Fix errors reported by Dialyzer

13 files changed, 190 insertions, 134 deletions

diff --git a/Makefile b/Makefile
index ac2652ff4d..fc3aab87dd 100644
--- a/Makefile
+++ b/Makefile
@@ -136,7 +136,7 @@ define PROJECT_ENV
 	  ]
 endef
 
-LOCAL_DEPS = sasl mnesia os_mon inets compiler syntax_tools
+LOCAL_DEPS = sasl mnesia os_mon inets compiler public_key crypto ssl syntax_tools
 BUILD_DEPS = rabbitmq_cli syslog
 DEPS = ranch lager rabbit_common ra sysmon_handler
 TEST_DEPS = rabbitmq_ct_helpers rabbitmq_ct_client_helpers amqp_client meck proper
diff --git a/src/rabbit_amqqueue.erl b/src/rabbit_amqqueue.erl
index 621ce95d41..c9c120df77 100644
--- a/src/rabbit_amqqueue.erl
+++ b/src/rabbit_amqqueue.erl
@@ -29,7 +29,7 @@
 -export([not_found/1, absent/2]).
 -export([list/0, list/1, info_keys/0, info/1, info/2, info_all/1, info_all/2,
          emit_info_all/5, list_local/1, info_local/1,
-	 emit_info_local/4, emit_info_down/4]).
+         emit_info_local/4, emit_info_down/4]).
 -export([list_down/1, count/1, list_names/0, list_names/1, list_local_names/0,
          list_with_possible_retry/1]).
 -export([list_by_type/1]).
@@ -81,11 +81,11 @@
 -type msg_id() :: non_neg_integer().
 -type ok_or_errors() ::
         'ok' | {'error', [{'error' | 'exit' | 'throw', any()}]}.
--type absent_reason() :: 'nodedown' | 'crashed'.
--type queue_or_absent() :: amqqueue:amqqueue() |
-                           {'absent', amqqueue:amqqueue(),absent_reason()}.
--type not_found_or_absent() ::
-        'not_found' | {'absent', amqqueue:amqqueue(), absent_reason()}.
+-type absent_reason() :: 'nodedown' | 'crashed' | stopped | timeout.
+-type queue_not_found() :: not_found.
+-type queue_absent() :: {'absent', amqqueue:amqqueue(), absent_reason()}.
+-type not_found_or_absent() :: queue_not_found() | queue_absent().
+-type quorum_states() :: #{Name :: atom() => rabbit_fifo_client:state()}.
 
 %%----------------------------------------------------------------------------
 
@@ -231,13 +231,14 @@ recover_durable_queues(QueuesAndRecoveryTerms) ->
                       [Pid, Error]) || {Pid, Error} <- Failures],
     [Q || {_, {new, Q}} <- Results].
 
--spec declare
-        (name(), boolean(), boolean(), rabbit_framing:amqp_table(),
-         rabbit_types:maybe(pid()), rabbit_types:username()) ->
-            {'new' | 'existing' | 'absent' | 'owner_died',
-             amqqueue:amqqueue()} |
-            {'new', amqqueue:amqqueue(), rabbit_fifo_client:state()} |
-            rabbit_types:channel_exit().
+-spec declare(name(),
+              boolean(),
+              boolean(),
+              rabbit_framing:amqp_table(),
+              rabbit_types:maybe(pid()),
+              rabbit_types:username()) ->
+    {'new' | 'existing' | 'absent' | 'owner_died', amqqueue:amqqueue()} |
+    rabbit_types:channel_exit().
 
 declare(QueueName, Durable, AutoDelete, Args, Owner, ActingUser) ->
     declare(QueueName, Durable, AutoDelete, Args, Owner, ActingUser, node()).
@@ -247,13 +248,17 @@ declare(QueueName, Durable, AutoDelete, Args, Owner, ActingUser) ->
 %% should be. Note that in some cases (e.g. with "nodes" policy in
 %% effect) this might not be possible to satisfy.
 
--spec declare
-        (name(), boolean(), boolean(), rabbit_framing:amqp_table(),
-         rabbit_types:maybe(pid()), rabbit_types:username(), node()) ->
-            {'new' | 'existing' | 'owner_died', amqqueue:amqqueue()} |
-            {'new', amqqueue:amqqueue(), rabbit_fifo_client:state()} |
-            {'absent', amqqueue:amqqueue(), absent_reason()} |
-            rabbit_types:channel_exit().
+-spec declare(name(),
+              boolean(),
+              boolean(),
+              rabbit_framing:amqp_table(),
+              rabbit_types:maybe(pid()),
+              rabbit_types:username(),
+              node()) ->
+    {'new' | 'existing' | 'owner_died', amqqueue:amqqueue()} |
+    {'new', amqqueue:amqqueue(), rabbit_fifo_client:state()} |
+    {'absent', amqqueue:amqqueue(), absent_reason()} |
+    rabbit_types:channel_exit().
 
 declare(QueueName = #resource{virtual_host = VHost}, Durable, AutoDelete, Args,
         Owner, ActingUser, Node) ->
@@ -317,7 +322,7 @@ get_queue_type(Args) ->
     end.
 
