client-libraries/ruby/lib/server.rb

   1 ##
   2 # This class represents a redis server instance.
   3
   4 class Server
   5
   6   ##
   7   # The amount of time to wait before attempting to re-establish a
   8   # connection with a server that is marked dead.
   9
  10   RETRY_DELAY = 30.0
  11
  12   ##
  13   # The host the redis server is running on.
  14
  15   attr_reader :host
  16
  17   ##
  18   # The port the redis server is listening on.
  19
  20   attr_reader :port
  21
  22   ##
  23   #
  24
  25   attr_reader :replica
  26
  27   ##
  28   # The time of next retry if the connection is dead.
  29
  30   attr_reader :retry
  31
  32   ##
  33   # A text status string describing the state of the server.
  34
  35   attr_reader :status
  36
  37   ##
  38   # Create a new Redis::Server object for the redis instance
  39   # listening on the given host and port.
  40
  41   def initialize(host, port = DEFAULT_PORT)
  42     raise ArgumentError, "No host specified" if host.nil? or host.empty?
  43     raise ArgumentError, "No port specified" if port.nil? or port.to_i.zero?
  44
  45     @host   = host
  46     @port   = port.to_i
  47
  48     @sock   = nil
  49     @retry  = nil
  50     @status = 'NOT CONNECTED'
  51     @timeout = 1
  52   end
  53
  54   ##
  55   # Return a string representation of the server object.
  56   def inspect
  57     "<Redis::Server: %s:%d (%s)>" % [@host, @port, @status]
  58   end
  59
  60   ##
  61   # Try to connect to the redis server targeted by this object.
  62   # Returns the connected socket object on success or nil on failure.
  63
  64   def socket
  65     return @sock if @sock and not @sock.closed?
  66
  67     @sock = nil
  68
  69     # If the host was dead, don't retry for a while.
  70     return if @retry and @retry > Time.now
  71
  72     # Attempt to connect if not already connected.
  73     begin
  74       @sock = connect_to(@host, @port, @timeout)
  75       @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1
  76       @retry  = nil
  77       @status = 'CONNECTED'
  78     rescue Errno::EPIPE, Errno::ECONNREFUSED => e
  79       puts "Socket died... socket: #{@sock.inspect}\n" if $debug
  80       @sock.close
  81       retry
  82     rescue SocketError, SystemCallError, IOError => err
  83       puts "Unable to open socket: #{err.class.name}, #{err.message}" if $debug
  84       mark_dead err
  85     end
  86
  87     return @sock
  88   end
  89
  90   def connect_to(host, port, timeout=nil)
  91     addrs = Socket.getaddrinfo('localhost', nil)
  92     addr = addrs.detect { |ad| ad[0] == 'AF_INET' }
  93     sock = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
  94     #addr = Socket.getaddrinfo(host, nil)
  95     #sock = Socket.new(Socket.const_get(addr[0][0]), Socket::SOCK_STREAM, 0)
  96
  97     if timeout
  98       secs = Integer(timeout)
  99       usecs = Integer((timeout - secs) * 1_000_000)
 100       optval = [secs, usecs].pack("l_2")
 101       sock.setsockopt Socket::SOL_SOCKET, Socket::SO_RCVTIMEO, optval
 102       sock.setsockopt Socket::SOL_SOCKET, Socket::SO_SNDTIMEO, optval
 103     end
 104     sock.connect(Socket.pack_sockaddr_in('6379', addr[3]))
 105     sock
 106   end
 107
 108   ##
 109   # Close the connection to the redis server targeted by this
 110   # object.  The server is not considered dead.
 111
 112   def close
 113     @sock.close if @sock && !@sock.closed?
 114     @sock   = nil
 115     @retry  = nil
 116     @status = "NOT CONNECTED"
 117   end
 118
 119   ##
 120   # Mark the server as dead and close its socket.
 121   def mark_dead(error)
 122     @sock.close if @sock && !@sock.closed?
 123     @sock   = nil
 124     @retry  = Time.now #+ RETRY_DELAY
 125
 126     reason = "#{error.class.name}: #{error.message}"
 127     @status = sprintf "%s:%s DEAD (%s), will retry at %s", @host, @port, reason, @retry
 128     puts @status
 129   end
 130
 131 end