private static void GetBucket_WithRandomInput_IsApproximatelyEvenlyDistributed(int bucketCount)
{
// ARRANGE
const int iterations = 10000;
Dictionary <int, int> counts = Enumerable.Range(0, bucketCount).ToDictionary(i => i, i => 0);
var cha = new ConsistentHashingAlgorithm(bucketCount, 1024);
var random = new Random(0);
var longBuffer = new byte[8];
double expectedCount = iterations / (double)bucketCount;
double maximumDifference = 0.15 * expectedCount;
// ACT
for (int i = 0; i < iterations; i++)
{
random.NextBytes(longBuffer);
long key = BitConverter.ToInt64(longBuffer, 0);
int bucket = cha.GetBucket(key);
counts[bucket]++;
}
// ASSERT
Console.WriteLine("Bucket count: {0}. Expected count: {1}. Maximum difference: {2}.", bucketCount, expectedCount, maximumDifference);
for (int i = 0; i < bucketCount; i++)
{
Console.WriteLine("Bucket: {0}. Actual count: {1}. Difference: {2}.", i, counts[i], Math.Abs(expectedCount - counts[i]));
((double)counts[i]).Should().BeApproximately(expectedCount, maximumDifference);
}
}
public void ReplicaCount_Always_ReturnsConstructorValue()
{
// ARRANGE
const int replicaCount = 1024;
var cha = new ConsistentHashingAlgorithm(8, replicaCount);
// ACT
int actual = cha.ReplicaCount;
// ASSERT
actual.Should().Be(replicaCount);
}
public void BucketCount_Always_ReturnsConstructorValue()
{
// ARRANGE
const int bucketCount = 8;
var cha = new ConsistentHashingAlgorithm(bucketCount, 1024);
// ACT
int actual = cha.BucketCount;
// ASSERT
actual.Should().Be(bucketCount);
}
public void GetBucket_WithSameKey_ReturnsSameBucket()
{
// ARRANGE
var cha = new ConsistentHashingAlgorithm(8, 1024);
const long key = 42;
// ACT
var bucketA = cha.GetBucket(key);
var bucketB = cha.GetBucket(key);
// ASSERT
bucketA.Should().Be(bucketB);
}