 -spec internal_declare(amqqueue:amqqueue(), boolean()) ->
-          queue_or_absent() | rabbit_misc:thunk(queue_or_absent()).
+    {created | existing, amqqueue:amqqueue()} | queue_absent().
 
 internal_declare(Q, Recover) ->
     ?try_mnesia_tx_or_upgrade_amqqueue_and_retry(
@@ -451,6 +456,8 @@ not_found_or_absent(Name) ->
         [Q] -> {absent, Q, nodedown} %% Q exists on stopped node
     end.
 
+-spec not_found_or_absent_dirty(name()) -> not_found_or_absent().
+
 not_found_or_absent_dirty(Name) ->
     %% We should read from both tables inside a tx, to get a
     %% consistent view. But the chances of an inconsistency are small,
@@ -460,12 +467,15 @@ not_found_or_absent_dirty(Name) ->
         {ok, Q}            -> {absent, Q, nodedown}
     end.
 
--spec with(name(), qfun(A), fun((not_found_or_absent()) -> B)) -> A | B.
+-spec with(name(),
+           qfun(A),
+           fun((not_found_or_absent()) -> rabbit_types:channel_exit())) ->
+    A | rabbit_types:channel_exit().
 
 with(Name, F, E) ->
     with(Name, F, E, 2000).
 
-with(Name, F, E, RetriesLeft) ->
+with(#resource{} = Name, F, E, RetriesLeft) ->
     case lookup(Name) of
         {ok, Q} when ?amqqueue_state_is(Q, live) andalso RetriesLeft =:= 0 ->
             %% Something bad happened to that queue, we are bailing out
@@ -502,6 +512,12 @@ with(Name, F, E, RetriesLeft) ->
             E(not_found_or_absent_dirty(Name))
     end.
 
+-spec retry_wait(amqqueue:amqqueue(),
+                 qfun(A),
+                 fun((not_found_or_absent()) -> rabbit_types:channel_exit()),
+                 non_neg_integer()) ->
+    A | rabbit_types:channel_exit().
+
 retry_wait(Q, F, E, RetriesLeft) ->
     Name = amqqueue:get_name(Q),
     QPid = amqqueue:get_pid(Q),
@@ -535,16 +551,22 @@ with(Name, F) -> with(Name, F, fun (E) -> {error, E} end).
 -spec with_or_die(name(), qfun(A)) -> A | rabbit_types:channel_exit().
 
 with_or_die(Name, F) ->
-    with(Name, F, fun (not_found)           -> not_found(Name);
-                      ({absent, Q, Reason}) -> absent(Q, Reason)
-                  end).
+    with(Name, F, die_fun(Name)).
+
+-spec die_fun(name()) ->
+    fun((not_found_or_absent()) -> rabbit_types:channel_exit()).
+
+die_fun(Name) ->
+    fun (not_found)           -> not_found(Name);
+        ({absent, Q, Reason}) -> absent(Q, Reason)
+    end.
 
--spec not_found(rabbit_types:r(atom())) -> rabbit_types:channel_exit().
+-spec not_found(name()) -> rabbit_types:channel_exit().
 
 not_found(R) -> rabbit_misc:protocol_error(not_found, "no ~s", [rabbit_misc:rs(R)]).
 
--spec absent(amqqueue:amqqueue(), rabbit_amqqueue:absent_reason()) ->
-          rabbit_types:channel_exit().
+-spec absent(amqqueue:amqqueue(), absent_reason()) ->
+    rabbit_types:channel_exit().
 
 absent(Q, AbsentReason) ->
     QueueName = amqqueue:get_name(Q),
@@ -552,6 +574,9 @@ absent(Q, AbsentReason) ->
     IsDurable = amqqueue:is_durable(Q),
     priv_absent(QueueName, QPid, IsDurable, AbsentReason).
 
+-spec priv_absent(name(), pid(), boolean(), absent_reason()) ->
+    rabbit_types:channel_exit().
+
 priv_absent(QueueName, QPid, true, nodedown) ->
     %% The assertion of durability is mainly there because we mention
     %% durability in the error message. That way we will hopefully
@@ -1006,7 +1031,7 @@ notify_policy_changed(Q) when ?amqqueue_is_quorum(Q) ->
 
 -spec consumers(amqqueue:amqqueue()) ->
           [{pid(), rabbit_types:ctag(), boolean(), non_neg_integer(),
-            rabbit_framing:amqp_table()}].
+            rabbit_framing:amqp_table(), rabbit_types:username()}].
 
 consumers(Q) when ?amqqueue_is_classic(Q) ->
     QPid = amqqueue:get_pid(Q),
@@ -1189,7 +1214,11 @@ purge(Q) when ?amqqueue_is_quorum(Q) ->
     NodeId = amqqueue:get_pid(Q),
     rabbit_quorum_queue:purge(NodeId).
 
