From 3ede4f22e1b80b97a6b9441686e931d55232253d Mon Sep 17 00:00:00 2001 From: Ulf Wiger Date: Sat, 5 Apr 2025 13:20:30 +0200 Subject: [PATCH] Register individual types, more docs --- README.md | 88 ++++++++++++++ src/gmser_dyn.erl | 292 ++++++++++++++++++++++++++++++++++++---------- 2 files changed, 319 insertions(+), 61 deletions(-) diff --git a/README.md b/README.md index a31eca6..f5d0dff 100644 --- a/README.md +++ b/README.md @@ -13,3 +13,91 @@ Test ---- $ rebar3 eunit + +Dynamic encoding +---- + +The module `gmser_dyn` offers dynamic encoding support, encoding most 'regular' +Erlang data types into an internal RLP representation. + +Main API: +* `encode(term()) -> iolist()` +* `encode_typed(template(), term()) -> iolist()` +* `decode(iolist()) -> term()` + +* `serialize(term()) -> binary()` +* `serialize_typed(template(), term()) -> binary()` +* `deserialize(binary()) -> term()` + +The basic types supported by the encoder are: +* `non_neg_integer()` (`int` , code: 248) +* `binary()` (`binary`, code: 249) +* `boolean()` (`bool` , code: 250) +* `list()` (`list` , code: 251) +* `map()` (`map` , code: 252) +* `tuple()` (`tuple` , code: 253) +* `gmser_id:id()` (`id` , code: 254) +* `atom()` (`label` , code: 255) + +When encoding `map` types, the map elements are first sorted. + +When specifying a map type for template-driven encoding, use +the `#{items => [{Key, Value}]}` construct. + +Labels +---- + +Labels correspond to (existing) atoms in Erlang. +Decoding of a label results in a call to `binary_to_existing_atom/2`, so will +fail if the corresponding atom does not already exist. + +It's possible to cache labels for more compact encoding. +Note that when caching labels, the same cache mapping needs to be used on the +decoder side. + +Labels are encoded as `[<<255>>, << AtomToBinary/binary >>]`. +If a cached label is used, the encoding becomes `[<<255>, [Ix]]`, where +`Ix` is the integer-encoded index value of the cached label. + +Examples +---- + +Dynamically encoded objects have the basic structure `[<<0>>,V,Obj]`, where `V` is the +integer-coded version, and `Obj` is the top-level encoding on the form `[Tag,Data]`. + +```erlang +E = fun(T) -> io:fwrite("~w~n", [gmser_dyn:encode(T)]) end. + +E(17) -> [<<0>>,<<1>>,[<<248>>,<<17>>]] +E(<<"abc">>) -> [<<0>>,<<1>>,[<<249>>,<<97,98,99>>]] +E(true) -> [<<0>>,<<1>>,[<<250>>,<<1>>]] +E(false) -> [<<0>>,<<1>>,[<<250>>,<<0>>]] +E([1,2]) -> [<<0>>,<<1>>,[<<251>>,[[<<248>>,<<1>>],[<<248>>,<<2>>]]]] +E({1,2}) -> [<<0>>,<<1>>,[<<253>>,[[<<248>>,<<1>>],[<<248>>,<<2>>]]]] +E(#{a=>1, b=>2}) -> + [<<0>>,<<1>>,[<<252>>,[[[<<255>>,<<97>>],[<<248>>,<<1>>]],[[<<255>>,<<98>>],[<<248>>,<<2>>]]]]] +E(gmser_id:create(account,<<1:256>>)) -> + [<<0>>,<<1>>,[<<254>>,<<1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1>>]] +``` + +Note that tuples and list are encoded the same way, except for the initial type tag. +Maps are encoded as `[, [KV1, KV2, ...]]`, where `[KV1, KV2, ...]