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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.
-module(couch_query_servers).
-behaviour(gen_server).
-export([start_link/0]).
-export([init/1, terminate/2, handle_call/3, handle_cast/2, handle_info/2,code_change/3]).
-export([start_doc_map/2, map_docs/2, stop_doc_map/1]).
-export([reduce/3, rereduce/3,validate_doc_update/5]).
-export([filter_docs/5]).
-export([with_ddoc_proc/2, proc_prompt/2, ddoc_prompt/3, ddoc_proc_prompt/3, json_doc/1]).
% -export([test/0]).
-include("couch_db.hrl").
-record(proc, {
pid,
lang,
ddoc_keys = [],
prompt_fun,
set_timeout_fun,
stop_fun
}).
start_link() ->
gen_server:start_link({local, couch_query_servers}, couch_query_servers, [], []).
start_doc_map(Lang, Functions) ->
Proc = get_os_process(Lang),
lists:foreach(fun(FunctionSource) ->
true = proc_prompt(Proc, [<<"add_fun">>, FunctionSource])
end, Functions),
{ok, Proc}.
map_docs(Proc, Docs) ->
% send the documents
Results = lists:map(
fun(Doc) ->
Json = couch_doc:to_json_obj(Doc, []),
FunsResults = proc_prompt(Proc, [<<"map_doc">>, Json]),
% the results are a json array of function map yields like this:
% [FunResults1, FunResults2 ...]
% where funresults is are json arrays of key value pairs:
% [[Key1, Value1], [Key2, Value2]]
% Convert the key, value pairs to tuples like
% [{Key1, Value1}, {Key2, Value2}]
lists:map(
fun(FunRs) ->
[list_to_tuple(FunResult) || FunResult <- FunRs]
end,
FunsResults)
end,
Docs),
{ok, Results}.
stop_doc_map(nil) ->
ok;
stop_doc_map(Proc) ->
ok = ret_os_process(Proc).
group_reductions_results([]) ->
[];
group_reductions_results(List) ->
{Heads, Tails} = lists:foldl(
fun([H|T], {HAcc,TAcc}) ->
{[H|HAcc], [T|TAcc]}
end, {[], []}, List),
case Tails of
[[]|_] -> % no tails left
[Heads];
_ ->
[Heads | group_reductions_results(Tails)]
end.
rereduce(_Lang, [], _ReducedValues) ->
{ok, []};
rereduce(Lang, RedSrcs, ReducedValues) ->
Grouped = group_reductions_results(ReducedValues),
Results = lists:zipwith(
fun
(<<"_", _/binary>> = FunSrc, Values) ->
{ok, [Result]} = builtin_reduce(rereduce, [FunSrc], [[[], V] || V <- Values], []),
Result;
(FunSrc, Values) ->
os_rereduce(Lang, [FunSrc], Values)
end, RedSrcs, Grouped),
{ok, Results}.
reduce(_Lang, [], _KVs) ->
{ok, []};
reduce(Lang, RedSrcs, KVs) ->
{OsRedSrcs, BuiltinReds} = lists:partition(fun
(<<"_", _/binary>>) -> false;
(_OsFun) -> true
end, RedSrcs),
{ok, OsResults} = os_reduce(Lang, OsRedSrcs, KVs),
{ok, BuiltinResults} = builtin_reduce(reduce, BuiltinReds, KVs, []),
recombine_reduce_results(RedSrcs, OsResults, BuiltinResults, []).
recombine_reduce_results([], [], [], Acc) ->
{ok, lists:reverse(Acc)};
recombine_reduce_results([<<"_", _/binary>>|RedSrcs], OsResults, [BRes|BuiltinResults], Acc) ->
recombine_reduce_results(RedSrcs, OsResults, BuiltinResults, [BRes|Acc]);
recombine_reduce_results([_OsFun|RedSrcs], [OsR|OsResults], BuiltinResults, Acc) ->
recombine_reduce_results(RedSrcs, OsResults, BuiltinResults, [OsR|Acc]).
