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add support for naming tasks, so that they can't be scheduled twice #1

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add support for naming tasks, so that they can't be scheduled twice #1

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140 changes: 102 additions & 38 deletions src/leader_cron.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@
-export([start_link/1,
status/0,
schedule_task/2,
schedule_task/3,
cancel_task/1,
task_status/1,
task_list/0,
Expand All @@ -69,9 +70,10 @@

-define(SERVER, ?MODULE).

-type task() :: {pid(),
leader_cron_task:schedule(),
leader_cron_task:mfargs()}.
-type task() :: {atom(),
pid(),
leader_cron_task:schedule(),
leader_cron_task:mfargs()}.

-record(state, {tasks = [], is_leader = false}).

Expand Down Expand Up @@ -125,18 +127,35 @@ status() ->
schedule_task(Schedule, Mfa) ->
gen_leader:leader_call(?SERVER, {schedule, {Schedule, Mfa}}).

%%--------------------------------------------------------------------
%% @doc
%% Schedules a named task. There can't be more than one task with
%% a name at a time. The name can't be "undefined" either. See
%% {@link leader_cron_task} for scheduling details.
%%
%% @end
%%--------------------------------------------------------------------

-spec schedule_task(atom(), Schedule, Mfa) -> {ok, pid()} | {error, term()} when
Schedule :: leader_cron_task:schedule(),
Mfa :: leader_cron_task:mfargs().

schedule_task(Name, Schedule, Mfa) ->
gen_leader:leader_call(?SERVER, {schedule, {Name, Schedule, Mfa}}).


%%--------------------------------------------------------------------
%% @doc
%% Cancels a task.
%%
%% @end
%%--------------------------------------------------------------------

-spec cancel_task(pid()) -> ok | {error, Reason} when
-spec cancel_task(pid() | atom()) -> ok | {error, Reason} when
Reason :: term().

cancel_task(Pid) ->
gen_leader:leader_call(?SERVER, {cancel, Pid}).
cancel_task(Ident) ->
gen_leader:leader_call(?SERVER, {cancel, Ident}).

%%--------------------------------------------------------------------
%% @doc
Expand All @@ -145,13 +164,13 @@ cancel_task(Pid) ->
%% @end
%%--------------------------------------------------------------------

-spec task_status(pid()) -> {Status, ScheduleTime, TaskPid} when
-spec task_status(pid() | atom()) -> {Status, ScheduleTime, TaskPid} when
Status :: leader_cron_task:status(),
ScheduleTime :: leader_cron_task:datetime(),
TaskPid :: pid().

task_status(Pid) ->
gen_leader:leader_call(?SERVER, {task_status, Pid}).
task_status(Ident) ->
gen_leader:leader_call(?SERVER, {task_status, Ident}).

%%--------------------------------------------------------------------
%% @doc
Expand Down Expand Up @@ -215,28 +234,49 @@ surrendered(State, Sync, _Election) ->
{ok, State3}.

%% @private
handle_leader_call({cancel, Name}, From, State, Election) when is_atom(Name) ->
case pid_for_name(Name, State#state.tasks) of
{error, Reason} ->
{reply, {error, Reason}, State};
Pid ->
handle_leader_call({cancel, Pid}, From, State, Election)
end;
handle_leader_call({cancel, Pid}, _From, State, Election) ->
Tasks = State#state.tasks,
{Reply, State1} = case lists:keyfind(Pid, 1, Tasks) of
{Reply, State1} = case lists:keyfind(Pid, 2, Tasks) of
false ->
{{error, no_such_pid}, State};
{Pid, _, _} ->
{_, Pid, _, _} ->
ok = leader_cron_task:stop(Pid),
Tasks1 = lists:keydelete(Pid, 1, Tasks),
Tasks1 = lists:keydelete(Pid, 2, Tasks),
send_tasks(Tasks1, Election),
{ok, State#state{tasks = Tasks1}}
end,
{reply, Reply, State1};
handle_leader_call({schedule, {Schedule, Mfa}}, _From, State, Election) ->
case leader_cron_task:start_link(Schedule, Mfa) of
{ok, Pid} ->
Task = {Pid, Schedule, Mfa},
TaskList = [Task|State#state.tasks],
State1 = State#state{tasks = TaskList},
ok = send_tasks(TaskList, Election),
{reply, {ok, Pid}, State1};
{error, Reason} ->
{reply, {error, Reason}, State}
handle_leader_call({schedule, {undefined, Schedule, Mfa}}, _From, State, Election);
handle_leader_call({schedule, {Name, Schedule, Mfa}}, _From, State, Election) ->
case not (Name == undefined) andalso lists:keymember(Name, 1, State#state.tasks) of
true ->
{reply, {error, already_exists}, State};
false ->
case leader_cron_task:start_link(Schedule, Mfa) of
{ok, Pid} ->
Task = {Name, Pid, Schedule, Mfa},
TaskList = [Task|State#state.tasks],
State1 = State#state{tasks = TaskList},
ok = send_tasks(TaskList, Election),
{reply, {ok, Pid}, State1};
{error, Reason} ->
{reply, {error, Reason}, State}
end
end;
handle_leader_call({task_status, Name}, From, State, Election) when is_atom(Name) ->
case pid_for_name(Name, State#state.tasks) of
{error, Reason} ->
{reply, {error, Reason}, State};
Pid ->
handle_leader_call({task_status, Pid}, From, State, Election)
end;
handle_leader_call({task_status, Pid}, _From, State, _Election) ->
Status = leader_cron_task:status(Pid),
Expand Down Expand Up @@ -320,9 +360,9 @@ send_tasks(Tasks, Election) ->

stop_tasks(State) ->
Tasks = State#state.tasks,
Tasks1 = lists:foldl(fun({Pid, Schedule, Mfa}, Acc) ->
Tasks1 = lists:foldl(fun({Name, Pid, Schedule, Mfa}, Acc) ->
ok = leader_cron_task:stop(Pid),
[{undefined, Schedule, Mfa}|Acc]
[{Name, undefined, Schedule, Mfa}|Acc]
end, [], Tasks),
State#state{tasks = Tasks1}.

