From 5b3520c23e98f08b72522de32c0846b4ff579e89 Mon Sep 17 00:00:00 2001
From: Simon MacMullen <simon@rabbitmq.com>
Date: Thu, 19 Jun 2014 17:59:47 +0100
Subject: Promote down slave to master if the master gets forgotten.

---
 src/rabbit_amqqueue.erl | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

(limited to 'src/rabbit_amqqueue.erl')

diff --git a/src/rabbit_amqqueue.erl b/src/rabbit_amqqueue.erl
index 7a10d239..4e23dbd2 100644
--- a/src/rabbit_amqqueue.erl
+++ b/src/rabbit_amqqueue.erl
@@ -258,15 +258,16 @@ declare(QueueName, Durable, AutoDelete, Args, Owner) ->
 declare(QueueName, Durable, AutoDelete, Args, Owner, Node) ->
     ok = check_declare_arguments(QueueName, Args),
     Q = rabbit_queue_decorator:set(
-          rabbit_policy:set(#amqqueue{name            = QueueName,
-                                      durable         = Durable,
-                                      auto_delete     = AutoDelete,
-                                      arguments       = Args,
-                                      exclusive_owner = Owner,
-                                      pid             = none,
-                                      slave_pids      = [],
-                                      sync_slave_pids = [],
-                                      gm_pids         = []})),
+          rabbit_policy:set(#amqqueue{name             = QueueName,
+                                      durable          = Durable,
+                                      auto_delete      = AutoDelete,
+                                      arguments        = Args,
+                                      exclusive_owner  = Owner,
+                                      pid              = none,
+                                      slave_pids       = [],
+                                      sync_slave_pids  = [],
+                                      down_slave_nodes = [],
+                                      gm_pids          = []})),
     Node = rabbit_mirror_queue_misc:initial_queue_node(Q, Node),
     gen_server2:call(start_queue_process(Node, Q), {init, new}, infinity).
 
@@ -666,15 +667,23 @@ forget_all_durable(Node) ->
           fun () ->
                   Qs = mnesia:match_object(rabbit_durable_queue,
                                            #amqqueue{_ = '_'}, write),
-                  [rabbit_binding:process_deletions(
-                     internal_delete1(Name)) ||
-                      #amqqueue{name = Name, pid = Pid} = Q <- Qs,
-                      node(Pid) =:= Node,
-                      rabbit_policy:get(<<"ha-mode">>, Q) =:= undefined],
+                  [forget_node_for_queue(Q) || #amqqueue{pid = Pid} = Q <- Qs,
+                      node(Pid) =:= Node],
                   ok
           end),
     ok.
 
+forget_node_for_queue(#amqqueue{name             = Name,
+                                down_slave_nodes = []}) ->
+    %% No slaves to recover from, queue is gone
+    rabbit_binding:process_deletions(internal_delete1(Name));
+
+forget_node_for_queue(Q = #amqqueue{down_slave_nodes = [H|T]}) ->
+    %% Promote a slave while down - it'll happily recover as a master
+    Q1 = Q#amqqueue{pid              = rabbit_misc:node_to_fake_pid(H),
+                    down_slave_nodes = T},
+    ok = mnesia:write(rabbit_durable_queue, Q1, write).
+
 run_backing_queue(QPid, Mod, Fun) ->
     gen_server2:cast(QPid, {run_backing_queue, Mod, Fun}).
 
-- 
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