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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 GoPivotal, Inc.
%% Copyright (c) 2010-2014 GoPivotal, 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([set_maximum_since_use/2, info/1, init_slave/1, await/1]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
code_change/3, handle_pre_hibernate/1, prioritise_call/4,
prioritise_cast/3, prioritise_info/3, format_message_queue/2]).
-export([joined/2, members_changed/3, handle_msg/3]).
-behaviour(gen_server2).
-behaviour(gm).
-include("rabbit.hrl").
-include("gm_specs.hrl").
%%----------------------------------------------------------------------------
-define(INFO_KEYS,
[pid,
name,
master_pid,
is_synchronised
]).
-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, ChState}
msg_id_ack, %% :: MsgId -> AckTag
msg_id_status,
known_senders,
%% Master depth - local depth
depth_delta
}).
%%----------------------------------------------------------------------------
set_maximum_since_use(QPid, Age) ->
gen_server2:cast(QPid, {set_maximum_since_use, Age}).
info(QPid) -> gen_server2:call(QPid, info, infinity).
await(SPid) -> gen_server2:call(SPid, await, infinity).
init(_) -> exit(cannot_be_called_directly).
init_slave(Q = #amqqueue{name = QName}) ->
?store_proc_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),
MRef = erlang:monitor(process, GM),
%% We ignore the DOWN message because we are also linked and
%% trapping exits, we just want to not get stuck and we will exit
%% later.
receive
{joined, GM} -> erlang:demonitor(MRef, [flush]),
ok;
{'DOWN', MRef, _, _, _} -> ok
end,
Self = self(),
Node = node(),
case rabbit_misc:execute_mnesia_transaction(
fun() -> init_it(Self, GM, Node, QName) end) of
{new, QPid, GMPids} ->
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 },
ok = rabbit_queue_index:erase(QName), %% For crash recovery
BQS = bq_init(BQ, Q1, new),
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(delegate),
depth_delta = undefined
},
ok = gm:broadcast(GM, request_depth),
ok = gm:validate_members(GM, [GM | [G || {G, _} <- GMPids]]),
rabbit_mirror_queue_misc:maybe_auto_sync(Q1),
{become, ?MODULE, State, hibernate};
{stale, StalePid} ->
rabbit_mirror_queue_misc:log_warning(
QName, "Detected stale HA master: ~p~n", [StalePid]),
gm:leave(GM),
{stop, {stale_master_pid, StalePid}, Q};
duplicate_live_master ->
gm:leave(GM),
{stop, {duplicate_live_master, Node}, Q};
existing ->
gm:leave(GM),
{stop, normal, Q};
master_in_recovery ->
gm:leave(GM),
%% The queue record vanished - we must have a master starting
%% concurrently with us. In that case we can safely decide to do
%% nothing here, and the master will start us in
%% master:init_with_existing_bq/3
{stop, normal, Q}
end.
init_it(Self, GM, Node, QName) ->
case mnesia:read({rabbit_queue, QName}) of
[Q = #amqqueue { pid = QPid, slave_pids = SPids, gm_pids = GMPids }] ->
case [Pid || Pid <- [QPid | SPids], node(Pid) =:= Node] of
[] -> add_slave(Q, Self, GM),
{new, QPid, GMPids};
[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 -> GMPids1 = [T || T = {_, S} <- GMPids,
S =/= SPid],
Q1 = Q#amqqueue{
slave_pids = SPids -- [SPid],
gm_pids = GMPids1},
add_slave(Q1, Self, GM),
{new, QPid, GMPids1}
end
end;
[] ->
master_in_recovery
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(await, _From, State) ->
{reply, ok, State};
handle_call({gm_deaths, DeadGMPids}, From,
State = #state { gm = GM, q = Q = #amqqueue {
name = QName, pid = MPid }}) ->
Self = self(),
case rabbit_mirror_queue_misc:remove_from_queue(QName, Self, DeadGMPids) 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),
%% Since GM is by nature lazy we need to make sure
%% there is some traffic when a master dies, to
%% make sure all slaves get informed of the
%% death. That is all process_death does, create
%% some traffic.
ok = gm:broadcast(GM, process_death),
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({sync_start, Ref, Syncer},
State = #state { depth_delta = DD,
backing_queue = BQ,
backing_queue_state = BQS }) ->
State1 = #state{rate_timer_ref = TRef} = ensure_rate_timer(State),
S = fun({MA, TRefN, BQSN}) ->
State1#state{depth_delta = undefined,
msg_id_ack = dict:from_list(MA),
rate_timer_ref = TRefN,
backing_queue_state = BQSN}
end,
case rabbit_mirror_queue_sync:slave(
DD, Ref, TRef, Syncer, BQ, BQS,
fun (BQN, BQSN) ->
BQSN1 = update_ram_duration(BQN, BQSN),
TRefN = rabbit_misc:send_after(?RAM_DURATION_UPDATE_INTERVAL,
self(), update_ram_duration),
{TRefN, BQSN1}
end) of
denied -> noreply(State1);
{ok, Res} -> noreply(set_delta(0, S(Res)));
{failed, Res} -> noreply(S(Res));
{stop, Reason, Res} -> {stop, Reason, S(Res)}
end;
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}) ->
BQS1 = update_ram_duration(BQ, BQS),
%% 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 = BQS1 }),
{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, ChPid, _Reason}, State) ->
local_sender_death(ChPid, State),
noreply(maybe_forget_sender(ChPid, down_from_ch, 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}.
