redis_client.rb

# RubyRedis is an alternative implementation of Ruby client library written
# by Salvatore Sanfilippo.
#
# The aim of this library is to create an alternative client library that is
# much simpler and does not implement every command explicitly but uses
# method_missing instead.

require 'socket'

class RedisClient
    BulkCommands = {
        "set"=>true, "setnx"=>true, "rpush"=>true, "lpush"=>true, "lset"=>true,
        "lrem"=>true, "sadd"=>true, "srem"=>true, "sismember"=>true,
        "echo"=>true, "getset"=>true, "smove"=>true
    }

    def initialize(opts={})
        opts = {:host => 'localhost', :port => '6379', :db => 0}.merge(opts)
        @host = opts[:host]
        @port = opts[:port]
        @db = opts[:db]
        connect_to_server
    end

    def to_s
        "Redis Client connected to #{@host}:#{@port} against DB #{@db}"
    end

    def connect_to_server
        @sock = TCPSocket.new(@host, @port, 0)
        call_command(["select",@db]) if @db != 0
    end

    def method_missing(*argv)
      method_name = argv.shift.to_s.downcase
      if BulkCommands[method_name]
        self.class.class_eval %{
          def #{method_name}(*argv)
            begin
              argv = argv.flatten
              bulk = argv[-1]
              argv[-1] = bulk.length
              @sock.write("#{method_name} \#\{argv.join(" ")\}\\r\\n\#\{bulk\}\\r\\n")
              read_reply
            rescue Errno::ECONNRESET
              @sock.close
              connect_to_server
              retry
            end
          end
        }
      else
        self.class.class_eval %{
          def #{method_name}(*argv)
            begin
              @sock.write("#{method_name} \#\{argv.join(" ")\}\\r\\n")
              read_reply
            rescue Errno::ECONNRESET
              @sock.close
              connect_to_server
              retry
            end
          end
        }
      end
      send method_name, argv
    end

    def select(*args)
        raise "SELECT not allowed, use the :db option when creating the object"
    end

    def [](key)
        get(key)
    end

    def []=(key,value)
        set(key,value)
    end

    def read_reply
        line = @sock.gets
        raise Errno::ECONNRESET,"Connection lost" if !line
        case line[0..0]
        when "-"
            raise line.strip
        when "+"
            line[1..-1].strip
        when ":"
            line[1..-1].to_i
        when "$"
            bulklen = line[1..-1].to_i
            return nil if bulklen == -1
            data = @sock.read(bulklen)
            @sock.read(2) # CRLF
            data
        when "*"
            objects = line[1..-1].to_i
            return nil if bulklen == -1
            res = []
            objects.times {
                res << read_reply
            }
            res
        end
    end
    
    private
      def call_command(argv)
          # this wrapper to raw_call_command handle reconnection on socket
          # error. We try to reconnect just one time, otherwise let the error
          # araise.
          begin
              raw_call_command(argv)
          rescue Errno::ECONNRESET
              @sock.close
              connect_to_server
              raw_call_command(argv)
          end
      end

      def raw_call_command(argv)
          bulk = nil
          argv[0] = argv[0].to_s.downcase
          if BulkCommands[argv[0]]
              bulk = argv[-1]
              argv[-1] = bulk.length
          end
          @sock.write(argv.join(" ")+"\r\n")
          @sock.write(bulk+"\r\n") if bulk
          read_reply
      end
end