%%%----------------------------------------------------------------------
%%% File : ejabberd_batch.erl
%%% Author : Paweł Chmielowski <pawel@process-one.net>
%%% Purpose : Batch tasks manager
%%% Created : 8 mar 2022 by Paweł Chmielowski <pawel@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2022 ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%----------------------------------------------------------------------
-module(ejabberd_batch).
-author("pawel@process-one.net").
-behaviour(gen_server).
-include("logger.hrl").
%% 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]).
-export([register_task/5, task_status/1, abort_task/1]).
-define(SERVER, ?MODULE).
-record(state, {tasks = #{}}).
-record(task, {state = not_started, pid, steps, done_steps}).
%%%===================================================================
%%% API
%%%===================================================================
%% @doc Spawns the server and registers the local name (unique)
-spec(start_link() ->
{ok, Pid :: pid()} | ignore | {error, Reason :: term()}).
start_link() ->
gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
register_task(Type, Steps, Rate, JobState, JobFun) ->
gen_server:call(?MODULE, {register_task, Type, Steps, Rate, JobState, JobFun}).
task_status(Type) ->
gen_server:call(?MODULE, {task_status, Type}).
abort_task(Type) ->
gen_server:call(?MODULE, {abort_task, Type}).
%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
%% @private
%% @doc Initializes the server
-spec(init(Args :: term()) ->
{ok, State :: #state{}} | {ok, State :: #state{}, timeout() | hibernate} |
{stop, Reason :: term()} | ignore).
init([]) ->
{ok, #state{}}.
%% @private
%% @doc Handling call messages
-spec(handle_call(Request :: term(), From :: {pid(), Tag :: term()},
State :: #state{}) ->
{reply, Reply :: term(), NewState :: #state{}} |
{reply, Reply :: term(), NewState :: #state{}, timeout() | hibernate} |
{noreply, NewState :: #state{}} |
{noreply, NewState :: #state{}, timeout() | hibernate} |
{stop, Reason :: term(), Reply :: term(), NewState :: #state{}} |
{stop, Reason :: term(), NewState :: #state{}}).
handle_call({register_task, Type, Steps, Rate, JobState, JobFun}, _From, #state{tasks = Tasks} = State) ->
case maps:get(Type, Tasks, #task{}) of
#task{state = S} when S == completed; S == not_started; S == aborted; S == failed ->
Pid = spawn(fun() -> work_loop(Type, JobState, JobFun, Rate, erlang:monotonic_time(second), 0) end),
Tasks2 = maps:put(Type, #task{state = working, pid = Pid, steps = Steps, done_steps = 0}, Tasks),
{reply, ok, #state{tasks = Tasks2}};
#task{state = working} ->
{reply, {error, in_progress}, State}
end;
handle_call({task_status, Type}, _From, #state{tasks = Tasks} = State) ->
case maps:get(Type, Tasks, none) of
none ->
{reply, not_started, State};
#task{state = not_started} ->
{reply, not_started, State};
#task{state = failed, done_steps = Steps, pid = Error} ->
{reply, {failed, Steps, Error}, State};
#task{state = aborted, done_steps = Steps} ->
{reply, {aborted, Steps}, State};
#task{state = working, done_steps = Steps} ->
{reply, {working, Steps}, State};
#task{state = completed, done_steps = Steps} ->
{reply, {completed, Steps}, State}
end;
handle_call({abort_task, Type}, _From, #state{tasks = Tasks} = State) ->
case maps:get(Type, Tasks, none) of
#task{state = working, pid = Pid} = T ->
Pid ! abort,
Tasks2 = maps:put(Type, T#task{state = aborted, pid = none}, Tasks),
{reply, aborted, State#state{tasks = Tasks2}};
_ ->
{reply, not_started, State}
end;
handle_call(_Request, _From, State = #state{}) ->
{reply, ok, State}.
%% @private
%% @doc Handling cast messages
-spec(handle_cast(Request :: term(), State :: #state{}) ->
{noreply, NewState :: #state{}} |
{noreply, NewState :: #state{}, timeout() | hibernate} |
{stop, Reason :: term(), NewState :: #state{}}).
handle_cast({task_finished, Type, Pid}, #state{tasks = Tasks} = State) ->
case maps:get(Type, Tasks, none) of
#task{state = working, pid = Pid2} = T when Pid == Pid2 ->
Tasks2 = maps:put(Type, T#task{state = completed, pid = none}, Tasks),
{noreply, State#state{tasks = Tasks2}};
_ ->
{noreply, State}
end;
handle_cast({task_progress, Type, Pid, Count}, #state{tasks = Tasks} = State) ->
case maps:get(Type, Tasks, none) of
#task{state = working, pid = Pid2, done_steps = Steps} = T when Pid == Pid2 ->
Tasks2 = maps:put(Type, T#task{done_steps = Steps + Count}, Tasks),
{noreply, State#state{tasks = Tasks2}};
_ ->
{noreply, State}
end;
handle_cast({task_error, Type, Pid, Error}, #state{tasks = Tasks} = State) ->
case maps:get(Type, Tasks, none) of
#task{state = working, pid = Pid2} = T when Pid == Pid2 ->
Tasks2 = maps:put(Type, T#task{state = failed, pid = Error}, Tasks),
{noreply, State#state{tasks = Tasks2}};
_ ->
{noreply, State}
end;
handle_cast(_Request, State = #state{}) ->
{noreply, State}.
%% @private
%% @doc Handling all non call/cast messages
-spec(handle_info(Info :: timeout() | term(), State :: #state{}) ->
{noreply, NewState :: #state{}} |
{noreply, NewState :: #state{}, timeout() | hibernate} |
{stop, Reason :: term(), NewState :: #state{}}).
handle_info(_Info, State = #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 :: (normal | shutdown | {shutdown, term()} | term()),
State :: #state{}) -> term()).
terminate(_Reason, _State = #state{}) ->
ok.
%% @private
%% @doc Convert process state when code is changed
-spec(code_change(OldVsn :: term() | {down, term()}, State :: #state{},
Extra :: term()) ->
{ok, NewState :: #state{}} | {error, Reason :: term()}).
code_change(_OldVsn, State = #state{}, _Extra) ->
{ok, State}.
%%%===================================================================
%%% Internal functions
%%%===================================================================
work_loop(Task, JobState, JobFun, Rate, StartDate, CurrentProgress) ->
try JobFun(JobState) of
{ok, _NewState, 0} ->
gen_server:cast(?MODULE, {task_finished, Task, self()});
{ok, NewState, Count} ->
gen_server:cast(?MODULE, {task_progress, Task, self(), Count}),
NewProgress = CurrentProgress + Count,
TimeSpent = erlang:monotonic_time(second) - StartDate,
SleepTime = max(0, NewProgress/Rate*60 - TimeSpent),
receive
abort -> ok
after round(SleepTime*1000) ->
work_loop(Task, NewState, JobFun, Rate, StartDate, NewProgress)
end;
{error, Error} ->
gen_server:cast(?MODULE, {task_error, Task, self(), Error})
catch _:_ ->
gen_server:cast(?MODULE, {task_error, Task, self(), internal_error})
end.