os_reduce(_Lang, [], _KVs) ->
{ok, []};
os_reduce(Lang, OsRedSrcs, KVs) ->
Proc = get_os_process(Lang),
OsResults = try proc_prompt(Proc, [<<"reduce">>, OsRedSrcs, KVs]) of
[true, Reductions] -> Reductions
after
ok = ret_os_process(Proc)
end,
{ok, OsResults}.
os_rereduce(_Lang, [], _KVs) ->
{ok, []};
os_rereduce(Lang, OsRedSrcs, KVs) ->
Proc = get_os_process(Lang),
try proc_prompt(Proc, [<<"rereduce">>, OsRedSrcs, KVs]) of
[true, [Reduction]] -> Reduction
after
ok = ret_os_process(Proc)
end.
builtin_reduce(_Re, [], _KVs, Acc) ->
{ok, lists:reverse(Acc)};
builtin_reduce(Re, [<<"_sum">>|BuiltinReds], KVs, Acc) ->
Sum = builtin_sum_rows(KVs),
builtin_reduce(Re, BuiltinReds, KVs, [Sum|Acc]);
builtin_reduce(reduce, [<<"_count">>|BuiltinReds], KVs, Acc) ->
Count = length(KVs),
builtin_reduce(reduce, BuiltinReds, KVs, [Count|Acc]);
builtin_reduce(rereduce, [<<"_count">>|BuiltinReds], KVs, Acc) ->
Count = builtin_sum_rows(KVs),
builtin_reduce(rereduce, BuiltinReds, KVs, [Count|Acc]);
builtin_reduce(Re, [<<"_stats">>|BuiltinReds], KVs, Acc) ->
Stats = builtin_stats(Re, KVs),
builtin_reduce(Re, BuiltinReds, KVs, [Stats|Acc]).
builtin_sum_rows(KVs) ->
lists:foldl(fun
([_Key, Value], Acc) when is_number(Value) ->
Acc + Value;
(_Else, _Acc) ->
throw({invalid_value, <<"builtin _sum function requires map values to be numbers">>})
end, 0, KVs).
builtin_stats(reduce, [[_,First]|Rest]) when is_number(First) ->
Stats = lists:foldl(fun([_K,V], {S,C,Mi,Ma,Sq}) when is_number(V) ->
{S+V, C+1, erlang:min(Mi,V), erlang:max(Ma,V), Sq+(V*V)};
(_, _) ->
throw({invalid_value,
<<"builtin _stats function requires map values to be numbers">>})
end, {First,1,First,First,First*First}, Rest),
{Sum, Cnt, Min, Max, Sqr} = Stats,
{[{sum,Sum}, {count,Cnt}, {min,Min}, {max,Max}, {sumsqr,Sqr}]};
builtin_stats(rereduce, [[_,First]|Rest]) ->
{[{sum,Sum0}, {count,Cnt0}, {min,Min0}, {max,Max0}, {sumsqr,Sqr0}]} = First,
Stats = lists:foldl(fun([_K,Red], {S,C,Mi,Ma,Sq}) ->
{[{sum,Sum}, {count,Cnt}, {min,Min}, {max,Max}, {sumsqr,Sqr}]} = Red,
{Sum+S, Cnt+C, erlang:min(Min,Mi), erlang:max(Max,Ma), Sqr+Sq}
end, {Sum0,Cnt0,Min0,Max0,Sqr0}, Rest),
{Sum, Cnt, Min, Max, Sqr} = Stats,
{[{sum,Sum}, {count,Cnt}, {min,Min}, {max,Max}, {sumsqr,Sqr}]}.
