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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 Developers of the Original Code are LShift Ltd,
%% Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
%% Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
%% are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
%% Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created by LShift Ltd are Copyright (C) 2007-2010 LShift
%% Ltd. Portions created by Cohesive Financial Technologies LLC are
%% Copyright (C) 2007-2010 Cohesive Financial Technologies
%% LLC. Portions created by Rabbit Technologies Ltd are Copyright
%% (C) 2007-2010 Rabbit Technologies Ltd.
%%
%% All Rights Reserved.
%%
%% Contributor(s): ______________________________________.
%%
-module(rabbit_heartbeat).
-export([start_heartbeat/2]).
start_heartbeat(_Sock, 0) ->
none;
start_heartbeat(Sock, TimeoutSec) ->
Parent = self(),
%% we check for incoming data every interval, and time out after
%% two checks with no change. As a result we will time out between
%% 2 and 3 intervals after the last data has been received.
spawn_link(fun () -> heartbeater(Sock, TimeoutSec * 1000,
recv_oct, 1,
fun () ->
Parent ! timeout,
stop
end,
erlang:monitor(process, Parent)) end),
%% the 'div 2' is there so that we don't end up waiting for nearly
%% 2 * TimeoutSec before sending a heartbeat in the boundary case
%% where the last message was sent just after a heartbeat.
spawn_link(fun () -> heartbeater(Sock, TimeoutSec * 1000 div 2,
send_oct, 0,
fun () ->
catch rabbit_net:send(Sock, rabbit_binary_generator:build_heartbeat_frame()),
continue
end,
erlang:monitor(process, Parent)) end),
ok.
%% Y-combinator, posted by Vladimir Sekissov to the Erlang mailing list
%% http://www.erlang.org/ml-archive/erlang-questions/200301/msg00053.html
y(X) ->
F = fun (P) -> X(fun (A) -> (P(P))(A) end) end,
F(F).
heartbeater(Sock, TimeoutMillisec, StatName, Threshold, Handler, MonitorRef) ->
Heartbeat =
fun (F) ->
fun ({StatVal, SameCount}) ->
receive
{'DOWN', MonitorRef, process, _Object, _Info} -> ok;
Other -> exit({unexpected_message, Other})
after TimeoutMillisec ->
case rabbit_net:getstat(Sock, [StatName]) of
{ok, [{StatName, NewStatVal}]} ->
if NewStatVal =/= StatVal ->
F({NewStatVal, 0});
SameCount < Threshold ->
F({NewStatVal, SameCount + 1});
true ->
case Handler() of
stop -> ok;
continue -> F({NewStatVal, 0})
end
end;
{error, einval} ->
%% the socket is dead, most
%% likely because the
%% connection is being shut
%% down -> terminate
ok;
{error, Reason} ->
exit({cannot_get_socket_stats, Reason})
end
end
end
end,
(y(Heartbeat))({0, 0}).
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