defmodule Postgrex.Types do
@moduledoc """
Encodes and decodes between PostgreSQL protocol and Elixir values.
"""
alias Postgrex.TypeInfo
import Postgrex.BinaryUtils
@typedoc """
PostgreSQL internal identifier that maps to a type. See
<https://www.postgresql.org/docs/9.4/static/datatype-oid.html>.
"""
@type oid :: pos_integer
@typedoc """
State used by the encoder/decoder functions
"""
@opaque state :: {module, :ets.tid()}
@typedoc """
Term used to describe type information
"""
@opaque type :: module | {module, [oid], [type]} | {module, nil, state}
### BOOTSTRAP TYPES AND EXTENSIONS ###
@doc false
@spec new(module) :: state
def new(module) do
{module, :ets.new(__MODULE__, [:protected, {:read_concurrency, true}])}
end
@doc false
@spec owner(state) :: {:ok, pid} | :error
def owner({_, table}) do
case :ets.info(table, :owner) do
owner when is_pid(owner) ->
{:ok, owner}
:undefined ->
:error
end
end
@doc false
@spec bootstrap_query({pos_integer, non_neg_integer, non_neg_integer}, state) :: binary | nil
def bootstrap_query(version, {_, table}) do
case :ets.info(table, :size) do
0 ->
# avoid loading information about table-types
# since there might be a lot them and most likely
# they won't be used; subsequent bootstrap will
# fetch them along with any other "new" types
filter_oids = """
WHERE (t.typrelid = 0)
AND (t.typelem = 0 OR NOT EXISTS (SELECT 1 FROM pg_catalog.pg_type s WHERE s.typrelid != 0 AND s.oid = t.typelem))
"""
build_bootstrap_query(version, filter_oids)
_ ->
nil
end
end
defp build_bootstrap_query(version, filter_oids) do
{typelem, join_domain} =
if version >= {9, 0, 0} do
{"coalesce(d.typelem, t.typelem)", "LEFT JOIN pg_type AS d ON t.typbasetype = d.oid"}
else
{"t.typelem", ""}
end
{rngsubtype, join_range} =
if version >= {9, 2, 0} do
{"coalesce(r.rngsubtype, 0)",
"LEFT JOIN pg_range AS r ON r.rngtypid = t.oid OR (t.typbasetype <> 0 AND r.rngtypid = t.typbasetype)"}
else
{"0", ""}
end
"""
SELECT t.oid, t.typname, t.typsend, t.typreceive, t.typoutput, t.typinput,
#{typelem}, #{rngsubtype}, ARRAY (
SELECT a.atttypid
FROM pg_attribute AS a
WHERE a.attrelid = t.typrelid AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
)
FROM pg_type AS t
#{join_domain}
#{join_range}
#{filter_oids}
"""
end
@doc false
@spec reload_query({pos_integer, non_neg_integer, non_neg_integer}, [oid, ...], state) ::
binary | nil
def reload_query(version, oids, {_, table}) do
case Enum.reject(oids, &:ets.member(table, &1)) do
[] ->
nil
oids ->
build_bootstrap_query(version, "WHERE t.oid IN (#{Enum.join(oids, ", ")})")
end
end
@doc false
@spec build_type_info(binary) :: TypeInfo.t()
def build_type_info(row) do
[oid, type, send, receive, output, input, array_oid, base_oid, comp_oids] = row_decode(row)
oid = String.to_integer(oid)
array_oid = String.to_integer(array_oid)
base_oid = String.to_integer(base_oid)
comp_oids = parse_oids(comp_oids)
%TypeInfo{
oid: oid,
type: :binary.copy(type),
send: :binary.copy(send),
receive: :binary.copy(receive),
output: :binary.copy(output),
input: :binary.copy(input),
array_elem: array_oid,
base_type: base_oid,
comp_elems: comp_oids
}
end
@doc false
@spec associate_type_infos([TypeInfo.t()], state) :: :ok
def associate_type_infos(type_infos, {module, table}) do
_ =
for %TypeInfo{oid: oid} = type_info <- type_infos do
true = :ets.insert_new(table, {oid, type_info, nil})
end
_ =
for %TypeInfo{oid: oid} = type_info <- type_infos do
info = find(type_info, :any, module, table)
true = :ets.update_element(table, oid, {3, info})
end
:ok
end
defp find(type_info, formats, module, table) do
case apply(module, :find, [type_info, formats]) do
{:super_binary, extension, nil} ->
{:binary, {extension, nil, {module, table}}}
{:super_binary, extension, sub_oids} when formats == :any ->
super_find(sub_oids, extension, module, table) ||
find(type_info, :text, module, table)
{:super_binary, extension, sub_oids} ->
super_find(sub_oids, extension, module, table)
nil ->
nil
info ->
info
end
end
defp super_find(sub_oids, extension, module, table) do
case sub_find(sub_oids, module, table, []) do
{:ok, sub_types} ->
{:binary, {extension, sub_oids, sub_types}}
:error ->
nil
end
end
defp sub_find([oid | oids], module, table, acc) do
case :ets.lookup(table, oid) do
[{_, _, {:binary, types}}] ->
sub_find(oids, module, table, [types | acc])
[{_, type_info, _}] ->
case find(type_info, :binary, module, table) do
{:binary, types} ->
sub_find(oids, module, table, [types | acc])
nil ->
:error
end
[] ->
:error
end
end
defp sub_find([], _, _, acc) do
{:ok, Enum.reverse(acc)}
end
defp row_decode(<<>>), do: []
defp row_decode(<<-1::int32(), rest::binary>>) do
[nil | row_decode(rest)]
end
defp row_decode(<<len::uint32(), value::binary(len), rest::binary>>) do
[value | row_decode(rest)]
end
defp parse_oids(nil) do
[]
end
defp parse_oids("{}") do
[]
end
defp parse_oids("{" <> rest) do
parse_oids(rest, [])
end
defp parse_oids(bin, acc) do
case Integer.parse(bin) do
{int, "," <> rest} -> parse_oids(rest, [int | acc])
{int, "}"} -> Enum.reverse([int | acc])
end
end
### TYPE ENCODING / DECODING ###
@doc """
Defines a type module with custom extensions and options.
