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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_mode_nodes).
-include("rabbit.hrl").
-behaviour(rabbit_mirror_queue_mode).
-export([description/0, suggested_queue_nodes/5, validate_policy/1]).
-rabbit_boot_step({?MODULE,
[{description, "mirror mode nodes"},
{mfa, {rabbit_registry, register,
[ha_mode, <<"nodes">>, ?MODULE]}},
{requires, rabbit_registry},
{enables, kernel_ready}]}).
description() ->
[{description, <<"Mirror queue to specified nodes">>}].
suggested_queue_nodes(Nodes0, MNode, _SNodes, SSNodes, Poss) ->
Nodes1 = [list_to_atom(binary_to_list(Node)) || Node <- Nodes0],
%% If the current master is not in the nodes specified, then what we want
%% to do depends on whether there are any synchronised slaves. If there
%% are then we can just kill the current master - the admin has asked for
%% a migration and we should give it to them. If there are not however
%% then we must keep the master around so as not to lose messages.
Nodes = case SSNodes of
[] -> lists:usort([MNode | Nodes1]);
_ -> Nodes1
end,
Unavailable = Nodes -- Poss,
Available = Nodes -- Unavailable,
case Available of
[] -> %% We have never heard of anything? Not much we can do but
%% keep the master alive.
{MNode, []};
_ -> case lists:member(MNode, Available) of
true -> {MNode, Available -- [MNode]};
false -> %% Make sure the new master is synced! In order to
%% get here SSNodes must not be empty.
[NewMNode | _] = SSNodes,
{NewMNode, Available -- [NewMNode]}
end
end.
validate_policy([]) ->
{error, "ha-mode=\"nodes\" list must be non-empty", []};
validate_policy(Nodes) when is_list(Nodes) ->
case [I || I <- Nodes, not is_binary(I)] of
[] -> ok;
Invalid -> {error, "ha-mode=\"nodes\" takes a list of strings, "
"~p was not a string", [Invalid]}
end;
validate_policy(Params) ->
{error, "ha-mode=\"nodes\" takes a list, ~p given", [Params]}.
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