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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) 2010-2011 VMware, Inc. All rights reserved.
%%
-module(rabbit_mirror_queue_misc).
-export([remove_from_queue/2, on_node_up/0,
drop_mirror/2, drop_mirror/3, add_mirror/2, add_mirror/3,
report_deaths/4]).
-include("rabbit.hrl").
%% If the dead pids include the queue pid (i.e. the master has died)
%% then only remove that if we are about to be promoted. Otherwise we
%% can have the situation where a slave updates the mnesia record for
%% a queue, promoting another slave before that slave realises it has
%% become the new master, which is bad because it could then mean the
%% slave (now master) receives messages it's not ready for (for
%% example, new consumers).
%% Returns {ok, NewMPid, DeadPids}
remove_from_queue(QueueName, DeadPids) ->
DeadNodes = [node(DeadPid) || DeadPid <- DeadPids],
rabbit_misc:execute_mnesia_transaction(
fun () ->
%% Someone else could have deleted the queue before we
%% get here.
case mnesia:read({rabbit_queue, QueueName}) of
[] -> {error, not_found};
[Q = #amqqueue { pid = QPid,
slave_pids = SPids }] ->
[QPid1 | SPids1] = Alive =
[Pid || Pid <- [QPid | SPids],
not lists:member(node(Pid), DeadNodes)],
case {{QPid, SPids}, {QPid1, SPids1}} of
{Same, Same} ->
{ok, QPid1, []};
_ when QPid =:= QPid1 orelse node(QPid1) =:= node() ->
%% Either master hasn't changed, so
%% we're ok to update mnesia; or we have
%% become the master.
Q1 = Q #amqqueue { pid = QPid1,
slave_pids = SPids1 },
ok = rabbit_amqqueue:store_queue(Q1),
{ok, QPid1, [QPid | SPids] -- Alive};
_ ->
%% Master has changed, and we're not it,
%% so leave alone to allow the promoted
%% slave to find it and make its
%% promotion atomic.
{ok, QPid1, []}
end
end
end).
on_node_up() ->
Qs =
rabbit_misc:execute_mnesia_transaction(
fun () ->
mnesia:foldl(
fun (#amqqueue { mirror_nodes = undefined }, QsN) ->
QsN;
(#amqqueue { name = QName,
mirror_nodes = all }, QsN) ->
[QName | QsN];
(#amqqueue { name = QName,
mirror_nodes = MNodes }, QsN) ->
case lists:member(node(), MNodes) of
true -> [QName | QsN];
false -> QsN
end
end, [], rabbit_queue)
end),
[add_mirror(Q, node()) || Q <- Qs],
ok.
drop_mirror(VHostPath, QueueName, MirrorNode) ->
drop_mirror(rabbit_misc:r(VHostPath, queue, QueueName), MirrorNode).
drop_mirror(Queue, MirrorNode) ->
if_mirrored_queue(
Queue,
fun (#amqqueue { name = Name, pid = QPid, slave_pids = SPids }) ->
case [Pid || Pid <- [QPid | SPids], node(Pid) =:= MirrorNode] of
[] ->
{error, {queue_not_mirrored_on_node, MirrorNode}};
[QPid] when SPids =:= [] ->
{error, cannot_drop_only_mirror};
[Pid] ->
rabbit_log:info(
"Dropping queue mirror on node ~p for ~s~n",
[MirrorNode, rabbit_misc:rs(Name)]),
exit(Pid, {shutdown, dropped}),
ok
end
end).
add_mirror(VHostPath, QueueName, MirrorNode) ->
add_mirror(rabbit_misc:r(VHostPath, queue, QueueName), MirrorNode).
add_mirror(Queue, MirrorNode) ->
if_mirrored_queue(
Queue,
fun (#amqqueue { name = Name, pid = QPid, slave_pids = SPids } = Q) ->
case [Pid || Pid <- [QPid | SPids], node(Pid) =:= MirrorNode] of
[] -> Result = rabbit_mirror_queue_slave_sup:start_child(
MirrorNode, [Q]),
rabbit_log:info(
"Adding mirror of queue ~s on node ~p: ~p~n",
[rabbit_misc:rs(Name), MirrorNode, Result]),
case Result of
{ok, _Pid} -> ok;
_ -> Result
end;
[_] -> {error, {queue_already_mirrored_on_node, MirrorNode}}
end
end).
if_mirrored_queue(Queue, Fun) ->
rabbit_amqqueue:with(
Queue, fun (#amqqueue { arguments = Args } = Q) ->
case rabbit_misc:table_lookup(Args, <<"x-ha-policy">>) of
undefined -> ok;
_ -> Fun(Q)
end
end).
report_deaths(_MirrorPid, _IsMaster, _QueueName, []) ->
ok;
report_deaths(MirrorPid, IsMaster, QueueName, DeadPids) ->
rabbit_event:notify(queue_mirror_deaths, [{name, QueueName},
{pids, DeadPids}]),
rabbit_log:info("Mirrored-queue (~s): ~s ~s saw deaths of mirrors ~s~n",
[rabbit_misc:rs(QueueName),
case IsMaster of
true -> "Master";
false -> "Slave"
end,
rabbit_misc:pid_to_string(MirrorPid),
[[rabbit_misc:pid_to_string(P), $ ] || P <- DeadPids]]).
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