Module: Switchman::ActiveRecord::ConnectionHandler

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

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.make_sharing_automagic(config, shard = Shard.current) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 8

def self.make_sharing_automagic(config, shard = Shard.current)
  # only load the shard name from the db if we have to
  if !config[:shard_name]
    # we may not be able to connect to this shard yet, cause it might be an empty database server
    shard = shard.call if shard.is_a?(Proc)
    shard_name = shard.name rescue nil
    return unless shard_name

    config[:shard_name] ||= 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 167

def clear_idle_connections!(since_when)
  connection_pool_list.each{ |pool| pool.clear_idle_connections!(since_when) }
end

#establish_connection(spec) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 20

def establish_connection(spec)
  # Just skip establishing a sharded connection if sharding isn't loaded; we'll do it again later
  # This only can happen when loading ActiveRecord::Base; after everything is loaded Shard will
  # be defined and this will actually establish a connection
  return unless defined?(Shard)
  pool = super

  # 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

  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

    config = pool.spec.config
    # automatically change config to allow for sharing connections with simple config
    ConnectionHandler.make_sharing_automagic(config)
    ConnectionHandler.make_sharing_automagic(Shard.default.database_server.config)

    if ::Rails.version < '6.0'
      ::ActiveRecord::Base.configurations[::Rails.env] = config.stringify_keys
    else
      # Adopted from the deprecated code that currently lives in rails proper
      remaining_configs = ::ActiveRecord::Base.configurations.configurations.reject { |db_config| db_config.env_name == ::Rails.env }
      new_config = ::ActiveRecord::DatabaseConfigurations.new(::Rails.env => config.stringify_keys).configurations
      new_configs = remaining_configs + new_config

      ::ActiveRecord::Base.configurations = new_configs
    end
  else
    # this is probably wrong now
    Shard.default.remove_instance_variable(:@name) if Shard.default.instance_variable_defined?(:@name)
  end

  @shard_connection_pools ||= { [:primary, Shard.default.database_server.shareable? ? ::Rails.env : Shard.default] => pool}

  category = pool.spec.name.to_sym
  proxy = ConnectionPoolProxy.new(category,
                                  pool,
                                  @shard_connection_pools)
  owner_to_pool[pool.spec.name] = proxy

  if first_time
    if Shard.default.database_server.config[:prefer_secondary]
      Shard.default.database_server.guard!
    end

    if Shard.default.is_a?(DefaultShard) && Shard.default.database_server.config[:secondary]
      Shard.default.database_server.guard!
      Shard.default(reload: 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 [:primary, :unsharded].include?(category) && 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 = nil
        shard_proc = -> do
          shard ||= server.shards.where(:name => nil).first
          shard ||= Shard.new(:database_server => server)
          shard
        end
        ConnectionHandler.make_sharing_automagic(server.config, shard_proc)
        ConnectionHandler.make_sharing_automagic(proxy.current_pool.spec.config, shard_proc)
      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 185

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

#remove_connection(spec_name) ⇒ Object 



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

def remove_connection(spec_name)
  # also remove pools based on the same spec name that are for shard category purposes
  # can't just use delete_if, because it's a Concurrent::Map, not a Hash
  owner_to_pool.keys.each do |k|
    next if k == spec_name

    v = owner_to_pool[k]
    owner_to_pool.delete(k) if v.is_a?(ConnectionPoolProxy) && v.default_pool.spec.name == spec_name
  end

  # unwrap the pool from inside a ConnectionPoolProxy
  pool = owner_to_pool[spec_name]
  owner_to_pool[spec_name] = pool.default_pool if pool.is_a?(ConnectionPoolProxy)

  # now let Rails do its thing with the data type it expects
  super
end

#retrieve_connection_pool(spec_name) ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 132

def retrieve_connection_pool(spec_name)
  owner_to_pool.fetch(spec_name) do
    if ancestor_pool = pool_from_any_process_for(spec_name)
      # 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.
      spec = if ancestor_pool.is_a?(ConnectionPoolProxy)
        ancestor_pool.default_pool.spec
      else
        ancestor_pool.spec
      end
      # avoid copying "duplicate" pools that implement shard categories.
      # they'll have a spec.name of primary, but a spec_name of something else, like unsharded
      if spec.name == spec_name
        pool = establish_connection(spec.to_hash)
        pool.instance_variable_set(:@schema_cache, ancestor_pool.schema_cache) if ancestor_pool.schema_cache
        next pool
      end
    end

    if spec_name != "primary"
      primary_pool = retrieve_connection_pool("primary")
      if primary_pool.is_a?(ConnectionPoolProxy)
        pool = ConnectionPoolProxy.new(spec_name.to_sym, primary_pool.default_pool, @shard_connection_pools)
        pool.schema_cache.copy_references(primary_pool.schema_cache)
        owner_to_pool[spec_name] = pool
      else
        primary_pool
      end
    else
      owner_to_pool[spec_name] = nil
    end
  end
end

#switchman_connection_pool_proxies ⇒ Object 



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# File 'lib/switchman/active_record/connection_handler.rb', line 171

def switchman_connection_pool_proxies
  owner_to_pool.values.uniq.select{|p| p.is_a?(ConnectionPoolProxy)}
end

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



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# File 'lib/switchman/active_record/connection_handler.rb', line 179

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