153 lines
5.2 KiB
Erlang
153 lines
5.2 KiB
Erlang
%%%-------------------------------------------------------------------
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%%% @author Fabio Salvini <fs@fabiosalvini.com>
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%%% @copyright (C) 2017, Fabio Salvini
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%%% @doc
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%%%
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%%% @end
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%%% Created : 2 Jul 2017 by Fabio Salvini <fs@fabiosalvini.com>
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%%%-------------------------------------------------------------------
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-module(watcher).
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-behaviour(gen_server).
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%% API
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-export([start_link/2]).
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%% gen_server callbacks
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-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
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terminate/2, code_change/3]).
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-define(SERVER, ?MODULE).
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-record(state, {file, supervisor, port}).
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%%%===================================================================
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%%% API
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @doc
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%% Starts the server
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%%
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%% @spec start_link(SupPid, File) -> {ok, Pid} | ignore | {error, Error}
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%% @end
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%%--------------------------------------------------------------------
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start_link(SupPid, File) ->
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gen_server:start_link(?MODULE, [SupPid, File], []).
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%%%===================================================================
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%%% gen_server callbacks
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Initializes the server
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%%
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%% @spec init(Args) -> {ok, State} |
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%% {ok, State, Timeout} |
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%% ignore |
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%% {stop, Reason}
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%% @end
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%%--------------------------------------------------------------------
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init([SupPid, File]) ->
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timer:sleep(1000),
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config ! {watcher_init, File},
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{ok, GeneralConfig} = application:get_env(log_monitor, general),
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TailCmd = proplists:get_value(tail_cmd, GeneralConfig),
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Cmd = TailCmd ++ " " ++ File,
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Port = open_port({spawn, Cmd}, [stderr_to_stdout, exit_status, binary]),
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{ok, #state{file = File, supervisor = SupPid, port = Port}}.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Handling call messages
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%%
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%% @spec handle_call(Request, From, State) ->
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%% {reply, Reply, State} |
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%% {reply, Reply, State, Timeout} |
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%% {noreply, State} |
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%% {noreply, State, Timeout} |
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%% {stop, Reason, Reply, State} |
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%% {stop, Reason, State}
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%% @end
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%%--------------------------------------------------------------------
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handle_call(_Request, _From, State) ->
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Reply = ok,
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{reply, Reply, State}.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Handling cast messages
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%%
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%% @spec handle_cast(Msg, State) -> {noreply, State} |
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%% {noreply, State, Timeout} |
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%% {stop, Reason, State}
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%% @end
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%%--------------------------------------------------------------------
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handle_cast(_Msg, State) ->
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{noreply, State}.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Handling all non call/cast messages
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%%
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%% @spec handle_info(Info, State) -> {noreply, State} |
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%% {noreply, State, Timeout} |
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%% {stop, Reason, State}
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%% @end
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%%--------------------------------------------------------------------
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handle_info(Msg, State = #state{file = _, supervisor = SupPid, port = Port}) ->
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case Msg of
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{Port, {data, Text}} ->
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GathererPid = gatherer_pid(SupPid),
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gen_fsm:send_event(GathererPid, {log_line, binary_to_list(Text)}),
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{noreply, State};
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{Port, {exit_status, _Status}} ->
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{stop, tail_exit, State}
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end.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% This function is called by a gen_server when it is about to
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%% terminate. It should be the opposite of Module:init/1 and do any
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%% necessary cleaning up. When it returns, the gen_server terminates
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%% with Reason. The return value is ignored.
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%%
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%% @spec terminate(Reason, State) -> void()
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%% @end
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%%--------------------------------------------------------------------
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terminate(_Reason, State) ->
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config ! {watcher_terminate, State#state.file},
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shutdown.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Convert process state when code is changed
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%%
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%% @spec code_change(OldVsn, State, Extra) -> {ok, NewState}
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%% @end
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%%--------------------------------------------------------------------
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code_change(_OldVsn, State, _Extra) ->
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{ok, State}.
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%%%===================================================================
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%%% Internal functions
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Get the Pid of the gatherer related to this watcher.
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%%
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%% @spec gatherer_pid(SupPid) -> pid()
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%% @end
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%%--------------------------------------------------------------------
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gatherer_pid(SupPid) ->
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hd([Pid || {Id, Pid, _, _} <- supervisor:which_children(SupPid), Id == gatherer]).
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