--spec requeue(pid(), [msg_id()],  pid(), #{Name :: atom() => rabbit_fifo_client:state()}) -> 'ok'.
+-spec requeue(pid(),
+              {rabbit_fifo:consumer_tag(), [msg_id()]},
+              pid(),
+              quorum_states()) ->
+    'ok'.
 
 requeue(QPid, {_, MsgIds}, ChPid, QuorumStates) when ?IS_CLASSIC(QPid) ->
     ok = delegate:invoke(QPid, {gen_server2, call, [{requeue, MsgIds, ChPid}, infinity]}),
@@ -1205,7 +1234,11 @@ requeue({Name, _} = QPid, {CTag, MsgIds}, _ChPid, QuorumStates)
             QuorumStates
     end.
 
--spec ack(pid(), [msg_id()], pid(), #{Name :: atom() => rabbit_fifo_client:state()}) -> 'ok'.
+-spec ack(pid(),
+          {rabbit_fifo:consumer_tag(), [msg_id()]},
+          pid(),
+          quorum_states()) ->
+    quorum_states().
 
 ack(QPid, {_, MsgIds}, ChPid, QueueStates) when ?IS_CLASSIC(QPid) ->
     delegate:invoke_no_result(QPid, {gen_server2, cast, [{ack, MsgIds, ChPid}]}),
@@ -1221,8 +1254,12 @@ ack({Name, _} = QPid, {CTag, MsgIds}, _ChPid, QuorumStates)
             QuorumStates
     end.
 
--spec reject(pid() | {atom(), node()}, [msg_id()], boolean(), pid(),
-             #{Name :: atom() => rabbit_fifo_client:state()}) -> 'ok'.
+-spec reject(pid() | amqqueue:ra_server_id(),
+             boolean(),
+             {rabbit_fifo:consumer_tag(), [msg_id()]},
+             pid(),
+             quorum_states()) ->
+    quorum_states().
 
 reject(QPid, Requeue, {_, MsgIds}, ChPid, QStates) when ?IS_CLASSIC(QPid) ->
     ok = delegate:invoke_no_result(QPid, {gen_server2, cast,
@@ -1265,17 +1302,20 @@ notify_down_all(QPids, ChPid, Timeout) ->
         Error         -> {error, Error}
     end.
 
--spec activate_limit_all(qpids(), pid()) -> ok_or_errors().
+-spec activate_limit_all(qpids(), pid()) -> ok.
 
 activate_limit_all(QRefs, ChPid) ->
     QPids = [P || P <- QRefs, ?IS_CLASSIC(P)],
     delegate:invoke_no_result(QPids, {gen_server2, cast,
                                       [{activate_limit, ChPid}]}).
 
--spec credit
-        (amqqueue:amqqueue(), pid(), rabbit_types:ctag(), non_neg_integer(),
-         boolean(), #{Name :: atom() => rabbit_fifo_client:state()}) ->
-            'ok'.
+-spec credit(amqqueue:amqqueue(),
+             pid(),
+             rabbit_types:ctag(),
+             non_neg_integer(),
+             boolean(),
+             quorum_states()) ->
+    {'ok', quorum_states()}.
 
 credit(Q, ChPid, CTag, Credit,
        Drain, QStates) when ?amqqueue_is_classic(Q) ->
@@ -1294,7 +1334,9 @@ credit(Q,
 
 -spec basic_get(amqqueue:amqqueue(), pid(), boolean(), pid(), rabbit_types:ctag(),
                 #{Name :: atom() => rabbit_fifo_client:state()}) ->
-          {'ok', non_neg_integer(), qmsg()} | 'empty'.
+          {'ok', non_neg_integer(), qmsg(), quorum_states()} |
+          {'empty', quorum_states()} |
+          rabbit_types:channel_exit().
 
 basic_get(Q, ChPid, NoAck, LimiterPid, _CTag, _)
   when ?amqqueue_is_classic(Q) ->
@@ -1421,10 +1463,7 @@ internal_delete1(QueueName, OnlyDurable, Reason) ->
     %% after the transaction.
     rabbit_binding:remove_for_destination(QueueName, OnlyDurable).
 
--spec internal_delete(name(), rabbit_types:username()) ->
-          'ok' | rabbit_types:connection_exit() |
-          fun (() ->
-              'ok' | rabbit_types:connection_exit()).
+-spec internal_delete(name(), rabbit_types:username()) -> 'ok'.
 
 internal_delete(QueueName, ActingUser) ->
     internal_delete(QueueName, ActingUser, normal).
@@ -1682,7 +1721,9 @@ pseudo_queue(QueueName, Pid) ->
 
 -spec pseudo_queue(name(), pid(), boolean()) -> amqqueue:amqqueue().
 
-pseudo_queue(QueueName, Pid, Durable) ->
+pseudo_queue(#resource{kind = queue} = QueueName, Pid, Durable)
+  when is_pid(Pid) andalso
+       is_boolean(Durable) ->
     amqqueue:new(QueueName,
                  Pid,
                  Durable,
@@ -1704,8 +1745,12 @@ deliver(Qs, Delivery) ->
     deliver(Qs, Delivery, untracked),
     ok.
 
