Module: Switchman::ActiveRecord::ConnectionHandler

Defined in:
lib/switchman/active_record/connection_handler.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(klass) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 22

def self.included(klass)
  klass.alias_method_chain(:establish_connection, :sharding)
  klass.alias_method_chain(:remove_connection, :sharding)
end

.make_sharing_automagic(config, shard) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 7

def self.make_sharing_automagic(config, shard)
  key = config[:adapter] == 'postgresql' ? :schema_search_path : :database

  # we may not be able to connect to this shard yet, cause it might be an empty database server
  shard_name = shard.name rescue nil
  return unless shard_name

  config[:shard_name] ||= shard_name
  if !config[key] || config[key] == shard_name
    # this may truncate the schema_search_path if it was not specified in database.yml
    # but that's what our old behavior was anyway, so I guess it's okay
    config[key] = '%{shard_name}'
  end
end

Instance Method Details

#establish_connection_with_sharding(name, spec) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 27

def establish_connection_with_sharding(name, spec)
  establish_connection_without_sharding(name, spec)

  # this is the first place that the adapter would have been required; but now we
  # need this addition ASAP since it will be called when loading the default shard below
  if defined?(::ActiveRecord::ConnectionAdapters::PostgreSQLAdapter)
    require "switchman/active_record/postgresql_adapter"
    ::ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.send(:include, ActiveRecord::PostgreSQLAdapter)
  end

  model = name.constantize
  pool = connection_pools[spec]

  first_time = !Shard.instance_variable_get(:@default)
  if first_time
    # Have to cache the default shard before we insert sharding, otherwise the first access
    # to sharding will recurse onto itself trying to access column information
    Shard.default

    # automatically change config to allow for sharing connections with simple config
    ConnectionHandler.make_sharing_automagic(spec.config, Shard.default)
    ConnectionHandler.make_sharing_automagic(Shard.default.database_server.config, Shard.default)
  end
  @shard_connection_pools ||= { Shard.default.database_server.id => pool }

  proxy = ConnectionPoolProxy.new(model.shard_category,
                                  pool,
                                  @shard_connection_pools)
  connection_pools[spec] = proxy

  initialize_categories(model)
  @class_to_pool[name] = proxy

  # reload the default shard if we just got a new connection
  # to where the Shards table is
  # DON'T do it if we're not the current connection handler - that means
  # we're in the middle of switching environments, and we don't want to
  # establish a connection with incorrect settings
  if (model == ::ActiveRecord::Base || model == Shard) && self == ::ActiveRecord::Base.connection_handler && !first_time
    Shard.default(true) unless first_time
    proxy.disconnect!
  end

  if first_time
    # do the change for other database servers, now that we can switch shards
    if Shard.default.is_a?(Shard)
      DatabaseServer.all.each do |server|
        next if server == Shard.default.database_server
        shard = server.shards.where(:name => nil).first
        shard ||= Shard.new(:database_server => server)
        ConnectionHandler.make_sharing_automagic(server.config, shard)
      end
    end
    # we may have established some connections above trying to infer the shard's name.
    # close them, so that someone that doesn't expect them doesn't try to fork
    # without closing them
    self.clear_all_connections!
  end
end

#initialize_categories(model = ::ActiveRecord::Base) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 122

def initialize_categories(model = ::ActiveRecord::Base)
  # now set up pools for models that inherit from this model, but with a different
  # sharding category
  Shard.const_get(:CATEGORIES).each do |category, models|
    next if category == :default
    next if category == model.shard_category

    this_proxy = nil
    Array(models).each do |category_model|
      category_model = category_model.constantize if category_model.is_a? String
      next unless category_model < model

      # don't replace existing connections
      next if @class_to_pool[category_model.name]

      default_pool = retrieve_connection_pool(model)
      default_pool = default_pool.default_pool if default_pool.is_a?(ConnectionPoolProxy)
      # look for an existing compatible proxy for this category
      this_proxy ||= ConnectionPoolProxy.new(category_model.shard_category, default_pool, @shard_connection_pools)
      @class_to_pool[category_model.name] = this_proxy
    end
  end
end

#remove_connection_with_sharding(model) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 87

def remove_connection_with_sharding(model)
  uninitialize_ar(model) if @class_to_pool[model.name].is_a?(ConnectionPoolProxy)
  remove_connection_without_sharding(model)
end