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Add optional pool utilization stats #141

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b0f5821
add optional pool utilization stats
Nov 27, 2020
9da6432
compatibility with erlang/otp 17; fix tests
Nov 27, 2020
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103 changes: 71 additions & 32 deletions src/poolboy.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@

-export([checkout/1, checkout/2, checkout/3, checkin/2, transaction/2,
transaction/3, child_spec/2, child_spec/3, child_spec/4, start/1,
start/2, start_link/1, start_link/2, stop/1, status/1]).
start/2, start_link/1, start_link/2, stop/1, status/1, stats/1]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
code_change/3]).
-export_type([pool/0]).
Expand Down Expand Up @@ -44,7 +44,10 @@
size = 5 :: non_neg_integer(),
overflow = 0 :: non_neg_integer(),
max_overflow = 10 :: non_neg_integer(),
strategy = lifo :: lifo | fifo
strategy = lifo :: lifo | fifo,
stats = false,
quant_start = erlang:monotonic_time(),
time_used = 0
}).

-spec checkout(Pool :: pool()) -> pid().
Expand Down Expand Up @@ -145,6 +148,15 @@ stop(Pool) ->
status(Pool) ->
gen_server:call(Pool, status).

-spec stats(Pool :: pool()) -> {ok, float()} | {error, disabled}.
stats(Pool) ->
case gen_server:call(Pool, stats) of
{error, disabled} -> {error, disabled};
{ok, {TimeTotal, TimeUsed, Workers}} ->
{ok, (TimeUsed / TimeTotal / Workers)}
end.


init({PoolArgs, WorkerArgs}) ->
process_flag(trap_exit, true),
Waiting = queue:new(),
Expand All @@ -162,6 +174,8 @@ init([{strategy, lifo} | Rest], WorkerArgs, State) ->
init(Rest, WorkerArgs, State#state{strategy = lifo});
init([{strategy, fifo} | Rest], WorkerArgs, State) ->
init(Rest, WorkerArgs, State#state{strategy = fifo});
init([{stats, StatsEnabled} | Rest], WorkerArgs, State) when is_boolean(StatsEnabled) ->
init(Rest, WorkerArgs, State#state{stats = StatsEnabled});
init([_ | Rest], WorkerArgs, State) ->
init(Rest, WorkerArgs, State);
init([], _WorkerArgs, #state{size = Size, supervisor = Sup} = State) ->
Expand All @@ -170,21 +184,21 @@ init([], _WorkerArgs, #state{size = Size, supervisor = Sup} = State) ->

handle_cast({checkin, Pid}, State = #state{monitors = Monitors}) ->
case ets:lookup(Monitors, Pid) of
[{Pid, _, MRef}] ->
[{Pid, _, MRef, MaybeStartedAt}] ->
true = erlang:demonitor(MRef),
true = ets:delete(Monitors, Pid),
NewState = handle_checkin(Pid, State),
NewState = handle_checkin(Pid, MaybeStartedAt, State),
{noreply, NewState};
[] ->
{noreply, State}
end;

