cartodb/config/initializers/zz_patch_reconnect.rb

# This patches the default behavior of ActiveRecord not recovering from PG::Error
# connection failures.
#
# When an ActiveRecord connection to PostgreSQL fails, it returns a
# PG::Error: connection not open.
#
# However, this does not close the connection, which is reused over and over,
# causing a failure even if the PostgreSQL server is already back.
#
# The original code was taken from:
# https://github.com/rails/rails/pull/6557
# which was not merged for some reason - instead
# https://github.com/rails/rails/pull/6654
# was merged, which does not fix the issue as, even though verify! now works,
# it is never called actively by Rails (tested on latest 3.2.x version).
#

#module ActiveRecord
#  module ConnectionAdapters
#    class PostgreSQLAdapter
#
#      # Queries the database and returns the results in an Array-like object
#      def query(sql, name = nil) #:nodoc:
#        wrap_execute(sql, name) do
#          result_as_array @connection.async_exec(sql)
#        end
#      end
#
#      # Executes an SQL statement, returning a PGresult object on success
#      # or raising a PGError exception otherwise.
#      def execute(sql, name = nil)
#        wrap_execute(sql, name) do
#          @connection.async_exec(sql)
#        end
#      end
#
#
#      def exec_query(sql, name = 'SQL', binds = [])
#        wrap_execute(sql, name, binds) do
#          result = binds.empty? ? exec_no_cache(sql, binds) :
#                                  exec_cache(sql, binds)
#
#          ret = ActiveRecord::Result.new(result.fields, result_as_array(result))
#          result.clear
#          return ret
#        end
#      end
#
#      def exec_delete(sql, name = 'SQL', binds = [])
#        wrap_execute(sql, name, binds) do
#          result = binds.empty? ? exec_no_cache(sql, binds) :
#                                  exec_cache(sql, binds)
#          affected = result.cmd_tuples
#          result.clear
#          affected
#        end
#      end
#
#      def wrap_execute(sql, name = "SQL", binds = [])
#        with_auto_reconnect do
#          log(sql, name, binds) do
#            yield
#          end
#        end
#      end
#
#      def with_auto_reconnect
#        yield
#
#      rescue ActiveRecord::StatementInvalid
#        raise unless @connection.status == PG::CONNECTION_BAD
#        raise unless open_transactions == 0
#
#        reconnect!
#        yield
#      rescue PG::Error => e
#        unless @connection.status == PG::CONNECTION_BAD
#          raise "Not valid connection status: #{@connection.status}. Error: #{e.message}"
#        end
#        raise unless open_transactions == 0
#        raise unless e.message =~ /result has been cleared/
#
#        reconnect!
#        yield
#      end
#    end
#  end
#end
#