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3.10.6
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4.2.0
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3.10.11
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3.9.16
3.9.15
3.9.11
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3.9.8
3.9.7
3.9.6
3.9.5
3.9.4
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3.8.26
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3.8.23
3.8.22
3.8.21
3.8.20
3.8.19
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3.8.6-rc.1
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3.8.5-rc.2
3.8.5-rc.1
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3.8.4-rc.1
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3.8.3-rc.2
3.8.3-rc.1
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3.8.2-rc.1
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3.7.27-rc.2
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3.7.26
3.7.25
3.7.25-rc.1
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3.7.23-rc.1
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3.7.22-rc.1
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3.7.20-rc.1
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3.7.18
3.7.18-rc.1
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3.7.17-rc.3
3.7.17-rc.2
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3.7.16
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3.7.16-rc.4
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3.7.16-rc.3
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3.7.16-rc.2
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3.7.16-rc.1
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3.7.16-beta.1
3.7.15
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3.7.14-rc.1
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3.7.8-rc.2
3.7.8-rc.1
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3.7.6-rc.2
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3.7.5-rc.1
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3.7.4-rc.3
3.7.4-rc.2
3.7.4-rc.1
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3.6.7-pre.1
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3.4.0
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3.0.2
0.0.0-rc.1
Modules shared by rabbitmq-server and rabbitmq-erlang-client
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Files
src/pmon.erl
%% 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) 2011-2022 VMware, Inc. or its affiliates. All rights reserved.
%%
-module(pmon).
%% Process Monitor
%% ================
%%
%% This module monitors processes so that every process has at most
%% 1 monitor.
%% Processes monitored can be dynamically added and removed.
%%
%% Unlike erlang:[de]monitor* functions, this module
%% provides basic querying capability and avoids contacting down nodes.
%%
%% It is used to monitor nodes, queue mirrors, and by
%% the queue collector, among other things.
-export([new/0, new/1, monitor/2, monitor_all/2, demonitor/2,
is_monitored/2, erase/2, monitored/1, is_empty/1]).
-compile({no_auto_import, [monitor/2]}).
-record(state, {monitors = #{} :: #{item() => reference()},
module = erlang :: module()}).
%%----------------------------------------------------------------------------
-export_type([?MODULE/0]).
-opaque(?MODULE() :: #state{}).
-type(item() :: pid() | {atom(), node()}).
-spec new() -> ?MODULE().
new() -> new(erlang).
-spec new('erlang' | 'delegate') -> ?MODULE().
new(Module) -> #state{module = Module}.
-spec monitor(item(), ?MODULE()) -> ?MODULE().
monitor(Item, S = #state{monitors = M, module = Module}) ->
case maps:is_key(Item, M) of
true -> S;
false -> case node_alive_shortcut(Item) of
true -> Ref = Module:monitor(process, Item),
S#state{monitors = maps:put(Item, Ref, M)};
false -> self() ! {'DOWN', fake_ref, process, Item,
nodedown},
S
end
end.
-spec monitor_all([item()], ?MODULE()) -> ?MODULE().
monitor_all([], S) -> S; %% optimisation
monitor_all([Item], S) -> monitor(Item, S); %% optimisation
monitor_all(Items, S) -> lists:foldl(fun monitor/2, S, Items).
-spec demonitor(item(), ?MODULE()) -> ?MODULE().
demonitor(Item, S = #state{monitors = M0, module = Module}) ->
case maps:take(Item, M0) of
{MRef, M} -> Module:demonitor(MRef),
S#state{monitors = M};
error -> S
end.
-spec is_monitored(item(), ?MODULE()) -> boolean().
is_monitored(Item, #state{monitors = M}) -> maps:is_key(Item, M).
-spec erase(item(), ?MODULE()) -> ?MODULE().
erase(Item, S = #state{monitors = M}) ->
S#state{monitors = maps:remove(Item, M)}.
-spec monitored(?MODULE()) -> [item()].
monitored(#state{monitors = M}) -> maps:keys(M).
-spec is_empty(?MODULE()) -> boolean().
is_empty(#state{monitors = M}) -> maps:size(M) == 0.
%%----------------------------------------------------------------------------
%% We check here to see if the node is alive in order to avoid trying
%% to connect to it if it isn't - this can cause substantial
%% slowdowns. We can't perform this shortcut if passed {Name, Node}
%% since we would need to convert that into a pid for the fake 'DOWN'
%% message, so we always return true here - but that's OK, it's just
%% an optimisation.
node_alive_shortcut(P) when is_pid(P) ->
lists:member(node(P), [node() | nodes()]);
node_alive_shortcut({_Name, _Node}) ->
true.