handle_cast({cancel_waiting, CRef}, State) ->
case ets:match(State#state.monitors, {'$1', CRef, '$2'}) of
[[Pid, MRef]] ->
case ets:match(State#state.monitors, {'$1', CRef, '$2', '$3'}) of
[[Pid, MRef, MaybeStartedAt]] ->
demonitor(MRef, [flush]),
true = ets:delete(State#state.monitors, Pid),
NewState = handle_checkin(Pid, State),
NewState = handle_checkin(Pid, MaybeStartedAt, State),
{noreply, NewState};
[] ->
Cancel = fun({_, Ref, MRef}) when Ref =:= CRef ->
Expand All @@ -206,15 +220,20 @@ handle_call({checkout, CRef, Block}, {FromPid, _} = From, State) ->
monitors = Monitors,
overflow = Overflow,
max_overflow = MaxOverflow,
strategy = Strategy} = State,
strategy = Strategy,
stats = StatsEnabled} = State,
case get_worker_with_strategy(Workers, Strategy) of
{{value, Pid}, Left} ->
MRef = erlang:monitor(process, FromPid),
true = ets:insert(Monitors, {Pid, CRef, MRef}),
MaybeStartedAt = if StatsEnabled -> erlang:monotonic_time();
true -> undefined end,
true = ets:insert(Monitors, {Pid, CRef, MRef, MaybeStartedAt}),
{reply, Pid, State#state{workers = Left}};
{empty, _Left} when MaxOverflow > 0, Overflow < MaxOverflow ->
{Pid, MRef} = new_worker(Sup, FromPid),
true = ets:insert(Monitors, {Pid, CRef, MRef}),
MaybeStartedAt = if StatsEnabled -> erlang:monotonic_time();
true -> undefined end,
true = ets:insert(Monitors, {Pid, CRef, MRef, MaybeStartedAt}),
{reply, Pid, State#state{overflow = Overflow + 1}};
{empty, _Left} when Block =:= false ->
{reply, full, State};
Expand All @@ -230,6 +249,13 @@ handle_call(status, _From, State) ->
overflow = Overflow} = State,
StateName = state_name(State),
{reply, {StateName, queue:len(Workers), Overflow, ets:info(Monitors, size)}, State};
handle_call(stats, _From, #state{stats = false} = State) ->
{reply, {error, disabled}, State};
handle_call(stats, _From, State) ->
{reply, {ok, {
erlang:monotonic_time() - State#state.quant_start,
State#state.time_used, State#state.size
}}, State#state{quant_start = erlang:monotonic_time(), time_used = 0}};
handle_call(get_avail_workers, _From, State) ->
Workers = State#state.workers,
{reply, Workers, State};
Expand All @@ -239,7 +265,7 @@ handle_call(get_all_workers, _From, State) ->
{reply, WorkerList, State};
handle_call(get_all_monitors, _From, State) ->
Monitors = ets:select(State#state.monitors,
[{{'$1', '_', '$2'}, [], [{{'$1', '$2'}}]}]),
[{{'$1', '_', '$2', '_'}, [], [{{'$1', '$2'}}]}]),
{reply, Monitors, State};
handle_call(stop, _From, State) ->
{stop, normal, ok, State};
Expand All @@ -248,10 +274,10 @@ handle_call(_Msg, _From, State) ->
{reply, Reply, State}.

handle_info({'DOWN', MRef, _, _, _}, State) ->
case ets:match(State#state.monitors, {'$1', '_', MRef}) of
[[Pid]] ->
case ets:match(State#state.monitors, {'$1', '_', MRef, '$2'}) of
[[Pid, MaybeStartedAt]] ->
true = ets:delete(State#state.monitors, Pid),
NewState = handle_checkin(Pid, State),
NewState = handle_checkin(Pid, MaybeStartedAt, State),
{noreply, NewState};
[] ->
Waiting = queue:filter(fun ({_, _, R}) -> R =/= MRef end, State#state.waiting),
Expand All @@ -261,10 +287,10 @@ handle_info({'EXIT', Pid, _Reason}, State) ->
#state{supervisor = Sup,
monitors = Monitors} = State,
case ets:lookup(Monitors, Pid) of
[{Pid, _, MRef}] ->
[{Pid, _, MRef, MaybeStartedAt}] ->
true = erlang:demonitor(MRef),
true = ets:delete(Monitors, Pid),
NewState = handle_worker_exit(Pid, State),
NewState = handle_worker_exit(Pid, MaybeStartedAt, State),
{noreply, NewState};
[] ->
case queue:member(Pid, State#state.workers) of
Expand Down Expand Up @@ -328,40 +354,53 @@ prepopulate(0, _Sup, Workers) ->
prepopulate(N, Sup, Workers) ->
prepopulate(N-1, Sup, queue:in(new_worker(Sup), Workers)).

