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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_view).
-export([is_progress_possible/1, remove_overlapping_shards/2, maybe_send_row/1,
transform_row/1, keydict/1, extract_view/4, get_shards/2,
check_down_shards/2, handle_worker_exit/3,
get_shard_replacements/2, maybe_update_others/5]).
-include_lib("fabric/include/fabric.hrl").
-include_lib("mem3/include/mem3.hrl").
-include_lib("couch/include/couch_db.hrl").
-include_lib("couch_mrview/include/couch_mrview.hrl").
%% @doc Check if a downed node affects any of our workers
-spec check_down_shards(#collector{}, node()) ->
{ok, #collector{}} | {error, any()}.
check_down_shards(Collector, BadNode) ->
#collector{callback=Callback, counters=Counters, user_acc=Acc} = Collector,
Filter = fun(#shard{node = Node}, _) -> Node == BadNode end,
BadCounters = fabric_dict:filter(Filter, Counters),
case fabric_dict:size(BadCounters) > 0 of
true ->
Reason = {nodedown, <<"progress not possible">>},
Callback({error, Reason}, Acc),
{error, Reason};
false ->
{ok, Collector}
end.
%% @doc Handle a worker that dies during a stream
-spec handle_worker_exit(#collector{}, #shard{}, any()) -> {error, any()}.
handle_worker_exit(Collector, _Worker, Reason) ->
#collector{callback=Callback, user_acc=Acc} = Collector,
{ok, Resp} = Callback({error, fabric_util:error_info(Reason)}, Acc),
{error, Resp}.
%% @doc looks for a fully covered keyrange in the list of counters
-spec is_progress_possible([{#shard{}, term()}]) -> boolean().
is_progress_possible([]) ->
false;
is_progress_possible(Counters) ->
Ranges = fabric_dict:fold(fun(#shard{range=[X,Y]}, _, A) -> [{X,Y}|A] end,
[], Counters),
[{Start, Tail0} | Rest] = lists:ukeysort(1, Ranges),
Result = lists:foldl(fun
(_, fail) ->
% we've already declared failure
fail;
(_, complete) ->
% this is the success condition, we can fast-forward
complete;
({X,_}, Tail) when X > (Tail+1) ->
% gap in the keyrange, we're dead
fail;
({_,Y}, Tail) ->
case erlang:max(Tail, Y) of
End when (End+1) =:= (2 bsl 31) ->
complete;
Else ->
% the normal condition, adding to the tail
Else
end
end, if (Tail0+1) =:= (2 bsl 31) -> complete; true -> Tail0 end, Rest),
(Start =:= 0) andalso (Result =:= complete).
-spec remove_overlapping_shards(#shard{}, [{#shard{}, any()}]) ->
[{#shard{}, any()}].
remove_overlapping_shards(#shard{range=[A,B]} = Shard0, Shards) ->
fabric_dict:filter(fun(#shard{range=[X,Y], node=Node, ref=Ref} = Shard, _) ->
if Shard =:= Shard0 ->
% we can't remove ourselves
true;
A < B, X >= A, X < B ->
% lower bound is inside our range
rexi:kill(Node, Ref),
false;
A < B, Y > A, Y =< B ->
% upper bound is inside our range
rexi:kill(Node, Ref),
false;
B < A, X >= A orelse B < A, X < B ->
% target shard wraps the key range, lower bound is inside
rexi:kill(Node, Ref),
false;
B < A, Y > A orelse B < A, Y =< B ->
% target shard wraps the key range, upper bound is inside
rexi:kill(Node, Ref),
false;
true ->
true
end
end, Shards).
maybe_send_row(#collector{limit=0} = State) ->
#collector{counters=Counters, user_acc=AccIn, callback=Callback} = State,
case fabric_dict:any(0, Counters) of
true ->
% we still need to send the total/offset header
{ok, State};
false ->
erase(meta_sent),
{_, Acc} = Callback(complete, AccIn),
{stop, State#collector{user_acc=Acc}}
end;
maybe_send_row(State) ->
#collector{
callback = Callback,
counters = Counters,
skip = Skip,
limit = Limit,
user_acc = AccIn
} = State,
case fabric_dict:any(0, Counters) of
true ->
{ok, State};
false ->
try get_next_row(State) of
{_, NewState} when Skip > 0 ->
maybe_send_row(NewState#collector{skip=Skip-1});
{Row, NewState} ->
case Callback(transform_row(possibly_embed_doc(NewState,Row)), AccIn) of
{stop, Acc} ->
{stop, NewState#collector{user_acc=Acc, limit=Limit-1}};
{ok, Acc} ->
maybe_send_row(NewState#collector{user_acc=Acc, limit=Limit-1})
end
catch complete ->
erase(meta_sent),
{_, Acc} = Callback(complete, AccIn),
{stop, State#collector{user_acc=Acc}}
end
end.
