[#1] – Implement shards:rename/2 (for local and distributed shards).

.travis.yml

@@ -1,9 +1,7 @@
 language: erlang
 otp_release:
-  - 19.0
+  - 19.2
   - 18.3
-  - 18.2.1
-  - 18.1
   - 18.0
 before_script:
   - epmd -daemon

rebar.config

@@ -70,7 +70,6 @@
 
 {dialyzer, [
   {warnings, [
-    race_conditions,
     no_return,
     unmatched_returns,
     error_handling

src/shards.erl

@@ -46,6 +46,7 @@
   new/2,
   next/2,
   prev/2,
+  rename/2,
   safe_fixtable/2,
   select/2, select/3, select/1,
   select_count/2,
@@ -479,6 +480,18 @@ next(Tab, Key1) ->
 prev(Tab, Key1) ->
   call(Tab, prev, [Tab, Key1]).
 
+%% @doc
+%% Wrapper to `shards_local:rename/3' and `shards_dist:rename/3'.
+%%
+%% @see shards_local:rename/3.
+%% @see shards_dist:rename/3.
+%% @end
+-spec rename(Tab, Name) -> Name | no_return() when
+  Tab   :: atom(),
+  Name  :: atom().
+rename(Tab, Name) ->
+  call(Tab, rename, [Tab, Name]).
+
 %% @doc
 %% Wrapper to `shards_local:safe_fixtable/2' and `shards_dist:safe_fixtable/2'.
 %%

src/shards_dist.erl

@@ -17,7 +17,6 @@
   delete/1, delete/3,
   delete_all_objects/2,
   delete_object/3,
-  new/2,
   insert/3,
   insert_new/3,
   lookup/3,
@@ -26,6 +25,8 @@
   match_delete/3,
   match_object/3,
   member/3,
+  new/2,
+  rename/3,
   select/3,
   select_count/3,
   select_delete/3,
@@ -70,7 +71,7 @@ join(Tab, Nodes) ->
 
 %% @private
 join_(Tab) ->
-  pg2:join(Tab, whereis(Tab)).
+  pg2:join(Tab, shards_local:get_pid(Tab)).
 
 -spec leave(Tab, Nodes) -> LeavedNodes when
   Tab         :: atom(),
@@ -198,7 +199,7 @@ lookup_element(Tab, Key, Pos, State) ->
         (_)                     -> true
       end, mapred(Tab, Map, nil, State, r)),
       case Filter of
-        [] -> exit({badarg, erlang:get_stacktrace()});
+        [] -> error(badarg);
         _  -> lists:append(Filter)
       end;
     Node ->
@@ -265,6 +266,19 @@ new(Name, Options, Nodes) ->
   _ = join(Name, AllNodes),
   Name.
 
+-spec rename(Tab, Name, State) -> Name | no_return() when
+  Tab   :: atom(),
+  Name  :: atom(),
+  State :: shards_state:state().
+rename(Tab, Name, State) ->
+  Map = {?SHARDS, rename, [Tab, Name, State]},
+  _ = mapred(Tab, nil, Map, nil, State, r),
+  Nodes = get_nodes(Tab),
+  ok = pg2:delete(Tab),
+  ok = pg2:create(Name),
+  Nodes = join(Name, Nodes),
+  Name.
+
 -spec select(Tab, MatchSpec, State) -> [Match] when
   Tab       :: atom(),
   MatchSpec :: ets:match_spec(),

src/shards_local.erl

@@ -88,6 +88,7 @@
   new/2,
   next/2, next/3,
   prev/2, prev/3,
+  rename/2, rename/3,
   safe_fixtable/2, safe_fixtable/3,
   select/2, select/3, select/4, select/1,
   select_count/2, select_count/3,
@@ -108,7 +109,8 @@
 -export([
   shard_name/2,
   pick/3,
-  list/2
+  list/2,
+  get_pid/1
 ]).
 
 %%%===================================================================
@@ -218,7 +220,7 @@ all() ->
 %% @end
 -spec delete(Tab :: atom()) -> true.
 delete(Tab) ->
-  ok = shards_sup:terminate_child(shards_sup, whereis(Tab)),
+  ok = shards_sup:terminate_child(shards_sup, get_pid(Tab)),
   true.
 