% use the function stored in ddoc.validate_doc_update to test an update.
validate_doc_update(DDoc, EditDoc, DiskDoc, Ctx, SecObj) ->
JsonEditDoc = couch_doc:to_json_obj(EditDoc, [revs]),
JsonDiskDoc = json_doc(DiskDoc),
case ddoc_prompt(DDoc, [<<"validate_doc_update">>], [JsonEditDoc, JsonDiskDoc, Ctx, SecObj]) of
1 ->
ok;
{[{<<"forbidden">>, Message}]} ->
throw({forbidden, Message});
{[{<<"unauthorized">>, Message}]} ->
throw({unauthorized, Message})
end.
json_doc(nil) -> null;
json_doc(Doc) ->
couch_doc:to_json_obj(Doc, [revs]).
filter_docs(Req, Db, DDoc, FName, Docs) ->
JsonReq = case Req of
{json_req, JsonObj} ->
JsonObj;
#httpd{} = HttpReq ->
couch_httpd_external:json_req_obj(HttpReq, Db)
end,
JsonDocs = [couch_doc:to_json_obj(Doc, [revs]) || Doc <- Docs],
[true, Passes] = ddoc_prompt(DDoc, [<<"filters">>, FName], [JsonDocs, JsonReq]),
{ok, Passes}.
ddoc_proc_prompt({Proc, DDocId}, FunPath, Args) ->
proc_prompt(Proc, [<<"ddoc">>, DDocId, FunPath, Args]).
ddoc_prompt(DDoc, FunPath, Args) ->
with_ddoc_proc(DDoc, fun({Proc, DDocId}) ->
proc_prompt(Proc, [<<"ddoc">>, DDocId, FunPath, Args])
end).
with_ddoc_proc(#doc{id=DDocId,revs={Start, [DiskRev|_]}}=DDoc, Fun) ->
Rev = couch_doc:rev_to_str({Start, DiskRev}),
DDocKey = {DDocId, Rev},
Proc = get_ddoc_process(DDoc, DDocKey),
try Fun({Proc, DDocId})
after
ok = ret_os_process(Proc)
end.
init([]) ->
% read config and register for configuration changes
% just stop if one of the config settings change. couch_server_sup
% will restart us and then we will pick up the new settings.
ok = couch_config:register(
fun("query_servers" ++ _, _) ->
supervisor:terminate_child(couch_secondary_services, query_servers),
supervisor:restart_child(couch_secondary_services, query_servers)
end),
ok = couch_config:register(
fun("native_query_servers" ++ _, _) ->
supervisor:terminate_child(couch_secondary_services, query_servers),
[supervisor:restart_child(couch_secondary_services, query_servers)]
end),
Langs = ets:new(couch_query_server_langs, [set, private]),
PidProcs = ets:new(couch_query_server_pid_langs, [set, private]),
LangProcs = ets:new(couch_query_server_procs, [set, private]),
% 'query_servers' specifies an OS command-line to execute.
lists:foreach(fun({Lang, Command}) ->
true = ets:insert(Langs, {?l2b(Lang),
couch_os_process, start_link, [Command]})
end, couch_config:get("query_servers")),
% 'native_query_servers' specifies a {Module, Func, Arg} tuple.
lists:foreach(fun({Lang, SpecStr}) ->
{ok, {Mod, Fun, SpecArg}} = couch_util:parse_term(SpecStr),
true = ets:insert(Langs, {?l2b(Lang),
Mod, Fun, SpecArg})
end, couch_config:get("native_query_servers")),
process_flag(trap_exit, true),
{ok, {Langs, % Keyed by language name, value is {Mod,Func,Arg}
PidProcs, % Keyed by PID, valus is a #proc record.
LangProcs % Keyed by language name, value is a #proc record
}}.
terminate(_Reason, {_Langs, PidProcs, _LangProcs}) ->
[couch_util:shutdown_sync(P) || {P,_} <- ets:tab2list(PidProcs)],
ok.
handle_call({get_proc, #doc{body={Props}}=DDoc, DDocKey}, _From, {Langs, PidProcs, LangProcs}=Server) ->
% Note to future self. Add max process limit.
