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43 lines
1.1 KiB
Erlang
43 lines
1.1 KiB
Erlang
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%% Feel free to use, reuse and abuse the code in this file.
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%% @doc Streaming handler.
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-module(toppage_handler).
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-export([init/3]).
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-export([rest_init/2]).
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-export([content_types_provided/2]).
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-export([streaming_csv/2]).
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init(_Transport, _Req, _Table) ->
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{upgrade, protocol, cowboy_rest}.
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rest_init(Req, Table) ->
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{ok, Req, Table}.
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content_types_provided(Req, State) ->
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{[
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{{<<"text">>, <<"csv">>, []}, streaming_csv}
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], Req, State}.
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streaming_csv(Req, Table) ->
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{N, Req1} = cowboy_req:binding(v1, Req, 1),
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MS = [{{'$1', '$2', '$3'}, [{'==', '$2', N}], ['$$']}],
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{{stream, result_streamer(Table, MS)}, Req1, Table}.
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result_streamer(Table, MS) ->
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fun (Socket, Transport) ->
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send_records(Socket, Transport, ets:select(Table, MS, 1))
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end.
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send_records(Socket, Transport, {[Rec], Cont}) ->
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timer:sleep(500),
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send_line(Socket, Transport, Rec),
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send_records(Socket, Transport, ets:select(Cont));
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send_records(_Socket, _Transport, '$end_of_table') ->
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ok.
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send_line(Socket, Transport, [Key, V1, V2]) ->
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Transport:send(Socket,
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[Key, $,, integer_to_list(V1), $,, integer_to_list(V2), $\r, $\n]).
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