Fix slot range calculation. (#55)

cluster/test/async/redis/cluster_client.rb

@@ -43,4 +43,13 @@
 
 		expect(result).to be == value
 	end
+
+	it "can map every slot to a client" do
+		clients = Async::Redis::ClusterClient::HASH_SLOTS.times.map do |slot|
+			client = cluster.client_for(slot)
+		end.uniq
+
+		expect(clients.size).to be == 3
+		expect(clients).not.to have_value(be_nil)
+	end
 end

lib/async/redis/cluster_client.rb

@@ -13,6 +13,9 @@ class ClusterClient
 			class ReloadError < StandardError
 			end
 
+			class SlotError < StandardError
+			end
+
 			Node = Struct.new(:id, :endpoint, :role, :health, :client)
 
 			class RangeMap
@@ -84,9 +87,11 @@ def client_for(slot, role = :master)
 					reload_cluster!
 				end
 
-				nodes = @shards.find(slot)
-
-				nodes = nodes.select{|node| node.role == role}
+				if nodes = @shards.find(slot)
+					nodes = nodes.select{|node| node.role == role}
+				else
+					raise SlotError, "No nodes found for slot #{slot}"
+				end
 
 				if node = nodes.sample
 					return (node.client ||= Client.new(node.endpoint))
@@ -106,7 +111,7 @@ def reload_cluster!(endpoints = @endpoints)
 						shard = shard.each_slice(2).to_h
 
 						slots = shard['slots']
-						range = Range.new(*slots, exclude_end: false)
+						range = Range.new(*slots)
 
 						nodes = shard['nodes'].map do |node|
 							node = node.each_slice(2).to_h
@@ -179,10 +184,10 @@ def crc16(bytes)
 				return sum
 			end
 
-			HASH_SLOTS = 16_384
-
 			public
 
+			HASH_SLOTS = 16_384
+
 			# Return Redis::Client for a given key.
 			# Modified from https://github.com/antirez/redis-rb-cluster/blob/master/cluster.rb#L104-L117
 			def slot_for(key)