refactor: update notes for willmsg
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William Yang
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975c7429e5
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d5247cb567
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@ -2241,8 +2241,7 @@ session_disconnect(_ClientInfo, _ConnInfo, undefined) ->
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%% When willmsg presents the decision whether or when to publish the Will Message are effected by
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%% the followings:
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%% - connecion state
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%% - If it is MQTT normal disconnection (RC: 0)
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%% - If it is MQTT normal disconnection (RC: 4)
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%% - If it is MQTT normal disconnection (RC: 0) or abnormal (RC != 0) from the *client*
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%% - will delay interval (MQTT 5.0 only)
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%% - session expire Session Expiry (MQTT 5.0 only)
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%% - EMQX operations on the client
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@ -2251,27 +2250,23 @@ session_disconnect(_ClientInfo, _ConnInfo, undefined) ->
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%% @NOTE:
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%% The caller does not need to take care of the case when process terminates while will_msg is published
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%% as it is designed by the spec.
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%% @NOTE:
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%% this function should be safe to be called multiple times in the life time of the connecion process, the willmsg
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%% must be delete from the state if it is published or cleared.
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-spec maybe_publish_will_msg(Reason, channel()) -> channel() when
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Reason ::
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%% Connection is terminating because session is taken over by another process.
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takenover
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%% Connection is terminating because of EMQX mgmt operation, also delete the session.
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%% Connection is terminating because of EMQX mgmt operation, the session state is deleted with none-zero RC code
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| kicked
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%% Connection is terminating because session is taken over by another process.
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%% Connection is terminating because of client clean start new session.
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| discarded
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%% Connection is terminating because session is expired
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| expired
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%% Connection is terminating because of socket close/error
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| sock_closed
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%% Connection is terminating with Reasons
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| {shutdown, atom()}
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%% Connection is terminating, delay willmsg publish is impossible.
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| ?chan_terminating
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%% Connection is terminating because of normal MQTT disconnection, implies delete the session.
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| normal.
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maybe_publish_will_msg(normal, Channel) ->
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%% [MQTT-3.1.2-8]
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Channel;
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%% Session is terminating, delay willmsg publish is impossible.
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| ?chan_terminating.
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maybe_publish_will_msg(_Reason, Channel = #channel{will_msg = undefined}) ->
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%% No will message to publish
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Channel;
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@ -2286,7 +2281,7 @@ maybe_publish_will_msg(
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ConnState =:= connecting orelse
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ConnState =:= reauthenticating
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->
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%% Wrong state to publish
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%% Wrong state to publish, they are intermediate state
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?tp(debug, willmsg_wrong_state, #{clientid => ClientId}),
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Channel;
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maybe_publish_will_msg(
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@ -2296,7 +2291,7 @@ maybe_publish_will_msg(
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}
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) ->
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%% Unconditionally publish will message for MQTT 3.1.1
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?tp(debug, willmsg_v3, #{clientid => ClientId}),
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?tp(debug, maybe_publish_willmsg_v3, #{clientid => ClientId}),
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_ = publish_will_msg(Channel#channel.clientinfo, WillMsg),
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Channel#channel{will_msg = undefined};
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maybe_publish_will_msg(
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@ -2316,12 +2311,12 @@ maybe_publish_will_msg(
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->
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%% For the cases that session MUST be gone impiles that the will message MUST be published
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%% a. expired (session expired)
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%% b. discarded (Session ends because another process starts new session with the same clientid)
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%% c. kicked. (kicked by operation)
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%% b. discarded (Session ends because of clean start)
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%% c. kicked. (kicked by operation, abnormal conn close)
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%% d. internal_error (maybe not recoverable)
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%% This ensures willmsg will be published if the willmsg timer is scheduled but not fired
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%% OR fired but not yet handled
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?tp(debug, willmsg_session_ends, #{clientid => ClientId}),
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?tp(debug, maybe_publish_willmsg_session_ends, #{clientid => ClientId, reason => Reason}),
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_ = publish_will_msg(ClientInfo, WillMsg),
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remove_willmsg(Channel);
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maybe_publish_will_msg(
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@ -2333,24 +2328,30 @@ maybe_publish_will_msg(
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}
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) ->
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%% TAKEOVER [MQTT-3.1.4-3]
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?tp(debug, willmsg_takeover, #{clientid => ClientId}),
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%% MQTT 5, Non-normative comment:
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%% """"
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%% If a Network Connection uses a Client Identifier of an existing Network Connection to the Server,
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%% the Will Message for the exiting connection is sent unless the new connection specifies Clean Start
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%% of 0 and the Will Delay is greater than zero. If the Will Delay is 0 the Will Message is sent at
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%% the close of the existing Network Connection, and if Clean Start is 1 the Will Message is sent
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%% because the Session ends.
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%% """"
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%% NOTE, above clean start=1 is `discard' scenarios not `takeover' scenario.
