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%% This Source Code Form is subject to the terms of the Mozilla Public
%% License, v. 2.0. If a copy of the MPL was not distributed with this
%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
%%
%% Copyright (c) 2007-2020 VMware, Inc. or its affiliates. All rights reserved.
%%
-module(rabbit_control_misc).
-export([emitting_map/4, emitting_map/5, emitting_map_with_exit_handler/4,
emitting_map_with_exit_handler/5, wait_for_info_messages/6,
spawn_emitter_caller/7, await_emitters_termination/1,
print_cmd_result/2]).
-spec emitting_map(pid(), reference(), fun(), list()) -> 'ok'.
-spec emitting_map(pid(), reference(), fun(), list(), atom()) -> 'ok'.
-spec emitting_map_with_exit_handler
(pid(), reference(), fun(), list()) -> 'ok'.
-spec emitting_map_with_exit_handler
(pid(), reference(), fun(), list(), 'continue') -> 'ok'.
-type fold_fun() :: fun((Item :: term(), AccIn :: term()) -> AccOut :: term()).
-spec wait_for_info_messages(pid(), reference(), fold_fun(), InitialAcc, timeout(), non_neg_integer()) -> OK | Err when
InitialAcc :: term(), Acc :: term(), OK :: {ok, Acc}, Err :: {error, term()}.
-spec spawn_emitter_caller(node(), module(), atom(), [term()], reference(), pid(), timeout()) -> 'ok'.
-spec await_emitters_termination([pid()]) -> 'ok'.
-spec print_cmd_result(atom(), term()) -> 'ok'.
emitting_map(AggregatorPid, Ref, Fun, List) ->
emitting_map(AggregatorPid, Ref, Fun, List, continue),
AggregatorPid ! {Ref, finished},
ok.
emitting_map(AggregatorPid, Ref, Fun, List, continue) ->
_ = emitting_map0(AggregatorPid, Ref, Fun, List, fun step/4),
ok.
emitting_map_with_exit_handler(AggregatorPid, Ref, Fun, List) ->
emitting_map_with_exit_handler(AggregatorPid, Ref, Fun, List, continue),
AggregatorPid ! {Ref, finished},
ok.
emitting_map_with_exit_handler(AggregatorPid, Ref, Fun, List, continue) ->
_ = emitting_map0(AggregatorPid, Ref, Fun, List, fun step_with_exit_handler/4),
ok.
emitting_map0(AggregatorPid, Ref, Fun, List, StepFun) ->
[StepFun(AggregatorPid, Ref, Fun, Item) || Item <- List].
step(AggregatorPid, Ref, Fun, Item) ->
AggregatorPid ! {Ref, Fun(Item), continue},
ok.
step_with_exit_handler(AggregatorPid, Ref, Fun, Item) ->
Noop = make_ref(),
case rabbit_misc:with_exit_handler(
fun () -> Noop end,
fun () -> Fun(Item) end) of
Noop ->
ok;
Res ->
AggregatorPid ! {Ref, Res, continue},
ok
end.
%% Invokes RPC for async info collection in separate (but linked to
%% the caller) process. Separate process waits for RPC to finish and
%% in case of errors sends them in wait_for_info_messages/5-compatible
%% form to aggregator process. Calling process is then expected to
%% do blocking call of wait_for_info_messages/5.
%%
%% Remote function MUST use calls to emitting_map/4 (and other
%% emitting_map's) to properly deliver requested information to an
%% aggregator process.
%%
%% If for performance reasons several parallel emitting_map's need to
%% be run, remote function MUST NOT return until all this
%% emitting_map's are done. And during all this time remote RPC
%% process MUST be linked to emitting
%% processes. await_emitters_termination/1 helper can be used as a
%% last statement of remote function to ensure this behaviour.
spawn_emitter_caller(Node, Mod, Fun, Args, Ref, Pid, Timeout) ->
_ = spawn_monitor(
fun () ->
case rpc_call_emitter(Node, Mod, Fun, Args, Ref, Pid, Timeout) of
{error, _} = Error ->
Pid ! {Ref, error, Error};
{bad_argument, _} = Error ->
Pid ! {Ref, error, Error};
{badrpc, _} = Error ->
Pid ! {Ref, error, Error};
_ ->
ok
end
end),
ok.
rpc_call_emitter(Node, Mod, Fun, Args, Ref, Pid, Timeout) ->
rabbit_misc:rpc_call(Node, Mod, Fun, Args++[Ref, Pid], Timeout).
