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-% Licensed under the Apache License, Version 2.0 (the "License");
-% you may not use this file except in compliance with the License.
-%
-% You may obtain a copy of the License at
-% http://www.apache.org/licenses/LICENSE-2.0
-%
-% Unless required by applicable law or agreed to in writing,
-% software distributed under the License is distributed on an
-% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
-% either express or implied.
-%
-% See the License for the specific language governing permissions
-% and limitations under the License.
-%
-% This file drew much inspiration from erlview, which was written by and
-% copyright Michael McDaniel [http://autosys.us], and is also under APL 2.0
-%
-%
-% This module provides the smallest possible native view-server.
-% With this module in-place, you can add the following to your couch INI files:
-% [native_query_servers]
-% erlang={couch_native_process, start_link, []}
-%
-% Which will then allow following example map function to be used:
-%
-% fun({Doc}) ->
-% % Below, we emit a single record - the _id as key, null as value
-% DocId = couch_util:get_value(Doc, <<"_id">>, null),
-% Emit(DocId, null)
-% end.
-%
-% which should be roughly the same as the javascript:
-% emit(doc._id, null);
-%
-% This module exposes enough functions such that a native erlang server can
-% act as a fully-fleged view server, but no 'helper' functions specifically
-% for simplifying your erlang view code. It is expected other third-party
-% extensions will evolve which offer useful layers on top of this view server
-% to help simplify your view code.
--module(couch_native_process).
--behaviour(gen_server).
-
--export([start_link/0,init/1,terminate/2,handle_call/3,handle_cast/2,code_change/3,
- handle_info/2]).
--export([set_timeout/2, prompt/2]).
-
--define(STATE, native_proc_state).
--record(evstate, {ddocs, funs=[], query_config=[], list_pid=nil, timeout=5000}).
-
--include("couch_db.hrl").
-
-start_link() ->
- gen_server:start_link(?MODULE, [], []).
-
-% this is a bit messy, see also couch_query_servers handle_info
-% stop(_Pid) ->
-% ok.
-
-set_timeout(Pid, TimeOut) ->
- gen_server:call(Pid, {set_timeout, TimeOut}).
-
-prompt(Pid, Data) when is_list(Data) ->
- gen_server:call(Pid, {prompt, Data}).
-
-% gen_server callbacks
-init([]) ->
- {ok, #evstate{ddocs=dict:new()}}.
-
-handle_call({set_timeout, TimeOut}, _From, State) ->
- {reply, ok, State#evstate{timeout=TimeOut}};
-
-handle_call({prompt, Data}, _From, State) ->
- ?LOG_DEBUG("Prompt native qs: ~s",[?JSON_ENCODE(Data)]),
- {NewState, Resp} = try run(State, to_binary(Data)) of
- {S, R} -> {S, R}
- catch
- throw:{error, Why} ->
- {State, [<<"error">>, Why, Why]}
- end,
-
- case Resp of
- {error, Reason} ->
- Msg = io_lib:format("couch native server error: ~p", [Reason]),
- {reply, [<<"error">>, <<"native_query_server">>, list_to_binary(Msg)], NewState};
- [<<"error">> | Rest] ->
- % Msg = io_lib:format("couch native server error: ~p", [Rest]),
- % TODO: markh? (jan)
- {reply, [<<"error">> | Rest], NewState};
- [<<"fatal">> | Rest] ->
- % Msg = io_lib:format("couch native server error: ~p", [Rest]),
- % TODO: markh? (jan)
- {stop, fatal, [<<"error">> | Rest], NewState};
- Resp ->
- {reply, Resp, NewState}
- end.
-
-handle_cast(foo, State) -> {noreply, State}.
-handle_info({'EXIT',_,normal}, State) -> {noreply, State};
-handle_info({'EXIT',_,Reason}, State) ->
- {stop, Reason, State}.
-terminate(_Reason, _State) -> ok.