--spec deliver([amqqueue:amqqueue()], rabbit_types:delivery(), #{Name :: atom() => rabbit_fifo_client:state()} | 'untracked') ->
-                        {qpids(), #{Name :: atom() => rabbit_fifo_client:state()}}.
+-spec deliver([amqqueue:amqqueue()],
+              rabbit_types:delivery(),
+              quorum_states() | 'untracked') ->
+    {qpids(),
+     [{amqqueue:ra_server_id(), name()}],
+     quorum_states()}.
 
 deliver([], _Delivery, QueueState) ->
     %% /dev/null optimisation
diff --git a/src/rabbit_mnesia.erl b/src/rabbit_mnesia.erl
index ab29faf368..61b9e10e70 100644
--- a/src/rabbit_mnesia.erl
+++ b/src/rabbit_mnesia.erl
@@ -136,20 +136,14 @@ init_from_config() ->
     {DiscoveredNodes, NodeType} =
         case rabbit_peer_discovery:discover_cluster_nodes() of
             {ok, {Nodes, Type} = Config}
-            when is_list(Nodes) andalso (Type == disc orelse Type == disk orelse Type == ram) ->
+              when is_list(Nodes) andalso
+                   (Type == disc orelse Type == disk orelse Type == ram) ->
                 case lists:foldr(FindBadNodeNames, [], Nodes) of
                     []       -> Config;
                     BadNames -> e({invalid_cluster_node_names, BadNames})
                 end;
             {ok, {_, BadType}} when BadType /= disc andalso BadType /= ram ->
                 e({invalid_cluster_node_type, BadType});
-            {ok, Nodes} when is_list(Nodes) ->
-                %% The legacy syntax (a nodes list without the node
-                %% type) is unsupported.
-                case lists:foldr(FindBadNodeNames, [], Nodes) of
-                    [] -> e(cluster_node_type_mandatory);
-                    _  -> e(invalid_cluster_nodes_conf)
-                end;
             {ok, _} ->
                 e(invalid_cluster_nodes_conf)
         end,
@@ -1025,6 +1019,8 @@ nodes_incl_me(Nodes) -> lists:usort([node()|Nodes]).
 
 nodes_excl_me(Nodes) -> Nodes -- [node()].
 
+-spec e(any()) -> no_return().
+
 e(Tag) -> throw({error, {Tag, error_description(Tag)}}).
 
 error_description({invalid_cluster_node_names, BadNames}) ->
@@ -1034,9 +1030,6 @@ error_description({invalid_cluster_node_type, BadType}) ->
     "In the 'cluster_nodes' configuration key, the node type is invalid "
         "(expected 'disc' or 'ram'): " ++
         lists:flatten(io_lib:format("~p", [BadType]));
-error_description(cluster_node_type_mandatory) ->
-    "The 'cluster_nodes' configuration key must indicate the node type: "
-        "either {[...], disc} or {[...], ram}";
 error_description(invalid_cluster_nodes_conf) ->
     "The 'cluster_nodes' configuration key is invalid, it must be of the "
         "form {[Nodes], Type}, where Nodes is a list of node names and "
diff --git a/src/rabbit_node_monitor.erl b/src/rabbit_node_monitor.erl
index 2d3b042fa4..cd46ade0e2 100644
--- a/src/rabbit_node_monitor.erl
+++ b/src/rabbit_node_monitor.erl
@@ -84,14 +84,13 @@ cluster_status_filename() ->
 quorum_filename() ->
     filename:join(rabbit_mnesia:dir(), "quorum").
 
--spec prepare_cluster_status_files() -> 'ok'.
+-spec prepare_cluster_status_files() -> 'ok' | no_return().
 
 prepare_cluster_status_files() ->
     rabbit_mnesia:ensure_mnesia_dir(),
-    Corrupt = fun(F) -> throw({error, corrupt_cluster_status_files, F}) end,
     RunningNodes1 = case try_read_file(running_nodes_filename()) of
                         {ok, [Nodes]} when is_list(Nodes) -> Nodes;
-                        {ok, Other}                       -> Corrupt(Other);
+                        {ok, Other}                       -> corrupt_cluster_status_files(Other);
                         {error, enoent}                   -> []
                     end,
     ThisNode = [node()],
@@ -105,7 +104,7 @@ prepare_cluster_status_files() ->
             {ok, [AllNodes0]} when is_list(AllNodes0) ->
                 {legacy_cluster_nodes(AllNodes0), legacy_disc_nodes(AllNodes0)};
             {ok, Files} ->
-                Corrupt(Files);
+                corrupt_cluster_status_files(Files);
             {error, enoent} ->
                 LegacyNodes = legacy_cluster_nodes([]),
                 {LegacyNodes, LegacyNodes}
@@ -113,6 +112,11 @@ prepare_cluster_status_files() ->
     AllNodes2 = lists:usort(AllNodes1 ++ RunningNodes2),
     ok = write_cluster_status({AllNodes2, DiscNodes, RunningNodes2}).
 
