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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_ft_query).
-behaviour(gen_server).
-export([start_link/1, execute/2]).
-export([init/1, terminate/2, handle_call/3, handle_cast/2, handle_info/2,code_change/3, stop/0]).
-define(ERR_HANDLE, {Port, {exit_status, Status}} -> {stop, {unknown_error, Status}, {unknown_error, Status}, Port}).
start_link(QueryExec) ->
gen_server:start_link({local, couch_ft_query}, couch_ft_query, QueryExec, []).
stop() ->
exit(whereis(couch_ft_query), close).
execute(DatabaseName, QueryString) ->
gen_server:call(couch_ft_query, {ft_query, DatabaseName, QueryString}).
init(QueryExec) ->
Port = open_port({spawn, QueryExec}, [{line, 1000}, exit_status, hide]),
{ok, Port}.
terminate(_Reason, _Server) ->
ok.
handle_call({ft_query, Database, QueryText}, _From, Port) ->
%% send the database name
true = port_command(Port, Database ++ "\n"),
true = port_command(Port, QueryText ++ "\n"),
case get_line(Port) of
"ok" ->
DocIds = read_query_results(Port, []),
{reply, {ok, DocIds}, Port};
"error" ->
ErrorId = get_line(Port),
ErrorMsg = get_line(Port),
{reply, {list_to_atom(ErrorId), ErrorMsg}, Port}
end.
read_query_results(Port, Acc) ->
case get_line(Port) of
"" -> % line by itself means all done
lists:reverse(Acc);
DocId ->
Score = get_line(Port),
read_query_results(Port, [{DocId, Score} | Acc])
end.
get_line(Port) ->
receive
{Port, {data, {eol, Line}}} ->
Line;
?ERR_HANDLE
end.
handle_cast(_Whatever, State) ->
{noreply, State}.
handle_info({Port, {exit_status, Status}}, Port) ->
{stop, {os_process_exited, Status}, Port};
handle_info(_Whatever, State) ->
{noreply, State}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
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