%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1997-2010. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%%
-module(mnesia_subscr).
-behaviour(gen_server).
-export([start/0,
set_debug_level/1,
subscribe/2,
unsubscribe/2,
unsubscribe_table/1,
subscribers/0,
report_table_event/4,
report_table_event/5,
report_table_event/6,
report_activity/1
]).
%% gen_server callbacks
-export([init/1,
handle_call/3,
handle_cast/2,
handle_info/2,
terminate/2,
code_change/3
]).
-include("mnesia.hrl").
-import(mnesia_lib, [error/2]).
-record(state, {supervisor, pid_tab}).
start() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [self()],
[{timeout, infinity}]).
set_debug_level(Level) ->
OldEnv = application:get_env(mnesia, debug),
case mnesia_monitor:patch_env(debug, Level) of
{error, Reason} ->
{error, Reason};
NewLevel ->
set_debug_level(NewLevel, OldEnv)
end.
set_debug_level(Level, OldEnv) ->
case mnesia:system_info(is_running) of
no when OldEnv == undefined ->
none;
no ->
{ok, E} = OldEnv,
E;
_ ->
Old = mnesia_lib:val(debug),
Local = mnesia:system_info(local_tables),
E = whereis(mnesia_event),
Sub = fun(Tab) -> subscribe(E, {table, Tab}) end,
UnSub = fun(Tab) -> unsubscribe(E, {table, Tab}) end,
case Level of
none ->
lists:foreach(UnSub, Local);
verbose ->
lists:foreach(UnSub, Local);
debug ->
lists:foreach(UnSub, Local -- [schema]),
Sub(schema);
trace ->
lists:foreach(Sub, Local)
end,
mnesia_lib:set(debug, Level),
Old
end.
subscribe(ClientPid, system) ->
change_subscr(activate, ClientPid, system);
subscribe(ClientPid, activity) ->
change_subscr(activate, ClientPid, activity);
subscribe(ClientPid, {table, Tab}) ->
change_subscr(activate, ClientPid, {table, Tab, simple});
subscribe(ClientPid, {table, Tab, simple}) ->
change_subscr(activate, ClientPid, {table, Tab, simple});
subscribe(ClientPid, {table, Tab, detailed}) ->
change_subscr(activate, ClientPid, {table, Tab, detailed});
subscribe(_ClientPid, What) ->
{error, {badarg, What}}.
unsubscribe(ClientPid, system) ->
change_subscr(deactivate, ClientPid, system);
unsubscribe(ClientPid, activity) ->
change_subscr(deactivate, ClientPid, activity);
unsubscribe(ClientPid, {table, Tab}) ->
change_subscr(deactivate, ClientPid, {table, Tab, simple});
unsubscribe(ClientPid, {table, Tab, simple}) ->
change_subscr(deactivate, ClientPid, {table, Tab, simple});
unsubscribe(ClientPid, {table, Tab, detailed}) ->
change_subscr(deactivate, ClientPid, {table, Tab, detailed});
unsubscribe(_ClientPid, What) ->
{error, {badarg, What}}.
unsubscribe_table(Tab) ->
call({change, {deactivate_table, Tab}}).
change_subscr(Kind, ClientPid, What) ->
call({change, {Kind, ClientPid, What}}).
subscribers() ->
[whereis(mnesia_event) | mnesia_lib:val(subscribers)].
report_activity({dirty, _pid}) ->
ok;
report_activity(Tid) ->
case ?catch_val(activity_subscribers) of
{'EXIT', _} -> ok;
Subscribers ->
deliver(Subscribers, {mnesia_activity_event, {complete, Tid}})
end.
report_table_event(Tab, Tid, Obj, Op) ->
case ?catch_val({Tab, commit_work}) of
{'EXIT', _} -> ok;
Commit ->
case lists:keysearch(subscribers, 1, Commit) of
false -> ok;
{value, Subs} ->
report_table_event(Subs, Tab, Tid, Obj, Op, undefined)
end
end.
