Class: Switchman::DatabaseServer

Inherits:
Object
  • Object
show all
Defined in:
lib/switchman/database_server.rb

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(id = nil, config = {}) ⇒ DatabaseServer

Returns a new instance of DatabaseServer.



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# File 'lib/switchman/database_server.rb', line 84

def initialize(id = nil, config = {})
  @id = id
  @config = config.deep_symbolize_keys
  @configs = {}
  @roles = [:primary]
end

Class Attribute Details

.creating_new_shard ⇒ Object

Returns the value of attribute creating_new_shard.



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# File 'lib/switchman/database_server.rb', line 10

def creating_new_shard
  @creating_new_shard
end

Instance Attribute Details

#id ⇒ Object

Returns the value of attribute id.



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# File 'lib/switchman/database_server.rb', line 7

def id
  @id
end

#roles ⇒ Object (readonly)

Returns the value of attribute roles.



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# File 'lib/switchman/database_server.rb', line 82

def roles
  @roles
end

Class Method Details

.all ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 12

def all
  database_servers.values
end

.all_roles ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 16

def all_roles
  @all_roles ||= all.map(&:roles).flatten.uniq
end

.create(settings = {}) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 27

def create(settings = {})
  raise 'database servers should be set up in database.yml' unless ::Rails.env.test?

  id = settings[:id]
  unless id
    @id ||= 0
    @id += 1
    id = @id
  end
  server = DatabaseServer.new(id.to_s, settings)
  server.instance_variable_set(:@fake, true)
  database_servers[server.id] = server
  ::ActiveRecord::Base.configurations.configurations <<
    ::ActiveRecord::DatabaseConfigurations::HashConfig.new(::Rails.env, "#{server.id}/primary", settings)
  Shard.send(:initialize_sharding)
  server
end

.find(id_or_all) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 20

def find(id_or_all)
  return all if id_or_all == :all
  return id_or_all.map { |id| database_servers[id || ::Rails.env] }.compact.uniq if id_or_all.is_a?(Array)

  database_servers[id_or_all || ::Rails.env]
end

.server_for_new_shard ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 45

def server_for_new_shard
  servers = all.select { |s| s.config[:open] }
  return find(nil) if servers.empty?

  servers[rand(servers.length)]
end

Instance Method Details

#cache_store ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 245

def cache_store
  @cache_store ||= Switchman.config[:cache_map][id] || Switchman.config[:cache_map][::Rails.env]
  @cache_store
end

#config(environment = :primary) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 115

def config(environment = :primary)
  @configs[environment] ||= begin
    case @config[environment]
    when Array
      @config[environment].map do |config|
        config = @config.merge((config || {}).symbolize_keys)
        # make sure GuardRail doesn't get any brilliant ideas about choosing the first possible server
        config.delete(environment)
        config
      end
    when Hash
      @config.merge(@config[environment])
    else
      @config
    end
  end
end

#connects_to_hash ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 91

def connects_to_hash
  self.class.all_roles.map do |role|
    config_role = role
    config_role = :primary unless roles.include?(role)
    config_name = :"#{id}/#{config_role}"
    config_name = :primary if id == ::Rails.env && config_role == :primary
    [role.to_sym, config_name]
  end.to_h
end

#create_new_shard(id: nil, name: nil, schema: true) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 164

def create_new_shard(id: nil, name: nil, schema: true)
  unless Shard.default.is_a?(Shard)
    raise NotImplementedError,
          "Cannot create new shards when sharding isn't initialized"
  end

  create_statement = -> { "CREATE SCHEMA #{name}" }
  password = " PASSWORD #{::ActiveRecord::Base.connection.quote(config[:password])}" if config[:password]
  sharding_config = Switchman.config
  config_create_statement = sharding_config[config[:adapter]]&.[](:create_statement)
  config_create_statement ||= sharding_config[:create_statement]
  if config_create_statement
    create_commands = Array(config_create_statement).dup
    create_statement = lambda {
      create_commands.map { |statement| format(statement, name: name, password: password) }
    }
  end

  id ||= begin
    id_seq = Shard.connection.quote(Shard.connection.quote_table_name('switchman_shards_id_seq'))
    next_id = Shard.connection.select_value("SELECT nextval(#{id_seq})")
    next_id.to_i
  end

  name ||= "#{config[:database]}_shard_#{id}"