%% if include_docs=true is used when keys and
%% the values contain "_id" then use the "_id"s
%% to retrieve documents and embed in result
possibly_embed_doc(_State,
#view_row{id=reduced}=Row) ->
Row;
possibly_embed_doc(_State,
#view_row{value=undefined}=Row) ->
Row;
possibly_embed_doc(#collector{db_name=DbName, query_args=Args},
#view_row{key=_Key, id=_Id, value=Value, doc=_Doc}=Row) ->
#mrargs{include_docs=IncludeDocs} = Args,
case IncludeDocs andalso is_tuple(Value) of
true ->
{Props} = Value,
Rev0 = couch_util:get_value(<<"_rev">>, Props),
case couch_util:get_value(<<"_id">>,Props) of
null -> Row#view_row{doc=null};
undefined -> Row;
IncId ->
% use separate process to call fabric:open_doc
% to not interfere with current call
{Pid, Ref} = spawn_monitor(fun() ->
exit(
case Rev0 of
undefined ->
case fabric:open_doc(DbName, IncId, []) of
{ok, NewDoc} ->
Row#view_row{doc=couch_doc:to_json_obj(NewDoc,[])};
{not_found, _} ->
Row#view_row{doc=null};
Else ->
Row#view_row{doc={error, Else}}
end;
Rev0 ->
Rev = couch_doc:parse_rev(Rev0),
case fabric:open_revs(DbName, IncId, [Rev], []) of
{ok, [{ok, NewDoc}]} ->
Row#view_row{doc=couch_doc:to_json_obj(NewDoc,[])};
{ok, [{{not_found, _}, Rev}]} ->
Row#view_row{doc=null};
Else ->
Row#view_row{doc={error, Else}}
end
end) end),
receive {'DOWN',Ref,process,Pid, Resp} ->
Resp
end
end;
_ -> Row
end.
keydict(undefined) ->
undefined;
keydict(Keys) ->
{Dict,_} = lists:foldl(fun(K, {D,I}) -> {dict:store(K,I,D), I+1} end,
{dict:new(),0}, Keys),
Dict.
%% internal %%
get_next_row(#collector{rows = []}) ->
throw(complete);
get_next_row(#collector{reducer = RedSrc} = St) when RedSrc =/= undefined ->
#collector{
query_args = #mrargs{direction = Dir},
keys = Keys,
rows = RowDict,
lang = Lang,
counters = Counters0,
collation = Collation
} = St,
{Key, RestKeys} = find_next_key(Keys, Dir, Collation, RowDict),
case dict:find(Key, RowDict) of
{ok, Records} ->
NewRowDict = dict:erase(Key, RowDict),
Counters = lists:foldl(fun(#view_row{worker={Worker,From}}, CntrsAcc) ->
case From of
{Pid, _} when is_pid(Pid) ->
gen_server:reply(From, ok);
Pid when is_pid(Pid) ->
rexi:stream_ack(From)
end,
fabric_dict:update_counter(Worker, -1, CntrsAcc)
end, Counters0, Records),
Wrapped = [[V] || #view_row{value=V} <- Records],
{ok, [Reduced]} = couch_query_servers:rereduce(Lang, [RedSrc], Wrapped),
NewSt = St#collector{keys=RestKeys, rows=NewRowDict, counters=Counters},
{#view_row{key=Key, id=reduced, value=Reduced}, NewSt};
error ->
get_next_row(St#collector{keys=RestKeys})
end;
get_next_row(State) ->
#collector{rows = [Row|Rest], counters = Counters0} = State,
{Worker, From} = Row#view_row.worker,
rexi:stream_ack(From),
Counters1 = fabric_dict:update_counter(Worker, -1, Counters0),
{Row, State#collector{rows = Rest, counters=Counters1}}.
%% TODO: rectify nil <-> undefined discrepancies
find_next_key(nil, Dir, Collation, RowDict) ->
find_next_key(undefined, Dir, Collation, RowDict);
find_next_key(undefined, Dir, Collation, RowDict) ->
CmpFun = fun(A, B) -> compare(Dir, Collation, A, B) end,
case lists:sort(CmpFun, dict:fetch_keys(RowDict)) of
[] ->
throw(complete);
[Key|_] ->
{Key, nil}
end;
find_next_key([], _, _, _) ->
throw(complete);
find_next_key([Key|Rest], _, _, _) ->
{Key, Rest}.
transform_row(#view_row{key=Key, id=reduced, value=Value}) ->
{row, [{key,Key}, {value,Value}]};
transform_row(#view_row{key=Key, id=undefined}) ->
{row, [{key,Key}, {id,error}, {value,not_found}]};
transform_row(#view_row{key=Key, id=Id, value=Value, doc=undefined}) ->
{row, [{id,Id}, {key,Key}, {value,Value}]};
transform_row(#view_row{key=Key, id=_Id, value=_Value, doc={error,Reason}}) ->
{row, [{id,error}, {key,Key}, {value,Reason}]};
transform_row(#view_row{key=Key, id=Id, value=Value, doc=Doc}) ->
{row, [{id,Id}, {key,Key}, {value,Value}, {doc,Doc}]}.
