client-libraries/ruby/lib/server.rb

   1 begin
   2   # Timeout code is courtesy of Ruby memcache-client
   3   #   http://github.com/mperham/memcache-client/tree
   4   # Try to use the SystemTimer gem instead of Ruby's timeout library
   5   # when running on something that looks like Ruby 1.8.x.  See:
   6   #   http://ph7spot.com/articles/system_timer
   7   # We don't want to bother trying to load SystemTimer on jruby and
   8   # ruby 1.9+.
   9   if defined?(JRUBY_VERSION) || (RUBY_VERSION >= '1.9')
  10     require 'timeout'
  11     RedisTimer = Timeout
  12   else
  13     require 'system_timer'
  14     RedisTimer = SystemTimer
  15   end
  16 rescue LoadError => e
  17   puts "[redis-rb] Could not load SystemTimer gem, falling back to Ruby's slower/unsafe timeout library: #{e.message}"
  18   require 'timeout'
  19   RedisTimer = Timeout
  20 end
  21
  22 ##
  23 # This class represents a redis server instance.
  24
  25 class Server
  26
  27   ##
  28   # The host the redis server is running on.
  29
  30   attr_reader :host
  31
  32   ##
  33   # The port the redis server is listening on.
  34
  35   attr_reader :port
  36
  37   ##
  38   # A text status string describing the state of the server.
  39
  40   attr_reader :status
  41
  42   ##
  43   # Create a new Redis::Server object for the redis instance
  44   # listening on the given host and port.
  45
  46   def initialize(host, port = DEFAULT_PORT, timeout = 10)
  47     raise ArgumentError, "No host specified" if host.nil? or host.empty?
  48     raise ArgumentError, "No port specified" if port.nil? or port.to_i.zero?
  49
  50     @host   = host
  51     @port   = port.to_i
  52
  53     @sock   = nil
  54     @status = 'NOT CONNECTED'
  55     @timeout = timeout
  56   end
  57
  58   ##
  59   # Return a string representation of the server object.
  60   def inspect
  61     "<Redis::Server: %s:%d (%s)>" % [@host, @port, @status]
  62   end
  63
  64   ##
  65   # Try to connect to the redis server targeted by this object.
  66   # Returns the connected socket object on success or nil on failure.
  67
  68   def socket
  69     return @sock if socket_alive?
  70     close
  71     # Attempt to connect if not already connected.
  72     begin
  73       @sock = connect_to(@host, @port, @timeout)
  74       @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1
  75       @status = 'CONNECTED'
  76     rescue Errno::EPIPE, Errno::ECONNREFUSED => e
  77       puts "Socket died... : #{e}\n" if $debug
  78       retry
  79     rescue SocketError, SystemCallError, IOError => err
  80       puts "Unable to open socket: #{err.class.name}, #{err.message}" if $debug
  81     end
  82     @sock
  83   end
  84
  85   def connect_to(host, port, timeout=nil)
  86     socket = TCPSocket.new(host, port)
  87     socket.set_encoding(Encoding::BINARY) if socket.respond_to?(:set_encoding)
  88     if timeout
  89       socket.instance_eval <<-EOR
  90         alias :blocking_readline :readline
  91         def readline(*args)
  92           RedisTimer.timeout(#{timeout}) do
  93             self.blocking_readline(*args)
  94           end
  95         end
  96         alias :blocking_read :read
  97         def read(*args)
  98           RedisTimer.timeout(#{timeout}) do
  99             self.blocking_read(*args)
 100           end
 101         end
 102         alias :blocking_write :write
 103         def write(*args)
 104           RedisTimer.timeout(#{timeout}) do
 105             self.blocking_write(*args)
 106           end
 107         end
 108       EOR
 109     end
 110     socket
 111   end
 112
 113   # Close the connection to the redis server targeted by this
 114   # object.
 115
 116   def close
 117     @sock.close if !@sock.nil? && !@sock.closed?
 118     @sock   = nil
 119     @status = "NOT CONNECTED"
 120   end
 121
 122   private
 123     def socket_alive?
 124       #BTM - TODO - FileStat is borked under JRuby
 125       unless defined?(JRUBY_VERSION)
 126         !@sock.nil? &&  !@sock.closed? && @sock.stat.readable?
 127       else
 128         !@sock.nil? &&  !@sock.closed?
 129       end
 130     end
 131 end