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)
  klass.send(:remove_method, :retrieve_connection_pool) if ::Rails.version >= '4'
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

#clear_idle_connections!(since_when) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 144

def clear_idle_connections!(since_when)
  # TODO in rails 4.2+ s/connection_pools.values/connection_pool_list/
  connection_pools.values.each{ |pool| pool.clear_idle_connections!(since_when) }
end

#establish_connection_with_sharding(owner, spec) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 28

def establish_connection_with_sharding(owner, spec)
  establish_connection_without_sharding(owner, 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

  # AR3 uses the name, AR4 uses the model
  model = case owner
          when String
            owner.constantize
          when Class
            owner
          else
            raise "unknown owner #{owner}"
          end
  pool = ::Rails.version < '4' ? connection_pools[spec] : owner_to_pool[owner.name]

  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)
  if ::Rails.version < '4'
    connection_pools[spec] = proxy
  else
    owner_to_pool[owner.name] = proxy
    class_to_pool.clear
  end

  if first_time
    if Shard.default.database_server.config[:prefer_slave]
      Shard.default.database_server.shackle!
    end

    if Shard.default.is_a?(DefaultShard) && Shard.default.database_server.config[:slave]
      Shard.default.database_server.shackle!
      Shard.default(true)
    end
  end

  if ::Rails.version < '4'
    initialize_categories(model)
    class_to_pool[model.name] = proxy
  end

  # 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 190

def initialize_categories(model = ::ActiveRecord::Base)
  if ::Rails.version < '4'
    # 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
  else
    class_to_pool.clear
  end
end

#remove_connection_with_sharding(model) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 114

def remove_connection_with_sharding(model)
  uninitialize_ar(model) if (::Rails.version < '4' ? class_to_pool : owner_to_pool)[model.name].is_a?(ConnectionPoolProxy)
  result = remove_connection_without_sharding(model)
  initialize_categories if ::Rails.version >= '4'
  result
end

#retrieve_connection_pool(klass) ⇒ Object 



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

def retrieve_connection_pool(klass)
  class_to_pool[klass.name] ||= begin
    original_klass = klass
    until pool = pool_for(klass)
      klass = klass.superclass
      break unless klass <= Base
    end

    if pool.is_a?(ConnectionPoolProxy) && pool.category != original_klass.shard_category
      default_pool = pool.default_pool
      pool = nil
      class_to_pool.each_value { |p| pool = p if p.is_a?(ConnectionPoolProxy) &&
          p.category == original_klass.shard_category &&
          p.default_pool == default_pool }
      pool ||= ConnectionPoolProxy.new(original_klass.shard_category, default_pool, @shard_connection_pools)
    end

    class_to_pool[original_klass.name] = pool
  end
end

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



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# File 'lib/switchman/active_record/connection_handler.rb', line 159

def uninitialize_ar(model = ::ActiveRecord::Base)
  # take the proxies out
  if ::Rails.version >= '4'
    pool = owner_to_pool[model.name]
    owner_to_pool[model.name] = pool.default_pool if pool
  else
    class_to_pool.each_key do |model_name|
      pool_model = model_name.constantize
      # only de-proxify models that inherit from what we're uninitializing
      next unless pool_model == model || pool_model < model
      proxy = class_to_pool[model_name]
      next unless proxy.is_a?(ConnectionPoolProxy)

      # make sure we're switched back to the default shard for the
      # connection that will remain
      if proxy.connected?
        Shard.default.activate(proxy.category) { proxy.connection }
      end
      connection_pools[proxy.spec] = proxy.default_pool
      class_to_pool[model_name] = proxy.default_pool
    end

    # prune dups that were created for implementing shard categories
    class_to_pool.each_key do |model_name|
      next if model_name == ::ActiveRecord::Base.name
      pool_model = model_name.constantize
      class_to_pool.delete(model_name) if retrieve_connection_pool(pool_model.superclass) == class_to_pool[model_name]
    end
  end
end