+-spec corrupt_cluster_status_files(any()) -> no_return().
+
+corrupt_cluster_status_files(F) ->
+    throw({error, corrupt_cluster_status_files, F}).
+
 -spec write_cluster_status(rabbit_mnesia:cluster_status()) -> 'ok'.
 
 write_cluster_status({All, Disc, Running}) ->
diff --git a/src/rabbit_peer_discovery.erl b/src/rabbit_peer_discovery.erl
index 2f4acee49e..2ed36d32ec 100644
--- a/src/rabbit_peer_discovery.erl
+++ b/src/rabbit_peer_discovery.erl
@@ -105,9 +105,15 @@ maybe_init() ->
     end.
 
 
--spec discover_cluster_nodes() -> {ok, Nodes :: list()} |
-                                  {ok, {Nodes :: list(), NodeType :: rabbit_types:node_type()}} |
-                                  {error, Reason :: string()}.
+%% This module doesn't currently sanity-check the return value of
+%% `Backend:list_nodes()`. Therefore, it could return something invalid:
+%% thus the `{œk, any()} in the spec.
+%%
+%% `rabbit_mnesia:init_from_config()` does some verifications.
+
+-spec discover_cluster_nodes() ->
+    {ok, {Nodes :: [node()], NodeType :: rabbit_types:node_type()} | any()} |
+    {error, Reason :: string()}.
 
 discover_cluster_nodes() ->
     Backend = backend(),
@@ -156,10 +162,7 @@ maybe_inject_randomized_delay() ->
 -spec inject_randomized_delay() -> ok.
 
 inject_randomized_delay() ->
-    {Min, Max} = case randomized_delay_range_in_ms() of
-                     {A, B} -> {A, B};
-                     [A, B] -> {A, B}
-                 end,
+    {Min, Max} = randomized_delay_range_in_ms(),
     case {Min, Max} of
         %% When the max value is set to 0, consider the delay to be disabled.
         %% In addition, `rand:uniform/1` will fail with a "no function clause"
@@ -258,12 +261,15 @@ unlock(Data) ->
 %% Implementation
 %%
 
--spec normalize(Nodes :: list() |
-                {Nodes :: list(), NodeType :: rabbit_types:node_type()} |
-                {ok, Nodes :: list()} |
-                {ok, {Nodes :: list(), NodeType :: rabbit_types:node_type()}} |
-                {error, Reason :: string()}) -> {ok, {Nodes :: list(), NodeType :: rabbit_types:node_type()}} |
-                                                {error, Reason :: string()}.
+-spec normalize(Nodes :: [node()] |
+                {Nodes :: [node()],
+                 NodeType :: rabbit_types:node_type()} |
+                {ok, Nodes :: [node()]} |
+                {ok, {Nodes :: [node()],
+                      NodeType :: rabbit_types:node_type()}} |
+                {error, Reason :: string()}) ->
+    {ok, {Nodes :: [node()], NodeType :: rabbit_types:node_type()}} |
+    {error, Reason :: string()}.
 
 normalize(Nodes) when is_list(Nodes) ->
   {ok, {Nodes, disc}};
@@ -296,14 +302,12 @@ node_prefix() ->
 
 
 
--spec append_node_prefix(Value :: binary() | list()) -> atom().
+-spec append_node_prefix(Value :: binary() | string()) -> string().
 
-append_node_prefix(Value) ->
+append_node_prefix(Value) when is_binary(Value) orelse is_list(Value) ->
     Val = rabbit_data_coercion:to_list(Value),
     Hostname = case string:tokens(Val, ?NODENAME_PART_SEPARATOR) of
-                   [_ExistingPrefix, Val] ->
-                       Val;
-                   [Val]                  ->
-                       Val
+                   [_ExistingPrefix, HN] -> HN;
+                   [HN]                  -> HN
                end,
     string:join([node_prefix(), Hostname], ?NODENAME_PART_SEPARATOR).
diff --git a/src/rabbit_peer_discovery_classic_config.erl b/src/rabbit_peer_discovery_classic_config.erl
index 6597d77da4..16b7861f5f 100644
--- a/src/rabbit_peer_discovery_classic_config.erl
+++ b/src/rabbit_peer_discovery_classic_config.erl
@@ -26,13 +26,12 @@
 %% API
 %%
 
--spec list_nodes() -> {ok, Nodes :: list()} | {error, Reason :: string()}.
+-spec list_nodes() -> {ok, {Nodes :: [node()], rabbit_types:node_type()}}.
 
 list_nodes() ->
-    case application:get_env(rabbit, cluster_nodes) of
-        {_Nodes, _NodeType} = Pair -> Pair;
-        Nodes when is_list(Nodes)  -> {Nodes, disc};
-        undefined                  -> {[], disc}
+    case application:get_env(rabbit, cluster_nodes, {[], disc}) of
+        {_Nodes, _NodeType} = Pair -> {ok, Pair};
+        Nodes when is_list(Nodes)  -> {ok, {Nodes, disc}}
     end.
 
