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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) 2007-2014 GoPivotal, Inc. All rights reserved.
%%
-module(rabbit_node_monitor).
-behaviour(gen_server).
-export([start_link/0]).
-export([running_nodes_filename/0,
cluster_status_filename/0, prepare_cluster_status_files/0,
write_cluster_status/1, read_cluster_status/0,
update_cluster_status/0, reset_cluster_status/0]).
-export([notify_node_up/0, notify_joined_cluster/0, notify_left_cluster/1]).
-export([partitions/0, partitions/1, subscribe/1]).
-export([pause_minority_guard/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
code_change/3]).
%% Utils
-export([all_rabbit_nodes_up/0, run_outside_applications/1, ping_all/0]).
-define(SERVER, ?MODULE).
-define(RABBIT_UP_RPC_TIMEOUT, 2000).
-define(RABBIT_DOWN_PING_INTERVAL, 1000).
-record(state, {monitors, partitions, subscribers, down_ping_timer, autoheal}).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-spec(start_link/0 :: () -> rabbit_types:ok_pid_or_error()).
-spec(running_nodes_filename/0 :: () -> string()).
-spec(cluster_status_filename/0 :: () -> string()).
-spec(prepare_cluster_status_files/0 :: () -> 'ok').
-spec(write_cluster_status/1 :: (rabbit_mnesia:cluster_status()) -> 'ok').
-spec(read_cluster_status/0 :: () -> rabbit_mnesia:cluster_status()).
-spec(update_cluster_status/0 :: () -> 'ok').
-spec(reset_cluster_status/0 :: () -> 'ok').
-spec(notify_node_up/0 :: () -> 'ok').
-spec(notify_joined_cluster/0 :: () -> 'ok').
-spec(notify_left_cluster/1 :: (node()) -> 'ok').
-spec(partitions/0 :: () -> [node()]).
-spec(partitions/1 :: ([node()]) -> [{node(), [node()]}]).
-spec(subscribe/1 :: (pid()) -> 'ok').
-spec(pause_minority_guard/0 :: () -> 'ok' | 'pausing').
-spec(all_rabbit_nodes_up/0 :: () -> boolean()).
-spec(run_outside_applications/1 :: (fun (() -> any())) -> pid()).
-spec(ping_all/0 :: () -> 'ok').
-endif.
%%----------------------------------------------------------------------------
%% Start
%%----------------------------------------------------------------------------
start_link() -> gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
%%----------------------------------------------------------------------------
%% Cluster file operations
%%----------------------------------------------------------------------------
%% The cluster file information is kept in two files. The "cluster
%% status file" contains all the clustered nodes and the disc nodes.
%% The "running nodes file" contains the currently running nodes or
%% the running nodes at shutdown when the node is down.
%%
%% We strive to keep the files up to date and we rely on this
%% assumption in various situations. Obviously when mnesia is offline
%% the information we have will be outdated, but it cannot be
%% otherwise.
running_nodes_filename() ->
filename:join(rabbit_mnesia:dir(), "nodes_running_at_shutdown").
cluster_status_filename() ->
rabbit_mnesia:dir() ++ "/cluster_nodes.config".
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);
{error, enoent} -> []
end,
ThisNode = [node()],
%% The running nodes file might contain a set or a list, in case
%% of the legacy file
RunningNodes2 = lists:usort(ThisNode ++ RunningNodes1),
{AllNodes1, DiscNodes} =
case try_read_file(cluster_status_filename()) of
{ok, [{AllNodes, DiscNodes0}]} ->
{AllNodes, DiscNodes0};
{ok, [AllNodes0]} when is_list(AllNodes0) ->
{legacy_cluster_nodes(AllNodes0), legacy_disc_nodes(AllNodes0)};
{ok, Files} ->
Corrupt(Files);
{error, enoent} ->
LegacyNodes = legacy_cluster_nodes([]),
{LegacyNodes, LegacyNodes}
end,
AllNodes2 = lists:usort(AllNodes1 ++ RunningNodes2),
ok = write_cluster_status({AllNodes2, DiscNodes, RunningNodes2}).
write_cluster_status({All, Disc, Running}) ->
ClusterStatusFN = cluster_status_filename(),
Res = case rabbit_file:write_term_file(ClusterStatusFN, [{All, Disc}]) of
ok ->
RunningNodesFN = running_nodes_filename(),
{RunningNodesFN,
rabbit_file:write_term_file(RunningNodesFN, [Running])};
E1 = {error, _} ->
{ClusterStatusFN, E1}
end,
case Res of
{_, ok} -> ok;
{FN, {error, E2}} -> throw({error, {could_not_write_file, FN, E2}})
end.
read_cluster_status() ->
case {try_read_file(cluster_status_filename()),
try_read_file(running_nodes_filename())} of
{{ok, [{All, Disc}]}, {ok, [Running]}} when is_list(Running) ->
{All, Disc, Running};
{Stat, Run} ->
throw({error, {corrupt_or_missing_cluster_files, Stat, Run}})
end.
update_cluster_status() ->
{ok, Status} = rabbit_mnesia:cluster_status_from_mnesia(),
write_cluster_status(Status).
reset_cluster_status() ->
write_cluster_status({[node()], [node()], [node()]}).