Expand All @@ -332,21 +372,21 @@ start_tasks(State) ->
TaskList = State#state.tasks,
TaskList1 = lists:foldl(
fun(Task, Acc) ->
{_, Schedule, Mfa} = Task,
case leader_cron_task:start_link(Schedule, Mfa) of
{ok, Pid} ->
[{Pid, Schedule, Mfa}|Acc];
{error, Reason} ->
Format = "Could not start task ~p ~p",
Message = io_lib:format(Format, [Mfa, Reason]),
error_logger:error_report(Message),
[{undefined, Schedule, Mfa}|Acc]
end
{Name, _, Schedule, Mfa} = Task,
case leader_cron_task:start_link(Schedule, Mfa) of
{ok, Pid} ->
[{Name, Pid, Schedule, Mfa}|Acc];
{error, Reason} ->
Format = "Could not start task ~p ~p, name: ~p",
Message = io_lib:format(Format, [Mfa, Reason, Name]),
error_logger:error_report(Message),
[{Name, undefined, Schedule, Mfa}|Acc]
end
end, [], TaskList),
State#state{tasks = TaskList1}.

remove_task_if_done(Task, Acc) ->
{Pid, _, _} = Task,
{_, Pid, _, _} = Task,
case leader_cron_task:status(Pid) of
{done, _, _} ->
ok = leader_cron_task:stop(Pid),
Expand All @@ -355,6 +395,14 @@ remove_task_if_done(Task, Acc) ->
[Task|Acc]
end.

pid_for_name(Name, Tasks) ->
case lists:keyfind(Name, 1, Tasks) of
false ->
{error, no_such_name};
{_, Pid, _, _} ->
Pid
end.

%%%===================================================================
%%% Unit Tests
%%%===================================================================
Expand All @@ -381,16 +429,17 @@ dying_task(TimeToLiveMillis) ->
all_test_() ->
{foreach,
fun() ->
leader_cron:start_link([node()]),
leader_cron:start_link([node()]),
Tasks = leader_cron:task_list(),
lists:foreach(fun({Pid, _, _}) ->
lists:foreach(fun({_, Pid, _, _}) ->
ok = leader_cron:cancel_task(Pid)
end, Tasks)
end,
[
fun test_single_node_task/0,
fun test_dying_task/0,
fun test_done_task_removal/0
fun test_done_task_removal/0,
fun test_single_named_task/0
]}.

test_single_node_task() ->
Expand All @@ -400,7 +449,7 @@ test_single_node_task() ->
{running, _, TaskPid} = leader_cron:task_status(SchedulerPid),
TaskPid ! go,
?assertMatch({waiting, _, TaskPid}, leader_cron:task_status(SchedulerPid)),
?assertEqual([{SchedulerPid, Schedule, Mfa}], leader_cron:task_list()),
?assertEqual([{undefined, SchedulerPid, Schedule, Mfa}], leader_cron:task_list()),
?assertEqual(true, is_process_alive(TaskPid)),
?assertEqual(ok, leader_cron:cancel_task(SchedulerPid)),
?assertEqual([], leader_cron:task_list()),
Expand All @@ -424,4 +473,19 @@ test_done_task_removal() ->
?assertEqual(ok, leader_cron:remove_done_tasks()),
?assertEqual([], leader_cron:task_list()).

test_single_named_task() ->
Name = test_task,
Schedule = {sleeper, 100},
Mfa = {leader_cron, simple_task, []},
{ok, SchedulerPid} = leader_cron:schedule_task(Name, Schedule, Mfa),
{error, already_exists} = leader_cron:schedule_task(Name, Schedule, Mfa),
{running, _, TaskPid} = leader_cron:task_status(Name),
TaskPid ! go,
?assertMatch({waiting, _, TaskPid}, leader_cron:task_status(Name)),
?assertEqual([{test_task, SchedulerPid, Schedule, Mfa}], leader_cron:task_list()),
?assertEqual(true, is_process_alive(TaskPid)),
?assertEqual(ok, leader_cron:cancel_task(Name)),
?assertEqual([], leader_cron:task_list()),
?assertEqual(false, is_process_alive(TaskPid)).

-endif.
2 changes: 1 addition & 1 deletion test/leader_cron_SUITE.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -200,7 +200,7 @@ basic_fail_over(Config) ->
true = Leader /= NewLeader,

% verify tasks
[{TaskPid1, Sched, Mfa}] = rpc:call(BNode, leader_cron, task_list, []),
[{_Name, TaskPid1, Sched, Mfa}] = rpc:call(BNode, leader_cron, task_list, []),
true = TaskPid /= TaskPid1,

% verify task running again
Expand Down