Slight refactorig of prior commit. Main goal was to preserve ordering of hosts on the

token ring; Set.to_a returns values in an "uncertain" order so we attempt to avoid it
all together.

Beneficial side effect of this change is that the impl moves to methods on Enumerable.

Author: absurdfarce

lib/cassandra/cluster/schema/replication_strategies/simple.rb

@@ -29,13 +29,10 @@ def replication_map(token_hosts, token_ring, replication_options)
             factor = size if size < factor
             replication_map = ::Hash.new
 
+            hosts_ring = token_ring.map { |t| token_hosts[t] }
             token_ring.each_with_index do |token, i|
-              replicas = ::Set.new
-              size.times do |j|
-                replicas << token_hosts[token_ring[(i + j) % size]]
-                break if replicas.size == factor
-              end
-              replication_map[token] = replicas.to_a.freeze
+              candidates = hosts_ring.cycle(2 * size).drop(i).take(size).uniq
+              replication_map[token] = candidates.take(factor).freeze
             end
 
             replication_map

spec/cassandra/cluster/schema/replication_strategies/simple_spec.rb

@@ -63,12 +63,15 @@ module ReplicationStrategies
 
             it do
               replication_map = subject.replication_map(token_hosts, token_ring, replication_options)
-              expect(replication_map[token_ring[0]].sort_by(&:ip).map do |host|
-                [host.ip]
-              end).to eq([
-                ['127.0.0.1'],
-                ['127.0.0.2'],
-                ['127.0.0.3'],
+              expect(replication_map[token_ring[0]].map(&:ip)).to eq([
+                '127.0.0.1',
+                '127.0.0.2',
+                '127.0.0.3',
+              ])
+              expect(replication_map[token_ring[2]].map(&:ip)).to eq([
+                '127.0.0.2',
+                '127.0.0.3',
+                '127.0.0.1',
               ])
             end
           end