Skip to content

Commit

Permalink
Use 'try'/'catch' rather than 'ets:whereis/1' for Khepri projections
Browse files Browse the repository at this point in the history 
`ets:whereis/1` adds some overhead - it's two ETS calls rather than one
when `ets:whereis/1` returns a table identifier. It's also not atomic:
the table could disappear between `ets:whereis/1` calls and the call to
read data from a projection. We replace all `ets:whereis/1` calls on
projection tables with `try`/`catch` and return default values when we
catch the `badarg` `error` which ETS emits when passed a non-existing
table name.

One special case though is `ets:info/2` which returns `undefined` when
passed a non-existing table names. That block is refactored to use a
`case` instead.
  • Loading branch information
@the-mikedavis
the-mikedavis committed Jul 12, 2024
1 parent d4ea90d commit 9f255db
Show file tree
Hide file tree
Showing 7 changed files with 247 additions and 253 deletions.
119 changes: 60 additions & 59 deletions deps/rabbit/src/rabbit_db_binding.erl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -413,11 +413,11 @@ get_all_in_mnesia() ->
end).

get_all_in_khepri() ->
case ets:whereis(?KHEPRI_BINDINGS_PROJECTION) of
undefined ->
[];
Table ->
[B || #route{binding = B} <- ets:tab2list(Table)]
try
[B || #route{binding = B} <- ets:tab2list(?KHEPRI_BINDINGS_PROJECTION)]
catch
error:badarg ->
[]
end.

-spec get_all(VHostName) -> [Binding] when
Expand All @@ -444,15 +444,16 @@ get_all_in_mnesia(VHost) ->
[B || #route{binding = B} <- rabbit_db:list_in_mnesia(?MNESIA_TABLE, Match)].

get_all_in_khepri(VHost) ->
case ets:whereis(?KHEPRI_BINDINGS_PROJECTION) of
undefined ->
[];
Table ->
VHostResource = rabbit_misc:r(VHost, '_'),
Match = #route{binding = #binding{source = VHostResource,
destination = VHostResource,
_ = '_'}},
[B || #route{binding = B} <- ets:match_object(Table, Match)]
try
VHostResource = rabbit_misc:r(VHost, '_'),
Match = #route{binding = #binding{source = VHostResource,
destination = VHostResource,
_ = '_'}},
[B || #route{binding = B} <- ets:match_object(
?KHEPRI_BINDINGS_PROJECTION, Match)]
catch
error:badarg ->
[]
end.

-spec get_all(Src, Dst, Reverse) -> [Binding] when
Expand Down Expand Up @@ -481,14 +482,15 @@ get_all_in_mnesia(SrcName, DstName, Reverse) ->
mnesia:async_dirty(Fun).

get_all_in_khepri(SrcName, DstName) ->
case ets:whereis(?KHEPRI_BINDINGS_PROJECTION) of
undefined ->
[];
Table ->
MatchHead = #route{binding = #binding{source = SrcName,
destination = DstName,
_ = '_'}},
[B || #route{binding = B} <- ets:match_object(Table, MatchHead)]
try
MatchHead = #route{binding = #binding{source = SrcName,
destination = DstName,
_ = '_'}},
[B || #route{binding = B} <- ets:match_object(
?KHEPRI_BINDINGS_PROJECTION, MatchHead)]
catch
error:badarg ->
[]
end.

%% -------------------------------------------------------------------
Expand Down Expand Up @@ -528,12 +530,13 @@ list_for_route(Route, true) ->
end.

get_all_for_source_in_khepri(Resource) ->
case ets:whereis(?KHEPRI_BINDINGS_PROJECTION) of
undefined ->
[];
Table ->
Route = #route{binding = #binding{source = Resource, _ = '_'}},
[B || #route{binding = B} <- ets:match_object(Table, Route)]
try
Route = #route{binding = #binding{source = Resource, _ = '_'}},
[B || #route{binding = B} <- ets:match_object(
?KHEPRI_BINDINGS_PROJECTION, Route)]
catch
error:badarg ->
[]
end.