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case will_delay_interval(WillMsg) of
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0 ->
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%% MQTT 5, Non-normative comment:
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%% """"
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%% If a Network Connection uses a Client Identifier of an existing Network Connection to the Server,
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%% the Will Message for the exiting connection is sent unless the new connection specifies Clean Start
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%% of 0 and the Will Delay is greater than zero. If the Will Delay is 0 the Will Message is sent at
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%% the close of the existing Network Connection, and if Clean Start is 1 the Will Message is sent
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%% because the Session ends.
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%% """"
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?tp(debug, maybe_publish_willmsg_takenover_pub, #{clientid => ClientId}),
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_ = publish_will_msg(ClientInfo, WillMsg);
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I when I > 0 ->
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%% @NOTE: We do not publish willmsg when EI > 0 but that does not mean we shall delay the willmsg publish
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%% because the session is already takenover by another process. If we delay the willmsg publish, the willmsg
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%% will be published as there is no chance to get it cancelled. This is not stated clearly in the MQTT spec.
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%% @NOTE Non-normative comment in MQTT 5.0 spec
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%% """
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%% One use of this is to avoid publishing Will Messages if there is a temporary network
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%% disconnection and the Client succeeds in reconnecting and continuing its Session
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%% before the Will Message is published.
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%% """
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?tp(debug, maybe_publish_willmsg_takenover_skip, #{clientid => ClientId}),
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skip
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end,
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%% Maybe we should cancel first then send
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remove_willmsg(Channel);
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maybe_publish_will_msg(
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{shutdown, _},
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@ -2363,9 +2364,10 @@ maybe_publish_will_msg(
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%% MQTT 5: 3.1.2.11.2 Session Expiry Interval
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%% If the Session Expiry Interval is absent the value 0 is used.
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%% If it is set to 0, or is absent, the Session ends when the Network Connection is closed.
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%% Expire_interval == 0, means session is over at the time of calling with shutdown.
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?tp(debug, willmsg_takeover, #{clientid => ClientId}),
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%% Expire_interval == 0, means session is end at the time of calling with shutdown.
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?tp(debug, maybe_publish_will_msg_shutdown, #{clientid => ClientId}),
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_ = publish_will_msg(ClientInfo, WillMsg),
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%% Maybe we should cancel first then send
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remove_willmsg(Channel);
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maybe_publish_will_msg(
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Reason,
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@ -2375,14 +2377,17 @@ maybe_publish_will_msg(
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conninfo = #{clientid := ClientId}
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}
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) ->
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%% Handles other Unknown Reasons.
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%% Default to handle other reasons
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case will_delay_interval(WillMsg) of
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0 ->
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?tp(debug, willmsg_other_publish, #{clientid => ClientId, reason => Reason}),
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?tp(debug, maybe_publish_will_msg_other_publish, #{
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clientid => ClientId, reason => Reason
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}),
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_ = publish_will_msg(ClientInfo, WillMsg),
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%% Maybe we should cancel first then send
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remove_willmsg(Channel);
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I when I > 0 ->
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?tp(debug, willmsg_other_delay, #{clientid => ClientId, reason => Reason}),
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?tp(debug, maybe_publish_will_msg_other_delay, #{clientid => ClientId, reason => Reason}),
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ensure_timer(will_message, timer:seconds(I), Channel)
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end.
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@ -41,6 +41,7 @@ init_per_suite(Config) ->
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[emqx],
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#{work_dir => emqx_cth_suite:work_dir(Config)}
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),
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emqx_logger:set_log_level(debug),
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[{apps, Apps} | Config].
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end_per_suite(Config) ->
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@ -284,7 +285,7 @@ t_takeover_clean_session_with_delayed_willmsg(Config) ->
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ct:pal("received: ~p", [[P || #{payload := P} <- Received]]),
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{IsWill1, ReceivedNoWill0} = filter_payload(Received, <<"willpayload_delay10">>),
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{IsWill2, _ReceivedNoWill} = filter_payload(ReceivedNoWill0, <<"willpayload_2">>),
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%% THEN: payload <<"willpayload_delay10">> should be published without delay.
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%% THEN: payload <<"willpayload_delay10">> should be published without delay
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?assert(IsWill1),
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?assertNot(IsWill2),
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emqtt:stop(CPid2),
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@ -432,7 +433,7 @@ t_takeover_before_session_expire_willdelay0(Config) ->
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],
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Commands =
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%% GIVEN: client connect with willmsg payload <<"willpayload_delay10">>
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%% and delay-interval 10s session expiry 3s.
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%% and delay-interval 0s session expiry 3s.