 -spec supports_registration() -> boolean().
diff --git a/src/rabbit_peer_discovery_dns.erl b/src/rabbit_peer_discovery_dns.erl
index ad277e08b0..031d1290b3 100644
--- a/src/rabbit_peer_discovery_dns.erl
+++ b/src/rabbit_peer_discovery_dns.erl
@@ -28,12 +28,13 @@
 %% API
 %%
 
--spec list_nodes() -> {ok, Nodes :: list()} | {error, Reason :: string()}.
+-spec list_nodes() ->
+    {ok, {Nodes :: [node()], rabbit_types:node_type()}}.
 
 list_nodes() ->
     case application:get_env(rabbit, cluster_formation) of
       undefined         ->
-        {[], disc};
+            {ok, {[], disc}};
       {ok, ClusterFormation} ->
         case proplists:get_value(peer_discovery_dns, ClusterFormation) of
             undefined ->
@@ -41,11 +42,11 @@ list_nodes() ->
                                  "but final config does not contain rabbit.cluster_formation.peer_discovery_dns. "
                                  "Cannot discover any nodes because seed hostname is not configured!",
                                  [?MODULE]),
-              {[], disc};
+              {ok, {[], disc}};
             Proplist  ->
               Hostname = rabbit_data_coercion:to_list(proplists:get_value(hostname, Proplist)),
 
-              {discover_nodes(Hostname, net_kernel:longnames()), rabbit_peer_discovery:node_type()}
+              {ok, {discover_nodes(Hostname, net_kernel:longnames()), rabbit_peer_discovery:node_type()}}
         end
     end.
 
diff --git a/src/rabbit_quorum_queue.erl b/src/rabbit_quorum_queue.erl
index b54de3a2e6..725d8086d9 100644
--- a/src/rabbit_quorum_queue.erl
+++ b/src/rabbit_quorum_queue.erl
@@ -43,7 +43,6 @@
 -include_lib("stdlib/include/qlc.hrl").
 -include("amqqueue.hrl").
 
--type ra_server_id() :: {Name :: atom(), Node :: node()}.
 -type msg_id() :: non_neg_integer().
 -type qmsg() :: {rabbit_types:r('queue'), pid(), msg_id(), boolean(), rabbit_types:message()}.
 
@@ -68,8 +67,8 @@
 
 %%----------------------------------------------------------------------------
 
--spec init_state(ra_server_id(), rabbit_types:r('queue')) ->
-                        rabbit_fifo_client:state().
+-spec init_state(amqqueue:ra_server_id(), rabbit_amqqueue:name()) ->
+    rabbit_fifo_client:state().
 init_state({Name, _}, QName = #resource{}) ->
     {ok, SoftLimit} = application:get_env(rabbit, quorum_commands_soft_limit),
     %% This lookup could potentially return an {error, not_found}, but we do not
@@ -84,7 +83,7 @@ init_state({Name, _}, QName = #resource{}) ->
                             fun() -> credit_flow:block(Name), ok end,
                             fun() -> credit_flow:unblock(Name), ok end).
 
--spec handle_event({'ra_event', ra_server_id(), any()}, rabbit_fifo_client:state()) ->
+-spec handle_event({'ra_event', amqqueue:ra_server_id(), any()}, rabbit_fifo_client:state()) ->
                           {'internal', Correlators :: [term()], rabbit_fifo_client:state()} |
                           {rabbit_fifo:client_msg(), rabbit_fifo_client:state()}.
 
@@ -92,8 +91,7 @@ handle_event({ra_event, From, Evt}, QState) ->
     rabbit_fifo_client:handle_ra_event(From, Evt, QState).
 
 -spec declare(amqqueue:amqqueue()) ->
-    {'new', amqqueue:amqqueue()} |
-    {existing, amqqueue:amqqueue()}.
+    {new | existing, amqqueue:amqqueue()} | rabbit_types:channel_exit().
 
 declare(Q) when ?amqqueue_is_quorum(Q) ->
     QName = amqqueue:get_name(Q),
@@ -264,9 +262,9 @@ recover(Queues) ->
              ok ->
                  % queue was restarted, good
                  ok;
-             {error, Err}
-               when Err == not_started orelse
-                    Err == name_not_registered ->
+             {error, Err1}
+               when Err1 == not_started orelse
+                    Err1 == name_not_registered ->
                  % queue was never started on this node
                  % so needs to be started from scratch.
                  Machine = ra_machine(Q0),
@@ -400,7 +398,8 @@ credit(CTag, Credit, Drain, QState) ->
 -spec basic_get(amqqueue:amqqueue(), NoAck :: boolean(), rabbit_types:ctag(),
                 rabbit_fifo_client:state()) ->
     {'ok', 'empty', rabbit_fifo_client:state()} |
-    {'ok', QLen :: non_neg_integer(), qmsg(), rabbit_fifo_client:state()}.
+    {'ok', QLen :: non_neg_integer(), qmsg(), rabbit_fifo_client:state()} |
+    {error, timeout | term()}.
 