%%----------------------------------------------------------------------------
%% Cluster notifications
%%----------------------------------------------------------------------------
notify_node_up() ->
Nodes = rabbit_mnesia:cluster_nodes(running) -- [node()],
gen_server:abcast(Nodes, ?SERVER,
{node_up, node(), rabbit_mnesia:node_type()}),
%% register other active rabbits with this rabbit
DiskNodes = rabbit_mnesia:cluster_nodes(disc),
[gen_server:cast(?SERVER, {node_up, N, case lists:member(N, DiskNodes) of
true -> disc;
false -> ram
end}) || N <- Nodes],
ok.
notify_joined_cluster() ->
Nodes = rabbit_mnesia:cluster_nodes(running) -- [node()],
gen_server:abcast(Nodes, ?SERVER,
{joined_cluster, node(), rabbit_mnesia:node_type()}),
ok.
notify_left_cluster(Node) ->
Nodes = rabbit_mnesia:cluster_nodes(running),
gen_server:abcast(Nodes, ?SERVER, {left_cluster, Node}),
ok.
%%----------------------------------------------------------------------------
%% Server calls
%%----------------------------------------------------------------------------
partitions() ->
gen_server:call(?SERVER, partitions, infinity).
partitions(Nodes) ->
{Replies, _} = gen_server:multi_call(Nodes, ?SERVER, partitions, infinity),
Replies.
subscribe(Pid) ->
gen_server:cast(?SERVER, {subscribe, Pid}).
%%----------------------------------------------------------------------------
%% pause_minority safety
%%----------------------------------------------------------------------------
%% If we are in a minority and pause_minority mode then a) we are
%% going to shut down imminently and b) we should not confirm anything
%% until then, since anything we confirm is likely to be lost.
%%
%% We could confirm something by having an HA queue see the minority
%% state (and fail over into it) before the node monitor stops us, or
%% by using unmirrored queues and just having them vanish (and
%% confiming messages as thrown away).
%%
%% So we have channels call in here before issuing confirms, to do a
%% lightweight check that we have not entered a minority state.
pause_minority_guard() ->
case get(pause_minority_guard) of
not_minority_mode ->
ok;
undefined ->
{ok, M} = application:get_env(rabbit, cluster_partition_handling),
case M of
pause_minority -> pause_minority_guard([]);
_ -> put(pause_minority_guard, not_minority_mode),
ok
end;
{minority_mode, Nodes} ->
pause_minority_guard(Nodes)
end.
pause_minority_guard(LastNodes) ->
case nodes() of
LastNodes -> ok;
_ -> put(pause_minority_guard, {minority_mode, nodes()}),
case majority() of
false -> pausing;
true -> ok
end
end.
%%----------------------------------------------------------------------------
%% gen_server callbacks
%%----------------------------------------------------------------------------
init([]) ->
%% We trap exits so that the supervisor will not just kill us. We
%% want to be sure that we are not going to be killed while
%% writing out the cluster status files - bad things can then
%% happen.
process_flag(trap_exit, true),
net_kernel:monitor_nodes(true, [nodedown_reason]),
{ok, _} = mnesia:subscribe(system),
{ok, #state{monitors = pmon:new(),
subscribers = pmon:new(),
partitions = [],
autoheal = rabbit_autoheal:init()}}.
handle_call(partitions, _From, State = #state{partitions = Partitions}) ->
{reply, Partitions, State};
handle_call(_Request, _From, State) ->
{noreply, State}.
%% Note: when updating the status file, we can't simply write the
%% mnesia information since the message can (and will) overtake the
%% mnesia propagation.
