Add Redis Cluster support

.gitignore

@@ -5,6 +5,7 @@ Gemfile.lock
 /tmp/
 /.idea
 /.yardoc
+/.bundle
 /coverage/*
 /doc/
 /examples/sentinel/sentinel.conf
@@ -14,3 +15,5 @@ Gemfile.lock
 /redis/*
 /test/db
 /test/test.conf
+appendonly.aof
+temp-rewriteaof-*.aof

.travis.yml

@@ -6,7 +6,7 @@ before_install:
   - gem update --system 2.6.14
   - gem --version
 
-script: make test
+script: make
 
 rvm:
   - 2.2.2
@@ -25,7 +25,7 @@ before_script:
 env:
   global:
     - VERBOSE=true
-    - TIMEOUT=1
+    - TIMEOUT=5
   matrix:
     - DRIVER=ruby      REDIS_BRANCH=3.0
     - DRIVER=ruby      REDIS_BRANCH=3.2

lib/redis.rb

@@ -31,12 +31,16 @@ def self.current=(redis)
   # @option options [Boolean] :inherit_socket (false) Whether to use socket in forked process or not
   # @option options [Array] :sentinels List of sentinels to contact
   # @option options [Symbol] :role (:master) Role to fetch via Sentinel, either `:master` or `:slave`
+  # @option options [Array<String, Hash{Symbol => String, Integer}>] :cluster List of cluster nodes to contact
+  # @option options [Boolean] :replica Whether to use readonly replica nodes in Redis Cluster or not
   # @option options [Class] :connector Class of custom connector
   #
   # @return [Redis] a new client instance
   def initialize(options = {})
     @options = options.dup
-    @original_client = @client = Client.new(options)
+    @cluster_mode = options.key?(:cluster)
+    client = @cluster_mode ? Cluster : Client
+    @original_client = @client = client.new(options)
     @queue = Hash.new { |h, k| h[k] = [] }
 
     super() # Monitor#initialize
@@ -274,9 +278,7 @@ def info(cmd = nil)
     synchronize do |client|
       client.call([:info, cmd].compact) do |reply|
         if reply.kind_of?(String)
-          reply = Hash[reply.split("\r\n").map do |line|
-            line.split(":", 2) unless line =~ /^(#|$)/
-          end.compact]
+          reply = HashifyInfo.call(reply)
 
           if cmd && cmd.to_s == "commandstats"
             # Extract nested hashes for INFO COMMANDSTATS
@@ -2818,6 +2820,41 @@ def sentinel(subcommand, *args)
     end
   end
 
+  # Sends `CLUSTER *` command to random node and returns its reply.
+  #
+  # @see https://redis.io/commands#cluster Reference of cluster command
+  #
+  # @param subcommand [String, Symbol] the subcommand of cluster command
+  #   e.g. `:slots`, `:nodes`, `:slaves`, `:info`
+  #
+  # @return [Object] depends on the subcommand
+  def cluster(subcommand, *args)
+    subcommand = subcommand.to_s.downcase
+    block = case subcommand
+            when 'slots'  then HashifyClusterSlots
+            when 'nodes'  then HashifyClusterNodes
+            when 'slaves' then HashifyClusterSlaves
+            when 'info'   then HashifyInfo
+            else Noop
+            end
+
+    # @see https://github.com/antirez/redis/blob/unstable/src/redis-trib.rb#L127 raw reply expected
+    block = Noop unless @cluster_mode
+
+    synchronize do |client|
+      client.call([:cluster, subcommand] + args, &block)
+    end
+  end
+
+  # Sends `ASKING` command to random node and returns its reply.
+  #
+  # @see https://redis.io/topics/cluster-spec#ask-redirection ASK redirection
+  #
+  # @return [String] `'OK'`
+  def asking
+    synchronize { |client| client.call(%i[asking]) }
+  end
+
   def id
     @original_client.id
   end
@@ -2831,6 +2868,8 @@ def dup
   end
 
   def connection
+    return @original_client.connection_info if @cluster_mode
+
     {
       host:     @original_client.host,
       port:     @original_client.port,
@@ -2896,6 +2935,56 @@ def method_missing(command, *args)
       end
     }
 
+  HashifyInfo =
+    lambda { |reply|
+      Hash[reply.split("\r\n").map do |line|
+        line.split(':', 2) unless line =~ /^(#|$)/
+      end.compact]
+    }
+
+  HashifyClusterNodeInfo =
+    lambda { |str|
+      arr = str.split(' ')
+      {
+        'node_id'        => arr[0],
+        'ip_port'        => arr[1],
+        'flags'          => arr[2].split(','),
+        'master_node_id' => arr[3],
+        'ping_sent'      => arr[4],
+        'pong_recv'      => arr[5],
+        'config_epoch'   => arr[6],
+        'link_state'     => arr[7],
+        'slots'          => arr[8].nil? ? nil : Range.new(*arr[8].split('-'))
+      }
+    }
+
+  HashifyClusterSlots =
+    lambda { |reply|
+      reply.map do |arr|
+        first_slot, last_slot = arr[0..1]
+        master = { 'ip' => arr[2][0], 'port' => arr[2][1], 'node_id' => arr[2][2] }
+        replicas = arr[3..-1].map { |r| { 'ip' => r[0], 'port' => r[1], 'node_id' => r[2] } }
+        {
+          'start_slot' => first_slot,
+          'end_slot'   => last_slot,
+          'master'     => master,
+          'replicas'   => replicas
+        }
+      end
+    }
+
+  HashifyClusterNodes =
+    lambda { |reply|
+      reply.split(/[\r\n]+/).map { |str| HashifyClusterNodeInfo.call(str) }
+    }
+
+  HashifyClusterSlaves =
+    lambda { |reply|
+      reply.map { |str| HashifyClusterNodeInfo.call(str) }
+    }
+
+  Noop = ->(reply) { reply }
+
   def _geoarguments(*args, options: nil, sort: nil, count: nil)
     args.push sort if sort
     args.push 'count', count if count
@@ -2918,11 +3007,11 @@ def _subscription(method, timeout, channels, block)
       @client = original
     end
   end
-
 end
 
 require_relative "redis/version"
 require_relative "redis/connection"
 require_relative "redis/client"
+require_relative "redis/cluster"
 require_relative "redis/pipeline"
 require_relative "redis/subscribe"