%% Backwards compatible for the moment when mnesia_tm get's updated!
report_table_event(Subscr, Tab, Tid, Obj, Op) ->
report_table_event(Subscr, Tab, Tid, Obj, Op, undefined).
report_table_event({subscribers, S1, S2}, Tab, Tid, _Obj, clear_table, _Old) ->
What = {delete, {schema, Tab}, Tid},
deliver(S1, {mnesia_table_event, What}),
TabDef = mnesia_schema:cs2list(?catch_val({Tab, cstruct})),
What2 = {write, {schema, Tab, TabDef}, Tid},
deliver(S1, {mnesia_table_event, What2}),
What3 = {delete, schema, {schema, Tab}, [{schema, Tab, TabDef}], Tid},
deliver(S2, {mnesia_table_event, What3}),
What4 = {write, schema, {schema, Tab, TabDef}, [], Tid},
deliver(S2, {mnesia_table_event, What4});
report_table_event({subscribers, Subscr, []}, Tab, Tid, Obj, Op, _Old) ->
What = {Op, patch_record(Tab, Obj), Tid},
deliver(Subscr, {mnesia_table_event, What});
report_table_event({subscribers, S1, S2}, Tab, Tid, Obj, Op, Old) ->
Standard = {Op, patch_record(Tab, Obj), Tid},
deliver(S1, {mnesia_table_event, Standard}),
Extended = what(Tab, Tid, Obj, Op, Old),
deliver(S2, Extended);
%% Backwards compatible for the moment when mnesia_tm get's updated!
report_table_event({subscribers, Subscr}, Tab, Tid, Obj, Op, Old) ->
report_table_event({subscribers, Subscr, []}, Tab, Tid, Obj, Op, Old).
patch_record(Tab, Obj) ->
case Tab == element(1, Obj) of
true ->
Obj;
false ->
setelement(1, Obj, Tab)
end.
what(Tab, Tid, {RecName, Key}, delete, undefined) ->
case catch mnesia_lib:db_get(Tab, Key) of
Old when is_list(Old) -> %% Op only allowed for set table.
{mnesia_table_event, {delete, Tab, {RecName, Key}, Old, Tid}};
_ ->
%% Record just deleted by a dirty_op or
%% the whole table has been deleted
ignore
end;
what(Tab, Tid, Obj, delete, Old) ->
{mnesia_table_event, {delete, Tab, Obj, Old, Tid}};
what(Tab, Tid, Obj, delete_object, _Old) ->
{mnesia_table_event, {delete, Tab, Obj, [Obj], Tid}};
what(Tab, Tid, Obj, write, undefined) ->
case catch mnesia_lib:db_get(Tab, element(2, Obj)) of
Old when is_list(Old) ->
{mnesia_table_event, {write, Tab, Obj, Old, Tid}};
{'EXIT', _} ->
ignore
end.
deliver(_, ignore) ->
ok;
deliver([Pid | Pids], Msg) ->
Pid ! Msg,
deliver(Pids, Msg);
deliver([], _Msg) ->
ok.
call(Msg) ->
Pid = whereis(?MODULE),
case Pid of
undefined ->
{error, {node_not_running, node()}};
Pid ->
Res = gen_server:call(Pid, Msg, infinity),
%% We get an exit signal if server dies
receive
{'EXIT', _Pid, _Reason} ->
{error, {node_not_running, node()}}
after 0 ->
Res
end
end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% Callback functions from gen_server
%%----------------------------------------------------------------------
%% Func: init/1
%% Returns: {ok, State} |
%% {ok, State, Timeout} |
%% {stop, Reason}
%%----------------------------------------------------------------------
init([Parent]) ->
process_flag(trap_exit, true),
ClientPid = whereis(mnesia_event),
link(ClientPid),
mnesia_lib:verbose("~p starting: ~p~n", [?MODULE, self()]),
Tab = ?ets_new_table(mnesia_subscr, [duplicate_bag, private]),
?ets_insert(Tab, {ClientPid, system}),
{ok, #state{supervisor = Parent, pid_tab = Tab}}.
%%----------------------------------------------------------------------
%% Func: handle_call/3
%% Returns: {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} | (terminate/2 is called)
%%----------------------------------------------------------------------
handle_call({change, How}, _From, State) ->
Reply = do_change(How, State#state.pid_tab),
{reply, Reply, State};
handle_call(Msg, _From, State) ->
error("~p got unexpected call: ~p~n", [?MODULE, Msg]),
{noreply, State}.
%%----------------------------------------------------------------------
%% Func: handle_cast/2
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
handle_cast(Msg, State) ->
error("~p got unexpected cast: ~p~n", [?MODULE, Msg]),
{noreply, State}.