 basic_get(Q, NoAck, CTag0, QState0) when ?amqqueue_is_quorum(Q) ->
     QName = amqqueue:get_name(Q),
@@ -420,6 +419,8 @@ basic_get(Q, NoAck, CTag0, QState0) when ?amqqueue_is_quorum(Q) ->
             IsDelivered = Count > 0,
             Msg = rabbit_basic:add_header(<<"x-delivery-count">>, long, Count, Msg0),
             {ok, MsgsReady, {QName, Id, MsgId, IsDelivered, Msg}, QState};
+        {error, _} = Err ->
+            Err;
         {timeout, _} ->
             {error, timeout}
     end.
@@ -482,7 +483,7 @@ basic_cancel(ConsumerTag, ChPid, OkMsg, QState0) ->
     maybe_send_reply(ChPid, OkMsg),
     rabbit_fifo_client:cancel_checkout(quorum_ctag(ConsumerTag), QState0).
 
--spec stateless_deliver(ra_server_id(), rabbit_types:delivery()) -> 'ok'.
+-spec stateless_deliver(amqqueue:ra_server_id(), rabbit_types:delivery()) -> 'ok'.
 
 stateless_deliver(ServerId, Delivery) ->
     ok = rabbit_fifo_client:untracked_enqueue([ServerId],
@@ -581,7 +582,7 @@ cluster_state(Name) ->
             end
     end.
 
--spec status(rabbit_types:vhost(), Name :: atom()) -> rabbit_types:infos() | {error, term()}.
+-spec status(rabbit_types:vhost(), Name :: rabbit_misc:resource_name()) -> rabbit_types:infos() | {error, term()}.
 
 status(Vhost, QueueName) ->
     %% Handle not found queues
@@ -885,6 +886,8 @@ format(Q) when ?is_amqqueue(Q) ->
 is_process_alive(Name, Node) ->
     erlang:is_pid(rpc:call(Node, erlang, whereis, [Name], ?TICK_TIME)).
 
+-spec quorum_messages(atom()) -> non_neg_integer().
+
 quorum_messages(QName) ->
     case ets:lookup(queue_coarse_metrics, QName) of
         [{_, _, _, M, _}] ->
diff --git a/src/rabbit_recovery_terms.erl b/src/rabbit_recovery_terms.erl
index 4e8ae128de..28bd9fc23a 100644
--- a/src/rabbit_recovery_terms.erl
+++ b/src/rabbit_recovery_terms.erl
@@ -117,7 +117,7 @@ upgrade_recovery_terms() ->
         [begin
              File = filename:join([QueuesDir, Dir, "clean.dot"]),
              case rabbit_file:read_term_file(File) of
-                 {ok, Terms} -> ok  = store(?MODULE, Dir, Terms);
+                 {ok, Terms} -> ok  = store_global_table(Dir, Terms);
                  {error, _}  -> ok
              end,
              file:delete(File)
@@ -134,7 +134,7 @@ dets_upgrade(Fun)->
     open_global_table(),
     try
         ok = dets:foldl(fun ({DirBaseName, Terms}, Acc) ->
-                                store(?MODULE, DirBaseName, Fun(Terms)),
+                                store_global_table(DirBaseName, Fun(Terms)),
                                 Acc
                         end, ok, ?MODULE),
         ok
@@ -160,8 +160,14 @@ close_global_table() ->
             ok
     end.
 
+store_global_table(DirBaseName, Terms) ->
+    dets:insert(?MODULE, {DirBaseName, Terms}).
+
 read_global(DirBaseName) ->
-    read(?MODULE, DirBaseName).
+    case dets:lookup(?MODULE, DirBaseName) of
+        [{_, Terms}] -> {ok, Terms};
+        _            -> {error, not_found}
+    end.
 
 delete_global_table() ->
     file:delete(filename:join(rabbit_mnesia:dir(), "recovery.dets")).
diff --git a/src/rabbit_table.erl b/src/rabbit_table.erl
index db16152d5b..9bf1d2c3f6 100644
--- a/src/rabbit_table.erl
+++ b/src/rabbit_table.erl
@@ -117,8 +117,6 @@ wait(TableNames, Timeout, Retries) ->
             throw(Error);
         {_, {error, Error}} ->
             rabbit_log:warning("Error while waiting for Mnesia tables: ~p~n", [Error]),
-            wait(TableNames, Timeout, Retries - 1);
-        _ ->
             wait(TableNames, Timeout, Retries - 1)
     end.
 
@@ -131,7 +129,7 @@ retry_timeout(_Retry = true) ->
               end,
     {retry_timeout(), Retries}.
 
