1 files changed, 70 insertions, 0 deletions
diff --git a/src/rabbit_mirror_queue_mode_nodes.erl b/src/rabbit_mirror_queue_mode_nodes.erl
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+++ b/src/rabbit_mirror_queue_mode_nodes.erl
@@ -0,0 +1,70 @@
+%% 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) 2010-2013 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]}.