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 94

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

Class Attribute Details

.all_roles ⇒ Object (readonly)

Returns the value of attribute all_roles.



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# File 'lib/switchman/database_server.rb', line 11

def all_roles
  @all_roles
end

.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 92

def roles
  @roles
end

Class Method Details

.all ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 13

def all
  database_servers.values
end

.create(settings = {}) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 24

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(:configure_connects_to)
  server
end

.find(id_or_all) ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 17

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

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

.guard_servers ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 49

def guard_servers
  all.each { |db| db.guard! if db.config[:prefer_secondary] }
end

.server_for_new_shard ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 42

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 253

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 126

def config(environment = :primary)
  @configs[environment] ||=
    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

#connects_to_hash ⇒ Object 



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

def connects_to_hash
  self.class.all_roles.to_h 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
end

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



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# File 'lib/switchman/database_server.rb', line 176

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}"

  schema_already_existed = false
  shard = nil
  Shard.connection.transaction do
    self.class.creating_new_shard = true
    DatabaseServer.send(:reference_role, :deploy)
    ::ActiveRecord::Base.connected_to(shard: self.id.to_sym, role: :deploy) do
      shard = Shard.create!(id: id,
                            name: name,
                            database_server_id: self.id)
      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 {}
      end
      old_verbose = ::ActiveRecord::Migration.verbose
      ::ActiveRecord::Migration.verbose = false

      unless schema == false
        shard.activate do
          ::ActiveRecord::Base.connection.transaction(requires_new: true) do
            ::ActiveRecord::Base.connection.migration_context.migrate
          end

          ::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
    raise
  ensure
    self.class.creating_new_shard = false
  end
end

#destroy ⇒ Object 



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

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 122

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 146

def guard!(environment = :secondary)
  DatabaseServer.send(:reference_role, environment)
  ::ActiveRecord::Base.connected_to_stack << { shard_roles: { id.to_sym => environment },
                                               klasses: [::ActiveRecord::Base] }
end

#primary_shard ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 270

def primary_shard
  return nil unless primary_shard_id

  Shard.lookup(primary_shard_id)
end

#primary_shard_id ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 276

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

#shard_name(shard) ⇒ Object 



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

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 168

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 157

def unguard
  return yield unless ::ActiveRecord::Base.role_overriden?(id.to_sym)

  begin
    unguard!
    yield
  ensure
    ::ActiveRecord::Base.connected_to_stack.pop
  end
end

#unguard! ⇒ Object 



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# File 'lib/switchman/database_server.rb', line 152

def unguard!
  ::ActiveRecord::Base.connected_to_stack << { shard_roles: { id.to_sym => :_switchman_inherit },
                                               klasses: [::ActiveRecord::Base] }
end