  Shard.connection.transaction do
    shard = Shard.create!(id: id,
                          name: name,
                          database_server_id: self.id)
    schema_already_existed = false

    begin
      self.class.creating_new_shard = true
      DatabaseServer.send(:reference_role, :deploy)
      ::ActiveRecord::Base.connected_to(shard: self.id.to_sym, role: :deploy) do
        if create_statement
          if ::ActiveRecord::Base.connection.select_value("SELECT 1 FROM pg_namespace WHERE nspname=#{::ActiveRecord::Base.connection.quote(name)}")
            schema_already_existed = true
            raise 'This schema already exists; cannot overwrite'
          end
          Array(create_statement.call).each do |stmt|
            ::ActiveRecord::Base.connection.execute(stmt)
          end
        end
        if config[:adapter] == 'postgresql'
          old_proc = ::ActiveRecord::Base.connection.raw_connection.set_notice_processor do
          end
        end
        old_verbose = ::ActiveRecord::Migration.verbose
        ::ActiveRecord::Migration.verbose = false

        unless schema == false
          shard.activate do
            reset_column_information

            ::ActiveRecord::Base.connection.transaction(requires_new: true) do
              ::ActiveRecord::Base.connection.migration_context.migrate
            end
            reset_column_information
            ::ActiveRecord::Base.descendants.reject do |m|
              m <= UnshardedRecord || !m.table_exists?
            end.each(&:define_attribute_methods)
          end
        end
      ensure
        ::ActiveRecord::Migration.verbose = old_verbose
        ::ActiveRecord::Base.connection.raw_connection.set_notice_processor(&old_proc) if old_proc
      end
      shard
    rescue
      shard.destroy
      shard.drop_database rescue nil unless schema_already_existed
      reset_column_information unless schema == false rescue nil
      raise
    ensure
      self.class.creating_new_shard = false
    end
  end
end

#destroy ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 101

def destroy
  self.class.send(:database_servers).delete(id) if id
  Shard.sharded_models.each do |klass|
    self.class.all_roles.each do |role|
      klass.connection_handler.remove_connection_pool(klass.connection_specification_name, role: role,
                                                                                           shard: id.to_sym)
    end
  end
end

#fake? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/switchman/database_server.rb', line 111

def fake?
  @fake
end

#guard!(environment = :secondary) ⇒ Object

locks this db to a specific environment, except for when doing writes (then it falls back to the current value of GuardRail.environment)



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# File 'lib/switchman/database_server.rb', line 140

def guard!(environment = :secondary)
  @guard_rail_environment = environment
end

#guard_rail_environment ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 133

def guard_rail_environment
  @guard_rail_environment || ::GuardRail.environment
end

#primary_shard ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 262

def primary_shard
  unless instance_variable_defined?(:@primary_shard)
    # if sharding isn't fully set up yet, we may not be able to query the shards table
    @primary_shard = Shard.default if Shard.default.database_server == self
    @primary_shard ||= shards.where(name: nil).first
  end
  @primary_shard
end

#shard_name(shard) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 250

def shard_name(shard)
  return config[:shard_name] if config[:shard_name]

  if shard == :bootstrap
    # rescue nil because the database may not exist yet; if it doesn't,
    # it will shortly, and this will be re-invoked
    ::ActiveRecord::Base.connection.current_schemas.first rescue nil
  else
    shard.activate { ::ActiveRecord::Base.connection_pool.default_schema }
  end
end

#shards ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 156

def shards
  if id == ::Rails.env
    Shard.where('database_server_id IS NULL OR database_server_id=?', id)
  else
    Shard.where(database_server_id: id)
  end
end

#unguard ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 148

def unguard
  old_env = @guard_rail_environment
  unguard!
  yield
ensure
  guard!(old_env)
end

#unguard! ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 144

def unguard!
  @guard_rail_environment = nil
end