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 = #state{backing_queue = BQ,
backing_queue_state = BQS}) ->
%% See rabbit_mirror_queue_master:terminate/2
terminate_common(State),
BQ:delete_and_terminate(R, BQS);
terminate(shutdown, State) ->
terminate_shutdown(shutdown, State);
terminate({shutdown, _} = R, State) ->
terminate_shutdown(R, State);
terminate(Reason, State = #state{backing_queue = BQ,
backing_queue_state = BQS}) ->
terminate_common(State),
BQ:delete_and_terminate(Reason, BQS);
terminate([_SPid], _Reason) ->
%% gm case
ok.
%% 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_shutdown(Reason, State = #state{backing_queue = BQ,
backing_queue_state = BQS}) ->
terminate_common(State),
BQ:terminate(Reason, BQS).
terminate_common(State) ->
ok = rabbit_memory_monitor:deregister(self()),
stop_rate_timer(stop_sync_timer(State)).
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, _Len, _State) ->
case Msg of
info -> 9;
{gm_deaths, _Dead} -> 5;
_ -> 0
end.
prioritise_cast(Msg, _Len, _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;
_ -> 0
end.
prioritise_info(Msg, _Len, _State) ->
case Msg of
update_ram_duration -> 8;
sync_timeout -> 6;
_ -> 0
end.
format_message_queue(Opt, MQ) -> rabbit_misc:format_message_queue(Opt, MQ).
%% ---------------------------------------------------------------------------
%% GM
%% ---------------------------------------------------------------------------
joined([SPid], _Members) -> SPid ! {joined, self()}, ok.
members_changed([_SPid], _Births, []) ->
ok;
members_changed([ SPid], _Births, Deaths) ->
case rabbit_misc:with_exit_handler(
rabbit_misc:const(ok),
fun() ->
gen_server2:call(SPid, {gm_deaths, Deaths}, infinity)
end) of
ok -> ok;
{promote, CPid} -> {become, rabbit_mirror_queue_coordinator, [CPid]}
end.
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) ->
%% 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, {sync_start, Ref, Syncer, SPids}) ->
case lists:member(SPid, SPids) of
true -> gen_server2:cast(SPid, {sync_start, Ref, Syncer});
false -> ok
end;
handle_msg([SPid], _From, Msg) ->
ok = gen_server2:cast(SPid, {gm, Msg}).
%% ---------------------------------------------------------------------------
%% 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_mandatory(#delivery{mandatory = false}) ->
ok;
send_mandatory(#delivery{mandatory = true,
sender = SenderPid,
msg_seq_no = MsgSeqNo}) ->
gen_server2:cast(SenderPid, {mandatory_received, MsgSeqNo}).
send_or_record_confirm(_, #delivery{ confirm = false }, MS, _State) ->
MS;
send_or_record_confirm(published, #delivery { sender = ChPid,
confirm = true,
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,
confirm = true,
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}.
-ifdef(use_specs).
-spec(promote_me/2 :: ({pid(), term()}, #state{}) -> no_return()).
-endif.
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_mirror_queue_misc:log_info(QName, "Promoting slave ~s to master~n",
[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(
QName, 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#delivery{mandatory = false} || %% [0]
{_ChPid, {PubQ, _PendCh, _ChState}} <- dict:to_list(SQ),
Delivery <- queue:to_list(PubQ)],
AwaitGmDown = [ChPid || {ChPid, {_, _, down_from_ch}} <- dict:to_list(SQ)],
KS1 = lists:foldl(fun (ChPid0, KS0) ->
pmon:demonitor(ChPid0, KS0)
end, KS, AwaitGmDown),
rabbit_misc:store_proc_name(rabbit_amqqueue_process, QName),
rabbit_amqqueue_process:init_with_backing_queue_state(
Q1, rabbit_mirror_queue_master, MasterState, RateTRef, Deliveries, KS1,
MTC).