` is the sorted +list of key-value tuples from `map:to_list(Map)`, but with the `tuple` type tag omitted. + +Template-driven encoding +---- + +Templates can be provided to the encoder by either naming an already registered +type, or by passing a template directly. The template will then be enforced, and +used to slightly compress the encoding. + +In the following example, as the encoder knows that `{11,12}` is encoded as a +tuple of two integers, it can omit the inner type tags. + +```erlang +ET = fun(Type,Term) -> io:fwrite("~w~n", [gmser_dyn:encode_typed(Type,Term)]) end. + +ET({int,int}, {11,12}) ->[<<0>>,<<1>>,[<<253>>,[<<11>>,<<12>>]]] +ET({int,int}, {11,a}) -> +** exception error: {illegal,int,a} ... +``` diff --git a/src/gmser_dyn.erl b/src/gmser_dyn.erl index d241562..2a194ef 100644 --- a/src/gmser_dyn.erl +++ b/src/gmser_dyn.erl @@ -14,11 +14,17 @@ , deserialize/1 , deserialize/2 ]). +%% register a type schema, inspect existing schema -export([ register_types/1 , registered_types/0 + , types_from_list/1 , revert_to_default_types/0 , dynamic_types/0 ]). +%% Register individual types, or cache labels +-export([ register_type/3 + , cache_label/2 ]). + -import(gmserialization, [ decode_field/2 ]). -define(VSN, 1). @@ -88,7 +94,7 @@ dynamic_types() -> , 252 => map , 253 => tuple , 254 => id - , 255 => label } + , 255 => label} , rev => #{ int => 248 , binary => 249 @@ -98,6 +104,8 @@ dynamic_types() -> , tuple => 253 , id => 254 , label => 255} + , labels => #{} + , rev_labels => #{} , templates => #{ int => int , binary => binary @@ -113,66 +121,13 @@ dynamic_types() -> vsn(Types) -> maps:get(vsn, Types, ?VSN). -register_types(Types) when is_map(Types) -> - Codes = maps:get(codes, Types, #{}), - Rev = rev_codes(Codes), - Templates = maps:get(templates, Types, #{}), - #{codes := Codes0, rev := Rev0, templates := Templates0} = - dynamic_types(), - Merged = #{ codes => maps:merge(Codes0, Codes) - , rev => maps:merge(Rev0, Rev) - , templates => maps:merge(Templates0, Templates) }, - assert_sizes(Merged), - assert_mappings(Merged), - persistent_term:put({?MODULE, types}, Merged). - -revert_to_default_types() -> - persistent_term:put({?MODULE, types}, dynamic_types()). - -assert_sizes(#{codes := Codes, rev := Rev, templates := Ts} = Types) -> - assert_sizes(map_size(Codes), map_size(Rev), map_size(Ts), Types). - -assert_sizes(Sz, Sz, Sz, _) -> - ok; -assert_sizes(Sz, RSz, Sz, Types) when RSz =/= Sz -> - %% Wrong size reverse mapping must mean duplicate mappings - %% We auto-generate the reverse-mappings, so we know there aren't - %% too many of them - ?LOG_ERROR("Reverse mapping size doesn't match codes size", []), - Codes = maps:get(codes, Types), - CodeVals = maps:values(Codes), - Duplicates = CodeVals -- lists:usort(CodeVals), - error({duplicate_mappings, Duplicates, Types}); -assert_sizes(Sz, _, TSz, Types) when Sz > TSz -> - ?LOG_ERROR("More codes than templates", []), - Tags = maps:keys(maps:get(rev, Types)), - Templates = maps:get(templates, Types), - Missing = [T || T <- Tags, - not is_map_key(T, Templates)], - error({missing_mappings, Missing, Types}); -assert_sizes(Sz, _, TSz, Types) when TSz > Sz -> - %% More mappings than codes. May not be horrible. - %% We check that all codes have mappings elsewhere. - ?LOG_WARNING("More templates than codes in ~p", [Types]), - ok. - -assert_mappings(#{rev := Rev, templates := Ts} = Types) -> - Tags = maps:keys(Rev), - case [T || T <- Tags, - not is_map_key(T, Ts)] of - [] -> - ok; - Missing -> - ?LOG_ERROR("Missing templates for ~p", [Missing]), - error({missing_templates, Missing, Types}) - end. - -rev_codes(Codes) -> - L = maps:to_list(Codes), - maps:from_list([{V, K} || {K, V} <- L]). - registered_types() -> - persistent_term:get({?MODULE, types}, dynamic_types()). + case persistent_term:get({?MODULE, types}, undefined) of + undefined -> + dynamic_types(); + Types when is_map(Types) -> + Types + end. template(TagOrCode, Vsn, Types) -> {Tag, Template} = get_template(TagOrCode, Types), @@ -190,6 +145,9 @@ dyn_template_(F, Vsn) -> true -> F end. +find_cached_label(Lbl, #{labels := Lbls}) -> + maps:find(Lbl, Lbls). + decode_(Fields, Vsn, Types, Acc) -> {_Tag, Term, Rest} = decode_field_(Fields, Vsn, Types), Acc1 = [Term | Acc], @@ -228,7 +186,7 @@ encode_typed_(Code, Term, Vsn, #{codes := Codes} = Types) when is_map_key(Code, {_Tag, Template} = template(Code, Vsn, Types), [encode_basic(int, Code), encode_from_template(Template, Term, Vsn, Types)]; encode_typed_(Tag, Term, Vsn, #{templates := Ts} = Types) when is_map_key(Tag, Ts) -> - Template = maps:get(Tag, Ts), + Template = dyn_template_(maps:get(Tag, Ts), Vsn), [emit_code(Tag, Types), encode_from_template(Template, Term, Vsn, Types)]; encode_typed_(MaybeTemplate, Term, Vsn, Types) -> encode_maybe_template(MaybeTemplate, Term, Vsn, Types). @@ -286,6 +244,9 @@ decode_from_template(Type, V, Vsn, Types) when is_tuple(Type), is_list(V) -> Zipped = lists:zip(tuple_to_list(Type), V), Items = [decode_from_template(T1, V1, Vsn, Types) || {T1, V1} <- Zipped], list_to_tuple(Items); +decode_from_template(label, [C], _, #{rev_labels := RLbls}) -> + Code = decode_basic(int, C), + maps:get(Code, RLbls); decode_from_template(Type, Fld, _, _) when Type == int ; Type == binary ; Type == bool @@ -310,6 +271,13 @@ encode_from_template([Type], List, _, Vsn, Types) -> [encode_from_template(Type, V, false, Vsn, Types) || V <- List]; encode_from_template(Type, List, _, Vsn, Types) when is_list(Type), is_list(List) -> encode_fields(Type, List, Vsn, Types); +encode_from_template(label, V, _, _, Types) -> + case find_cached_label(V, Types) of + error -> + encode_basic(label, V); + {ok, Code} when is_integer(Code) -> + [encode_basic(int, Code)] + end; encode_from_template(Type, V, _, _, _Types) when Type == id ; Type == binary ; Type == bool @@ -365,6 +333,152 @@ rlp_decode(Bin) -> rlp_encode(Fields) -> gmser_rlp:encode(Fields). +%% =========================================================================== +%% Type registration and validation code + +register_types(Types) when is_map(Types) -> + Codes = maps:get(codes, Types, #{}), + Rev = rev_codes(Codes), + Templates = maps:get(templates, Types, #{}), + Labels = maps:get(labels, Types, #{}), + #{codes := Codes0, rev := Rev0, labels := Labels0, templates := Templates0} = + dynamic_types(), + Merged = #{ codes => maps:merge(Codes0, Codes) + , rev => maps:merge(Rev0, Rev) + , templates => maps:merge(Templates0, Templates) + , labels => maps:merge(Labels0, Labels) }, + assert_sizes(Merged), + assert_mappings(Merged), + Merged1 = assert_label_cache(Merged), + put_types(Merged1). + +put_types(Types) -> + persistent_term:put({?MODULE, types}, Types). + +types_from_list(L) -> + lists:foldl(fun elem_to_type/2, dynamic_types(), L). + +register_type(Code, Tag, Template) when is_integer(Code), Code >= 0 -> + #{codes := Codes, rev := Rev, templates := Temps} = Types = registered_types(), + case {is_map_key(Code, Codes), is_map_key(Tag, Rev)} of + {false, false} -> + New = Types#{ codes := Codes#{Code => Tag} + , rev := Rev#{Tag => Code} + , templates := Temps#{Tag => Template} }, + put_types(New), + New; + {true, _} -> error(code_exists); + {_, true} -> error(tag_exists) + end. + +cache_label(Code, Label) when is_integer(Code), Code >= 0, is_atom(Label) -> + #{labels := Lbls, rev_labels := RevLbls} = Types = registered_types(), + case {is_map_key(Label, Lbls), is_map_key(Code, RevLbls)} of + {false, false} -> + New = Types#{ labels := Lbls#{Label => Code} + , rev_labels := RevLbls#{Code => Label} }, + put_types(New), + New; + {true,_} -> error(label_exists); + {_,true} -> error(code_exists) + end. + +elem_to_type({Tag, Code, Template}, Acc) when is_atom(Tag), is_integer(Code) -> + #{codes := Codes, rev := Rev, templates := Temps} = Acc, + case {is_map_key(Tag, Rev), is_map_key(Code, Codes)} of + {false, false} -> + Acc#{ codes := Codes#{Code => Tag} + , rev := Rev#{Tag => Code} + , templates => Temps#{Tag => Template} + }; + {true, _} -> error({duplicate_tag, Tag}); + {_, true} -> error({duplicate_code, Code}) + end; +elem_to_type({labels, Lbls}, Acc) -> + lists:foldl(fun add_label/2, Acc, Lbls); +elem_to_type(Elem, _) -> + error({invalid_type_list_element, Elem}). + +add_label({L, Code}, #{labels := Lbls, rev_labels := RevLbls} = Acc) + when is_atom(L), is_integer(Code), Code > 0 -> + case {is_map_key(L, Lbls), is_map_key(Code, RevLbls)} of + {false, false} -> + Acc#{labels := Lbls#{L => Code}, + rev_labels := RevLbls#{Code => L}}; + {true, _} -> error({duplicate_label, L}); + {_, true} -> error({duplicate_label_code, Code}) + end; +add_label(Elem, _) -> + error({invalid_label_elem, Elem}). + + +revert_to_default_types() -> + persistent_term:put({?MODULE, types}, dynamic_types()). + +assert_sizes(#{codes := Codes, rev := Rev, templates := Ts} = Types) -> + assert_sizes(map_size(Codes), map_size(Rev), map_size(Ts), Types). + +assert_sizes(Sz, Sz, Sz, _) -> + ok; +assert_sizes(Sz, RSz, Sz, Types) when RSz =/= Sz -> + %% Wrong size reverse mapping must mean duplicate mappings + %% We auto-generate the reverse-mappings, so we know there aren't + %% too many of them + ?LOG_ERROR("Reverse mapping size doesn't match codes size", []), + Codes = maps:get(codes, Types), + CodeVals = maps:values(Codes), + Duplicates = CodeVals -- lists:usort(CodeVals), + error({duplicate_mappings, Duplicates, Types}); +assert_sizes(Sz, _, TSz, Types) when Sz > TSz -> + ?LOG_ERROR("More codes than templates", []), + Tags = maps:keys(maps:get(rev, Types)), + Templates = maps:get(templates, Types), + Missing = [T || T <- Tags, + not is_map_key(T, Templates)], + error({missing_mappings, Missing, Types}); +assert_sizes(Sz, _, TSz, Types) when TSz > Sz -> + %% More mappings