--spec retry_timeout() -> {non_neg_integer() | infinity, non_neg_integer()}.
+-spec retry_timeout() -> non_neg_integer() | infinity.
 
 retry_timeout() ->
     case application:get_env(rabbit, mnesia_table_loading_retry_timeout) of
diff --git a/src/rabbit_upgrade.erl b/src/rabbit_upgrade.erl
index 214a1e390b..f452d5c92f 100644
--- a/src/rabbit_upgrade.erl
+++ b/src/rabbit_upgrade.erl
@@ -174,25 +174,34 @@ upgrade_mode(AllNodes) ->
             end;
         [Another|_] ->
             MyVersion = rabbit_version:desired_for_scope(mnesia),
-            ErrFun = fun (ClusterVersion) ->
-                             %% The other node(s) are running an
-                             %% unexpected version.
-                             die("Cluster upgrade needed but other nodes are "
-                                 "running ~p~nand I want ~p",
-                                 [ClusterVersion, MyVersion])
-                     end,
             case rpc:call(Another, rabbit_version, desired_for_scope,
                           [mnesia]) of
-                {badrpc, {'EXIT', {undef, _}}} -> ErrFun(unknown_old_version);
-                {badrpc, Reason}               -> ErrFun({unknown, Reason});
-                CV                             -> case rabbit_version:matches(
-                                                         MyVersion, CV) of
-                                                      true  -> secondary;
-                                                      false -> ErrFun(CV)
-                                                  end
+                {badrpc, {'EXIT', {undef, _}}} ->
+                    die_because_cluster_upgrade_needed(unknown_old_version,
+                                                       MyVersion);
+                {badrpc, Reason} ->
+                    die_because_cluster_upgrade_needed({unknown, Reason},
+                                                       MyVersion);
+                CV -> case rabbit_version:matches(
+                             MyVersion, CV) of
+                          true  -> secondary;
+                          false -> die_because_cluster_upgrade_needed(
+                                     CV, MyVersion)
+                      end
             end
     end.
 
+-spec die_because_cluster_upgrade_needed(any(), any()) -> no_return().
+
+die_because_cluster_upgrade_needed(ClusterVersion, MyVersion) ->
+    %% The other node(s) are running an
+    %% unexpected version.
+    die("Cluster upgrade needed but other nodes are "
+        "running ~p~nand I want ~p",
+        [ClusterVersion, MyVersion]).
+
+-spec die(string(), list()) -> no_return().
+
 die(Msg, Args) ->
     %% We don't throw or exit here since that gets thrown
     %% straight out into do_boot, generating an erl_crash.dump
diff --git a/src/rabbit_version.erl b/src/rabbit_version.erl
index a63d60058c..4a79ef9938 100644
--- a/src/rabbit_version.erl
+++ b/src/rabbit_version.erl
@@ -214,8 +214,9 @@ check_version_consistency(This, Remote, Name) ->
     check_version_consistency(This, Remote, Name, fun (A, B) -> A =:= B end).
 
 -spec check_version_consistency
-        (string(), string(), string(), string()) ->
-                                          rabbit_types:ok_or_error(any()).
+        (string(), string(), string(),
+         fun((string(), string()) -> boolean())) ->
+    rabbit_types:ok_or_error(any()).
 
 check_version_consistency(This, Remote, Name, Comp) ->
     case Comp(This, Remote) of
diff --git a/src/rabbit_vhost.erl b/src/rabbit_vhost.erl
index c5b28e7e1c..9180f9ca0a 100644
--- a/src/rabbit_vhost.erl
+++ b/src/rabbit_vhost.erl
@@ -108,10 +108,6 @@ do_add(VHostPath, ActingUser) ->
             rabbit_event:notify(vhost_created, info(VHostPath)
                                 ++ [{user_who_performed_action, ActingUser}]),
             R;
-        {error, {no_such_vhost, VHostPath}} ->
-            Msg = rabbit_misc:format("failed to set up vhost '~s': it was concurrently deleted!",
-                                     [VHostPath]),
-            {error, Msg};
         {error, Reason} ->
             Msg = rabbit_misc:format("failed to set up vhost '~s': ~p",
                                      [VHostPath, Reason]),
@@ -215,10 +211,7 @@ assert_benign({error, {absent, Q, _}}, ActingUser) ->
     %% Removing the mnesia entries here is safe. If/when the down node
     %% restarts, it will clear out the on-disk storage of the queue.
     QName = amqqueue:get_name(Q),
-    case rabbit_amqqueue:internal_delete(QName, ActingUser) of
-        ok                 -> ok;
-        {error, not_found} -> ok
-    end.
+    rabbit_amqqueue:internal_delete(QName, ActingUser).
 
 internal_delete(VHostPath, ActingUser) ->
     [ok = rabbit_auth_backend_internal:clear_permissions(
@@ -275,7 +268,7 @@ assert(VHostPath) -> case exists(VHostPath) of
                          false -> throw({error, {no_such_vhost, VHostPath}})
                      end.
 
--spec update(rabbit_types:vhost(), rabbit_misc:thunk(A)) -> A.
+-spec update(rabbit_types:vhost(), fun((#vhost{}) -> #vhost{})) -> #vhost{}.
 
 update(VHostPath, Fun) ->
     case mnesia:read({rabbit_vhost, VHostPath}) of