 %% @equiv delete(Tab, Key, shards_state:new())
@@ -297,8 +299,8 @@ file2tab(Filenames, Options) ->
         {ok, Info} ->
           {name, ShardTabName} = lists:keyfind(name, 1, Info),
           {ShardTabName, FN};
-        {error, Reason} ->
-          throw({error, Reason})
+        {error, _} = Error ->
+          throw(Error)
       end
     end || FN <- Filenames],
     Tab = name_from_shard(First),
@@ -638,7 +640,7 @@ lookup_element(Tab, Key, Pos, State) ->
         (_)           -> true
       end, mapred(Tab, {LookupElem, [Key, Pos]}, State)),
       case Filter of
-        [] -> exit({badarg, erlang:get_stacktrace()});
+        [] -> error(badarg);
         _  -> lists:append(Filter)
       end;
     Shard ->
@@ -849,8 +851,11 @@ member(Tab, Key, State) ->
   Options :: [option()].
 new(Name, Options) ->
   case shards_sup:start_child([Name, Options]) of
-    {ok, _} -> Name;
-    _       -> throw(badarg)
+    {ok, Pid} ->
+      true = register(Name, Pid),
+      Name;
+    _ ->
+      error(badarg)
   end.
 
 %% @equiv next(Tab, Key1, shards_state:new())
@@ -916,6 +921,39 @@ prev(Tab, Key1, State) ->
       next(Tab, Key1, State)
   end.
 
+%% @equiv rename(Tab, Name, shards_state:new())
+rename(Tab, Name) ->
+  rename(Tab, Name, shards_state:new()).
+
+%% @doc
+%% Equivalent to `ets:rename/2'.
+%%
+%% Renames the table name and all its associated shard tables.
+%% If something unexpected occurs during the process, an exception
+%% will be thrown.
+%%
+%% @see ets:rename/2.
+%% @end
+-spec rename(Tab, Name, State) -> Name | no_return() when
+  Tab   :: atom(),
+  Name  :: atom(),
+  State :: shards_state:state().
+rename(Tab, Name, State) ->
+  _ = lists:foreach(fun(Shard) ->
+    ShardName = shard_name(Tab, Shard),
+    NewShardName = shard_name(Name, Shard),
+    NewShardName = do_rename(ShardName, NewShardName)
+  end, lists:seq(0, shards_state:n_shards(State) - 1)),
+  do_rename(Tab, Name).
+
+%% @private
+do_rename(OldName, NewName) ->
+  NewName = ets:rename(OldName, NewName),
+  Pid = get_pid(OldName),
+  true = unregister(OldName),
+  true = register(NewName, Pid),
+  NewName.
+
 %% @equiv safe_fixtable(Tab, Fix, shards_state:new())
 safe_fixtable(Tab, Fix) ->
   safe_fixtable(Tab, Fix, shards_state:new()).
@@ -1340,6 +1378,19 @@ list(TabName, NumShards) ->
   Shards = lists:seq(0, NumShards - 1),
   [shard_name(TabName, Shard) || Shard <- Shards].
 
+%% @doc
+%% Returns the PID associated to the table `Tab'.
+%% <ul>
+%% <li>`TabName': Table name.</li>
+%% </ul>
+%% @end
+-spec get_pid(Tab :: atom()) -> pid() | no_return().
+get_pid(Tab) ->
+  case whereis(Tab) of
+    undefined -> error(badarg);
+    Pid       -> Pid
+  end.
+
 %%%===================================================================
 %%% Internal functions
 %%%===================================================================

src/shards_owner_sup.erl

@@ -31,15 +31,15 @@
   Options  :: [term()],
   Response :: supervisor:startlink_ret().
 start_link(Name, Options) ->
-  supervisor:start_link({local, Name}, ?MODULE, [Name, Options]).
+  supervisor:start_link(?MODULE, [Name, Options]).
 
 %%%===================================================================
 %%% Supervisor callbacks
 %%%===================================================================
 
 %% @hidden
 init([Name, Options]) ->
-  % ETS table to hold state info.
+  % ETS table to store state info.
   Name = ets:new(Name, [
     set,
     named_table,

test/dist_SUITE.erl

@@ -17,7 +17,8 @@
 -mixin([
   {test_helper, [
     t_basic_ops/1,
-    t_update_ops/1
+    t_update_ops/1,
+    t_rename/1
   ]}
 ]).
 
@@ -48,6 +49,7 @@ groups() ->
     t_update_ops,
     t_match_ops,
     t_select_ops,
+    t_rename,
     t_eject_node_on_failure,
     t_delete_and_auto_setup_tab
   ]}].

test/local_SUITE.erl

@@ -25,6 +25,7 @@
     t_fold_ops/1,
     t_info_ops/1,
     t_tab2list_tab2file_file2tab/1,
+    t_rename/1,
     t_equivalent_ops/1
   ]}
 ]).
@@ -79,6 +80,10 @@ t_shard_restarted_when_down(_Config) ->
   tab1 = shards:new(tab1, []),
   tab2 = shards:new(tab2, [{restart_strategy, one_for_all}]),
 
+  try shards_local:get_pid(wrong)
+  catch _:badarg -> ok
+  end,
+
   % insert some values
   true = shards:insert(tab1, [{1, 1}, {2, 2}, {3, 3}]),
   true = shards:insert(tab2, [{1, 1}, {2, 2}, {3, 3}]),