.

Bug: http://b/121156651
Test: ran tests
Change-Id: Ib5b2eb05d2b1eb8c4a10b182a8703510a3ef0cea
This commit is contained in:
Elliott Hughes 2018-12-18 14:47:25 -08:00
parent 0c499a69e3
commit 72a54a41a7
1 changed files with 8 additions and 6 deletions
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14
tests/stdlib_test.cpp
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@ -876,16 +876,18 @@ TEST(stdlib, getloadavg) {
ASSERT_EQ(3, getloadavg(load, INT_MAX));
// Read /proc/loadavg and check that it's "close enough".
load[0] = nan("");
double expected[3];
std::unique_ptr<FILE, decltype(&fclose)> fp{fopen("/proc/loadavg", "re"), fclose};
ASSERT_EQ(3, fscanf(fp.get(), "%lf %lf %lf", &expected[0], &expected[1], &expected[2]));
load[0] = load[1] = load[2] = nan("");
ASSERT_EQ(3, getloadavg(load, 3));
// It's probably too flaky if we look at the 1-minute average, so we just place a NaN there
// and check that it's overwritten with _something_.
// Check that getloadavg(3) at least overwrote the NaNs.
ASSERT_FALSE(isnan(load[0]));
// For the others, rounding to an integer is pessimistic but at least gives us a sanity check.
ASSERT_DOUBLE_EQ(rint(expected[1]), rint(load[1]));
ASSERT_DOUBLE_EQ(rint(expected[2]), rint(load[2]));
ASSERT_FALSE(isnan(load[1]));
ASSERT_FALSE(isnan(load[2]));
// And that the difference between /proc/loadavg and getloadavg(3) is "small".
ASSERT_TRUE(fabs(expected[0] - load[0]) < 0.5) << expected[0] << ' ' << load[0];
ASSERT_TRUE(fabs(expected[1] - load[1]) < 0.5) << expected[1] << ' ' << load[1];
ASSERT_TRUE(fabs(expected[2] - load[2]) < 0.5) << expected[2] << ' ' << load[2];
}