-code_change(_OldVersion, State, _Extra) -> {ok, State}.
-
-run(#evstate{list_pid=Pid}=State, [<<"list_row">>, Row]) when is_pid(Pid) ->
- Pid ! {self(), list_row, Row},
- receive
- {Pid, chunks, Data} ->
- {State, [<<"chunks">>, Data]};
- {Pid, list_end, Data} ->
- receive
- {'EXIT', Pid, normal} -> ok
- after State#evstate.timeout ->
- throw({timeout, list_cleanup})
- end,
- process_flag(trap_exit, erlang:get(do_trap)),
- {State#evstate{list_pid=nil}, [<<"end">>, Data]}
- after State#evstate.timeout ->
- throw({timeout, list_row})
- end;
-run(#evstate{list_pid=Pid}=State, [<<"list_end">>]) when is_pid(Pid) ->
- Pid ! {self(), list_end},
- Resp =
- receive
- {Pid, list_end, Data} ->
- receive
- {'EXIT', Pid, normal} -> ok
- after State#evstate.timeout ->
- throw({timeout, list_cleanup})
- end,
- [<<"end">>, Data]
- after State#evstate.timeout ->
- throw({timeout, list_end})
- end,
- process_flag(trap_exit, erlang:get(do_trap)),
- {State#evstate{list_pid=nil}, Resp};
-run(#evstate{list_pid=Pid}=State, _Command) when is_pid(Pid) ->
- {State, [<<"error">>, list_error, list_error]};
-run(#evstate{ddocs=DDocs}, [<<"reset">>]) ->
- {#evstate{ddocs=DDocs}, true};
-run(#evstate{ddocs=DDocs}, [<<"reset">>, QueryConfig]) ->
- {#evstate{ddocs=DDocs, query_config=QueryConfig}, true};
-run(#evstate{funs=Funs}=State, [<<"add_fun">> , BinFunc]) ->
- FunInfo = makefun(State, BinFunc),
- {State#evstate{funs=Funs ++ [FunInfo]}, true};
-run(State, [<<"map_doc">> , Doc]) ->
- Resp = lists:map(fun({Sig, Fun}) ->
- erlang:put(Sig, []),
- Fun(Doc),
- lists:reverse(erlang:get(Sig))
- end, State#evstate.funs),
- {State, Resp};
-run(State, [<<"reduce">>, Funs, KVs]) ->
- {Keys, Vals} =
- lists:foldl(fun([K, V], {KAcc, VAcc}) ->
- {[K | KAcc], [V | VAcc]}
- end, {[], []}, KVs),
- Keys2 = lists:reverse(Keys),
- Vals2 = lists:reverse(Vals),
- {State, catch reduce(State, Funs, Keys2, Vals2, false)};
-run(State, [<<"rereduce">>, Funs, Vals]) ->
- {State, catch reduce(State, Funs, null, Vals, true)};
-run(#evstate{ddocs=DDocs}=State, [<<"ddoc">>, <<"new">>, DDocId, DDoc]) ->
- DDocs2 = store_ddoc(DDocs, DDocId, DDoc),
- {State#evstate{ddocs=DDocs2}, true};
-run(#evstate{ddocs=DDocs}=State, [<<"ddoc">>, DDocId | Rest]) ->
- DDoc = load_ddoc(DDocs, DDocId),
- ddoc(State, DDoc, Rest);
-run(_, Unknown) ->
- ?LOG_ERROR("Native Process: Unknown command: ~p~n", [Unknown]),
- throw({error, unknown_command}).
-
-ddoc(State, {DDoc}, [FunPath, Args]) ->
- % load fun from the FunPath
- BFun = lists:foldl(fun
- (Key, {Props}) when is_list(Props) ->
- couch_util:get_value(Key, Props, nil);
- (_Key, Fun) when is_binary(Fun) ->
- Fun;
- (_Key, nil) ->
- throw({error, not_found});
- (_Key, _Fun) ->
- throw({error, malformed_ddoc})
- end, {DDoc}, FunPath),
- ddoc(State, makefun(State, BFun, {DDoc}), FunPath, Args).
