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author | Simon MacMullen <simon@rabbitmq.com> | 2013-04-11 15:37:59 +0100 |
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committer | Simon MacMullen <simon@rabbitmq.com> | 2013-04-11 15:37:59 +0100 |
commit | 1d82b4ffcd52d2f9b8ed3de776d2080d07366674 (patch) | |
tree | 7f7dde0e789fabff1c5f2caf122df49848137cfe /src/rabbit_mirror_queue_mode_exactly.erl | |
parent | 13d5ac8c71cea4835be5e6d42e66d5c6cf36b20f (diff) | |
download | rabbitmq-server-1d82b4ffcd52d2f9b8ed3de776d2080d07366674.tar.gz |
Move mirrored queue modes into a behaviour and implementations thereof.
Diffstat (limited to 'src/rabbit_mirror_queue_mode_exactly.erl')
-rw-r--r-- | src/rabbit_mirror_queue_mode_exactly.erl | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/src/rabbit_mirror_queue_mode_exactly.erl b/src/rabbit_mirror_queue_mode_exactly.erl new file mode 100644 index 00000000..2a42c383 --- /dev/null +++ b/src/rabbit_mirror_queue_mode_exactly.erl @@ -0,0 +1,56 @@ +%% 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_mode_exactly). + +-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 exactly"}, + {mfa, {rabbit_registry, register, + [ha_mode, <<"exactly">>, ?MODULE]}}, + {requires, rabbit_registry}, + {enables, kernel_ready}]}). + +description() -> + [{description, <<"Mirror queue to a specified number of nodes">>}]. + +%% When we need to add nodes, we randomise our candidate list as a +%% crude form of load-balancing. TODO it would also be nice to +%% randomise the list of ones to remove when we have too many - we +%% would have to take account of synchronisation though. +suggested_queue_nodes(Count, MNode, SNodes, _SSNodes, Poss) -> + SCount = Count - 1, + {MNode, case SCount > length(SNodes) of + true -> Cand = shuffle((Poss -- [MNode]) -- SNodes), + SNodes ++ lists:sublist(Cand, SCount - length(SNodes)); + false -> lists:sublist(SNodes, SCount) + end}. + +shuffle(L) -> + {A1,A2,A3} = now(), + random:seed(A1, A2, A3), + {_, L1} = lists:unzip(lists:keysort(1, [{random:uniform(), N} || N <- L])), + L1. + +validate_policy(N) when is_integer(N) andalso N > 0 -> + ok; +validate_policy(Params) -> + {error, "ha-mode=\"exactly\" takes an integer, ~p given", [Params]}. |