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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(fabric_doc_atts).
-compile(tuple_calls).
-include_lib("fabric/include/fabric.hrl").
-include_lib("couch/include/couch_db.hrl").
-export([
receiver/3,
receiver_callback/2
]).
receiver(_Req, _DbName, undefined) ->
<<"">>;
receiver(_Req, _DbName, {unknown_transfer_encoding, Unknown}) ->
exit({unknown_transfer_encoding, Unknown});
receiver(Req, DbName, chunked) ->
MiddleMan = spawn(fun() -> middleman(Req, DbName, chunked) end),
{fabric_attachment_receiver, MiddleMan, chunked};
receiver(_Req, _DbName, 0) ->
<<"">>;
receiver(Req, DbName, Length) when is_integer(Length) ->
maybe_send_continue(Req),
Middleman = spawn(fun() -> middleman(Req, DbName, Length) end),
{fabric_attachment_receiver, Middleman, Length};
receiver(_Req, _DbName, Length) ->
exit({length_not_integer, Length}).
receiver_callback(Middleman, chunked) ->
fun(4096, ChunkFun, State) ->
write_chunks(Middleman, ChunkFun, State)
end;
receiver_callback(Middleman, Length) when is_integer(Length) ->
fun() ->
Middleman ! {self(), gimme_data},
Timeout = fabric_util:attachments_timeout(),
receive
{Middleman, Data} ->
rexi:reply(attachment_chunk_received),
Data
after Timeout ->
exit(timeout)
end
end.
%%
%% internal
%%
maybe_send_continue(#httpd{mochi_req = MochiReq} = Req) ->
case couch_httpd:header_value(Req, "expect") of
undefined ->
ok;
Expect ->
case string:to_lower(Expect) of
"100-continue" ->
MochiReq:start_raw_response({100, gb_trees:empty()});
_ ->
ok
end
end.
write_chunks(MiddleMan, ChunkFun, State) ->
MiddleMan ! {self(), gimme_data},
Timeout = fabric_util:attachments_timeout(),
receive
{MiddleMan, ChunkRecordList} ->
rexi:reply(attachment_chunk_received),
case flush_chunks(ChunkRecordList, ChunkFun, State) of
{continue, NewState} ->
write_chunks(MiddleMan, ChunkFun, NewState);
{done, NewState} ->
NewState
end
after Timeout ->
exit(timeout)
end.
flush_chunks([], _ChunkFun, State) ->
{continue, State};
flush_chunks([{0, _}], _ChunkFun, State) ->
{done, State};
flush_chunks([Chunk | Rest], ChunkFun, State) ->
NewState = ChunkFun(Chunk, State),
flush_chunks(Rest, ChunkFun, NewState).
receive_unchunked_attachment(_Req, 0) ->
ok;
receive_unchunked_attachment(Req, Length) ->
receive
{MiddleMan, go} ->
Data = couch_httpd:recv(Req, 0),
MiddleMan ! {self(), Data}
end,
receive_unchunked_attachment(Req, Length - size(Data)).
middleman(Req, DbName, chunked) ->
% spawn a process to actually receive the uploaded data
RcvFun = fun(ChunkRecord, ok) ->
receive
{From, go} -> From ! {self(), ChunkRecord}
end,
ok
end,
Receiver = spawn(fun() -> couch_httpd:recv_chunked(Req, 4096, RcvFun, ok) end),
% take requests from the DB writers and get data from the receiver
N = mem3:n(DbName),
Timeout = fabric_util:attachments_timeout(),
middleman_loop(Receiver, N, [], [], Timeout);
middleman(Req, DbName, Length) ->
Receiver = spawn(fun() -> receive_unchunked_attachment(Req, Length) end),
N = mem3:n(DbName),
Timeout = fabric_util:attachments_timeout(),
middleman_loop(Receiver, N, [], [], Timeout).
middleman_loop(Receiver, N, Counters0, ChunkList0, Timeout) ->
receive
{From, gimme_data} ->
% Figure out how far along this writer (From) is in the list
ListIndex =
case fabric_dict:lookup_element(From, Counters0) of
undefined -> 0;
I -> I
end,
% Talk to the receiver to get another chunk if necessary
ChunkList1 =
if
ListIndex == length(ChunkList0) ->
Receiver ! {self(), go},
receive
{Receiver, ChunkRecord} ->
ChunkList0 ++ [ChunkRecord]
end;
true ->
ChunkList0
end,
% reply to the writer
Reply = lists:nthtail(ListIndex, ChunkList1),
From ! {self(), Reply},
% Update the counter for this writer
Counters1 = fabric_dict:update_counter(From, length(Reply), Counters0),
% Drop any chunks that have been sent to all writers
Size = fabric_dict:size(Counters1),
NumToDrop = lists:min([I || {_, I} <- Counters1]),
{ChunkList3, Counters3} =
if
Size == N andalso NumToDrop > 0 ->
ChunkList2 = lists:nthtail(NumToDrop, ChunkList1),
Counters2 = [{F, I - NumToDrop} || {F, I} <- Counters1],
{ChunkList2, Counters2};
true ->
{ChunkList1, Counters1}
end,
middleman_loop(Receiver, N, Counters3, ChunkList3, Timeout)
after Timeout ->
exit(Receiver, kill),
ok
end.
|