-
-ddoc(State, {_, Fun}, [<<"validate_doc_update">>], Args) ->
- {State, (catch apply(Fun, Args))};
-ddoc(State, {_, Fun}, [<<"filters">>|_], [Docs, Req]) ->
- Resp = lists:map(fun(Doc) -> (catch Fun(Doc, Req)) =:= true end, Docs),
- {State, [true, Resp]};
-ddoc(State, {_, Fun}, [<<"shows">>|_], Args) ->
- Resp = case (catch apply(Fun, Args)) of
- FunResp when is_list(FunResp) ->
- FunResp;
- {FunResp} ->
- [<<"resp">>, {FunResp}];
- FunResp ->
- FunResp
- end,
- {State, Resp};
-ddoc(State, {_, Fun}, [<<"updates">>|_], Args) ->
- Resp = case (catch apply(Fun, Args)) of
- [JsonDoc, JsonResp] ->
- [<<"up">>, JsonDoc, JsonResp]
- end,
- {State, Resp};
-ddoc(State, {Sig, Fun}, [<<"lists">>|_], Args) ->
- Self = self(),
- SpawnFun = fun() ->
- LastChunk = (catch apply(Fun, Args)),
- case start_list_resp(Self, Sig) of
- started ->
- receive
- {Self, list_row, _Row} -> ignore;
- {Self, list_end} -> ignore
- after State#evstate.timeout ->
- throw({timeout, list_cleanup_pid})
- end;
- _ ->
- ok
- end,
- LastChunks =
- case erlang:get(Sig) of
- undefined -> [LastChunk];
- OtherChunks -> [LastChunk | OtherChunks]
- end,
- Self ! {self(), list_end, lists:reverse(LastChunks)}
- end,
- erlang:put(do_trap, process_flag(trap_exit, true)),
- Pid = spawn_link(SpawnFun),
- Resp =
- receive
- {Pid, start, Chunks, JsonResp} ->
- [<<"start">>, Chunks, JsonResp]
- after State#evstate.timeout ->
- throw({timeout, list_start})
- end,
- {State#evstate{list_pid=Pid}, Resp}.
-
-store_ddoc(DDocs, DDocId, DDoc) ->
- dict:store(DDocId, DDoc, DDocs).
-load_ddoc(DDocs, DDocId) ->
- try dict:fetch(DDocId, DDocs) of
- {DDoc} -> {DDoc}
- catch
- _:_Else -> throw({error, ?l2b(io_lib:format("Native Query Server missing DDoc with Id: ~s",[DDocId]))})
- end.
-
-bindings(State, Sig) ->
- bindings(State, Sig, nil).
-bindings(State, Sig, DDoc) ->
- Self = self(),
-
- Log = fun(Msg) ->
- ?LOG_INFO(Msg, [])
- end,
-
- Emit = fun(Id, Value) ->
- Curr = erlang:get(Sig),
- erlang:put(Sig, [[Id, Value] | Curr])
- end,
-
- Start = fun(Headers) ->
- erlang:put(list_headers, Headers)
- end,
-
- Send = fun(Chunk) ->
- Curr =
- case erlang:get(Sig) of
- undefined -> [];
- Else -> Else
- end,
- erlang:put(Sig, [Chunk | Curr])
- end,
-
- GetRow = fun() ->
- case start_list_resp(Self, Sig) of
- started ->
- ok;
- _ ->
- Chunks =
- case erlang:get(Sig) of
- undefined -> [];
- CurrChunks -> CurrChunks
- end,
- Self ! {self(), chunks, lists:reverse(Chunks)}
- end,
- erlang:put(Sig, []),
- receive
- {Self, list_row, Row} -> Row;
- {Self, list_end} -> nil
- after State#evstate.timeout ->
- throw({timeout, list_pid_getrow})
- end
- end,
-
- FoldRows = fun(Fun, Acc) -> foldrows(GetRow, Fun, Acc) end,
-
- Bindings = [
- {'Log', Log},
- {'Emit', Emit},
- {'Start', Start},
- {'Send', Send},
- {'GetRow', GetRow},
- {'FoldRows', FoldRows}
- ],
- case DDoc of
- {_Props} ->
- Bindings ++ [{'DDoc', DDoc}];
- _Else -> Bindings
- end.