Lang = proplists:get_value(<<"language">>, Props, <<"javascript">>),
case ets:lookup(LangProcs, Lang) of
[{Lang, [P|Rest]}] ->
% find a proc in the set that has the DDoc
case proc_with_ddoc(DDoc, DDocKey, [P|Rest]) of
{ok, Proc} ->
rem_from_list(LangProcs, Lang, Proc),
{reply, {ok, Proc, get_query_server_config()}, Server};
Error ->
{reply, Error, Server}
end;
_ ->
case (catch new_process(Langs, Lang)) of
{ok, Proc} ->
add_value(PidProcs, Proc#proc.pid, Proc),
case proc_with_ddoc(DDoc, DDocKey, [Proc]) of
{ok, Proc2} ->
{reply, {ok, Proc2, get_query_server_config()}, Server};
Error ->
{reply, Error, Server}
end;
Error ->
{reply, Error, Server}
end
end;
handle_call({get_proc, Lang}, _From, {Langs, PidProcs, LangProcs}=Server) ->
% Note to future self. Add max process limit.
case ets:lookup(LangProcs, Lang) of
[{Lang, [Proc|_]}] ->
rem_from_list(LangProcs, Lang, Proc),
{reply, {ok, Proc, get_query_server_config()}, Server};
_ ->
case (catch new_process(Langs, Lang)) of
{ok, Proc} ->
add_value(PidProcs, Proc#proc.pid, Proc),
{reply, {ok, Proc, get_query_server_config()}, Server};
Error ->
{reply, Error, Server}
end
end;
handle_call({unlink_proc, Pid}, _From, {_, PidProcs, _}=Server) ->
rem_value(PidProcs, Pid),
unlink(Pid),
{reply, ok, Server};
handle_call({ret_proc, Proc}, _From, {_, PidProcs, LangProcs}=Server) ->
% Along with max process limit, here we should check
% if we're over the limit and discard when we are.
add_value(PidProcs, Proc#proc.pid, Proc),
add_to_list(LangProcs, Proc#proc.lang, Proc),
link(Proc#proc.pid),
{reply, true, Server}.
handle_cast(_Whatever, Server) ->
{noreply, Server}.
handle_info({'EXIT', Pid, Status}, {_, PidProcs, LangProcs}=Server) ->
case ets:lookup(PidProcs, Pid) of
[{Pid, Proc}] ->
case Status of
normal -> ok;
_ -> ?LOG_DEBUG("Linked process died abnormally: ~p (reason: ~p)", [Pid, Status])
end,
rem_value(PidProcs, Pid),
catch rem_from_list(LangProcs, Proc#proc.lang, Proc),
{noreply, Server};
[] ->
case Status of
normal ->
{noreply, Server};
_ ->
{stop, Status, Server}
end
end.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
% Private API
get_query_server_config() ->
ReduceLimit = list_to_atom(
couch_config:get("query_server_config","reduce_limit","true")),
{[{<<"reduce_limit">>, ReduceLimit}]}.
new_process(Langs, Lang) ->
case ets:lookup(Langs, Lang) of
[{Lang, Mod, Func, Arg}] ->
{ok, Pid} = apply(Mod, Func, Arg),
{ok, #proc{lang=Lang,
pid=Pid,
% Called via proc_prompt, proc_set_timeout, and proc_stop
prompt_fun={Mod, prompt},
set_timeout_fun={Mod, set_timeout},
stop_fun={Mod, stop}}};
_ ->
{unknown_query_language, Lang}
end.
proc_with_ddoc(DDoc, DDocKey, LangProcs) ->
DDocProcs = lists:filter(fun(#proc{ddoc_keys=Keys}) ->
lists:any(fun(Key) ->
Key == DDocKey
end, Keys)
end, LangProcs),
case DDocProcs of
[DDocProc|_] ->
?LOG_DEBUG("DDocProc found for DDocKey: ~p",[DDocKey]),
{ok, DDocProc};
[] ->
[TeachProc|_] = LangProcs,
?LOG_DEBUG("Teach ddoc to new proc ~p with DDocKey: ~p",[TeachProc, DDocKey]),
{ok, SmartProc} = teach_ddoc(DDoc, DDocKey, TeachProc),
{ok, SmartProc}
end.
