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 26

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)
  klass.send(:remove_method, :pool_for)
end

.make_sharing_automagic(config) ⇒ Object 



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

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

  # only load the shard name from the db if we have to
  if config[key] || !config[:shard_name]
    # we may not be able to connect to this shard yet, cause it might be an empty database server
    shard_name = Shard.current.name rescue nil
    return unless shard_name

    config[:shard_name] ||= shard_name
  end

  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 164

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 33

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.prepend(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 = 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)
    ConnectionHandler.make_sharing_automagic(Shard.default.database_server.config)

    ::ActiveRecord::Base.configurations[::Rails.env] = spec.instance_variable_get(:@config).stringify_keys
  end
  @shard_connection_pools ||= { [:master, Shard.default.database_server.shareable? ? ::Rails.env : Shard.default] => pool}

  proxy = ConnectionPoolProxy.new(model.shard_category,
                                  pool,
                                  @shard_connection_pools)
  owner_to_pool[owner.name] = proxy
  class_to_pool.clear

  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

  # 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(reload: true, with_fallback: true)
    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)
        shard.activate do
          ConnectionHandler.make_sharing_automagic(server.config)
          ConnectionHandler.make_sharing_automagic(proxy.current_pool.spec.config)
        end
      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

  proxy
end

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



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# File 'lib/switchman/active_record/connection_handler.rb', line 189

def initialize_categories(model = ::ActiveRecord::Base)
  class_to_pool.clear
end

#pool_for(owner) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 124

def pool_for(owner)
  # copypasted from AR#ConnectionHandler other than proxy handling

  owner_to_pool.fetch(owner.name) {
    if ancestor_pool = pool_from_any_process_for(owner)
      # A connection was established in an ancestor process that must have
      # subsequently forked. We can't reuse the connection, but we can copy
      # the specification and establish a new connection with it.
      if ancestor_pool.is_a?(ConnectionPoolProxy)
        establish_connection owner, ancestor_pool.default_pool.spec
      else
        establish_connection owner, ancestor_pool.spec
      end
    else
      owner_to_pool[owner.name] = nil
    end
  }
end

#remove_connection_with_sharding(model) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 117

def remove_connection_with_sharding(model)
  uninitialize_ar(model) if owner_to_pool[model.name].is_a?(ConnectionPoolProxy)
  result = remove_connection_without_sharding(model)
  initialize_categories
  result
end

#retrieve_connection_pool(klass) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 143

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

#switchman_connection_pool_proxies ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 169

def switchman_connection_pool_proxies
  class_to_pool.values.uniq
end

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



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# File 'lib/switchman/active_record/connection_handler.rb', line 183

def uninitialize_ar(model = ::ActiveRecord::Base)
  # take the proxies out
  pool = owner_to_pool[model.name]
  owner_to_pool[model.name] = pool.default_pool if pool
end