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Track timer state to optimize message publication (stable branch) #54

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Merged
merged 1 commit into from
Jun 8, 2016
Merged

Track timer state to optimize message publication (stable branch) #54

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53 changes: 24 additions & 29 deletions src/rabbit_delayed_message.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,7 @@ disable_plugin() ->
%%--------------------------------------------------------------------

init([]) ->
{ok, #state{timer = make_ref()}}.
{ok, #state{timer = not_set}}.

handle_call({delay_message, Exchange, Delivery, Delay},
_From, State = #state{timer = CurrTimer}) ->
Expand All @@ -127,14 +127,12 @@ handle_call({delay_message, Exchange, Delivery, Delay},
handle_call(_Req, _From, State) ->
{reply, unknown_request, State}.

handle_cast(go, State = #state{timer = CurrTimer}) ->
maybe_delay_first(CurrTimer),
{noreply, State};
handle_cast(go, State) ->
{noreply, State#state{timer = maybe_delay_first()}};
handle_cast(_C, State) ->
{noreply, State}.

handle_info({timeout, _TimerRef, {deliver, Key}},
State = #state{timer = CurrTimer}) ->
handle_info({timeout, _TimerRef, {deliver, Key}}, State) ->
case mnesia:dirty_read(?TABLE_NAME, Key) of
[] ->
ok;
Expand All @@ -143,8 +141,7 @@ handle_info({timeout, _TimerRef, {deliver, Key}},
mnesia:dirty_delete(?TABLE_NAME, Key),
mnesia:dirty_delete(?INDEX_TABLE_NAME, Key)
end,

{noreply, State#state{timer = maybe_delay_first(CurrTimer)}};
{noreply, State#state{timer = maybe_delay_first()}};
handle_info(_I, State) ->
{noreply, State}.

Expand All @@ -155,7 +152,7 @@ code_change(_, State, _) -> {ok, State}.

%%--------------------------------------------------------------------

maybe_delay_first(CurrTimer) ->
maybe_delay_first() ->
case mnesia:dirty_first(?INDEX_TABLE_NAME) of
%% destructuring to prevent matching '$end_of_table'
#delay_key{timestamp = FirstTS} = Key2 ->
Expand All @@ -164,7 +161,7 @@ maybe_delay_first(CurrTimer) ->
start_timer(FirstTS - Now, Key2);
_ ->
%% nothing to do
CurrTimer
not_set
end.

route(#delay_key{exchange = Ex}, Deliveries) ->
Expand All @@ -183,26 +180,24 @@ internal_delay_message(CurrTimer, Exchange, Delivery, Delay) ->
make_index(DelayTS, Exchange)),
mnesia:dirty_write(?TABLE_NAME,
make_delay(DelayTS, Exchange, Delivery)),
case erlang:read_timer(CurrTimer) of
false ->
%% last timer expired, we set a new timer for
%% the next message to be delivered
case mnesia:dirty_first(?INDEX_TABLE_NAME) of
%% destructuring to prevent matching '$end_of_table'
#delay_key{timestamp = FirstTS} = Key
when FirstTS < DelayTS ->
%% there are messages that expired and need to be delivered
{ok, start_timer(FirstTS - Now, Key)};
case CurrTimer of
not_set ->
%% No timer in progress, so we start our own.
{ok, maybe_delay_first()};
_ ->
case erlang:read_timer(CurrTimer) of
false ->
%% Timer is already expired. Handler will be invoked soon.
{ok, CurrTimer};
CurrMS when Delay < CurrMS ->
%% Current timer lasts longer that new message delay
erlang:cancel_timer(CurrTimer),
{ok, start_timer(Delay, make_key(DelayTS, Exchange))};
_ ->
%% empty table or DelayTS <= FirstTS
{ok, start_timer(Delay, make_key(DelayTS, Exchange))}
end;
CurrMS when Delay < CurrMS ->
%% Current timer lasts longer that new message delay
erlang:cancel_timer(CurrTimer),
{ok, start_timer(Delay, make_key(DelayTS, Exchange))};
_ ->
{ok, CurrTimer}
%% Timer is set to expire sooner than this
%% message's scheduled delivery time.
{ok, CurrTimer}
end
end.

%% Key will be used upon message receipt to fetch
Expand Down