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Diffstat (limited to 'deps/rabbit/src/rabbit_sysmon_minder.erl')
| -rw-r--r-- | deps/rabbit/src/rabbit_sysmon_minder.erl | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/deps/rabbit/src/rabbit_sysmon_minder.erl b/deps/rabbit/src/rabbit_sysmon_minder.erl new file mode 100644 index 0000000000..a0402e5ebe --- /dev/null +++ b/deps/rabbit/src/rabbit_sysmon_minder.erl @@ -0,0 +1,156 @@ +%% ------------------------------------------------------------------- +%% Copyright (c) 2007-2010 Basho Technologies, Inc. All Rights Reserved. +%% Copyright (c) 2018-2020 VMware, Inc. or its affiliates. All rights reserved. +%% +%% This file is provided to you under the Apache License, +%% Version 2.0 (the "License"); you may not use this file +%% except in compliance with the License. You may obtain +%% a copy of the License at +%% +%% https://www.apache.org/licenses/LICENSE-2.0 +%% +%% Unless required by applicable law or agreed to in writing, +%% software distributed under the License is distributed on an +%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +%% KIND, either express or implied. See the License for the +%% specific language governing permissions and limitations +%% under the License. +%% +%% ------------------------------------------------------------------- + +-module(rabbit_sysmon_minder). + +-behaviour(gen_server). + +%% API +-export([start_link/0]). + +%% gen_server callbacks +-export([init/1, handle_call/3, handle_cast/2, handle_info/2, + terminate/2, code_change/3]). + +-record(state, {}). + +%%%=================================================================== +%%% API +%%%=================================================================== + +%%-------------------------------------------------------------------- +%% @doc +%% Starts the server +%% +%% @spec start_link() -> {ok, Pid} | ignore | {error, Error} +%% @end +%%-------------------------------------------------------------------- +start_link() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + +%%%=================================================================== +%%% gen_server callbacks +%%%=================================================================== + +%%-------------------------------------------------------------------- +%% @private +%% @doc +%% Initializes the server +%% +%% @spec init(Args) -> {ok, State} | +%% {ok, State, Timeout} | +%% ignore | +%% {stop, Reason} +%% @end +%%-------------------------------------------------------------------- +init([]) -> + %% Add our system_monitor event handler. We do that here because + %% we have a process at our disposal (i.e. ourself) to receive the + %% notification in the very unlikely event that the + %% sysmon_handler has crashed and been removed from the + %% sysmon_handler gen_event server. (If we had a supervisor + %% or app-starting process add the handler, then if the handler + %% crashes, nobody will act on the crash notification.) + rabbit_sysmon_handler:add_handler(), + {ok, #state{}}. + +%%-------------------------------------------------------------------- +%% @private +%% @doc +%% Handling call messages +%% +%% @spec handle_call(Request, From, State) -> +%% {reply, Reply, State} | +%% {reply, Reply, State, Timeout} | +%% {noreply, State} | +%% {noreply, State, Timeout} | +%% {stop, Reason, Reply, State} | +%% {stop, Reason, State} +%% @end +%%-------------------------------------------------------------------- +handle_call(_Request, _From, State) -> + Reply = ok, + {reply, Reply, State}. + +%%-------------------------------------------------------------------- +%% @private +%% @doc +%% Handling cast messages +%% +%% @spec handle_cast(Msg, State) -> {noreply, State} | +%% {noreply, State, Timeout} | +%% {stop, Reason, State} +%% @end +%%-------------------------------------------------------------------- +handle_cast(_Msg, State) -> + {noreply, State}. + +%%-------------------------------------------------------------------- +%% @private +%% @doc +%% Handling all non call/cast messages +%% +%% @spec handle_info(Info, State) -> {noreply, State} | +%% {noreply, State, Timeout} | +%% {stop, Reason, State} +%% @end +%%-------------------------------------------------------------------- +handle_info({gen_event_EXIT, rabbit_sysmon_handler, _}, State) -> + %% SASL will create an error message, no need for us to duplicate it. + %% + %% Our handler should never crash, but it did indeed crash. If + %% there's a pathological condition somewhere that's generating + %% lots of unforseen things that crash core's custom handler, we + %% could make things worse by jumping back into the exploding + %% volcano. Wait a little bit before jumping back. Besides, the + %% system_monitor data is nice but is not critical: there is no + %% need to make things worse if things are indeed bad, and if we + %% miss a few seconds of system_monitor events, the world will not + %% end. + timer:sleep(2*1000), + rabbit_sysmon_handler:add_handler(), + {noreply, State}; +handle_info(_Info, State) -> + {noreply, State}. + +%%-------------------------------------------------------------------- +%% @private +%% @doc +%% This function is called by a gen_server when it is about to +%% terminate. It should be the opposite of Module:init/1 and do any +%% necessary cleaning up. When it returns, the gen_server terminates +%% with Reason. The return value is ignored. +%% +%% @spec terminate(Reason, State) -> void() +%% @end +%%-------------------------------------------------------------------- +terminate(_Reason, _State) -> + ok. + +%%-------------------------------------------------------------------- +%% @private +%% @doc +%% Convert process state when code is changed +%% +%% @spec code_change(OldVsn, State, Extra) -> {ok, NewState} +%% @end +%%-------------------------------------------------------------------- +code_change(_OldVsn, State, _Extra) -> + {ok, State}. |