%% Aggregator process expects correct numbers of explicits ACKs about
%% finished emission process. While everything is linked, we still
%% need somehow to wait for termination of all emitters before
%% returning from RPC call - otherwise links will be just broken with
%% reason 'normal' and we can miss some errors, and subsequently
%% hang.
await_emitters_termination(Pids) ->
Monitors = [erlang:monitor(process, Pid) || Pid <- Pids],
collect_monitors(Monitors).
collect_monitors([]) ->
ok;
collect_monitors([Monitor|Rest]) ->
receive
{'DOWN', Monitor, process, _Pid, normal} ->
collect_monitors(Rest);
{'DOWN', Monitor, process, _Pid, noproc} ->
%% There is a link and a monitor to a process. Matching
%% this clause means that process has gracefully
%% terminated even before we've started monitoring.
collect_monitors(Rest);
{'DOWN', _, process, Pid, Reason} when Reason =/= normal,
Reason =/= noproc ->
exit({emitter_exit, Pid, Reason})
end.
%% Wait for result of one or more calls to emitting_map-family
%% functions.
%%
%% Number of expected acknowledgments is specified by ChunkCount
%% argument. Most common usage will be with ChunkCount equals to
%% number of live nodes, but it's not mandatory - thus more generic
%% name of 'ChunkCount' was chosen.
wait_for_info_messages(Pid, Ref, Fun, Acc0, Timeout, ChunkCount) ->
_ = notify_if_timeout(Pid, Ref, Timeout),
wait_for_info_messages(Ref, Fun, Acc0, ChunkCount).
wait_for_info_messages(Ref, Fun, Acc0, ChunksLeft) ->
receive
{Ref, finished} when ChunksLeft =:= 1 ->
{ok, Acc0};
{Ref, finished} ->
wait_for_info_messages(Ref, Fun, Acc0, ChunksLeft - 1);
{Ref, {timeout, T}} ->
exit({error, {timeout, (T / 1000)}});
{Ref, []} ->
wait_for_info_messages(Ref, Fun, Acc0, ChunksLeft);
{Ref, Result, continue} ->
wait_for_info_messages(Ref, Fun, Fun(Result, Acc0), ChunksLeft);
{Ref, error, Error} ->
{error, simplify_emission_error(Error)};
{'DOWN', _MRef, process, _Pid, normal} ->
wait_for_info_messages(Ref, Fun, Acc0, ChunksLeft);
{'DOWN', _MRef, process, _Pid, Reason} ->
{error, simplify_emission_error(Reason)};
_Msg ->
wait_for_info_messages(Ref, Fun, Acc0, ChunksLeft)
end.
simplify_emission_error({badrpc, {'EXIT', {{nocatch, EmissionError}, _Stacktrace}}}) ->
EmissionError;
simplify_emission_error({{nocatch, EmissionError}, _Stacktrace}) ->
EmissionError;
simplify_emission_error({error, _} = Error) ->
Error;
simplify_emission_error({bad_argument, _} = Error) ->
Error;
simplify_emission_error(Anything) ->
{error, Anything}.
notify_if_timeout(_, _, infinity) ->
ok;
notify_if_timeout(Pid, Ref, Timeout) ->
erlang:send_after(Timeout, Pid, {Ref, {timeout, Timeout}}).
print_cmd_result(authenticate_user, _Result) -> io:format("Success~n");
print_cmd_result(join_cluster, already_member) -> io:format("The node is already a member of this cluster~n").
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