class ActiveRecord::ConnectionAdapters::Mysql2Adapter

def active?
  return false unless @connection
  @connection.ping
end

def configure_connection
  @connection.query_options.merge!(:as => :array)
  super
end

def connect
  @connection = Mysql2::Client.new(@config)
  configure_connection
end

def disconnect!
  super
  unless @connection.nil?
    @connection.close
    @connection = nil
  end
end

def each_hash(result) # :nodoc:
  if block_given?
    result.each(:as => :hash, :symbolize_keys => true) do |row|
      yield row
    end
  else
    to_enum(:each_hash, result)
  end
end

def error_number(exception)
  exception.error_number if exception.respond_to?(:error_number)
end

def exec_delete(sql, name, binds)
  execute to_sql(sql, binds), name
  @connection.affected_rows
end

def exec_insert(sql, name, binds, pk = nil, sequence_name = nil)
  execute to_sql(sql, binds), name
end

def exec_query(sql, name = 'SQL', binds = [])
  result = execute(sql, name)
  ActiveRecord::Result.new(result.fields, result.to_a)
end

def execute(sql, name = nil)
  if @connection
    # make sure we carry over any changes to ActiveRecord::Base.default_timezone that have been
    # made since we established the connection
    @connection.query_options[:database_timezone] = ActiveRecord::Base.default_timezone
  end
  super
end

def explain(arel, binds = [])
  sql     = "EXPLAIN #{to_sql(arel, binds.dup)}"
  start   = Time.now
  result  = exec_query(sql, 'EXPLAIN', binds)
  elapsed = Time.now - start
  ExplainPrettyPrinter.new.pp(result, elapsed)
end

def initialize(connection, logger, connection_options, config)
  super
  @visitor = BindSubstitution.new self
  configure_connection
end

def initialize_schema_migrations_table
  if @config[:encoding] == 'utf8mb4'
    ActiveRecord::SchemaMigration.create_table(MAX_INDEX_LENGTH_FOR_UTF8MB4)
  else
    ActiveRecord::SchemaMigration.create_table
  end
end

def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
  super
  id_value || @connection.last_id
end

def last_inserted_id(result)
  @connection.last_id
end

def new_column(field, default, type, null, collation, extra = "") # :nodoc:
  Column.new(field, default, type, null, collation, strict_mode?, extra)
end

def quote_string(string)
  @connection.escape(string)
end

def reconnect!
  super
  disconnect!
  connect
end

def select(sql, name = nil, binds = [])
  exec_query(sql, name)
end

def select_rows(sql, name = nil, binds = [])
  execute(sql, name).to_a
end

def set_field_encoding field_name
  field_name
end

def supports_explain?
  true
end

def version
  @version ||= @connection.info[:version].scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
end