Class: Rails::Sharding::ConnectionHandler

Inherits:
Object
  • Object
show all
Defined in:
lib/rails/sharding/connection_handler.rb

Defined Under Namespace

Classes: ConnectionPoolOwner

Class Method Summary collapse

Class Method Details

.connected?(shard_group, shard_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rails/sharding/connection_handler.rb', line 52

def self.connected?(shard_group, shard_name)
  connection_handler.connected?(connection_pool_owner(shard_group, shard_name))
end

.connection_pool(shard_group, shard_name) ⇒ Object 



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# File 'lib/rails/sharding/connection_handler.rb', line 40

def self.connection_pool(shard_group, shard_name)
  connection_handler.retrieve_connection_pool(connection_pool_owner(shard_group, shard_name))
rescue Errors::ConnectionPoolRetrievalError
  # mimicking behavior of rails at:
  # https://github.com/rails/rails/blob/4-2-stable/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb#507
  raise ActiveRecord::ConnectionNotEstablished, "No connection pool for shard #{connection_name(shard_group, shard_name)}"
end

.establish_all_connections ⇒ Object

Establishes connections to all shards in all shard groups. Despite the name, this actually only creates a connection pool with zero connections for each shard. The connections will be allocated for each thread when #retrieve_connection or #with_connection are called



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# File 'lib/rails/sharding/connection_handler.rb', line 8

def self.establish_all_connections
  Core.shard_groups.each do |shard_group|
    Core.shard_names(shard_group).each do |shard_name|
      establish_connection(shard_group, shard_name)
    end
  end
end

.establish_connection(shard_group, shard_name, environment = nil) ⇒ Object

Establishes a connection to a single shard in a single shard group



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# File 'lib/rails/sharding/connection_handler.rb', line 17

def self.establish_connection(shard_group, shard_name, environment=nil)
  self.setup unless defined? @@connection_handler

  unless configurations = (environment.nil? ? Core.configurations : Core.configurations(environment))
    raise Errors::ConfigNotFoundError, "Cannot find configuration for environment '#{environment}' in #{Config.shards_config_file}"
  end

  unless shard_group_configurations = configurations[shard_group.to_s]
    raise Errors::ConfigNotFoundError, "Cannot find configuration for shard_group '#{shard_group}' in environment '#{environment}' in #{Config.shards_config_file}"
  end

  resolver = ActiveRecord::ConnectionAdapters::ConnectionSpecification::Resolver.new(shard_group_configurations)
  begin
    connection_spec = resolver.spec(shard_name.to_sym)
  rescue ActiveRecord::AdapterNotSpecified => e
    raise Errors::ConfigNotFoundError, "Cannot find configuration for shard '#{shard_group}:#{shard_name}' in environment '#{environment}' in #{Config.shards_config_file}"
  end

  # since rails requires a class to be the connection owner, we trick rails passing
  # an instance of the ConnectionPoolOwner class, that responds to the #name method
  connection_handler.establish_connection(connection_pool_owner(shard_group, shard_name), connection_spec)
end

.remove_connection(shard_group, shard_name) ⇒ Object 



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# File 'lib/rails/sharding/connection_handler.rb', line 60

def self.remove_connection(shard_group, shard_name)
  connection_handler.remove_connection(connection_pool_owner(shard_group, shard_name))
end

.retrieve_connection(shard_group, shard_name) ⇒ Object 



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# File 'lib/rails/sharding/connection_handler.rb', line 48

def self.retrieve_connection(shard_group, shard_name)
  connection_handler.retrieve_connection(connection_pool_owner(shard_group, shard_name))
end

.with_connection(shard_group, shard_name, &block) ⇒ Object 



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# File 'lib/rails/sharding/connection_handler.rb', line 56

def self.with_connection(shard_group, shard_name, &block)
	connection_pool(shard_group, shard_name).with_connection(&block)
end