%% 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) 2010-2013 VMware, Inc. All rights reserved. %% -module(rabbit_mirror_queue_slave). %% For general documentation of HA design, see %% rabbit_mirror_queue_coordinator %% %% We receive messages from GM and from publishers, and the gm %% messages can arrive either before or after the 'actual' message. %% All instructions from the GM group must be processed in the order %% in which they're received. -export([start_link/1, set_maximum_since_use/2, info/1]). -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3, handle_pre_hibernate/1, prioritise_call/3, prioritise_cast/2, prioritise_info/2]). -export([joined/2, members_changed/3, handle_msg/3]). -behaviour(gen_server2). -behaviour(gm). -include("rabbit.hrl"). %%---------------------------------------------------------------------------- -include("gm_specs.hrl"). -ifdef(use_specs). %% Shut dialyzer up -spec(promote_me/2 :: (_, _) -> no_return()). -endif. %%---------------------------------------------------------------------------- -define(CREATION_EVENT_KEYS, [pid, name, master_pid, is_synchronised ]). -define(INFO_KEYS, ?CREATION_EVENT_KEYS). -define(SYNC_INTERVAL, 25). %% milliseconds -define(RAM_DURATION_UPDATE_INTERVAL, 5000). -define(DEATH_TIMEOUT, 20000). %% 20 seconds -record(state, { q, gm, backing_queue, backing_queue_state, sync_timer_ref, rate_timer_ref, sender_queues, %% :: Pid -> {Q Msg, Set MsgId} msg_id_ack, %% :: MsgId -> AckTag msg_id_status, known_senders, %% Master depth - local depth depth_delta }). start_link(Q) -> gen_server2:start_link(?MODULE, Q, []). set_maximum_since_use(QPid, Age) -> gen_server2:cast(QPid, {set_maximum_since_use, Age}). info(QPid) -> gen_server2:call(QPid, info, infinity). init(Q = #amqqueue { name = QName }) -> %% We join the GM group before we add ourselves to the amqqueue %% record. As a result: %% 1. We can receive msgs from GM that correspond to messages we will %% never receive from publishers. %% 2. When we receive a message from publishers, we must receive a %% message from the GM group for it. %% 3. However, that instruction from the GM group can arrive either %% before or after the actual message. We need to be able to %% distinguish between GM instructions arriving early, and case (1) %% above. %% process_flag(trap_exit, true), %% amqqueue_process traps exits too. {ok, GM} = gm:start_link(QName, ?MODULE, [self()], fun rabbit_misc:execute_mnesia_transaction/1), receive {joined, GM} -> ok end, Self = self(), Node = node(), case rabbit_misc:execute_mnesia_transaction( fun() -> init_it(Self, GM, Node, QName) end) of {new, QPid} -> erlang:monitor(process, QPid), ok = file_handle_cache:register_callback( rabbit_amqqueue, set_maximum_since_use, [Self]), ok = rabbit_memory_monitor:register( Self, {rabbit_amqqueue, set_ram_duration_target, [Self]}), {ok, BQ} = application:get_env(backing_queue_module), Q1 = Q #amqqueue { pid = QPid }, BQS = bq_init(BQ, Q1, false), State = #state { q = Q1, gm = GM, backing_queue = BQ, backing_queue_state = BQS, rate_timer_ref = undefined, sync_timer_ref = undefined, sender_queues = dict:new(), msg_id_ack = dict:new(), msg_id_status = dict:new(), known_senders = pmon:new(), depth_delta = undefined }, rabbit_event:notify(queue_slave_created, infos(?CREATION_EVENT_KEYS, State)), ok = gm:broadcast(GM, request_depth), {ok, State, hibernate, {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}; {stale, StalePid} -> {stop, {stale_master_pid, StalePid}}; duplicate_live_master -> {stop, {duplicate_live_master, Node}}; existing -> gm:leave(GM), ignore end. init_it(Self, GM, Node, QName) -> [Q = #amqqueue { pid = QPid, slave_pids = SPids, gm_pids = GMPids }] = mnesia:read({rabbit_queue, QName}), case [Pid || Pid <- [QPid | SPids], node(Pid) =:= Node] of [] -> add_slave(Q, Self, GM), {new, QPid}; [QPid] -> case rabbit_misc:is_process_alive(QPid) of true -> duplicate_live_master; false -> {stale, QPid} end; [SPid] -> case rabbit_misc:is_process_alive(SPid) of true -> existing; false -> Q1 = Q#amqqueue { slave_pids = SPids -- [SPid], gm_pids = [T || T = {_, S} <- GMPids, S =/= SPid] }, add_slave(Q1, Self, GM), {new, QPid} end end. %% Add to the end, so they are in descending order of age, see %% rabbit_mirror_queue_misc:promote_slave/1 add_slave(Q = #amqqueue { slave_pids = SPids, gm_pids = GMPids }, New, GM) -> rabbit_mirror_queue_misc:store_updated_slaves( Q#amqqueue{slave_pids = SPids ++ [New], gm_pids = [{GM, New} | GMPids]}). handle_call({deliver, Delivery, true}, From, State) -> %% Synchronous, "mandatory" deliver mode. gen_server2:reply(From, ok), noreply(maybe_enqueue_message(Delivery, State)); handle_call({gm_deaths, Deaths}, From, State = #state { q = Q = #amqqueue { name = QName, pid = MPid }}) -> Self = self(), case rabbit_mirror_queue_misc:remove_from_queue(QName, Self, Deaths) of {error, not_found} -> gen_server2:reply(From, ok), {stop, normal, State}; {ok, Pid, DeadPids} -> rabbit_mirror_queue_misc:report_deaths(Self, false, QName, DeadPids), case Pid of MPid -> %% master hasn't changed gen_server2:reply(From, ok), noreply(State); Self -> %% we've become master QueueState = promote_me(From, State), {become, rabbit_amqqueue_process, QueueState, hibernate}; _ -> %% master has changed to not us gen_server2:reply(From, ok), erlang:monitor(process, Pid), noreply(State #state { q = Q #amqqueue { pid = Pid } }) end end; handle_call(info, _From, State) -> reply(infos(?INFO_KEYS, State), State). handle_cast({run_backing_queue, Mod, Fun}, State) -> noreply(run_backing_queue(Mod, Fun, State)); handle_cast({gm, Instruction}, State) -> handle_process_result(process_instruction(Instruction, State)); handle_cast({deliver, Delivery = #delivery{sender = Sender}, true, Flow}, State) -> %% Asynchronous, non-"mandatory", deliver mode. case Flow of flow -> credit_flow:ack(Sender); noflow -> ok end, noreply(maybe_enqueue_message(Delivery, State)); handle_cast({set_maximum_since_use, Age}, State) -> ok = file_handle_cache:set_maximum_since_use(Age), noreply(State); handle_cast({set_ram_duration_target, Duration}, State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> BQS1 = BQ:set_ram_duration_target(Duration, BQS), noreply(State #state { backing_queue_state = BQS1 }). handle_info(update_ram_duration, State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> {RamDuration, BQS1} = BQ:ram_duration(BQS), DesiredDuration = rabbit_memory_monitor:report_ram_duration(self(), RamDuration), BQS2 = BQ:set_ram_duration_target(DesiredDuration, BQS1), %% Don't call noreply/1, we don't want to set timers {State1, Timeout} = next_state(State #state { rate_timer_ref = undefined, backing_queue_state = BQS2 }), {noreply, State1, Timeout}; handle_info(sync_timeout, State) -> noreply(backing_queue_timeout( State #state { sync_timer_ref = undefined })); handle_info(timeout, State) -> noreply(backing_queue_timeout(State)); handle_info({'DOWN', _MonitorRef, process, MPid, _Reason}, State = #state { gm = GM, q = #amqqueue { pid = MPid } }) -> ok = gm:broadcast(GM, process_death), noreply(State); handle_info({'DOWN', _MonitorRef, process, ChPid, _Reason}, State) -> noreply(local_sender_death(ChPid, State)); handle_info({'EXIT', _Pid, Reason}, State) -> {stop, Reason, State}; handle_info({bump_credit, Msg}, State) -> credit_flow:handle_bump_msg(Msg), noreply(State); handle_info(Msg, State) -> {stop, {unexpected_info, Msg}, State}. %% If the Reason is shutdown, or {shutdown, _}, it is not the queue %% being deleted: it's just the node going down. Even though we're a %% slave, we have no idea whether or not we'll be the only copy coming %% back up. Thus we must assume we will be, and preserve anything we %% have on disk. terminate(_Reason, #state { backing_queue_state = undefined }) -> %% We've received a delete_and_terminate from gm, thus nothing to %% do here. ok; terminate({shutdown, dropped} = R, #state { backing_queue = BQ, backing_queue_state = BQS }) -> %% See rabbit_mirror_queue_master:terminate/2 BQ:delete_and_terminate(R, BQS); terminate(Reason, #state { q = Q, gm = GM, backing_queue = BQ, backing_queue_state = BQS, rate_timer_ref = RateTRef }) -> ok = gm:leave(GM), QueueState = rabbit_amqqueue_process:init_with_backing_queue_state( Q, BQ, BQS, RateTRef, [], pmon:new(), dict:new()), rabbit_amqqueue_process:terminate(Reason, QueueState); terminate([_SPid], _Reason) -> %% gm case ok. code_change(_OldVsn, State, _Extra) -> {ok, State}. handle_pre_hibernate(State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> {RamDuration, BQS1} = BQ:ram_duration(BQS), DesiredDuration = rabbit_memory_monitor:report_ram_duration(self(), RamDuration), BQS2 = BQ:set_ram_duration_target(DesiredDuration, BQS1), BQS3 = BQ:handle_pre_hibernate(BQS2), {hibernate, stop_rate_timer(State #state { backing_queue_state = BQS3 })}. prioritise_call(Msg, _From, _State) -> case Msg of info -> 9; {gm_deaths, _Deaths} -> 5; _ -> 0 end. prioritise_cast(Msg, _State) -> case Msg of {set_ram_duration_target, _Duration} -> 8; {set_maximum_since_use, _Age} -> 8; {run_backing_queue, _Mod, _Fun} -> 6; {gm, _Msg} -> 5; {post_commit, _Txn, _AckTags} -> 4; _ -> 0 end. prioritise_info(Msg, _State) -> case Msg of update_ram_duration -> 8; sync_timeout -> 6; _ -> 0 end. %% --------------------------------------------------------------------------- %% GM %% --------------------------------------------------------------------------- joined([SPid], _Members) -> SPid ! {joined, self()}, ok. members_changed([_SPid], _Births, []) -> ok; members_changed([ SPid], _Births, Deaths) -> inform_deaths(SPid, Deaths). handle_msg([_SPid], _From, request_depth) -> %% This is only of value to the master ok; handle_msg([_SPid], _From, {ensure_monitoring, _Pid}) -> %% This is only of value to the master ok; handle_msg([_SPid], _From, process_death) -> %% Since GM is by nature lazy we need to make sure there is some %% traffic when a master dies, to make sure we get informed of the %% death. That's all process_death does, create some traffic. We %% must not take any notice of the master death here since it %% comes without ordering guarantees - there could still be %% messages from the master we have yet to receive. When we get %% members_changed, then there will be no more messages. ok; handle_msg([CPid], _From, {delete_and_terminate, _Reason} = Msg) -> ok = gen_server2:cast(CPid, {gm, Msg}), {stop, {shutdown, ring_shutdown}}; handle_msg([SPid], _From, Msg) -> ok = gen_server2:cast(SPid, {gm, Msg}). inform_deaths(SPid, Deaths) -> case gen_server2:call(SPid, {gm_deaths, Deaths}, infinity) of ok -> ok; {promote, CPid} -> {become, rabbit_mirror_queue_coordinator, [CPid]} end. %% --------------------------------------------------------------------------- %% Others %% --------------------------------------------------------------------------- infos(Items, State) -> [{Item, i(Item, State)} || Item <- Items]. i(pid, _State) -> self(); i(name, #state { q = #amqqueue { name = Name } }) -> Name; i(master_pid, #state { q = #amqqueue { pid = MPid } }) -> MPid; i(is_synchronised, #state { depth_delta = DD }) -> DD =:= 0; i(Item, _State) -> throw({bad_argument, Item}). bq_init(BQ, Q, Recover) -> Self = self(), BQ:init(Q, Recover, fun (Mod, Fun) -> rabbit_amqqueue:run_backing_queue(Self, Mod, Fun) end). run_backing_queue(rabbit_mirror_queue_master, Fun, State) -> %% Yes, this might look a little crazy, but see comments in %% confirm_sender_death/1 Fun(?MODULE, State); run_backing_queue(Mod, Fun, State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> State #state { backing_queue_state = BQ:invoke(Mod, Fun, BQS) }. send_or_record_confirm(_, #delivery{ msg_seq_no = undefined }, MS, _State) -> MS; send_or_record_confirm(published, #delivery { sender = ChPid, msg_seq_no = MsgSeqNo, message = #basic_message { id = MsgId, is_persistent = true } }, MS, #state { q = #amqqueue { durable = true } }) -> dict:store(MsgId, {published, ChPid, MsgSeqNo} , MS); send_or_record_confirm(_Status, #delivery { sender = ChPid, msg_seq_no = MsgSeqNo }, MS, _State) -> ok = rabbit_misc:confirm_to_sender(ChPid, [MsgSeqNo]), MS. confirm_messages(MsgIds, State = #state { msg_id_status = MS }) -> {CMs, MS1} = lists:foldl( fun (MsgId, {CMsN, MSN} = Acc) -> %% We will never see 'discarded' here case dict:find(MsgId, MSN) of error -> %% If it needed confirming, it'll have %% already been done. Acc; {ok, published} -> %% Still not seen it from the channel, just %% record that it's been confirmed. {CMsN, dict:store(MsgId, confirmed, MSN)}; {ok, {published, ChPid, MsgSeqNo}} -> %% Seen from both GM and Channel. Can now %% confirm. {rabbit_misc:gb_trees_cons(ChPid, MsgSeqNo, CMsN), dict:erase(MsgId, MSN)}; {ok, confirmed} -> %% It's already been confirmed. This is %% probably it's been both sync'd to disk %% and then delivered and ack'd before we've %% seen the publish from the %% channel. Nothing to do here. Acc end end, {gb_trees:empty(), MS}, MsgIds), rabbit_misc:gb_trees_foreach(fun rabbit_misc:confirm_to_sender/2, CMs), State #state { msg_id_status = MS1 }. handle_process_result({ok, State}) -> noreply(State); handle_process_result({stop, State}) -> {stop, normal, State}. promote_me(From, #state { q = Q = #amqqueue { name = QName }, gm = GM, backing_queue = BQ, backing_queue_state = BQS, rate_timer_ref = RateTRef, sender_queues = SQ, msg_id_ack = MA, msg_id_status = MS, known_senders = KS }) -> rabbit_log:info("Mirrored-queue (~s): Promoting slave ~s to master~n", [rabbit_misc:rs(QName), rabbit_misc:pid_to_string(self())]), Q1 = Q #amqqueue { pid = self() }, {ok, CPid} = rabbit_mirror_queue_coordinator:start_link( Q1, GM, rabbit_mirror_queue_master:sender_death_fun(), rabbit_mirror_queue_master:depth_fun()), true = unlink(GM), gen_server2:reply(From, {promote, CPid}), %% Everything that we're monitoring, we need to ensure our new %% coordinator is monitoring. MPids = pmon:monitored(KS), ok = rabbit_mirror_queue_coordinator:ensure_monitoring(CPid, MPids), %% We find all the messages that we've received from channels but %% not from gm, and pass them to the %% queue_process:init_with_backing_queue_state to be enqueued. %% %% We also have to requeue messages which are pending acks: the %% consumers from the master queue have been lost and so these %% messages need requeuing. They might also be pending %% confirmation, and indeed they might also be pending arrival of %% the publication from the channel itself, if we received both %% the publication and the fetch via gm first! Requeuing doesn't %% affect confirmations: if the message was previously pending a %% confirmation then it still will be, under the same msg_id. So %% as a master, we need to be prepared to filter out the %% publication of said messages from the channel (is_duplicate %% (thus such requeued messages must remain in the msg_id_status %% (MS) which becomes seen_status (SS) in the master)). %% %% Then there are messages we already have in the queue, which are %% not currently pending acknowledgement: %% 1. Messages we've only received via gm: %% Filter out subsequent publication from channel through %% validate_message. Might have to issue confirms then or %% later, thus queue_process state will have to know that %% there's a pending confirm. %% 2. Messages received via both gm and channel: %% Queue will have to deal with issuing confirms if necessary. %% %% MS contains the following three entry types: %% %% a) published: %% published via gm only; pending arrival of publication from %% channel, maybe pending confirm. %% %% b) {published, ChPid, MsgSeqNo}: %% published via gm and channel; pending confirm. %% %% c) confirmed: %% published via gm only, and confirmed; pending publication %% from channel. %% %% d) discarded: %% seen via gm only as discarded. Pending publication from %% channel %% %% The forms a, c and d only, need to go to the master state %% seen_status (SS). %% %% The form b only, needs to go through to the queue_process %% state to form the msg_id_to_channel mapping (MTC). %% %% No messages that are enqueued from SQ at this point will have %% entries in MS. %% %% Messages that are extracted from MA may have entries in MS, and %% those messages are then requeued. However, as discussed above, %% this does not affect MS, nor which bits go through to SS in %% Master, or MTC in queue_process. St = [published, confirmed, discarded], SS = dict:filter(fun (_MsgId, Status) -> lists:member(Status, St) end, MS), AckTags = [AckTag || {_MsgId, AckTag} <- dict:to_list(MA)], MasterState = rabbit_mirror_queue_master:promote_backing_queue_state( CPid, BQ, BQS, GM, AckTags, SS, MPids), MTC = dict:fold(fun (MsgId, {published, ChPid, MsgSeqNo}, MTC0) -> gb_trees:insert(MsgId, {ChPid, MsgSeqNo}, MTC0); (_Msgid, _Status, MTC0) -> MTC0 end, gb_trees:empty(), MS), Deliveries = [Delivery || {_ChPid, {PubQ, _PendCh}} <- dict:to_list(SQ), Delivery <- queue:to_list(PubQ)], rabbit_amqqueue_process:init_with_backing_queue_state( Q1, rabbit_mirror_queue_master, MasterState, RateTRef, Deliveries, KS, MTC). noreply(State) -> {NewState, Timeout} = next_state(State), {noreply, ensure_rate_timer(NewState), Timeout}. reply(Reply, State) -> {NewState, Timeout} = next_state(State), {reply, Reply, ensure_rate_timer(NewState), Timeout}. next_state(State = #state{backing_queue = BQ, backing_queue_state = BQS}) -> {MsgIds, BQS1} = BQ:drain_confirmed(BQS), State1 = confirm_messages(MsgIds, State #state { backing_queue_state = BQS1 }), case BQ:needs_timeout(BQS1) of false -> {stop_sync_timer(State1), hibernate }; idle -> {stop_sync_timer(State1), ?SYNC_INTERVAL}; timed -> {ensure_sync_timer(State1), 0 } end. backing_queue_timeout(State = #state { backing_queue = BQ }) -> run_backing_queue(BQ, fun (M, BQS) -> M:timeout(BQS) end, State). ensure_sync_timer(State = #state { sync_timer_ref = undefined }) -> TRef = erlang:send_after(?SYNC_INTERVAL, self(), sync_timeout), State #state { sync_timer_ref = TRef }; ensure_sync_timer(State) -> State. stop_sync_timer(State = #state { sync_timer_ref = undefined }) -> State; stop_sync_timer(State = #state { sync_timer_ref = TRef }) -> erlang:cancel_timer(TRef), State #state { sync_timer_ref = undefined }. ensure_rate_timer(State = #state { rate_timer_ref = undefined }) -> TRef = erlang:send_after(?RAM_DURATION_UPDATE_INTERVAL, self(), update_ram_duration), State #state { rate_timer_ref = TRef }; ensure_rate_timer(State) -> State. stop_rate_timer(State = #state { rate_timer_ref = undefined }) -> State; stop_rate_timer(State = #state { rate_timer_ref = TRef }) -> erlang:cancel_timer(TRef), State #state { rate_timer_ref = undefined }. ensure_monitoring(ChPid, State = #state { known_senders = KS }) -> State #state { known_senders = pmon:monitor(ChPid, KS) }. local_sender_death(ChPid, State = #state { known_senders = KS }) -> ok = case pmon:is_monitored(ChPid, KS) of false -> ok; true -> credit_flow:peer_down(ChPid), confirm_sender_death(ChPid) end, State. confirm_sender_death(Pid) -> %% We have to deal with the possibility that we'll be promoted to %% master before this thing gets run. Consequently we set the %% module to rabbit_mirror_queue_master so that if we do become a %% rabbit_amqqueue_process before then, sane things will happen. Fun = fun (?MODULE, State = #state { known_senders = KS, gm = GM }) -> %% We're running still as a slave ok = case pmon:is_monitored(Pid, KS) of false -> ok; true -> gm:broadcast(GM, {ensure_monitoring, [Pid]}), confirm_sender_death(Pid) end, State; (rabbit_mirror_queue_master, State) -> %% We've become a master. State is now opaque to %% us. When we became master, if Pid was still known %% to us then we'd have set up monitoring of it then, %% so this is now a noop. State end, %% Note that we do not remove our knowledge of this ChPid until we %% get the sender_death from GM. {ok, _TRef} = timer:apply_after( ?DEATH_TIMEOUT, rabbit_amqqueue, run_backing_queue, [self(), rabbit_mirror_queue_master, Fun]), ok. maybe_enqueue_message( Delivery = #delivery { message = #basic_message { id = MsgId }, sender = ChPid }, State = #state { sender_queues = SQ, msg_id_status = MS }) -> State1 = ensure_monitoring(ChPid, State), %% We will never see {published, ChPid, MsgSeqNo} here. case dict:find(MsgId, MS) of error -> {MQ, PendingCh} = get_sender_queue(ChPid, SQ), MQ1 = queue:in(Delivery, MQ), SQ1 = dict:store(ChPid, {MQ1, PendingCh}, SQ), State1 #state { sender_queues = SQ1 }; {ok, Status} -> MS1 = send_or_record_confirm( Status, Delivery, dict:erase(MsgId, MS), State1), SQ1 = remove_from_pending_ch(MsgId, ChPid, SQ), State1 #state { msg_id_status = MS1, sender_queues = SQ1 } end. get_sender_queue(ChPid, SQ) -> case dict:find(ChPid, SQ) of error -> {queue:new(), sets:new()}; {ok, Val} -> Val end. remove_from_pending_ch(MsgId, ChPid, SQ) -> case dict:find(ChPid, SQ) of error -> SQ; {ok, {MQ, PendingCh}} -> dict:store(ChPid, {MQ, sets:del_element(MsgId, PendingCh)}, SQ) end. publish_or_discard(Status, ChPid, MsgId, State = #state { sender_queues = SQ, msg_id_status = MS }) -> %% We really are going to do the publish/discard right now, even %% though we may not have seen it directly from the channel. But %% we cannot issues confirms until the latter has happened. So we %% need to keep track of the MsgId and its confirmation status in %% the meantime. State1 = ensure_monitoring(ChPid, State), {MQ, PendingCh} = get_sender_queue(ChPid, SQ), {MQ1, PendingCh1, MS1} = case queue:out(MQ) of {empty, _MQ2} -> {MQ, sets:add_element(MsgId, PendingCh), dict:store(MsgId, Status, MS)}; {{value, Delivery = #delivery { message = #basic_message { id = MsgId } }}, MQ2} -> {MQ2, PendingCh, %% We received the msg from the channel first. Thus %% we need to deal with confirms here. send_or_record_confirm(Status, Delivery, MS, State1)}; {{value, #delivery {}}, _MQ2} -> %% The instruction was sent to us before we were %% within the slave_pids within the #amqqueue{} %% record. We'll never receive the message directly %% from the channel. And the channel will not be %% expecting any confirms from us. {MQ, PendingCh, MS} end, SQ1 = dict:store(ChPid, {MQ1, PendingCh1}, SQ), State1 #state { sender_queues = SQ1, msg_id_status = MS1 }. process_instruction({publish, ChPid, MsgProps, Msg = #basic_message { id = MsgId }}, State) -> State1 = #state { backing_queue = BQ, backing_queue_state = BQS } = publish_or_discard(published, ChPid, MsgId, State), BQS1 = BQ:publish(Msg, MsgProps, ChPid, BQS), {ok, State1 #state { backing_queue_state = BQS1 }}; process_instruction({publish_delivered, ChPid, MsgProps, Msg = #basic_message { id = MsgId }}, State) -> State1 = #state { backing_queue = BQ, backing_queue_state = BQS } = publish_or_discard(published, ChPid, MsgId, State), {AckTag, BQS1} = BQ:publish_delivered(Msg, MsgProps, ChPid, BQS), {ok, maybe_store_ack(true, MsgId, AckTag, State1 #state { backing_queue_state = BQS1 })}; process_instruction({discard, ChPid, MsgId}, State) -> State1 = #state { backing_queue = BQ, backing_queue_state = BQS } = publish_or_discard(discarded, ChPid, MsgId, State), BQS1 = BQ:discard(MsgId, ChPid, BQS), {ok, State1 #state { backing_queue_state = BQS1 }}; process_instruction({drop, Length, Dropped, AckRequired}, State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> QLen = BQ:len(BQS), ToDrop = case QLen - Length of N when N > 0 -> N; _ -> 0 end, State1 = lists:foldl( fun (const, StateN = #state{backing_queue_state = BQSN}) -> {{#basic_message{id = MsgId}, _, AckTag, _}, BQSN1} = BQ:fetch(AckRequired, BQSN), maybe_store_ack( AckRequired, MsgId, AckTag, StateN #state { backing_queue_state = BQSN1 }) end, State, lists:duplicate(ToDrop, const)), {ok, case AckRequired of true -> State1; false -> update_delta(ToDrop - Dropped, State1) end}; process_instruction({fetch, AckRequired, MsgId, Remaining}, State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> QLen = BQ:len(BQS), {ok, case QLen - 1 of Remaining -> {{#basic_message{id = MsgId}, _IsDelivered, AckTag, Remaining}, BQS1} = BQ:fetch(AckRequired, BQS), maybe_store_ack(AckRequired, MsgId, AckTag, State #state { backing_queue_state = BQS1 }); _ when QLen =< Remaining andalso AckRequired -> State; _ when QLen =< Remaining -> update_delta(-1, State) end}; process_instruction({ack, MsgIds}, State = #state { backing_queue = BQ, backing_queue_state = BQS, msg_id_ack = MA }) -> {AckTags, MA1} = msg_ids_to_acktags(MsgIds, MA), {MsgIds1, BQS1} = BQ:ack(AckTags, BQS), [] = MsgIds1 -- MsgIds, %% ASSERTION {ok, update_delta(length(MsgIds1) - length(MsgIds), State #state { msg_id_ack = MA1, backing_queue_state = BQS1 })}; process_instruction({requeue, MsgIds}, State = #state { backing_queue = BQ, backing_queue_state = BQS, msg_id_ack = MA }) -> {AckTags, MA1} = msg_ids_to_acktags(MsgIds, MA), {_MsgIds, BQS1} = BQ:requeue(AckTags, BQS), {ok, State #state { msg_id_ack = MA1, backing_queue_state = BQS1 }}; process_instruction({sender_death, ChPid}, State = #state { sender_queues = SQ, msg_id_status = MS, known_senders = KS }) -> {ok, case pmon:is_monitored(ChPid, KS) of false -> State; true -> MS1 = case dict:find(ChPid, SQ) of error -> MS; {ok, {_MQ, PendingCh}} -> lists:foldl(fun dict:erase/2, MS, sets:to_list(PendingCh)) end, State #state { sender_queues = dict:erase(ChPid, SQ), msg_id_status = MS1, known_senders = pmon:demonitor(ChPid, KS) } end}; process_instruction({depth, Depth}, State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> {ok, set_delta(Depth - BQ:depth(BQS), State)}; process_instruction({delete_and_terminate, Reason}, State = #state { backing_queue = BQ, backing_queue_state = BQS }) -> BQ:delete_and_terminate(Reason, BQS), {stop, State #state { backing_queue_state = undefined }}. msg_ids_to_acktags(MsgIds, MA) -> {AckTags, MA1} = lists:foldl( fun (MsgId, {Acc, MAN}) -> case dict:find(MsgId, MA) of error -> {Acc, MAN}; {ok, AckTag} -> {[AckTag | Acc], dict:erase(MsgId, MAN)} end end, {[], MA}, MsgIds), {lists:reverse(AckTags), MA1}. maybe_store_ack(false, _MsgId, _AckTag, State) -> State; maybe_store_ack(true, MsgId, AckTag, State = #state { msg_id_ack = MA }) -> State #state { msg_id_ack = dict:store(MsgId, AckTag, MA) }. set_delta(0, State = #state { depth_delta = undefined }) -> ok = record_synchronised(State#state.q), State #state { depth_delta = 0 }; set_delta(NewDelta, State = #state { depth_delta = undefined }) -> true = NewDelta > 0, %% assertion State #state { depth_delta = NewDelta }; set_delta(NewDelta, State = #state { depth_delta = Delta }) -> update_delta(NewDelta - Delta, State). update_delta(_DeltaChange, State = #state { depth_delta = undefined }) -> State; update_delta( DeltaChange, State = #state { depth_delta = 0 }) -> 0 = DeltaChange, %% assertion: we cannot become unsync'ed State; update_delta( DeltaChange, State = #state { depth_delta = Delta }) -> true = DeltaChange =< 0, %% assertion: we cannot become 'less' sync'ed set_delta(Delta + DeltaChange, State #state { depth_delta = undefined }). record_synchronised(#amqqueue { name = QName }) -> Self = self(), rabbit_misc:execute_mnesia_transaction( fun () -> case mnesia:read({rabbit_queue, QName}) of [] -> ok; [Q = #amqqueue { sync_slave_pids = SSPids }] -> rabbit_mirror_queue_misc:store_updated_slaves( Q #amqqueue { sync_slave_pids = [Self | SSPids] }), ok end end).