%% [0] We reset mandatory to false here because we will have sent the
%% mandatory_received already as soon as we got the message
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,
backing_queue_state = BQS }) ->
State#state{backing_queue_state = BQ:timeout(BQS)}.
ensure_sync_timer(State) ->
rabbit_misc:ensure_timer(State, #state.sync_timer_ref,
?SYNC_INTERVAL, sync_timeout).
stop_sync_timer(State) -> rabbit_misc:stop_timer(State, #state.sync_timer_ref).
ensure_rate_timer(State) ->
rabbit_misc:ensure_timer(State, #state.rate_timer_ref,
?RAM_DURATION_UPDATE_INTERVAL,
update_ram_duration).
stop_rate_timer(State) -> rabbit_misc:stop_timer(State, #state.rate_timer_ref).
ensure_monitoring(ChPid, State = #state { known_senders = KS }) ->
State #state { known_senders = pmon:monitor(ChPid, KS) }.
local_sender_death(ChPid, #state { known_senders = KS }) ->
%% The channel will be monitored iff we have received a delivery
%% from it but not heard about its death from the master. So if it
%% is monitored we need to point the death out to the master (see
%% essay).
ok = case pmon:is_monitored(ChPid, KS) of
false -> ok;
true -> confirm_sender_death(ChPid)
end.
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
%%
%% See comment in local_sender_death/2; we might have
%% received a sender_death in the meanwhile so check
%% again.
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 as well as a DOWN notification.
{ok, _TRef} = timer:apply_after(
?DEATH_TIMEOUT, rabbit_amqqueue, run_backing_queue,
[self(), rabbit_mirror_queue_master, Fun]),
ok.
forget_sender(_, running) -> false;
forget_sender(down_from_gm, down_from_gm) -> false; %% [1]
forget_sender(Down1, Down2) when Down1 =/= Down2 -> true.
%% [1] If another slave goes through confirm_sender_death/1 before we
%% do we can get two GM sender_death messages in a row for the same
%% channel - don't treat that as anything special.
%% Record and process lifetime events from channels. Forget all about a channel
%% only when down notifications are received from both the channel and from gm.
maybe_forget_sender(ChPid, ChState, State = #state { sender_queues = SQ,
msg_id_status = MS,
known_senders = KS }) ->
case dict:find(ChPid, SQ) of
error ->
State;
{ok, {MQ, PendCh, ChStateRecord}} ->
case forget_sender(ChState, ChStateRecord) of
true ->
credit_flow:peer_down(ChPid),
State #state { sender_queues = dict:erase(ChPid, SQ),
msg_id_status = lists:foldl(
fun dict:erase/2,
MS, sets:to_list(PendCh)),
known_senders = pmon:demonitor(ChPid, KS) };
false ->
SQ1 = dict:store(ChPid, {MQ, PendCh, ChState}, SQ),
State #state { sender_queues = SQ1 }
end
end.
maybe_enqueue_message(
Delivery = #delivery { message = #basic_message { id = MsgId },
sender = ChPid },
State = #state { sender_queues = SQ, msg_id_status = MS }) ->
send_mandatory(Delivery), %% must do this before confirms
State1 = ensure_monitoring(ChPid, State),
%% We will never see {published, ChPid, MsgSeqNo} here.
case dict:find(MsgId, MS) of
error ->
{MQ, PendingCh, ChState} = get_sender_queue(ChPid, SQ),
MQ1 = queue:in(Delivery, MQ),
SQ1 = dict:store(ChPid, {MQ1, PendingCh, ChState}, 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(), running};
{ok, Val} -> Val
end.
remove_from_pending_ch(MsgId, ChPid, SQ) ->
case dict:find(ChPid, SQ) of
error ->
SQ;
{ok, {MQ, PendingCh, ChState}} ->
dict:store(ChPid, {MQ, sets:del_element(MsgId, PendingCh), ChState},
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 issue 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, ChState} = 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, ChState}, 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, true, 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),
true = BQ:is_empty(BQS),
{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}) ->
{{MsgId, AckTag}, BQSN1} = BQ:drop(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({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 { known_senders = KS }) ->
%% The channel will be monitored iff we have received a message
%% from it. In this case we just want to avoid doing work if we
%% never got any messages.
{ok, case pmon:is_monitored(ChPid, KS) of
false -> State;
true -> maybe_forget_sender(ChPid, down_from_gm, State)
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 }).
update_ram_duration(BQ, BQS) ->
{RamDuration, BQS1} = BQ:ram_duration(BQS),
DesiredDuration =
rabbit_memory_monitor:report_ram_duration(self(), RamDuration),
BQ:set_ram_duration_target(DesiredDuration, BQS1).
record_synchronised(#amqqueue { name = QName }) ->
Self = self(),
case rabbit_misc:execute_mnesia_transaction(
fun () ->
case mnesia:read({rabbit_queue, QName}) of
[] ->
ok;
[Q1 = #amqqueue { sync_slave_pids = SSPids }] ->
Q2 = Q1#amqqueue{sync_slave_pids = [Self | SSPids]},
rabbit_mirror_queue_misc:store_updated_slaves(Q2),
{ok, Q2}
end
end) of
ok -> ok;
{ok, Q} -> rabbit_mirror_queue_misc:maybe_drop_master_after_sync(Q)
end.
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