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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 VMware, Inc.
%% Copyright (c) 2007-2011 VMware, Inc. All rights reserved.
%%
-module(rabbit_heartbeat).
-export([start_heartbeat_sender/3, start_heartbeat_receiver/3,
start_heartbeat_fun/1, pause_monitor/1, resume_monitor/1]).
-include("rabbit.hrl").
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-export_type([heartbeaters/0]).
-export_type([start_heartbeat_fun/0]).
-type(heartbeaters() :: {rabbit_types:maybe(pid()), rabbit_types:maybe(pid())}).
-type(heartbeat_callback() :: fun (() -> any())).
-type(start_heartbeat_fun() ::
fun((rabbit_net:socket(), non_neg_integer(), heartbeat_callback(),
non_neg_integer(), heartbeat_callback()) ->
no_return())).
-spec(start_heartbeat_sender/3 ::
(rabbit_net:socket(), non_neg_integer(), heartbeat_callback()) ->
rabbit_types:ok(pid())).
-spec(start_heartbeat_receiver/3 ::
(rabbit_net:socket(), non_neg_integer(), heartbeat_callback()) ->
rabbit_types:ok(pid())).
-spec(start_heartbeat_fun/1 ::
(pid()) -> start_heartbeat_fun()).
-spec(pause_monitor/1 :: (heartbeaters()) -> 'ok').
-spec(resume_monitor/1 :: (heartbeaters()) -> 'ok').
-endif.
%%----------------------------------------------------------------------------
start_heartbeat_sender(Sock, TimeoutSec, SendFun) ->
%% 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.
heartbeater(
{Sock, TimeoutSec * 1000 div 2, send_oct, 0,
fun () ->
SendFun(),
continue
end}).
start_heartbeat_receiver(Sock, TimeoutSec, ReceiveFun) ->
%% 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.
heartbeater({Sock, TimeoutSec * 1000, recv_oct, 1, fun () ->
ReceiveFun(),
stop
end}).
start_heartbeat_fun(SupPid) ->
fun (Sock, SendTimeoutSec, SendFun, ReceiveTimeoutSec, ReceiveFun) ->
{ok, Sender} =
start_heartbeater(SendTimeoutSec, SupPid, Sock,
SendFun, heartbeat_sender,
start_heartbeat_sender),
{ok, Receiver} =
start_heartbeater(ReceiveTimeoutSec, SupPid, Sock,
ReceiveFun, heartbeat_receiver,
start_heartbeat_receiver),
{Sender, Receiver}
end.
pause_monitor({_Sender, none}) ->
ok;
pause_monitor({_Sender, Receiver}) ->
Receiver ! pause,
ok.
resume_monitor({_Sender, none}) ->
ok;
resume_monitor({_Sender, Receiver}) ->
Receiver ! resume,
ok.
%%----------------------------------------------------------------------------
start_heartbeater(0, _SupPid, _Sock, _TimeoutFun, _Name, _Callback) ->
{ok, none};
start_heartbeater(TimeoutSec, SupPid, Sock, TimeoutFun, Name, Callback) ->
supervisor2:start_child(
SupPid, {Name,
{rabbit_heartbeat, Callback,
[Sock, TimeoutSec, TimeoutFun]},
transient, ?MAX_WAIT, worker, [rabbit_heartbeat]}).
heartbeater(Params) ->
{ok, proc_lib:spawn_link(fun () -> heartbeater(Params, {0, 0}) end)}.
heartbeater({Sock, TimeoutMillisec, StatName, Threshold, Handler} = Params,
{StatVal, SameCount}) ->
Recurse = fun (V) -> heartbeater(Params, V) end,
receive
pause ->
receive
resume ->
Recurse({0, 0});
Other ->
exit({unexpected_message, Other})
end;
Other ->
exit({unexpected_message, Other})
after TimeoutMillisec ->
case rabbit_net:getstat(Sock, [StatName]) of
{ok, [{StatName, NewStatVal}]} ->
if NewStatVal =/= StatVal ->
Recurse({NewStatVal, 0});
SameCount < Threshold ->
Recurse({NewStatVal, SameCount + 1});
true ->
case Handler() of
stop -> ok;
continue -> Recurse({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.
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