handle_cast({node_up, Node, NodeType},
State = #state{monitors = Monitors}) ->
case pmon:is_monitored({rabbit, Node}, Monitors) of
true -> {noreply, State};
false -> rabbit_log:info("rabbit on node ~p up~n", [Node]),
{AllNodes, DiscNodes, RunningNodes} = read_cluster_status(),
write_cluster_status({add_node(Node, AllNodes),
case NodeType of
disc -> add_node(Node, DiscNodes);
ram -> DiscNodes
end,
add_node(Node, RunningNodes)}),
ok = handle_live_rabbit(Node),
{noreply, State#state{
monitors = pmon:monitor({rabbit, Node}, Monitors)}}
end;
handle_cast({joined_cluster, Node, NodeType}, State) ->
{AllNodes, DiscNodes, RunningNodes} = read_cluster_status(),
write_cluster_status({add_node(Node, AllNodes),
case NodeType of
disc -> add_node(Node, DiscNodes);
ram -> DiscNodes
end,
RunningNodes}),
{noreply, State};
handle_cast({left_cluster, Node}, State) ->
{AllNodes, DiscNodes, RunningNodes} = read_cluster_status(),
write_cluster_status({del_node(Node, AllNodes), del_node(Node, DiscNodes),
del_node(Node, RunningNodes)}),
{noreply, State};
handle_cast({subscribe, Pid}, State = #state{subscribers = Subscribers}) ->
{noreply, State#state{subscribers = pmon:monitor(Pid, Subscribers)}};
handle_cast(_Msg, State) ->
{noreply, State}.
handle_info({'DOWN', _MRef, process, {rabbit, Node}, _Reason},
State = #state{monitors = Monitors, subscribers = Subscribers}) ->
rabbit_log:info("rabbit on node ~p down~n", [Node]),
{AllNodes, DiscNodes, RunningNodes} = read_cluster_status(),
write_cluster_status({AllNodes, DiscNodes, del_node(Node, RunningNodes)}),
[P ! {node_down, Node} || P <- pmon:monitored(Subscribers)],
{noreply, handle_dead_rabbit(
Node,
State#state{monitors = pmon:erase({rabbit, Node}, Monitors)})};
handle_info({'DOWN', _MRef, process, Pid, _Reason},
State = #state{subscribers = Subscribers}) ->
{noreply, State#state{subscribers = pmon:erase(Pid, Subscribers)}};
handle_info({nodedown, Node, Info}, State) ->
rabbit_log:info("node ~p down: ~p~n",
[Node, proplists:get_value(nodedown_reason, Info)]),
{noreply, handle_dead_node(Node, State)};
handle_info({mnesia_system_event,
{inconsistent_database, running_partitioned_network, Node}},
State = #state{partitions = Partitions,
monitors = Monitors,
autoheal = AState}) ->
%% We will not get a node_up from this node - yet we should treat it as
%% up (mostly).
State1 = case pmon:is_monitored({rabbit, Node}, Monitors) of
true -> State;
false -> State#state{
monitors = pmon:monitor({rabbit, Node}, Monitors)}
end,
ok = handle_live_rabbit(Node),
Partitions1 = ordsets:to_list(
ordsets:add_element(Node, ordsets:from_list(Partitions))),
{noreply, State1#state{partitions = Partitions1,
autoheal = rabbit_autoheal:maybe_start(AState)}};
handle_info({autoheal_msg, Msg}, State = #state{autoheal = AState,
partitions = Partitions}) ->
AState1 = rabbit_autoheal:handle_msg(Msg, AState, Partitions),
{noreply, State#state{autoheal = AState1}};
handle_info(ping_nodes, State) ->
%% We ping nodes when some are down to ensure that we find out
%% about healed partitions quickly. We ping all nodes rather than
%% just the ones we know are down for simplicity; it's not expensive
%% to ping the nodes that are up, after all.
State1 = State#state{down_ping_timer = undefined},
Self = self(),
%% We ping in a separate process since in a partition it might
%% take some noticeable length of time and we don't want to block
%% the node monitor for that long.
spawn_link(fun () ->
ping_all(),
case all_nodes_up() of
true -> ok;
false -> Self ! ping_again
end
end),
{noreply, State1};
handle_info(ping_again, State) ->
{noreply, ensure_ping_timer(State)};
handle_info(_Info, State) ->
{noreply, State}.
terminate(_Reason, State) ->
rabbit_misc:stop_timer(State, #state.down_ping_timer),
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%----------------------------------------------------------------------------
%% Functions that call the module specific hooks when nodes go up/down
%%----------------------------------------------------------------------------
handle_dead_node(Node, State = #state{autoheal = Autoheal}) ->
%% In general in rabbit_node_monitor we care about whether the
%% rabbit application is up rather than the node; we do this so
%% that we can respond in the same way to "rabbitmqctl stop_app"
%% and "rabbitmqctl stop" as much as possible.