`Postgrex.Types.define/3` must be called on its own file, outside of
any module and function, as it only needs to be defined once during
compilation.
Type modules are given to Postgrex on `start_link` via the `:types`
option and are used to control how Postgrex encodes and decodes data
coming from Postgrex.
For example, to define a new type module with a custom extension
called `MyExtension` while also changing `Postgrex`'s default
behaviour regarding binary decoding, you may create a new file
called "lib/my_app/postgrex_types.ex" with the following:
Postgrex.Types.define(MyApp.PostgrexTypes, [MyExtension], [decode_binary: :reference])
The line above will define a new module, called `MyApp.PostgrexTypes`
which can be passed as `:types` when starting Postgrex. The type module
works by rewriting and inlining the extensions' encode and decode
expressions in an optimal fashion for postgrex to encode parameters and
decode multiple rows at a time.
## Extensions
Extensions is a list of `Postgrex.Extension` modules or a 2-tuple
containing the module and a keyword list. The keyword, defaulting
to `[]`, will be passed to the modules `init/1` callback.
Extensions at the front of the list will take priority over later
extensions when the `matching/1` callback returns have conflicting
matches. If an extension is not provided for a type then Postgrex
will fallback to default encoding/decoding methods where possible.
All extensions that ship as part of Postgrex are included out of the
box.
See `Postgrex.Extension` for more information on extensions.
## Options
* `:null` - The atom to use as a stand in for postgres' `NULL` in
encoding and decoding. The module attribute `@null` is registered
with the value so that extension can access the value if desired
(default: `nil`);
* `:decode_binary` - Either `:copy` to copy binary values when decoding
with default extensions that return binaries or `:reference` to use a
reference counted binary of the binary received from the socket.
Referencing a potentially larger binary can be more efficient if the binary
value is going to be garbaged collected soon because a copy is avoided.
However the larger binary can not be garbage collected until all references
are garbage collected (default: `:copy`);
* `:json` - The JSON module to encode and decode JSON binaries, calls
`module.encode_to_iodata!/1` to encode and `module.decode!/1` to decode.
If `nil` then no default JSON handling
(default: `Application.get_env(:postgrex, :json_library, Jason)`);
* `:bin_opt_info` - Either `true` to enable binary optimisation information,
or `false` to disable, for more information see `Kernel.SpecialForms.<<>>/1`
in Elixir (default: `false`);
* `:debug_defaults` - Generate debug information when building default
extensions so they point to the proper source. Enabling such option
will increase the time to compile the type module (default: `false`);
* `:moduledoc` - The moduledoc to be used for the generated module.
"""
def define(module, extensions, opts \\ []) do
Postgrex.TypeModule.define(module, extensions, opts)
end
@doc false
@spec encode_params([term], [type], state) :: iodata | :error
def encode_params(params, types, {mod, _}) do
apply(mod, :encode_params, [params, types])
end
@doc false
@spec decode_rows(binary, [type], [row], state) ::
{:more, iodata, [row], non_neg_integer} | {:ok, [row], binary}
when row: var
def decode_rows(binary, types, rows, {mod, _}) do
apply(mod, :decode_rows, [binary, types, rows])
end
@doc false
@spec decode_simple(binary, state) :: [String.t()]
def decode_simple(binary, {mod, _}) do
apply(mod, :decode_simple, [binary])
end
@doc false
@spec fetch(oid, state) ::
{:ok, {:binary | :text, type}} | {:error, TypeInfo.t() | nil, module}
def fetch(oid, {mod, table}) do
try do
:ets.lookup_element(table, oid, 3)
rescue
ArgumentError ->
{:error, nil, mod}
else
{_, _} = info ->
{:ok, info}
nil ->
fetch_type_info(oid, mod, table)
end
end
defp fetch_type_info(oid, mod, table) do
try do
:ets.lookup_element(table, oid, 2)
rescue
ArgumentError ->
{:error, nil, mod}
else
type_info ->
{:error, type_info, mod}
end
end
end