%% -------------------------------------------------------------------
Expand Down Expand Up @@ -563,13 +566,14 @@ get_all_for_destination_in_mnesia(Dst) ->
mnesia:async_dirty(Fun).

get_all_for_destination_in_khepri(Destination) ->
case ets:whereis(?KHEPRI_BINDINGS_PROJECTION) of
undefined ->
[];
Table ->
Match = #route{binding = #binding{destination = Destination,
_ = '_'}},
[B || #route{binding = B} <- ets:match_object(Table, Match)]
try
Match = #route{binding = #binding{destination = Destination,
_ = '_'}},
[B || #route{binding = B} <- ets:match_object(
?KHEPRI_BINDINGS_PROJECTION, Match)]
catch
error:badarg ->
[]
end.

%% -------------------------------------------------------------------
Expand Down Expand Up @@ -644,15 +648,16 @@ match_in_mnesia(SrcName, Match) ->
Routes, Match(Binding)].

match_in_khepri(SrcName, Match) ->
case ets:whereis(?KHEPRI_BINDINGS_PROJECTION) of
undefined ->
[];
Table ->
MatchHead = #route{binding = #binding{source = SrcName,
_ = '_'}},
Routes = ets:select(Table, [{MatchHead, [], [['$_']]}]),
[Dest || [#route{binding = Binding = #binding{destination = Dest}}] <-
Routes, Match(Binding)]
try
MatchHead = #route{binding = #binding{source = SrcName,
_ = '_'}},
Routes = ets:select(
?KHEPRI_BINDINGS_PROJECTION, [{MatchHead, [], [['$_']]}]),
[Dest || [#route{binding = Binding = #binding{destination = Dest}}] <-
Routes, Match(Binding)]
catch
error:badarg ->
[]
end.

%% Routing - HOT CODE PATH
Expand Down Expand Up @@ -686,26 +691,22 @@ match_routing_key_in_mnesia(SrcName, RoutingKeys, UseIndex) ->
route_in_mnesia_v1(SrcName, RoutingKeys)
end.

match_routing_key_in_khepri(Src, ['_']) ->
try
MatchHead = #index_route{source_key = {Src, '_'},
destination = '$1',
_ = '_'},
ets:select(?KHEPRI_INDEX_ROUTE_PROJECTION, [{MatchHead, [], ['$1']}])
catch
error:badarg ->
[]
end;
match_routing_key_in_khepri(Src, RoutingKeys) ->
case ets:whereis(?KHEPRI_INDEX_ROUTE_PROJECTION) of
undefined ->
[];
Table ->
do_match_routing_key_in_khepri(Table, Src, RoutingKeys)
end.

do_match_routing_key_in_khepri(Table, Src, ['_']) ->
MatchHead = #index_route{source_key = {Src, '_'},
destination = '$1',
_ = '_'},
ets:select(Table, [{MatchHead, [], ['$1']}]);

do_match_routing_key_in_khepri(Table, Src, RoutingKeys) ->
lists:foldl(
fun(RK, Acc) ->
try
Dst = ets:lookup_element(
Table,
?KHEPRI_INDEX_ROUTE_PROJECTION,
{Src, RK},
#index_route.destination),
Dst ++ Acc
Expand Down
24 changes: 11 additions & 13 deletions deps/rabbit/src/rabbit_db_exchange.erl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -183,14 +183,12 @@ get_in_mnesia(Name) ->
rabbit_mnesia:dirty_read({?MNESIA_TABLE, Name}).

get_in_khepri(Name) ->
case ets:whereis(?KHEPRI_PROJECTION) of
undefined ->
{error, not_found};
Table ->
case ets:lookup(Table, Name) of
[X] -> {ok, X};
[] -> {error, not_found}
end
try ets:lookup(?KHEPRI_PROJECTION, Name) of
[X] -> {ok, X};
[] -> {error, not_found}
catch
error:badarg ->
{error, not_found}
end.

%% -------------------------------------------------------------------
Expand Down Expand Up @@ -233,11 +231,11 @@ get_many_in_mnesia(Table, Names) when is_list(Names) ->
lists:append([ets:lookup(Table, Name) || Name <- Names]).

get_many_in_khepri(Names) when is_list(Names) ->
case ets:whereis(?KHEPRI_PROJECTION) of
undefined ->
[];
Table ->
lists:append([ets:lookup(Table, Name) || Name <- Names])
try
lists:append([ets:lookup(?KHEPRI_PROJECTION, Name) || Name <- Names])
catch
error:badarg ->
[]
end.

%% -------------------------------------------------------------------
Expand Down
Loading

0 comments on commit 9f255db

Please sign in to comment.