%%
%% However, for pause_minority mode we can't do this, since we
%% depend on looking at whether other nodes are up to decide
%% whether to come back up ourselves - if we decide that based on
%% the rabbit application we would go down and never come back.
case application:get_env(rabbit, cluster_partition_handling) of
{ok, pause_minority} ->
case majority() of
true -> ok;
false -> await_cluster_recovery()
end,
State;
{ok, ignore} ->
State;
{ok, autoheal} ->
State#state{autoheal = rabbit_autoheal:node_down(Node, Autoheal)};
{ok, Term} ->
rabbit_log:warning("cluster_partition_handling ~p unrecognised, "
"assuming 'ignore'~n", [Term]),
State
end.
await_cluster_recovery() ->
rabbit_log:warning("Cluster minority status detected - awaiting recovery~n",
[]),
run_outside_applications(fun () ->
rabbit:stop(),
wait_for_cluster_recovery()
end),
ok.
run_outside_applications(Fun) ->
spawn(fun () ->
%% If our group leader is inside an application we are about
%% to stop, application:stop/1 does not return.
group_leader(whereis(init), self()),
%% Ensure only one such process at a time, the
%% exit(badarg) is harmless if one is already running
try register(rabbit_outside_app_process, self()) of
true -> Fun()
catch error:badarg -> ok
end
end).
wait_for_cluster_recovery() ->
ping_all(),
case majority() of
true -> rabbit:start();
false -> timer:sleep(?RABBIT_DOWN_PING_INTERVAL),
wait_for_cluster_recovery()
end.
handle_dead_rabbit(Node, State = #state{partitions = Partitions,
autoheal = Autoheal}) ->
%% TODO: This may turn out to be a performance hog when there are
%% lots of nodes. We really only need to execute some of these
%% statements on *one* node, rather than all of them.
ok = rabbit_networking:on_node_down(Node),
ok = rabbit_amqqueue:on_node_down(Node),
ok = rabbit_alarm:on_node_down(Node),
ok = rabbit_mnesia:on_node_down(Node),
%% If we have been partitioned, and we are now in the only remaining
%% partition, we no longer care about partitions - forget them. Note
%% that we do not attempt to deal with individual (other) partitions
%% going away. It's only safe to forget anything about partitions when
%% there are no partitions.
Partitions1 = case Partitions -- (Partitions -- alive_rabbit_nodes()) of
[] -> [];
_ -> Partitions
end,
ensure_ping_timer(
State#state{partitions = Partitions1,
autoheal = rabbit_autoheal:rabbit_down(Node, Autoheal)}).
ensure_ping_timer(State) ->
rabbit_misc:ensure_timer(
State, #state.down_ping_timer, ?RABBIT_DOWN_PING_INTERVAL, ping_nodes).
handle_live_rabbit(Node) ->
ok = rabbit_amqqueue:on_node_up(Node),
ok = rabbit_alarm:on_node_up(Node),
ok = rabbit_mnesia:on_node_up(Node).
%%--------------------------------------------------------------------
%% Internal utils
%%--------------------------------------------------------------------
try_read_file(FileName) ->
case rabbit_file:read_term_file(FileName) of
{ok, Term} -> {ok, Term};
{error, enoent} -> {error, enoent};
{error, E} -> throw({error, {cannot_read_file, FileName, E}})
end.
legacy_cluster_nodes(Nodes) ->
%% We get all the info that we can, including the nodes from
%% mnesia, which will be there if the node is a disc node (empty
%% list otherwise)
lists:usort(Nodes ++ mnesia:system_info(db_nodes)).
legacy_disc_nodes(AllNodes) ->
case AllNodes == [] orelse lists:member(node(), AllNodes) of
true -> [node()];
false -> []
end.
add_node(Node, Nodes) -> lists:usort([Node | Nodes]).
del_node(Node, Nodes) -> Nodes -- [Node].
%%--------------------------------------------------------------------
%% mnesia:system_info(db_nodes) (and hence
%% rabbit_mnesia:cluster_nodes(running)) does not give reliable
%% results when partitioned. So we have a small set of replacement
%% functions here. "rabbit" in a function's name implies we test if
%% the rabbit application is up, not just the node.
%% As we use these functions to decide what to do in pause_minority
%% state, they *must* be fast, even in the case where TCP connections
%% are timing out. So that means we should be careful about whether we
%% connect to nodes which are currently disconnected.
majority() ->
Nodes = rabbit_mnesia:cluster_nodes(all),
length(alive_nodes(Nodes)) / length(Nodes) > 0.5.
all_nodes_up() ->
Nodes = rabbit_mnesia:cluster_nodes(all),
length(alive_nodes(Nodes)) =:= length(Nodes).
all_rabbit_nodes_up() ->
Nodes = rabbit_mnesia:cluster_nodes(all),
length(alive_rabbit_nodes(Nodes)) =:= length(Nodes).
alive_nodes(Nodes) -> [N || N <- Nodes, lists:member(N, [node()|nodes()])].
alive_rabbit_nodes() -> alive_rabbit_nodes(rabbit_mnesia:cluster_nodes(all)).
alive_rabbit_nodes(Nodes) ->
[N || N <- alive_nodes(Nodes), rabbit:is_running(N)].
%% This one is allowed to connect!
ping_all() ->
[net_adm:ping(N) || N <- rabbit_mnesia:cluster_nodes(all)],
ok.
|