%%----------------------------------------------------------------------
%% Func: handle_info/2
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
handle_info({'EXIT', Pid, _R}, State) when Pid == State#state.supervisor ->
{stop, shutdown, State};
handle_info({'EXIT', Pid, _Reason}, State) ->
handle_exit(Pid, State#state.pid_tab),
{noreply, State};
handle_info(Msg, State) ->
error("~p got unexpected info: ~p~n", [?MODULE, Msg]),
{noreply, State}.
%%----------------------------------------------------------------------
%% Func: terminate/2
%% Purpose: Shutdown the server
%% Returns: any (ignored by gen_server)
%%----------------------------------------------------------------------
terminate(Reason, State) ->
prepare_stop(State#state.pid_tab),
mnesia_monitor:terminate_proc(?MODULE, Reason, State).
%%----------------------------------------------------------------------
%% Func: code_change/3
%% Purpose: Upgrade process when its code is to be changed
%% Returns: {ok, NewState}
%%----------------------------------------------------------------------
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%----------------------------------------------------------------------
%%% Internal functions
%%%----------------------------------------------------------------------
do_change({activate, ClientPid, system}, SubscrTab) when is_pid(ClientPid) ->
Var = subscribers,
activate(ClientPid, system, Var, subscribers(), SubscrTab);
do_change({activate, ClientPid, activity}, SubscrTab) when is_pid(ClientPid) ->
Var = activity_subscribers,
activate(ClientPid, activity, Var, mnesia_lib:val(Var), SubscrTab);
do_change({activate, ClientPid, {table, Tab, How}}, SubscrTab) when is_pid(ClientPid) ->
case ?catch_val({Tab, where_to_read}) of
Node when Node == node() ->
Var = {Tab, commit_work},
activate(ClientPid, {table, Tab, How}, Var, mnesia_lib:val(Var), SubscrTab);
{'EXIT', _} ->
{error, {no_exists, Tab}};
_Node ->
{error, {not_active_local, Tab}}
end;
do_change({deactivate, ClientPid, system}, SubscrTab) ->
Var = subscribers,
deactivate(ClientPid, system, Var, SubscrTab);
do_change({deactivate, ClientPid, activity}, SubscrTab) ->
Var = activity_subscribers,
deactivate(ClientPid, activity, Var, SubscrTab);
do_change({deactivate, ClientPid, {table, Tab, How}}, SubscrTab) ->
Var = {Tab, commit_work},
deactivate(ClientPid, {table, Tab, How}, Var, SubscrTab);
do_change({deactivate_table, Tab}, SubscrTab) ->
Var = {Tab, commit_work},
case ?catch_val(Var) of
{'EXIT', _} ->
{error, {no_exists, Tab}};
CommitWork ->
case lists:keysearch(subscribers, 1, CommitWork) of
false ->
ok;
{value, Subs} ->
Simple = {table, Tab, simple},
Detailed = {table, Tab, detailed},
Fs = fun(C) -> deactivate(C, Simple, Var, SubscrTab) end,
Fd = fun(C) -> deactivate(C, Detailed, Var, SubscrTab) end,
case Subs of
{subscribers, L1, L2} ->
lists:foreach(Fs, L1),
lists:foreach(Fd, L2);
{subscribers, L1} ->
lists:foreach(Fs, L1)
end
end,
{ok, node()}
end;
do_change(_, _) ->
{error, badarg}.
activate(ClientPid, What, Var, OldSubscribers, SubscrTab) ->
Old =
if Var == subscribers orelse Var == activity_subscribers ->
OldSubscribers;
true ->
case lists:keysearch(subscribers, 1, OldSubscribers) of
false -> [];
{value, Subs} ->
case Subs of
{subscribers, L1, L2} ->
L1 ++ L2;
{subscribers, L1} ->
L1
end
end
end,
case lists:member(ClientPid, Old) of
false ->
%% Don't care about checking old links
case catch link(ClientPid) of
true ->
?ets_insert(SubscrTab, {ClientPid, What}),
add_subscr(Var, What, ClientPid),
{ok, node()};
{'EXIT', _Reason} ->
{error, {no_exists, ClientPid}}
end;
true ->
{error, {already_exists, What}}
end.
