Class: MemCache::Server

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

Overview

This class represents a memcached server instance.

Constant Summary collapse

CONNECT_TIMEOUT =

The amount of time to wait to establish a connection with a memcached server. If a connection cannot be established within this time limit, the server will be marked as down.

0.25
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) 


720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
 
# File 'lib/memcache.rb', line 720

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

  @multithread = memcache.multithread
  @mutex = Mutex.new

  @sock   = nil
  @retry  = nil
  @status = 'NOT CONNECTED'
end

Instance Attribute Details

#host ⇒ Object (readonly)

The host the memcached server is running on.



692
693
694
 
# File 'lib/memcache.rb', line 692

def host
  @host
end

#multithread ⇒ Object (readonly)

Returns the value of attribute multithread.



714
715
716
 
# File 'lib/memcache.rb', line 714

def multithread
  @multithread
end

#port ⇒ Object (readonly)

The port the memcached server is listening on.



697
698
699
 
# File 'lib/memcache.rb', line 697

def port
  @port
end

#retry ⇒ Object (readonly)

The time of next retry if the connection is dead.



707
708
709
 
# File 'lib/memcache.rb', line 707

def retry
  @retry
end

#status ⇒ Object (readonly)

A text status string describing the state of the server.



712
713
714
 
# File 'lib/memcache.rb', line 712

def status
  @status
end

#weight ⇒ Object (readonly)

The weight given to the server.



702
703
704
 
# File 'lib/memcache.rb', line 702

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) 


749
750
751
 
# File 'lib/memcache.rb', line 749

def alive?
  !!socket
end

#close ⇒ Object

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



789
790
791
792
793
794
795
796
797
 
# File 'lib/memcache.rb', line 789

def close
  @mutex.lock if @multithread
  @sock.close if @sock && !@sock.closed?
  @sock   = nil
  @retry  = nil
  @status = "NOT CONNECTED"
ensure
  @mutex.unlock if @multithread
end

#inspect ⇒ Object

Return a string representation of the server object.



739
740
741
 
# File 'lib/memcache.rb', line 739

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



757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
 
# File 'lib/memcache.rb', line 757

def socket
  @mutex.lock if @multithread
  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 = timeout CONNECT_TIMEOUT do
      TCPSocket.new @host, @port
    end
    if Socket.constants.include? 'TCP_NODELAY' then
      @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1
    end
    @retry  = nil
    @status = 'CONNECTED'
  rescue SocketError, SystemCallError, IOError, Timeout::Error => err
    mark_dead err.message
  end

  return @sock
ensure
  @mutex.unlock if @multithread
end