-
-% thanks to erlview, via:
-% http://erlang.org/pipermail/erlang-questions/2003-November/010544.html
-makefun(State, Source) ->
- Sig = couch_util:md5(Source),
- BindFuns = bindings(State, Sig),
- {Sig, makefun(State, Source, BindFuns)}.
-makefun(State, Source, {DDoc}) ->
- Sig = couch_util:md5(lists:flatten([Source, term_to_binary(DDoc)])),
- BindFuns = bindings(State, Sig, {DDoc}),
- {Sig, makefun(State, Source, BindFuns)};
-makefun(_State, Source, BindFuns) when is_list(BindFuns) ->
- FunStr = binary_to_list(Source),
- {ok, Tokens, _} = erl_scan:string(FunStr),
- Form = case (catch erl_parse:parse_exprs(Tokens)) of
- {ok, [ParsedForm]} ->
- ParsedForm;
- {error, {LineNum, _Mod, [Mesg, Params]}}=Error ->
- io:format(standard_error, "Syntax error on line: ~p~n", [LineNum]),
- io:format(standard_error, "~s~p~n", [Mesg, Params]),
- throw(Error)
- end,
- Bindings = lists:foldl(fun({Name, Fun}, Acc) ->
- erl_eval:add_binding(Name, Fun, Acc)
- end, erl_eval:new_bindings(), BindFuns),
- {value, Fun, _} = erl_eval:expr(Form, Bindings),
- Fun.
-
-reduce(State, BinFuns, Keys, Vals, ReReduce) ->
- Funs = case is_list(BinFuns) of
- true ->
- lists:map(fun(BF) -> makefun(State, BF) end, BinFuns);
- _ ->
- [makefun(State, BinFuns)]
- end,
- Reds = lists:map(fun({_Sig, Fun}) ->
- Fun(Keys, Vals, ReReduce)
- end, Funs),
- [true, Reds].
-
-foldrows(GetRow, ProcRow, Acc) ->
- case GetRow() of
- nil ->
- {ok, Acc};
- Row ->
- case (catch ProcRow(Row, Acc)) of
- {ok, Acc2} ->
- foldrows(GetRow, ProcRow, Acc2);
- {stop, Acc2} ->
- {ok, Acc2}
- end
- end.
-
-start_list_resp(Self, Sig) ->
- case erlang:get(list_started) of
- undefined ->
- Headers =
- case erlang:get(list_headers) of
- undefined -> {[{<<"headers">>, {[]}}]};
- CurrHdrs -> CurrHdrs
- end,
- Chunks =
- case erlang:get(Sig) of
- undefined -> [];
- CurrChunks -> CurrChunks
- end,
- Self ! {self(), start, lists:reverse(Chunks), Headers},
- erlang:put(list_started, true),
- erlang:put(Sig, []),
- started;
- _ ->
- ok
- end.
-
-to_binary({Data}) ->
- Pred = fun({Key, Value}) ->
- {to_binary(Key), to_binary(Value)}
- end,
- {lists:map(Pred, Data)};
-to_binary(Data) when is_list(Data) ->
- [to_binary(D) || D <- Data];
-to_binary(null) ->
- null;
-to_binary(true) ->
- true;
-to_binary(false) ->
- false;
-to_binary(Data) when is_atom(Data) ->
- list_to_binary(atom_to_list(Data));
-to_binary(Data) ->
- Data.