/*
* Ensure that we randomly select the lesser-used volumes with appropriate
* frequency.
*/
/// <exception cref="System.Exception"/>
public virtual void DoRandomizedTest(float preferencePercent, int lowSpaceVolumes
, int highSpaceVolumes)
{
Random random = new Random(123L);
AvailableSpaceVolumeChoosingPolicy <FsVolumeSpi> policy = new AvailableSpaceVolumeChoosingPolicy
<FsVolumeSpi>(random);
IList <FsVolumeSpi> volumes = new AList <FsVolumeSpi>();
// Volumes with 1MB free space
for (int i = 0; i < lowSpaceVolumes; i++)
{
FsVolumeSpi volume = Org.Mockito.Mockito.Mock <FsVolumeSpi>();
Org.Mockito.Mockito.When(volume.GetAvailable()).ThenReturn(1024L * 1024L);
volumes.AddItem(volume);
}
// Volumes with 3MB free space
for (int i_1 = 0; i_1 < highSpaceVolumes; i_1++)
{
FsVolumeSpi volume = Org.Mockito.Mockito.Mock <FsVolumeSpi>();
Org.Mockito.Mockito.When(volume.GetAvailable()).ThenReturn(1024L * 1024L * 3);
volumes.AddItem(volume);
}
InitPolicy(policy, preferencePercent);
long lowAvailableSpaceVolumeSelected = 0;
long highAvailableSpaceVolumeSelected = 0;
for (int i_2 = 0; i_2 < RandomizedIterations; i_2++)
{
FsVolumeSpi volume = policy.ChooseVolume(volumes, 100);
for (int j = 0; j < volumes.Count; j++)
{
// Note how many times the first low available volume was selected
if (volume == volumes[j] && j == 0)
{
lowAvailableSpaceVolumeSelected++;
}
// Note how many times the first high available volume was selected
if (volume == volumes[j] && j == lowSpaceVolumes)
{
highAvailableSpaceVolumeSelected++;
break;
}
}
}
// Calculate the expected ratio of how often low available space volumes
// were selected vs. high available space volumes.
float expectedSelectionRatio = preferencePercent / (1 - preferencePercent);
GenericTestUtils.AssertValueNear((long)(lowAvailableSpaceVolumeSelected * expectedSelectionRatio
), highAvailableSpaceVolumeSelected, RandomizedAllowedError);
}