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[{fun start_client/5, [ClientId, ClientId, ?QOS_1, WillOpts]}] ++
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[
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{fun start_client/5, [
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@ -467,6 +468,7 @@ t_takeover_before_session_expire_willdelay0(Config) ->
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Received = [Msg || {publish, Msg} <- ?drainMailbox(1000)],
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ct:pal("received: ~p", [[P || #{payload := P} <- Received]]),
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{IsWill, _ReceivedNoWill} = filter_payload(Received, <<"willpayload_delay10">>),
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%% THEN: willmsg is published
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?assert(IsWill),
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emqtt:stop(CPidSub),
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emqtt:stop(CPid2),
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@ -526,6 +528,7 @@ t_takeover_before_session_expire(Config) ->
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Received = [Msg || {publish, Msg} <- ?drainMailbox(1000)],
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ct:pal("received: ~p", [[P || #{payload := P} <- Received]]),
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{IsWill, ReceivedNoWill} = filter_payload(Received, <<"willpayload_delay10">>),
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%% THEN: No Willmsg is published
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?assertNot(IsWill),
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?assertNotEqual([], ReceivedNoWill),
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emqtt:stop(CPidSub),
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@ -610,7 +613,7 @@ t_takeover_session_then_abnormal_disconnect(Config) ->
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],
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Commands =
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%% GIVEN: client connect with willmsg payload <<"willpayload_delay10">>
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%% and delay-interval 10s, session expiry 3s.
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%% and will-delay-interval 10s > session expiry 3s.
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[{fun start_client/5, [ClientId, ClientId, ?QOS_1, WillOpts]}] ++
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[
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{fun start_client/5, [
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@ -645,7 +648,7 @@ t_takeover_session_then_abnormal_disconnect(Config) ->
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Received = [Msg || {publish, Msg} <- ?drainMailbox(1000)],
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ct:pal("received: ~p", [[P || #{payload := P} <- Received]]),
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{IsWill, ReceivedNoWill} = filter_payload(Received, <<"willpayload_delay10">>),
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%% THEN: willmsg is published before session expiry
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%% THEN: willmsg is not published before session expiry
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?assertNot(IsWill),
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?assertNotEqual([], ReceivedNoWill),
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Received1 = [Msg || {publish, Msg} <- ?drainMailbox(3000)],
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@ -668,7 +671,16 @@ t_takeover_session_then_abnormal_disconnect_2(Config) ->
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{proto_ver, ?config(mqtt_vsn, Config)},
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{clean_start, false},
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{will_topic, WillTopic},
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{will_payload, <<"willpayload_delay10">>},
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{will_payload, <<"willpayload_delay1">>},
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{will_qos, 1},
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{will_props, #{'Will-Delay-Interval' => 1}},
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{properties, #{'Session-Expiry-Interval' => 3}}
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],
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WillOpts2 = [
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{proto_ver, ?config(mqtt_vsn, Config)},
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{clean_start, false},
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{will_topic, WillTopic},
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{will_payload, <<"willpayload_delay2">>},
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{will_qos, 1},
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{will_props, #{'Will-Delay-Interval' => 0}},
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{properties, #{'Session-Expiry-Interval' => 3}}
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@ -691,9 +703,9 @@ t_takeover_session_then_abnormal_disconnect_2(Config) ->
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[]
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}
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] ++
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%% GIVEN: client reconnect with willmsg payload <<"willpayload_delay10">>
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%% and delay-interval 0s, session expiry 3s.
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[{fun start_client/5, [ClientId, ClientId, ?QOS_1, WillOpts]}],
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%% GIVEN: client *reconnect* with willmsg payload <<"willpayload_delay2">>
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%% and will-delay-interval 0s, session expiry 3s.
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[{fun start_client/5, [ClientId, ClientId, ?QOS_1, WillOpts2]}],
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FCtx = lists:foldl(
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fun({Fun, Args}, Ctx) ->
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@ -707,12 +719,15 @@ t_takeover_session_then_abnormal_disconnect_2(Config) ->
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assert_client_exit(CPid1, ?config(mqtt_vsn, Config), takenover),
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%% WHEN: client disconnect abnormally
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emqtt:disconnect(CPid2, ?RC_DISCONNECT_WITH_WILL_MESSAGE),
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Received = [Msg || {publish, Msg} <- ?drainMailbox(1000)],
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Received = [Msg || {publish, Msg} <- ?drainMailbox(2000)],
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ct:pal("received: ~p", [[P || #{payload := P} <- Received]]),
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{IsWill, ReceivedNoWill} = filter_payload(Received, <<"willpayload_delay10">>),
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%% THEN: willmsg is published after session expiry
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?assert(IsWill),
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{IsWill, ReceivedNoWill} = filter_payload(Received, <<"willpayload_delay1">>),
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%% THEN: willmsg1 of old conn is not published because will-delay-interval > 0
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?assertNot(IsWill),
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?assertNotEqual([], ReceivedNoWill),
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%% THEN: willmsg1 is published because will-delay-interval is 0
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{IsWill2, _} = filter_payload(Received, <<"willpayload_delay2">>),
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?assert(IsWill2),
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emqtt:stop(CPidSub),
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?assert(not is_process_alive(CPid1)),
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?assert(not is_process_alive(CPid2)),
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