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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_changes_feed).
-behaviour(gen_server).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
code_change/3]).
-export([start/2, start_link/2, next/1, stop/1]).
-define(MIN_BUFFER_SIZE, 100).
-include("couch_db.hrl").
-include("../ibrowse/ibrowse.hrl").
-record (state, {
conn = nil,
reqid = nil,
count = 0,
reply_to = nil,
rows = queue:new(),
complete = false
}).
start(Url, Options) ->
gen_server:start(?MODULE, [Url, Options], []).
start_link(Url, Options) ->
gen_server:start_link(?MODULE, [Url, Options], []).
next(Server) ->
?LOG_DEBUG("~p at ~p received next_change call", [?MODULE, Server]),
gen_server:call(Server, next_change, infinity).
stop(Server) ->
gen_server:call(Server, stop).
init([{remote, Url}, Options]) ->
Since = proplists:get_value(since, Options, 0),
Continuous = proplists:get_value(continuous, Options, false),
{Pid, ReqId} = start_http_request(lists:concat([Url, "/_changes",
"?style=all_docs", "&since=", Since, "&continuous=", Continuous])),
{ok, #state{conn=Pid, reqid=ReqId}};
init([{local, DbName}, Options]) ->
init([{remote, "http://" ++ couch_config:get("httpd", "bind_address") ++ ":"
++ couch_config:get("httpd", "port") ++ "/" ++ DbName}, Options]).
handle_call(next_change, From, State) ->
#state{
reqid = Id,
complete = Complete,
count = Count,
rows = Rows
} = State,
ok = maybe_stream_next(Complete, Count, Id),
case queue:out(Rows) of
{{value, Row}, NewRows} ->
{reply, Row, State#state{count=Count-1, rows=NewRows}};
{empty, Rows} ->
if State#state.complete ->
{stop, normal, complete, State};
% State#state.waiting_on_headers ->
% {noreply, State#state{reply_to=From}};
true ->
{noreply, State#state{reply_to=From}}
end
end;
handle_call(stop, _From, State) ->
catch ibrowse:stop_worker_process(State#state.conn),
{stop, normal, ok, State}.
handle_cast(_Msg, State) ->
{noreply, State}.
handle_info({ibrowse_async_headers, Id, "200", _}, #state{reqid=Id}=State) ->
#state{
complete = Complete,
count = Count
} = State,
?LOG_DEBUG("~p reqid ~p ibrowse_async_headers 200", [?MODULE, Id]),
ok = maybe_stream_next(Complete, Count, Id),
{noreply, State};
handle_info({ibrowse_async_headers, Id, "301", Hdrs}, #state{reqid=Id}=State) ->
?LOG_DEBUG("~p reqid ~p ibrowse_async_headers 301", [?MODULE, Id]),
catch ibrowse:stop_worker_process(State#state.conn),
Url = mochiweb_headers:get_value("Location", mochiweb_headers:make(Hdrs)),
{Pid, ReqId} = start_http_request(Url),
{noreply, State#state{conn=Pid, reqid=ReqId}};
handle_info({ibrowse_async_headers, Id, Code, Hdrs}, #state{reqid=Id}=State) ->
?LOG_ERROR("replicator changes feed failed with code ~s and Headers ~n~p",
[Code,Hdrs]),
{stop, {error, list_to_integer(Code)}, State};
handle_info({ibrowse_async_response, Id, Msg}, #state{reqid=Id} = State) ->
?LOG_DEBUG("~p reqid ~p ibrowse_async_response ~p", [?MODULE, Id, Msg]),
#state{
complete = Complete,
count = Count,
rows = Rows
} = State,
try
Row = decode_row(Msg),
case State of
#state{reply_to=nil} ->
{noreply, State#state{count=Count+1, rows = queue:in(Row, Rows)}};
#state{count=0, reply_to=From}->
gen_server:reply(From, Row),
{noreply, State#state{reply_to=nil}}
end
catch
throw:{invalid_json, Msg} ->
?LOG_DEBUG("got invalid_json ~p", [Msg]),
ok = maybe_stream_next(Complete, Count, Id),
{noreply, State}
end;
handle_info({ibrowse_async_response_end, Id}, #state{reqid=Id} = State) ->
?LOG_DEBUG("got ibrowse_async_response_end ~p", [State#state.reply_to]),
case State of
#state{reply_to=nil} ->
{noreply, State#state{complete=true}};
#state{count=0, reply_to=From}->
gen_server:reply(From, complete),
{stop, normal, State}
end;
handle_info(Msg, State) ->
?LOG_INFO("unexpected message ~p", [Msg]),
{noreply, State}.
terminate(_Reason, #state{conn=Pid}) when is_pid(Pid) ->
catch ibrowse:stop_worker_process(Pid),
ok;
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
decode_row([$,, $\n | Rest]) ->
decode_row(Rest);
decode_row(Row) ->
?JSON_DECODE(Row).
maybe_stream_next(false, Count, Id) when Count < ?MIN_BUFFER_SIZE ->
?LOG_DEBUG("~p reqid ~p streaming next chunk", [?MODULE, Id]),
ibrowse:stream_next(Id);
maybe_stream_next(_Complete, _Count, Id) ->
?LOG_DEBUG("~p reqid ~p not streaming", [?MODULE, Id]),
ok.
start_http_request(RawUrl) ->
Url = ibrowse_lib:parse_url(RawUrl),
{ok, Pid} = ibrowse:spawn_link_worker_process(Url#url.host, Url#url.port),
Opts = [
{stream_to, {self(), once}},
{inactivity_timeout, 30000}
],
{ibrowse_req_id, Id} =
ibrowse:send_req_direct(Pid, RawUrl, [], get, [], Opts, infinity),
{Pid, Id}.
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