Class: MemCache::Server

Inherits:
Object
  • Object
show all
Defined in:
lib/memcache.rb

Overview

This class represents a memcached server instance.

Constant Summary collapse

RETRY_DELAY =

The amount of time to wait before attempting to re-establish a connection with a server that is marked dead.

30.0

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(memcache, host, port = DEFAULT_PORT, weight = DEFAULT_WEIGHT) ⇒ Server

Create a new MemCache::Server object for the memcached instance listening on the given host and port, weighted by the given weight.

Raises:

  • (ArgumentError) 


1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
 
# File 'lib/memcache.rb', line 1003

def initialize(memcache, host, port = DEFAULT_PORT, weight = DEFAULT_WEIGHT)
  raise ArgumentError, "No host specified" if host.nil? or host.empty?
  raise ArgumentError, "No port specified" if port.nil? or port.to_i.zero?

  @host   = host
  @port   = port.to_i
  @weight = weight.to_i

  @sock   = nil
  @retry  = nil
  @status = 'NOT CONNECTED'
  @timeout = memcache.timeout
  @logger = memcache.logger
end

Instance Attribute Details

#host ⇒ Object (readonly)

The host the memcached server is running on.



975
976
977
 
# File 'lib/memcache.rb', line 975

def host
  @host
end

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



997
998
999
 
# File 'lib/memcache.rb', line 997

def logger
  @logger
end

#port ⇒ Object (readonly)

The port the memcached server is listening on.



980
981
982
 
# File 'lib/memcache.rb', line 980

def port
  @port
end

#retry ⇒ Object (readonly)

The time of next retry if the connection is dead.



990
991
992
 
# File 'lib/memcache.rb', line 990

def retry
  @retry
end

#status ⇒ Object (readonly)

A text status string describing the state of the server.



995
996
997
 
# File 'lib/memcache.rb', line 995

def status
  @status
end

#weight ⇒ Object (readonly)

The weight given to the server.



985
986
987
 
# File 'lib/memcache.rb', line 985

def weight
  @weight
end

Instance Method Details

#alive? ⇒ Boolean

Check whether the server connection is alive. This will cause the socket to attempt to connect if it isn’t already connected and or if the server was previously marked as down and the retry time has been exceeded.

Returns:

  • (Boolean) 


1031
1032
1033
 
# File 'lib/memcache.rb', line 1031

def alive?
  !!socket
end

#close ⇒ Object

Close the connection to the memcached server targeted by this object. The server is not considered dead.



1095
1096
1097
1098
1099
1100
 
# File 'lib/memcache.rb', line 1095

def close
  @sock.close if @sock && !@sock.closed?
  @sock   = nil
  @retry  = nil
  @status = "NOT CONNECTED"
end

#connect_to(host, port, timeout = nil) ⇒ Object 



1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
 
# File 'lib/memcache.rb', line 1061

def connect_to(host, port, timeout=nil)
  sock = nil
  if timeout
    MemCacheTimer.timeout(timeout) do
      sock = TCPSocket.new(host, port)
    end
  else
    sock = TCPSocket.new(host, port)
  end

  io = MemCache::BufferedIO.new(sock)
  io.read_timeout = timeout
  # Getting reports from several customers, including 37signals,
  # that the non-blocking timeouts in 1.7.5 don't seem to be reliable.
  # It can't hurt to set the underlying socket timeout also, if possible.
  if timeout
    secs = Integer(timeout)
    usecs = Integer((timeout - secs) * 1_000_000)
    optval = [secs, usecs].pack("l_2")
    begin
      io.setsockopt Socket::SOL_SOCKET, Socket::SO_RCVTIMEO, optval
      io.setsockopt Socket::SOL_SOCKET, Socket::SO_SNDTIMEO, optval
    rescue Exception => ex
      # Solaris, for one, does not like/support socket timeouts.
      @logger.info "[memcache-client] Unable to use raw socket timeouts: #{ex.class.name}: #{ex.message}" if @logger
    end
  end
  io
end

#inspect ⇒ Object

Return a string representation of the server object.



1021
1022
1023
 
# File 'lib/memcache.rb', line 1021

def inspect
  "<MemCache::Server: %s:%d [%d] (%s)>" % [@host, @port, @weight, @status]
end

#mark_dead(error) ⇒ Object

Mark the server as dead and close its socket.



1105
1106
1107
1108
1109
1110
1111
1112
1113
 
# File 'lib/memcache.rb', line 1105

def mark_dead(error)
  @sock.close if @sock && !@sock.closed?
  @sock   = nil
  @retry  = Time.now + RETRY_DELAY

  reason = "#{error.class.name}: #{error.message}"
  @status = sprintf "%s:%s DEAD (%s), will retry at %s", @host, @port, reason, @retry
  @logger.info { @status } if @logger
end

#socket ⇒ Object

Try to connect to the memcached server targeted by this object. Returns the connected socket object on success or nil on failure.



1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
 
# File 'lib/memcache.rb', line 1039

def socket
  return @sock if @sock and not @sock.closed?

  @sock = nil

  # If the host was dead, don't retry for a while.
  return if @retry and @retry > Time.now

  # Attempt to connect if not already connected.
  begin
    @sock = connect_to(@host, @port, @timeout)
    @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1
    @retry  = nil
    @status = 'CONNECTED'
  rescue SocketError, SystemCallError, IOError, Timeout::Error => err
    logger.warn { "Unable to open socket: #{err.class.name}, #{err.message}" } if logger
    mark_dead err
  end

  return @sock
end