compare(_, _, A, A) -> true;
compare(fwd, <<"raw">>, A, B) -> A < B;
compare(rev, <<"raw">>, A, B) -> B < A;
compare(fwd, _, A, B) -> couch_ejson_compare:less_json(A, B);
compare(rev, _, A, B) -> couch_ejson_compare:less_json(B, A).
extract_view(Pid, ViewName, [], _ViewType) ->
couch_log:error("missing_named_view ~p", [ViewName]),
exit(Pid, kill),
exit(missing_named_view);
extract_view(Pid, ViewName, [View|Rest], ViewType) ->
case lists:member(ViewName, view_names(View, ViewType)) of
true ->
if ViewType == reduce ->
{index_of(ViewName, view_names(View, reduce)), View};
true ->
View
end;
false ->
extract_view(Pid, ViewName, Rest, ViewType)
end.
view_names(View, Type) when Type == red_map; Type == reduce ->
[Name || {Name, _} <- View#mrview.reduce_funs];
view_names(View, map) ->
View#mrview.map_names.
index_of(X, List) ->
index_of(X, List, 1).
index_of(_X, [], _I) ->
not_found;
index_of(X, [X|_Rest], I) ->
I;
index_of(X, [_|Rest], I) ->
index_of(X, Rest, I+1).
get_shards(DbName, #mrargs{stable=true}) ->
mem3:ushards(DbName);
get_shards(DbName, #mrargs{stable=false}) ->
mem3:shards(DbName).
maybe_update_others(DbName, DDoc, ShardsInvolved, ViewName,
#mrargs{update=lazy} = Args) ->
ShardsNeedUpdated = mem3:shards(DbName) -- ShardsInvolved,
lists:foreach(fun(#shard{node=Node, name=ShardName}) ->
rpc:cast(Node, fabric_rpc, update_mrview, [ShardName, DDoc, ViewName, Args])
end, ShardsNeedUpdated);
maybe_update_others(_DbName, _DDoc, _ShardsInvolved, _ViewName, _Args) ->
ok.
get_shard_replacements(DbName, UsedShards0) ->
% We only want to generate a replacements list from shards
% that aren't already used.
AllLiveShards = mem3:live_shards(DbName, [node() | nodes()]),
UsedShards = [S#shard{ref=undefined} || S <- UsedShards0],
UnusedShards = AllLiveShards -- UsedShards,
% If we have more than one copy of a range then we don't
% want to try and add a replacement to any copy.
RangeCounts = lists:foldl(fun(#shard{range=R}, Acc) ->
dict:update_counter(R, 1, Acc)
end, dict:new(), UsedShards),
% For each seq shard range with a count of 1, find any
% possible replacements from the unused shards. The
% replacement list is keyed by range.
lists:foldl(fun(#shard{range=Range}, Acc) ->
case dict:find(Range, RangeCounts) of
{ok, 1} ->
Repls = [S || S <- UnusedShards, S#shard.range =:= Range],
% Only keep non-empty lists of replacements
if Repls == [] -> Acc; true ->
[{Range, Repls} | Acc]
end;
_ ->
Acc
end
end, [], UsedShards).
% unit test
is_progress_possible_test() ->
EndPoint = 2 bsl 31,
T1 = [[0, EndPoint-1]],
?assertEqual(is_progress_possible(mk_cnts(T1)),true),
T2 = [[0,10],[11,20],[21,EndPoint-1]],
?assertEqual(is_progress_possible(mk_cnts(T2)),true),
% gap
T3 = [[0,10],[12,EndPoint-1]],
?assertEqual(is_progress_possible(mk_cnts(T3)),false),
% outside range
T4 = [[1,10],[11,20],[21,EndPoint-1]],
?assertEqual(is_progress_possible(mk_cnts(T4)),false),
% outside range
T5 = [[0,10],[11,20],[21,EndPoint]],
?assertEqual(is_progress_possible(mk_cnts(T5)),false).
remove_overlapping_shards_test() ->
meck:new(rexi),
meck:expect(rexi, kill, fun(_, _) -> ok end),
EndPoint = 2 bsl 31,
T1 = [[0,10],[11,20],[21,EndPoint-1]],
Shards = mk_cnts(T1,3),
?assertEqual(orddict:size(
remove_overlapping_shards(#shard{name=list_to_atom("node-3"),
node=list_to_atom("node-3"),
range=[11,20]},
Shards)),7),
meck:unload(rexi).
mk_cnts(Ranges) ->
Shards = lists:map(fun(Range) ->
#shard{range=Range}
end,
Ranges),
orddict:from_list([{Shard,nil} || Shard <- Shards]).
mk_cnts(Ranges, NoNodes) ->
orddict:from_list([{Shard,nil}
|| Shard <-
lists:flatten(lists:map(
fun(Range) ->
mk_shards(NoNodes,Range,[])
end, Ranges))]
).
mk_shards(0,_Range,Shards) ->
Shards;
mk_shards(NoNodes,Range,Shards) ->
NodeName = list_to_atom("node-" ++ integer_to_list(NoNodes)),
mk_shards(NoNodes-1,Range,
[#shard{name=NodeName, node=NodeName, range=Range} | Shards]).
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