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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_rep_writer).
-export([start_link/4]).
-include("couch_db.hrl").
start_link(Parent, _Target, Reader, _PostProps) ->
{ok, spawn_link(fun() -> writer_loop(Parent, Reader) end)}.
writer_loop(Parent, Reader) ->
case couch_rep_reader:next(Reader) of
{complete, FinalSeq} ->
Parent ! {writer_checkpoint, FinalSeq},
ok;
{HighSeq, Docs} ->
DocCount = length(Docs),
{ok, Target0} = gen_server:call(Parent, get_target_db, infinity),
Target = open_db(Target0),
try write_docs(Target, Docs) of
{ok, []} ->
Parent ! {update_stats, docs_written, DocCount};
{ok, Errors} ->
ErrorCount = length(Errors),
Parent ! {update_stats, doc_write_failures, ErrorCount},
Parent ! {update_stats, docs_written, DocCount - ErrorCount}
catch
{attachment_request_failed, Err} ->
?LOG_DEBUG("writer failed to write an attachment ~p", [Err]),
exit({attachment_request_failed, Err, Docs})
after
close_db(Target)
end,
Parent ! {writer_checkpoint, HighSeq},
couch_rep_att:cleanup(),
couch_util:should_flush(),
writer_loop(Parent, Reader)
end.
write_docs(#http_db{} = Db, Docs) ->
{DocsAtts, DocsNoAtts} = lists:partition(
fun(#doc{atts=[]}) -> false; (_) -> true end,
Docs
),
ErrorsJson0 = write_bulk_docs(Db, DocsNoAtts),
ErrorsJson = lists:foldl(
fun(Doc, Acc) -> write_multi_part_doc(Db, Doc) ++ Acc end,
ErrorsJson0,
DocsAtts
),
{ok, ErrorsJson};
write_docs(Db, Docs) ->
couch_db:update_docs(Db, Docs, [delay_commit], replicated_changes).
write_bulk_docs(_Db, []) ->
[];
write_bulk_docs(#http_db{headers = Headers} = Db, Docs) ->
JsonDocs = [
couch_doc:to_json_obj(Doc, [revs]) || Doc <- Docs
],
Request = Db#http_db{
resource = "_bulk_docs",
method = post,
body = {[{new_edits, false}, {docs, JsonDocs}]},
headers = couch_util:proplist_apply_field({"Content-Type", "application/json"}, [{"X-Couch-Full-Commit", "false"} | Headers])
},
ErrorsJson = case couch_rep_httpc:request(Request) of
{FailProps} ->
exit({target_error, couch_util:get_value(<<"error">>, FailProps)});
List when is_list(List) ->
List
end,
[write_docs_1(V) || V <- ErrorsJson].
write_multi_part_doc(#http_db{headers=Headers} = Db, #doc{atts=Atts} = Doc) ->
JsonBytes = ?JSON_ENCODE(
couch_doc:to_json_obj(
Doc,
[follows, att_encoding_info, attachments, revs]
)
),
Boundary = couch_uuids:random(),
{ContentType, Len} = couch_doc:len_doc_to_multi_part_stream(
Boundary, JsonBytes, Atts, true
),
StreamerPid = spawn_link(
fun() -> streamer_fun(Boundary, JsonBytes, Atts) end
),
BodyFun = fun(Acc) ->
DataQueue = case Acc of
nil ->
StreamerPid ! {start, self()},
receive
{queue, Q} ->
Q
end;
Queue ->
Queue
end,
case couch_work_queue:dequeue(DataQueue) of
closed ->
eof;
{ok, Data} ->
{ok, iolist_to_binary(Data), DataQueue}
end
end,
Request = Db#http_db{
resource = couch_util:encode_doc_id(Doc),
method = put,
qs = [{new_edits, false}],
body = {BodyFun, nil},
headers = [
{"x-couch-full-commit", "false"},
{"Content-Type", ?b2l(ContentType)},
{"Content-Length", Len} | Headers
]
},
Result = case couch_rep_httpc:request(Request) of
{[{<<"error">>, Error}, {<<"reason">>, Reason}]} ->
{Pos, [RevId | _]} = Doc#doc.revs,
ErrId = couch_util:to_existing_atom(Error),
[{Doc#doc.id, couch_doc:rev_to_str({Pos, RevId})}, {ErrId, Reason}];
_ ->
[]
end,
StreamerPid ! stop,
Result.
streamer_fun(Boundary, JsonBytes, Atts) ->
receive
stop ->
ok;
{start, From} ->
% better use a brand new queue, to ensure there's no garbage from
% a previous (failed) iteration
{ok, DataQueue} = couch_work_queue:new(
[{max_size, 1024 * 1024}, {max_items, 1000}]),
From ! {queue, DataQueue},
couch_doc:doc_to_multi_part_stream(
Boundary,
JsonBytes,
Atts,
fun(Data) ->
couch_work_queue:queue(DataQueue, Data)
end,
true
),
couch_work_queue:close(DataQueue),
streamer_fun(Boundary, JsonBytes, Atts)
end.
write_docs_1({Props}) ->
Id = couch_util:get_value(<<"id">>, Props),
Rev = couch_doc:parse_rev(couch_util:get_value(<<"rev">>, Props)),
ErrId = couch_util:to_existing_atom(couch_util:get_value(<<"error">>, Props)),
Reason = couch_util:get_value(<<"reason">>, Props),
{{Id, Rev}, {ErrId, Reason}}.
open_db(#db{name = Name, user_ctx = UserCtx}) ->
{ok, Db} = couch_db:open(Name, [{user_ctx, UserCtx}]),
Db;
open_db(HttpDb) ->
HttpDb.
close_db(#db{} = Db) ->
couch_db:close(Db);
close_db(_HttpDb) ->
ok.
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