Class: WhoCan::ConnectionManager

Inherits:
Object
  • Object
show all
Includes:
Deferred::Accessors, Logging
Defined in:
lib/who_can/connection_manager.rb

Overview

Note:

this class will automatically fail-back when the primary is re-established.

This class handles setting up the AMQP connection. You must start the EventMachine reactor before running anything in this class

Keeps two connections open, a primary and secondary, and reacts to changes in their state. In the non-failure case, when a client calls #connection on us, they will receive the primary connection (once it’s been established). If the primary is down, or the connection can’t be established for some reason, then the secondary is returned.

When a failover situation happens (i.e. the primary goes down) the on_failure callback will be fired. When that callback is fired, the users of this class are expected to clean up and wait until the on_recovery deferred is fired. The on_recovery deferred is fired when there is at least one open connection to a broker available.

TODO: determine how long to wait for connection to primary before failing

over to secondary.

Constant Summary collapse

DEFAULT_OPTIONS = 
{
  :primary_grace_time => 5.0
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Logging

included, #logger

Constructor Details

#initialize(primary_opts, secondary_opts, opts = {}) ⇒ ConnectionManager

Returns a new instance of ConnectionManager.

Parameters:

  • primary_cnx (AMQP-URL, Hash) —

    valid argument to AMQP.connect to be used as the primary connection.

  • secondary_cnx (AMQP-URL, Hash) —

    valid argument to AMQP.connect to be used as the secondary connection.

  • opts (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (opts):

  • :primary_grace_time (Float) — default: 5.0 —

    how long we should wait during startup for the primary to connect before giving up and just using the secondary connection



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# File 'lib/who_can/connection_manager.rb', line 144

def initialize(primary_opts, secondary_opts, opts={})
  opts = opts.with_indifferent_access.reverse_merge(DEFAULT_OPTIONS)

  @primary_opts   = primary_opts
  @secondary_opts = secondary_opts

  @primary_grace_time = opts[:primary_grace_time]

  if @primary_opts.kind_of?(ConnectionWrapper)
    @primary = @primary_opts
    @primary.name ||= 'primary'
  else
    @primary = ConnectionWrapper.new(primary_opts, :name => 'primary')
  end

  if @secondary_opts.kind_of?(ConnectionWrapper)
    @secondary = @secondary_opts
    @secondary.name ||= 'secondary'
  else
    @secondary = ConnectionWrapper.new(secondary_opts, :name => 'secondary')
  end

  @active_connection = nil

  super()
end

Instance Attribute Details

#primary ⇒ Object (readonly)

Returns the value of attribute primary.



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# File 'lib/who_can/connection_manager.rb', line 33

def primary
  @primary
end

#primary_grace_time ⇒ Object

Returns the value of attribute primary_grace_time.



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# File 'lib/who_can/connection_manager.rb', line 35

def primary_grace_time
  @primary_grace_time
end

#primary_opts ⇒ Object (readonly)

Returns the value of attribute primary_opts.



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# File 'lib/who_can/connection_manager.rb', line 33

def primary_opts
  @primary_opts
end

#secondary ⇒ Object (readonly)

Returns the value of attribute secondary.



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# File 'lib/who_can/connection_manager.rb', line 33

def secondary
  @secondary
end

#secondary_opts ⇒ Object (readonly)

Returns the value of attribute secondary_opts.



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# File 'lib/who_can/connection_manager.rb', line 33

def secondary_opts
  @secondary_opts
end

Instance Method Details

#close(*a, &b) ⇒ Object 



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# File 'lib/who_can/connection_manager.rb', line 183

def close(*a, &b)
  on_close(&b)
  super(*a)
end

#close!(*a, &b) ⇒ Object 



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# File 'lib/who_can/connection_manager.rb', line 188

def close!(*a, &b)
  on_close(&b)
  super(*a)
end

#connection ⇒ Object 



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# File 'lib/who_can/connection_manager.rb', line 193

def connection
  @active_connection
end

#primary_connected? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/who_can/connection_manager.rb', line 197

def primary_connected?
  primary and primary.connected?
end

#secondary_connected? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/who_can/connection_manager.rb', line 201

def secondary_connected?
  secondary and secondary.connected?
end

#start(*a, &b) ⇒ Object 



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# File 'lib/who_can/connection_manager.rb', line 171

def start(*a, &b)
  on_open(&b)
  super(*a)
end

#start!(&blk) ⇒ Object

connect to the broker, handle reconnections. barf if transition to :start_up state is not possible



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# File 'lib/who_can/connection_manager.rb', line 178

def start!(&blk)
  on_open(&b)
  super(*a)
end

#usable? ⇒ Boolean Also known as: useable?

Returns:

  • (Boolean) 


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# File 'lib/who_can/connection_manager.rb', line 205

def usable?
  failed_over? or degraded? or connected?
end