Class: Cassandra::LoadBalancing::Policy Abstract

Inherits:

Object

• Object
• Cassandra::LoadBalancing::Policy

Defined in:

lib/cassandra/load_balancing.rb

Overview

This class is abstract.

Actual load balancing policies don't need to extend this class, only implement its methods. This class exists for documentation purposes only.

Direct Known Subclasses

Cassandra::LoadBalancing::Policies::DCAwareRoundRobin, Cassandra::LoadBalancing::Policies::RoundRobin, Cassandra::LoadBalancing::Policies::TokenAware, Cassandra::LoadBalancing::Policies::WhiteList

Instance Method Summary

• #distance(host) ⇒ Symbol

  Returns a distance that determines how many connections (if any) the driver will open to the host.

• #host_down(host) ⇒ Object
• #host_found(host) ⇒ Object
• #host_lost(host) ⇒ Object
• #host_up(host) ⇒ Object
• #inspect ⇒ String

  A console-friendly representation of this policy.

• #plan(keyspace, statement, options) ⇒ Cassandra::LoadBalancing::Plan

  Load balancing plan is used to determine the order in which hosts should be tried in case of a network failure.

• #setup(cluster) ⇒ void

  Allows policy to initialize with the cluster instance.

• #teardown(cluster) ⇒ void

  Allows policy to release any external resources it might be holding.

Instance Method Details

#distance(host) ⇒ Symbol

Returns a distance that determines how many connections (if any) the driver will open to the host.

Parameters:

• host (Cassandra::Host) —

  a host instance

Returns:

• (Symbol) —

  distance to host. Must be one of DISTANCES

# File 'lib/cassandra/load_balancing.rb', line 68

def distance(host)
end

#host_down(host) ⇒ Object

See Also:

• Cassandra::Listener#host_down

# File 'lib/cassandra/load_balancing.rb', line 51

def host_down(host)
end

#host_found(host) ⇒ Object

See Also:

• Cassandra::Listener#host_found

# File 'lib/cassandra/load_balancing.rb', line 55

def host_found(host)
end

#host_lost(host) ⇒ Object

See Also:

• Cassandra::Listener#host_lost

# File 'lib/cassandra/load_balancing.rb', line 59

def host_lost(host)
end

#host_up(host) ⇒ Object

See Also:

• Cassandra::Listener#host_up

# File 'lib/cassandra/load_balancing.rb', line 47

def host_up(host)
end

#inspect ⇒ String

Returns a console-friendly representation of this policy.

Returns:

• (String) —

  a console-friendly representation of this policy

# File 'lib/cassandra/load_balancing.rb', line 85

def inspect
  "#<#{self.class.name}:0x#{self.object_id.to_s(16)}>"
end

#plan(keyspace, statement, options) ⇒ Cassandra::LoadBalancing::Plan

Note:

Hosts that should be ignored, must not be included in the Plan

Load balancing plan is used to determine the order in which hosts should be tried in case of a network failure.

Parameters:

• keyspace (String) —

  current keyspace of the Session

• statement (Cassandra::Statement) —

  actual statement to be executed

• options (Cassandra::Execution::Options) —

  execution options to be used

Returns:

• (Cassandra::LoadBalancing::Plan) —

  a load balancing plan

Raises:

• (NotImplementedError) —

  override this method to return a plan

# File 'lib/cassandra/load_balancing.rb', line 81

def plan(keyspace, statement, options)
end

#setup(cluster) ⇒ void

This method returns an undefined value.

Allows policy to initialize with the cluster instance. This method is called once before connecting to the cluster.

Parameters:

• cluster (Cassandra::Cluster) —

  current cluster instance

# File 'lib/cassandra/load_balancing.rb', line 34

def setup(cluster)
end

#teardown(cluster) ⇒ void

This method returns an undefined value.

Allows policy to release any external resources it might be holding. This method is called once the cluster has been terminated after calling Cluster#close

Parameters:

• cluster (Cassandra::Cluster) —

  current cluster instance

# File 'lib/cassandra/load_balancing.rb', line 43

def teardown(cluster)
end