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 amount of time to wait before attempting to re-establish a
  29   # connection with a server that is marked dead.
  30
  31   RETRY_DELAY = 30.0
  32
  33   ##
  34   # The host the redis server is running on.
  35
  36   attr_reader :host
  37
  38   ##
  39   # The port the redis server is listening on.
  40
  41   attr_reader :port
  42
  43   ##
  44   #
  45
  46   attr_reader :replica
  47
  48   ##
  49   # The time of next retry if the connection is dead.
  50
  51   attr_reader :retry
  52
  53   ##
  54   # A text status string describing the state of the server.
  55
  56   attr_reader :status
  57
  58   ##
  59   # Create a new Redis::Server object for the redis instance
  60   # listening on the given host and port.
  61
  62   def initialize(host, port = DEFAULT_PORT, timeout = 10)
  63     raise ArgumentError, "No host specified" if host.nil? or host.empty?
  64     raise ArgumentError, "No port specified" if port.nil? or port.to_i.zero?
  65
  66     @host   = host
  67     @port   = port.to_i
  68
  69     @sock   = nil
  70     @retry  = nil
  71     @status = 'NOT CONNECTED'
  72     @timeout = timeout
  73   end
  74
  75   ##
  76   # Return a string representation of the server object.
  77   def inspect
  78     "<Redis::Server: %s:%d (%s)>" % [@host, @port, @status]
  79   end
  80
  81   ##
  82   # Try to connect to the redis server targeted by this object.
  83   # Returns the connected socket object on success or nil on failure.
  84
  85   def socket
  86     return @sock if @sock and not @sock.closed?
  87
  88     @sock = nil
  89
  90     # If the host was dead, don't retry for a while.
  91     return if @retry and @retry > Time.now
  92
  93     # Attempt to connect if not already connected.
  94     begin
  95       @sock = connect_to(@host, @port, @timeout)
  96       @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1
  97       @retry  = nil
  98       @status = 'CONNECTED'
  99     rescue Errno::EPIPE, Errno::ECONNREFUSED => e
 100       puts "Socket died... socket: #{@sock.inspect}\n" if $debug
 101       @sock.close
 102       retry
 103     rescue SocketError, SystemCallError, IOError => err
 104       puts "Unable to open socket: #{err.class.name}, #{err.message}" if $debug
 105       mark_dead err
 106     end
 107     @sock
 108   end
 109
 110   def connect_to(host, port, timeout=nil)
 111     socket = TCPSocket.new(host, port, 0)
 112     if timeout
 113       socket.instance_eval <<-EOR
 114         alias :blocking_gets :gets
 115         def gets(*args)
 116           RedisTimer.timeout(#{timeout}) do
 117             self.blocking_gets(*args)
 118           end
 119         end
 120         alias :blocking_read :read
 121         def read(*args)
 122           RedisTimer.timeout(#{timeout}) do
 123             self.blocking_read(*args)
 124           end
 125         end
 126         alias :blocking_write :write
 127         def write(*args)
 128           RedisTimer.timeout(#{timeout}) do
 129             self.blocking_write(*args)
 130           end
 131         end
 132       EOR
 133     end
 134     socket
 135   end
 136
 137   ##
 138   # Close the connection to the redis server targeted by this
 139   # object.  The server is not considered dead.
 140
 141   def close
 142     @sock.close if @sock && !@sock.closed?
 143     @sock   = nil
 144     @retry  = nil
 145     @status = "NOT CONNECTED"
 146   end
 147
 148   ##
 149   # Mark the server as dead and close its socket.
 150   def mark_dead(error)
 151     @sock.close if @sock && !@sock.closed?
 152     @sock   = nil
 153     @retry  = Time.now #+ RETRY_DELAY
 154
 155     reason = "#{error.class.name}: #{error.message}"
 156     @status = sprintf "%s:%s DEAD (%s), will retry at %s", @host, @port, reason, @retry
 157     puts @status
 158   end
 159
 160 end