@Test
public void mappedServersTest() {
Map<Integer, String> servers = new HashMap<>();
servers.put(0, "server0");
servers.put(1, "server1");
HashFunction md5 = Hashing.md5();
List<PartitionEntry> triggers = generateTriggers(3, 1000);
Map<Integer, String> newPartition;
Map<Integer, String> oldPartition;
print("initial - test 2 servers " + servers.toString());
newPartition = new HashMap<>();
for (PartitionEntry trigger : triggers) {
newPartition.put(
trigger.hashCode(),
servers.get(Hashing.consistentHash(md5.hashInt(trigger.hashCode()), 2)));
}
for (int buckets = 3; buckets < 10; buckets++) {
servers.put(buckets - 1, "server" + (buckets - 1));
print("test " + buckets + " servers " + servers.toString());
oldPartition = newPartition;
newPartition = new HashMap<>();
for (PartitionEntry trigger : triggers) {
newPartition.put(
trigger.hashCode(),
servers.get(Hashing.consistentHash(md5.hashInt(trigger.hashCode()), buckets)));
}
int changes = comparePartitions(oldPartition, newPartition);
print(
"Changes from "
+ (buckets - 1)
+ " to "
+ buckets
+ " servers: "
+ changes
+ " of "
+ oldPartition.size());
print("" + (((float) changes / (float) oldPartition.size()) * 100) + " % moved");
print(
"K("
+ oldPartition.size()
+ ")/n("
+ buckets
+ "): "
+ ((float) oldPartition.size() / (float) buckets));
}
}
@Test
public void consistentHashTest() {
HashFunction md5 = Hashing.md5();
List<PartitionEntry> triggers = generateTriggers(3, 1000);
Map<Integer, Integer> newPartition;
Map<Integer, Integer> oldPartition;
print("initial - test 2 servers");
newPartition = new HashMap<>();
for (PartitionEntry trigger : triggers) {
newPartition.put(
trigger.hashCode(), Hashing.consistentHash(md5.hashInt(trigger.hashCode()), 2));
}
for (int buckets = 3; buckets < 10; buckets++) {
print("test " + buckets + " servers");
oldPartition = newPartition;
newPartition = new HashMap<>();
for (PartitionEntry trigger : triggers) {
newPartition.put(
trigger.hashCode(), Hashing.consistentHash(md5.hashInt(trigger.hashCode()), buckets));
}
int changes = comparePartitions(oldPartition, newPartition);
print(
"Changes from "
+ (buckets - 1)
+ " to "
+ buckets
+ " servers: "
+ changes
+ " of "
+ oldPartition.size());
print("" + (((float) changes / (float) oldPartition.size()) * 100) + " % moved");
print(
"K("
+ oldPartition.size()
+ ")/n("
+ buckets
+ "): "
+ ((float) oldPartition.size() / (float) buckets));
}
for (int buckets = 10; buckets > 3; buckets--) {
print("test " + buckets + " servers");
oldPartition = newPartition;
newPartition = new HashMap<>();
for (PartitionEntry trigger : triggers) {
newPartition.put(
trigger.hashCode(), Hashing.consistentHash(md5.hashInt(trigger.hashCode()), buckets));
}
int changes = comparePartitions(oldPartition, newPartition);
print(
"Changes from "
+ (buckets)
+ " to "
+ (buckets - 1)
+ " servers: "
+ changes
+ " of "
+ oldPartition.size());
print("" + (((float) changes / (float) oldPartition.size()) * 100) + " % moved");
print(
"K("
+ oldPartition.size()
+ ")/n("
+ buckets
+ "): "
+ ((float) oldPartition.size() / (float) buckets));
}
}