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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(mango_cursor).
-export([
create/3,
explain/1,
execute/3,
maybe_filter_indexes_by_ddoc/2,
remove_indexes_with_partial_filter_selector/1,
maybe_add_warning/3
]).
-include_lib("couch/include/couch_db.hrl").
-include("mango.hrl").
-include("mango_cursor.hrl").
-include("mango_idx.hrl").
-ifdef(HAVE_DREYFUS).
-define(CURSOR_MODULES, [
mango_cursor_view,
mango_cursor_text,
mango_cursor_special
]).
-else.
-define(CURSOR_MODULES, [
mango_cursor_view,
mango_cursor_special
]).
-endif.
-define(SUPERVISOR, mango_cursor_sup).
create(Db, Selector0, Opts) ->
Selector = mango_selector:normalize(Selector0),
UsableIndexes = mango_idx:get_usable_indexes(Db, Selector, Opts),
case mango_cursor:maybe_filter_indexes_by_ddoc(UsableIndexes, Opts) of
[] ->
% use_index doesn't match a valid index - fall back to a valid one
create_cursor(Db, UsableIndexes, Selector, Opts);
UserSpecifiedIndex ->
create_cursor(Db, UserSpecifiedIndex, Selector, Opts)
end.
explain(#cursor{}=Cursor) ->
#cursor{
index = Idx,
selector = Selector,
opts = Opts0,
limit = Limit,
skip = Skip,
fields = Fields
} = Cursor,
Mod = mango_idx:cursor_mod(Idx),
Opts = lists:keydelete(user_ctx, 1, Opts0),
{[
{dbname, mango_idx:dbname(Idx)},
{index, mango_idx:to_json(Idx)},
{partitioned, mango_idx:partitioned(Idx)},
{selector, Selector},
{opts, {Opts}},
{limit, Limit},
{skip, Skip},
{fields, Fields}
] ++ Mod:explain(Cursor)}.
execute(#cursor{index=Idx}=Cursor, UserFun, UserAcc) ->
Mod = mango_idx:cursor_mod(Idx),
Mod:execute(Cursor, UserFun, UserAcc).
maybe_filter_indexes_by_ddoc(Indexes, Opts) ->
case lists:keyfind(use_index, 1, Opts) of
{use_index, []} ->
[];
{use_index, [DesignId]} ->
filter_indexes(Indexes, DesignId);
{use_index, [DesignId, ViewName]} ->
filter_indexes(Indexes, DesignId, ViewName)
end.
filter_indexes(Indexes, DesignId0) ->
DesignId = case DesignId0 of
<<"_design/", _/binary>> ->
DesignId0;
Else ->
<<"_design/", Else/binary>>
end,
FiltFun = fun(I) -> mango_idx:ddoc(I) == DesignId end,
lists:filter(FiltFun, Indexes).
filter_indexes(Indexes0, DesignId, ViewName) ->
Indexes = filter_indexes(Indexes0, DesignId),
FiltFun = fun(I) -> mango_idx:name(I) == ViewName end,
lists:filter(FiltFun, Indexes).
remove_indexes_with_partial_filter_selector(Indexes) ->
FiltFun = fun(Idx) ->
case mango_idx:get_partial_filter_selector(Idx) of
undefined -> true;
_ -> false
end
end,
lists:filter(FiltFun, Indexes).
create_cursor(Db, Indexes, Selector, Opts) ->
[{CursorMod, CursorModIndexes} | _] = group_indexes_by_type(Indexes),
CursorMod:create(Db, CursorModIndexes, Selector, Opts).
group_indexes_by_type(Indexes) ->
IdxDict = lists:foldl(fun(I, D) ->
dict:append(mango_idx:cursor_mod(I), I, D)
end, dict:new(), Indexes),
% The first cursor module that has indexes will be
% used to service this query. This is so that we
% don't suddenly switch indexes for existing client
% queries.
lists:flatmap(fun(CMod) ->
case dict:find(CMod, IdxDict) of
{ok, CModIndexes} ->
[{CMod, CModIndexes}];
error ->
[]
end
end, ?CURSOR_MODULES).
maybe_add_warning(UserFun, #cursor{index = Index, opts = Opts}, UserAcc) ->
NoIndexWarning = case Index#idx.type of
<<"special">> ->
<<"no matching index found, create an index to optimize query time">>;
_ ->
ok
end,
UseIndexInvalidWarning = case lists:keyfind(use_index, 1, Opts) of
{use_index, []} ->
NoIndexWarning;
{use_index, [DesignId]} ->
case filter_indexes([Index], DesignId) of
[] ->
fmt("_design/~s was not used because it does not contain a valid index for this query.",
[ddoc_name(DesignId)]);
_ ->
NoIndexWarning
end;
{use_index, [DesignId, ViewName]} ->
case filter_indexes([Index], DesignId, ViewName) of
[] ->
fmt("_design/~s, ~s was not used because it is not a valid index for this query.",
[ddoc_name(DesignId), ViewName]);
_ ->
NoIndexWarning
end
end,
maybe_add_warning_int(UseIndexInvalidWarning, UserFun, UserAcc).
maybe_add_warning_int(ok, _, UserAcc) ->
UserAcc;
maybe_add_warning_int(Warning, UserFun, UserAcc) ->
couch_stats:increment_counter([mango, unindexed_queries]),
Arg = {add_key, warning, Warning},
{_Go, UserAcc0} = UserFun(Arg, UserAcc),
UserAcc0.
fmt(Format, Args) ->
iolist_to_binary(io_lib:format(Format, Args)).
ddoc_name(<<"_design/", Name/binary>>) ->
Name;
ddoc_name(Name) ->
Name.
|