than codes. May not be horrible. + %% We check that all codes have mappings elsewhere. + ?LOG_WARNING("More templates than codes in ~p", [Types]), + ok. + +assert_mappings(#{rev := Rev, templates := Ts} = Types) -> + Tags = maps:keys(Rev), + case [T || T <- Tags, + not is_map_key(T, Ts)] of + [] -> + ok; + Missing -> + ?LOG_ERROR("Missing templates for ~p", [Missing]), + error({missing_templates, Missing, Types}) + end. + +assert_label_cache(#{labels := Labels} = Types) -> + Ls = maps:keys(Labels), + case [L || L <- Ls, not is_atom(L)] of + [] -> ok; + _NonAtoms -> + error(non_atoms_in_label_cache) + end, + Rev = [{C,L} || {L,C} <- maps:to_list(Labels)], + case [C || {C,_} <- Rev, not is_integer(C)] of + [] -> ok; + _NonInts -> error(non_integer_label_cache_codes) + end, + RevLabels = maps:from_list(Rev), + case map_size(RevLabels) == map_size(Labels) of + true -> + Types#{rev_labels => RevLabels}; + false -> + error(non_unique_label_cache_codes) + end. + +rev_codes(Codes) -> + L = maps:to_list(Codes), + maps:from_list([{V, K} || {K, V} <- L]). + +%% =========================================================================== +%% Unit tests -ifdef(TEST). @@ -402,6 +516,10 @@ user_types_test_() -> end, [ ?_test(t_reg_typed_tuple()) , ?_test(t_reg_chain_objects_array()) + , ?_test(t_reg_template_fun()) + , ?_test(t_reg_template_vsnd_fun()) + , ?_test(t_reg_label_cache()) + , ?_test(t_reg_label_cache2()) ]}. t_round_trip(T) -> @@ -440,4 +558,56 @@ t_reg_chain_objects_array() -> Enc = encode_typed(coa, Values), Values = decode(Enc). +t_reg_template_fun() -> + Template = fun() -> {int,int} end, + New = register_type(1010, tup2f0, Template), + ?debugFmt("New = ~p", [New]), + E = encode_typed(tup2f0, {3,4}), + {3,4} = decode(E), + ok. + +t_reg_template_vsnd_fun() -> + Template = fun(1) -> {int,int} end, + New = register_type(1011, tup2f1, Template), + ?debugFmt("New = ~p", [New]), + E = encode_typed(tup2f1, {3,4}), + {3,4} = decode(E), + ok. + + +t_reg_label_cache() -> + Enc0 = gmser_dyn:encode('1'), + ?debugFmt("Enc0 (no cache): ~w", [Enc0]), + MyTypes1 = #{codes => #{1003 => lbl_tup2}, templates => #{ lbl_tup2 => {label,label} }}, + register_types(MyTypes1), + Enc0a = gmser_dyn:encode_typed(lbl_tup2, {'1','1'}), + ?debugFmt("Enc0a (no cache): ~w", [Enc0a]), + {'1','1'} = gmser_dyn:decode(Enc0a), + MyTypes2 = MyTypes1#{labels => #{'1' => 49}}, % atom_to_list('1') == [49] + register_types(MyTypes2), + Enc1 = gmser_dyn:encode('1'), + Enc1a = gmser_dyn:encode_typed(lbl_tup2, {'1','1'}), + ?debugFmt("Enc1 (w/ cache): ~w", [Enc1]), + ?debugFmt("Enc1a (w/ cache): ~w", [Enc1a]), + {'1','1'} = gmser_dyn:decode(Enc1a), + true = Enc0 =/= Enc1, + Enc2 = gmser_dyn:encode_typed(label, '1'), + ?debugFmt("Enc2 (typed): ~w", [Enc2]), + true = Enc2 == Enc1, + true = Enc0a =/= Enc1a. + +t_reg_label_cache2() -> + TFromL = gmser_dyn:types_from_list( + [ {lbl_tup2, 1003, {label, label}} + , {labels, + [{'1', 49}]} + ]), + ?debugFmt("TFromL = ~w", [TFromL]), + register_types(TFromL), + Tup = {'1', '1'}, + Enc = gmser_dyn:encode_typed(lbl_tup2, Tup), + [<<0>>,<<1>>,[<<3,235>>,[[<<49>>],[<<49>>]]]] = Enc, + Tup = gmser_dyn:decode(Enc). + + -endif.