Class: EM::Voldemort::Connection

Inherits:
Object
  • Object
show all
Defined in:
lib/em-voldemort/connection.rb

Overview

TCP connection to one Voldemort node. The connection can be used to access multiple stores. Automatically reconnects if the connection is lost, but does not automatically retry failed requests (that is the cluster’s job).

Defined Under Namespace

Modules: Handler Classes: FailHandler

Constant Summary collapse

DEFAULT_PROTOCOL =

Voldemort’s protobuf-based protocol

'pb0'
STATUS_CHECK_PERIOD =

Every 5 seconds, check on the health of the connection

5
REQUEST_TIMEOUT =

If a request takes longer than 5 seconds, close the connection

5

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Connection

Returns a new instance of Connection.



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# File 'lib/em-voldemort/connection.rb', line 12

def initialize(options={})
  @host = options[:host] or raise ArgumentError, "#{self.class.name} requires :host"
  @port = options[:port] or raise ArgumentError, "#{self.class.name} requires :port"
  @node_id = options[:node_id]
  @protocol = options[:protocol] || DEFAULT_PROTOCOL
  @logger = options[:logger] || Logger.new($stdout)
  @health = :good
end

Instance Attribute Details

#health ⇒ Object (readonly)

Returns the value of attribute health.



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# File 'lib/em-voldemort/connection.rb', line 6

def health
  @health
end

#host ⇒ Object (readonly)

Returns the value of attribute host.



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# File 'lib/em-voldemort/connection.rb', line 6

def host
  @host
end

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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# File 'lib/em-voldemort/connection.rb', line 6

def logger
  @logger
end

#node_id ⇒ Object (readonly)

Returns the value of attribute node_id.



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# File 'lib/em-voldemort/connection.rb', line 6

def node_id
  @node_id
end

#port ⇒ Object (readonly)

Returns the value of attribute port.



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# File 'lib/em-voldemort/connection.rb', line 6

def port
  @port
end

#protocol ⇒ Object (readonly)

Returns the value of attribute protocol.



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# File 'lib/em-voldemort/connection.rb', line 6

def protocol
  @protocol
end

Instance Method Details

#close ⇒ Object

Waits for the outstanding request (if any) to complete, then gracefully shuts down the connection. Returns a deferrable that succeeds once the connection is closed (never fails).



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# File 'lib/em-voldemort/connection.rb', line 38

def close
  return @closing_deferrable if @closing_deferrable
  @closing_deferrable = EM::DefaultDeferrable.new
  @timer.cancel

  if @handler
    @handler.close_gracefully
  else
    @closing_deferrable.succeed
  end

  @handler = FailHandler.new(self)
  @health = :bad
  @closing_deferrable
end

#connect ⇒ Object

Establishes a connection to the node. Calling #connect is optional, since it also happens automatically when you start making requests.



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# File 'lib/em-voldemort/connection.rb', line 23

def connect
  force_connect unless @handler
end

#connection_closed(handler, reason = nil) ⇒ Object

Called by the connection handler when the connection is closed for any reason (closed by us, closed by peer, rejected, timeout etc). Do not call from application code.



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# File 'lib/em-voldemort/connection.rb', line 56

def connection_closed(handler, reason=nil)
  logger.info ["Connection to Voldemort node #{host}:#{port} closed", reason].compact.join(': ')
  @handler = FailHandler.new(self) if handler.equal? @handler
  @health = :bad
  @closing_deferrable.succeed if @closing_deferrable
end

#send_request(request) ⇒ Object

Sends a request to the node, given as a binary string (not including the request size prefix). Establishes a connection if necessary. If a request is already in progress, this request is queued up. Returns a deferrable that succeeds with the node’s response (again without the size prefix), or fails if there was a network-level error.



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# File 'lib/em-voldemort/connection.rb', line 31

def send_request(request)
  connect
  @handler.enqueue_request(request)
end