proc_prompt(Proc, Args) ->
{Mod, Func} = Proc#proc.prompt_fun,
apply(Mod, Func, [Proc#proc.pid, Args]).
proc_stop(Proc) ->
{Mod, Func} = Proc#proc.stop_fun,
apply(Mod, Func, [Proc#proc.pid]).
proc_set_timeout(Proc, Timeout) ->
{Mod, Func} = Proc#proc.set_timeout_fun,
apply(Mod, Func, [Proc#proc.pid, Timeout]).
teach_ddoc(DDoc, {DDocId, _Rev}=DDocKey, #proc{ddoc_keys=Keys}=Proc) ->
% send ddoc over the wire
% we only share the rev with the client we know to update code
% but it only keeps the latest copy, per each ddoc, around.
true = proc_prompt(Proc, [<<"ddoc">>, <<"new">>, DDocId, couch_doc:to_json_obj(DDoc, [])]),
% we should remove any other ddocs keys for this docid
% because the query server overwrites without the rev
Keys2 = [{D,R} || {D,R} <- Keys, D /= DDocId],
% add ddoc to the proc
{ok, Proc#proc{ddoc_keys=[DDocKey|Keys2]}}.
get_ddoc_process(#doc{} = DDoc, DDocKey) ->
% remove this case statement
case gen_server:call(couch_query_servers, {get_proc, DDoc, DDocKey}) of
{ok, Proc, QueryConfig} ->
% process knows the ddoc
case (catch proc_prompt(Proc, [<<"reset">>, QueryConfig])) of
true ->
proc_set_timeout(Proc, list_to_integer(couch_config:get(
"couchdb", "os_process_timeout", "5000"))),
link(Proc#proc.pid),
gen_server:call(couch_query_servers, {unlink_proc, Proc#proc.pid}),
Proc;
_ ->
catch proc_stop(Proc),
get_ddoc_process(DDoc, DDocKey)
end;
Error ->
throw(Error)
end.
get_os_process(Lang) ->
case gen_server:call(couch_query_servers, {get_proc, Lang}) of
{ok, Proc, QueryConfig} ->
case (catch proc_prompt(Proc, [<<"reset">>, QueryConfig])) of
true ->
proc_set_timeout(Proc, list_to_integer(couch_config:get(
"couchdb", "os_process_timeout", "5000"))),
link(Proc#proc.pid),
gen_server:call(couch_query_servers, {unlink_proc, Proc#proc.pid}),
Proc;
_ ->
catch proc_stop(Proc),
get_os_process(Lang)
end;
Error ->
throw(Error)
end.
ret_os_process(Proc) ->
true = gen_server:call(couch_query_servers, {ret_proc, Proc}),
catch unlink(Proc#proc.pid),
ok.
add_value(Tid, Key, Value) ->
true = ets:insert(Tid, {Key, Value}).
rem_value(Tid, Key) ->
true = ets:delete(Tid, Key).
add_to_list(Tid, Key, Value) ->
case ets:lookup(Tid, Key) of
[{Key, Vals}] ->
true = ets:insert(Tid, {Key, [Value|Vals]});
[] ->
true = ets:insert(Tid, {Key, [Value]})
end.
rem_from_list(Tid, Key, Value) when is_record(Value, proc)->
Pid = Value#proc.pid,
case ets:lookup(Tid, Key) of
[{Key, Vals}] ->
% make a new values list that doesn't include the Value arg
NewValues = [Val || #proc{pid=P}=Val <- Vals, P /= Pid],
ets:insert(Tid, {Key, NewValues});
[] -> ok
end;
rem_from_list(Tid, Key, Value) ->
case ets:lookup(Tid, Key) of
[{Key, Vals}] ->
% make a new values list that doesn't include the Value arg
NewValues = [Val || Val <- Vals, Val /= Value],
ets:insert(Tid, {Key, NewValues});
[] -> ok
end.
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