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%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (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.mozilla.org/MPL/
%%
%% 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.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developer of the Original Code is GoPivotal, Inc.
%% Copyright (c) 2007-2014 GoPivotal, Inc. All rights reserved.
%%
-module(rabbit_event).
-include("rabbit.hrl").
-export([start_link/0]).
-export([init_stats_timer/2, init_disabled_stats_timer/2,
ensure_stats_timer/3, stop_stats_timer/2, reset_stats_timer/2]).
-export([stats_level/2, if_enabled/3]).
-export([notify/2, notify/3, notify_if/3]).
-export([sync_notify/2, sync_notify/3]).
%%----------------------------------------------------------------------------
-record(state, {level, interval, timer}).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-export_type([event_type/0, event_props/0, event_timestamp/0, event/0]).
-type(event_type() :: atom()).
-type(event_props() :: term()).
-type(event_timestamp() ::
{non_neg_integer(), non_neg_integer(), non_neg_integer()}).
-type(event() :: #event { type :: event_type(),
props :: event_props(),
reference :: 'none' | reference(),
timestamp :: event_timestamp() }).
-type(level() :: 'none' | 'coarse' | 'fine').
-type(timer_fun() :: fun (() -> 'ok')).
-type(container() :: tuple()).
-type(pos() :: non_neg_integer()).
-spec(start_link/0 :: () -> rabbit_types:ok_pid_or_error()).
-spec(init_stats_timer/2 :: (container(), pos()) -> container()).
-spec(init_disabled_stats_timer/2 :: (container(), pos()) -> container()).
-spec(ensure_stats_timer/3 :: (container(), pos(), term()) -> container()).
-spec(stop_stats_timer/2 :: (container(), pos()) -> container()).
-spec(reset_stats_timer/2 :: (container(), pos()) -> container()).
-spec(stats_level/2 :: (container(), pos()) -> level()).
-spec(if_enabled/3 :: (container(), pos(), timer_fun()) -> 'ok').
-spec(notify/2 :: (event_type(), event_props()) -> 'ok').
-spec(notify/3 :: (event_type(), event_props(), reference() | 'none') -> 'ok').
-spec(notify_if/3 :: (boolean(), event_type(), event_props()) -> 'ok').
-spec(sync_notify/2 :: (event_type(), event_props()) -> 'ok').
-spec(sync_notify/3 :: (event_type(), event_props(),
reference() | 'none') -> 'ok').
-endif.
%%----------------------------------------------------------------------------
start_link() ->
gen_event:start_link({local, ?MODULE}).
%% The idea is, for each stat-emitting object:
%%
%% On startup:
%% init_stats_timer(State)
%% notify(created event)
%% if_enabled(internal_emit_stats) - so we immediately send something
%%
%% On wakeup:
%% ensure_stats_timer(State, emit_stats)
%% (Note we can't emit stats immediately, the timer may have fired 1ms ago.)
%%
%% emit_stats:
%% if_enabled(internal_emit_stats)
%% reset_stats_timer(State) - just bookkeeping
%%
%% Pre-hibernation:
%% if_enabled(internal_emit_stats)
%% stop_stats_timer(State)
%%
%% internal_emit_stats:
%% notify(stats)
init_stats_timer(C, P) ->
{ok, StatsLevel} = application:get_env(rabbit, collect_statistics),
{ok, Interval} = application:get_env(rabbit, collect_statistics_interval),
setelement(P, C, #state{level = StatsLevel, interval = Interval,
timer = undefined}).
init_disabled_stats_timer(C, P) ->
setelement(P, C, #state{level = none, interval = 0, timer = undefined}).
ensure_stats_timer(C, P, Msg) ->
case element(P, C) of
#state{level = Level, interval = Interval, timer = undefined} = State
when Level =/= none ->
TRef = erlang:send_after(Interval, self(), Msg),
setelement(P, C, State#state{timer = TRef});
#state{} ->
C
end.
stop_stats_timer(C, P) ->
case element(P, C) of
#state{timer = TRef} = State when TRef =/= undefined ->
case erlang:cancel_timer(TRef) of
false -> C;
_ -> setelement(P, C, State#state{timer = undefined})
end;
#state{} ->
C
end.
reset_stats_timer(C, P) ->
case element(P, C) of
#state{timer = TRef} = State when TRef =/= undefined ->
setelement(P, C, State#state{timer = undefined});
#state{} ->
C
end.
stats_level(C, P) ->
#state{level = Level} = element(P, C),
Level.
if_enabled(C, P, Fun) ->
case element(P, C) of
#state{level = none} -> ok;
#state{} -> Fun(), ok
end.
notify_if(true, Type, Props) -> notify(Type, Props);
notify_if(false, _Type, _Props) -> ok.
notify(Type, Props) -> notify(Type, Props, none).
notify(Type, Props, Ref) ->
gen_event:notify(?MODULE, event_cons(Type, Props, Ref)).
sync_notify(Type, Props) -> sync_notify(Type, Props, none).
sync_notify(Type, Props, Ref) ->
gen_event:sync_notify(?MODULE, event_cons(Type, Props, Ref)).
event_cons(Type, Props, Ref) ->
#event{type = Type,
props = Props,
reference = Ref,
timestamp = os:timestamp()}.
|
