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 57

def initialize(id = nil, config = {})
  @id = id
  @config = config.deep_symbolize_keys
  @configs = {}
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 8

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 5

def id
  @id
end

Class Method Details

.all ⇒ Object 



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

def all
  database_servers.values
end

.create(settings = {}) ⇒ Object 



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

def create(settings = {})
  raise "database servers should be set up in database.yml" unless ::Rails.env.test?
  id = settings[:id]
  if !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
end

.find(id_or_all) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 14

def find(id_or_all)
  return self.all if id_or_all == :all
  return id_or_all.map { |id| self.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 33

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 251

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

#config(environment = :master) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 72

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

#create_new_shard(options = {}) ⇒ Object

Raises:

  • (NotImplementedError) 


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

def create_new_shard(options = {})
  raise NotImplementedError.new("Cannot create new shards when sharding isn't initialized") unless Shard.default.is_a?(Shard)

  name = options[:name]
  create_schema = options[:schema]
  # look for another shard associated with this db
  other_shard = self.shards.where("name<>':memory:' OR name IS NULL").order(:id).first

  case config[:adapter]
    when 'postgresql'
      create_statement = lambda { "CREATE SCHEMA #{name}" }
      password = " PASSWORD #{::ActiveRecord::Base.connection.quote(config[:password])}" if config[:password]
    else
      create_statement = lambda { "CREATE DATABASE #{name}" }
  end
  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| statement.gsub('%{name}', name).gsub('%{password}', password || '') }
    }
  end

  create_shard = lambda do
    shard_id = options.fetch(:id) do
      case config[:adapter]
        when 'postgresql'
          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
        else
          nil
      end
    end

    if name.nil?
      base_name = self.config[:database].to_s % self.config
      base_name = nil if base_name == ':memory:'
      base_name << '_' if base_name
      base_id = shard_id || SecureRandom.uuid
      name = "#{base_name}shard_#{base_id}"
    end

    shard = Shard.create!(:id => shard_id,
                          :name => name,
                          :database_server => self)

    begin
      self.class.creating_new_shard = true
      shard.activate(*Shard.categories) do
        ::Shackles.activate(:deploy) do
          begin
            if create_statement
              Array(create_statement.call).each do |stmt|
                ::ActiveRecord::Base.connection.execute(stmt)
              end
              # have to disconnect and reconnect to the correct db
              if self.shareable? && other_shard
                other_shard.activate { ::ActiveRecord::Base.connection }
              else
                ::ActiveRecord::Base.connection_pool.current_pool.disconnect!
              end
            end
            old_proc = ::ActiveRecord::Base.connection.raw_connection.set_notice_processor {} if config[:adapter] == 'postgresql'
            old_verbose = ::ActiveRecord::Migration.verbose
            ::ActiveRecord::Migration.verbose = false

            unless create_schema == false
              reset_column_information

              migrate = ::Rails.version >= '5.2' ?
                -> { ::ActiveRecord::Base.connection.migration_context.migrate } :
                -> { ::ActiveRecord::Migrator.migrate(::ActiveRecord::Migrator.migrations_paths) }
              if ::ActiveRecord::Base.connection.supports_ddl_transactions?
                ::ActiveRecord::Base.connection.transaction(requires_new: true, &migrate)
              else
                migrate.call
              end
              reset_column_information
              ::ActiveRecord::Base.descendants.reject { |m| m == Shard || !m.table_exists? }.each(&:define_attribute_methods)
            end
          ensure
            ::ActiveRecord::Migration.verbose = old_verbose
            ::ActiveRecord::Base.connection.raw_connection.set_notice_processor(&old_proc) if old_proc
          end
        end
      end
      shard
    rescue
      shard.destroy
      shard.drop_database rescue nil
      reset_column_information unless create_schema == false rescue nil
      raise
    ensure
      self.class.creating_new_shard = false
    end
  end

  if Shard.connection.supports_ddl_transactions? && self.shareable? && other_shard
    Shard.transaction do
      other_shard.activate do
        ::ActiveRecord::Base.connection.transaction(&create_shard)
      end
    end
  else
    create_shard.call
  end
end

#destroy ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 63

def destroy
  raise "database servers should be set up in database.yml" unless ::Rails.env.test?
  self.class.send(:database_servers).delete(self.id) if self.id
end

#fake? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/switchman/database_server.rb', line 68

def fake?
  @fake
end

#pool_key ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 136

def pool_key
  self.id == ::Rails.env ? nil : self.id
end

#primary_shard ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 274

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

#shackle!(environment = :slave) ⇒ Object

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



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# File 'lib/switchman/database_server.rb', line 96

def shackle!(environment = :slave)
  @shackles_environment = environment
end

#shackles_environment ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 89

def shackles_environment
  @shackles_environment || ::Shackles.environment
end

#shard_name(shard) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 258

def shard_name(shard)
  if config[:shard_name]
    config[:shard_name]
  elsif config[:adapter] == 'postgresql'
    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
  else
    config[:database]
  end
end

#shards ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 128

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

#shareable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/switchman/database_server.rb', line 112

def shareable?
  @shareable_environment_key ||= []
  environment = shackles_environment
  explicit_user = ::Shackles.global_config[:username]
  return @shareable if @shareable_environment_key == [environment, explicit_user]
  @shareable_environment_key = [environment, explicit_user]
  if explicit_user
    username = explicit_user
  else
    config = self.config(environment)
    config = config.first if config.is_a?(Array)
    username = config[:username]
  end
  @shareable = username !~ /%?\{[a-zA-Z0-9_]+\}/
end

#unshackle ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 104

def unshackle
  old_env = @shackles_environment
  unshackle!
  yield
ensure
  shackle!(old_env)
end

#unshackle! ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 100

def unshackle!
  @shackles_environment = nil
end