%%-record(subscribers, {pids = []}). Old subscriber record removed
%% To solve backward compatibility, this code is a cludge..
add_subscr(subscribers, _What, Pid) ->
mnesia_lib:add(subscribers, Pid),
{ok, node()};
add_subscr(activity_subscribers, _What, Pid) ->
mnesia_lib:add(activity_subscribers, Pid),
{ok, node()};
add_subscr({Tab, commit_work}, What, Pid) ->
Commit = mnesia_lib:val({Tab, commit_work}),
case lists:keysearch(subscribers, 1, Commit) of
false ->
Subscr =
case What of
{table, _, simple} ->
{subscribers, [Pid], []};
{table, _, detailed} ->
{subscribers, [], [Pid]}
end,
mnesia_lib:add({Tab, subscribers}, Pid),
mnesia_lib:set({Tab, commit_work},
mnesia_lib:sort_commit([Subscr | Commit]));
{value, Old} ->
{L1, L2} =
case Old of
{subscribers, L} -> %% Old Way
{L, []};
{subscribers, SL1, SL2} ->
{SL1, SL2}
end,
Subscr =
case What of
{table, _, simple} ->
{subscribers, [Pid | L1], L2};
{table, _, detailed} ->
{subscribers, L1, [Pid | L2]}
end,
NewC = lists:keyreplace(subscribers, 1, Commit, Subscr),
mnesia_lib:set({Tab, commit_work},
mnesia_lib:sort_commit(NewC)),
mnesia_lib:add({Tab, subscribers}, Pid)
end.
deactivate(ClientPid, What, Var, SubscrTab) ->
?ets_match_delete(SubscrTab, {ClientPid, What}),
case catch ?ets_lookup_element(SubscrTab, ClientPid, 1) of
List when is_list(List) ->
ignore;
{'EXIT', _} ->
unlink(ClientPid)
end,
del_subscr(Var, What, ClientPid),
{ok, node()}.
del_subscr(subscribers, _What, Pid) ->
mnesia_lib:del(subscribers, Pid);
del_subscr(activity_subscribers, _What, Pid) ->
mnesia_lib:del(activity_subscribers, Pid);
del_subscr({Tab, commit_work}, What, Pid) ->
Commit = mnesia_lib:val({Tab, commit_work}),
case lists:keysearch(subscribers, 1, Commit) of
false ->
false;
{value, Old} ->
{L1, L2} =
case Old of
{subscribers, L} -> %% Old Way
{L, []};
{subscribers, SL1, SL2} ->
{SL1, SL2}
end,
Subscr =
case What of %% Ignore user error delete subscr from any list
{table, _, simple} ->
NewL1 = lists:delete(Pid, L1),
NewL2 = lists:delete(Pid, L2),
{subscribers, NewL1, NewL2};
{table, _, detailed} ->
NewL1 = lists:delete(Pid, L1),
NewL2 = lists:delete(Pid, L2),
{subscribers, NewL1, NewL2}
end,
case Subscr of
{subscribers, [], []} ->
NewC = lists:keydelete(subscribers, 1, Commit),
mnesia_lib:del({Tab, subscribers}, Pid),
mnesia_lib:set({Tab, commit_work},
mnesia_lib:sort_commit(NewC));
_ ->
NewC = lists:keyreplace(subscribers, 1, Commit, Subscr),
mnesia_lib:del({Tab, subscribers}, Pid),
mnesia_lib:set({Tab, commit_work},
mnesia_lib:sort_commit(NewC))
end
end.
handle_exit(ClientPid, SubscrTab) ->
do_handle_exit(?ets_lookup(SubscrTab, ClientPid)),
?ets_delete(SubscrTab, ClientPid).
do_handle_exit([{ClientPid, What} | Tail]) ->
case What of
system ->
del_subscr(subscribers, What, ClientPid);
activity ->
del_subscr(activity_subscribers, What, ClientPid);
{_, Tab, _Level} ->
del_subscr({Tab, commit_work}, What, ClientPid)
end,
do_handle_exit(Tail);
do_handle_exit([]) ->
ok.
prepare_stop(SubscrTab) ->
mnesia_lib:report_system_event({mnesia_down, node()}),
do_prepare_stop(?ets_first(SubscrTab), SubscrTab).
do_prepare_stop('$end_of_table', _SubscrTab) ->
ok;
do_prepare_stop(ClientPid, SubscrTab) ->
Next = ?ets_next(SubscrTab, ClientPid),
handle_exit(ClientPid, SubscrTab),
unlink(ClientPid),
do_prepare_stop(Next, SubscrTab).