handle_checkin(Pid, State) ->
handle_checkin(Pid, StartedAt, State0) ->
#state{supervisor = Sup,
waiting = Waiting,
monitors = Monitors,
overflow = Overflow} = State,
overflow = Overflow,
stats = StatsEnabled} = State0,
State1 = handle_checkin_stats(StatsEnabled, StartedAt, State0),
case queue:out(Waiting) of
{{value, {From, CRef, MRef}}, Left} ->
true = ets:insert(Monitors, {Pid, CRef, MRef}),
MaybeStartedAt = if StatsEnabled -> erlang:monotonic_time();
true -> undefined end,
true = ets:insert(Monitors, {Pid, CRef, MRef, MaybeStartedAt}),
gen_server:reply(From, Pid),
State#state{waiting = Left};
State1#state{waiting = Left};
{empty, Empty} when Overflow > 0 ->
ok = dismiss_worker(Sup, Pid),
State#state{waiting = Empty, overflow = Overflow - 1};
State1#state{waiting = Empty, overflow = Overflow - 1};
{empty, Empty} ->
Workers = queue:in(Pid, State#state.workers),
State#state{workers = Workers, waiting = Empty, overflow = 0}
Workers = queue:in(Pid, State1#state.workers),
State1#state{workers = Workers, waiting = Empty, overflow = 0}
end.

handle_worker_exit(Pid, State) ->
handle_checkin_stats(false, _, State) -> State;
handle_checkin_stats(_, undefined, State) -> State;
handle_checkin_stats(_, StartedAt, #state{time_used = TimeUsed} = State) ->
State#state{time_used = TimeUsed + (erlang:monotonic_time() - StartedAt)}.

handle_worker_exit(Pid, StartedAt, State0) ->
#state{supervisor = Sup,
monitors = Monitors,
overflow = Overflow} = State,
case queue:out(State#state.waiting) of
overflow = Overflow,
stats = StatsEnabled} = State0,
State1 = handle_checkin_stats(StatsEnabled, StartedAt, State0),
case queue:out(State1#state.waiting) of
{{value, {From, CRef, MRef}}, LeftWaiting} ->
NewWorker = new_worker(State#state.supervisor),
true = ets:insert(Monitors, {NewWorker, CRef, MRef}),
NewWorker = new_worker(State1#state.supervisor),
MaybeStartedAt = if StatsEnabled -> erlang:monotonic_time();
true -> undefined end,
true = ets:insert(Monitors, {NewWorker, CRef, MRef, MaybeStartedAt}),
gen_server:reply(From, NewWorker),
State#state{waiting = LeftWaiting};
State1#state{waiting = LeftWaiting};
{empty, Empty} when Overflow > 0 ->
State#state{overflow = Overflow - 1, waiting = Empty};
State1#state{overflow = Overflow - 1, waiting = Empty};
{empty, Empty} ->
W = filter_worker_by_pid(Pid, State#state.workers),
W = filter_worker_by_pid(Pid, State1#state.workers),
Workers = queue:in(new_worker(Sup), W),
State#state{workers = Workers, waiting = Empty}
State1#state{workers = Workers, waiting = Empty}
end.

state_name(State = #state{overflow = Overflow}) when Overflow < 1 ->
Expand Down
27 changes: 26 additions & 1 deletion test/poolboy_tests.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,11 @@ pool_test_() ->
{<<"Recover from timeout without exit handling">>,
fun transaction_timeout_without_exit/0},
{<<"Recover from transaction timeout">>,
fun transaction_timeout/0}
fun transaction_timeout/0},
{<<"Pool behaves when stats disabled">>,
fun pool_stats_disabled/0},
{<<"Pool behaves when stats enabled">>,
fun pool_stats_enabled/0}
]
}.

Expand Down Expand Up @@ -124,6 +128,21 @@ transaction_timeout() ->
?assertEqual({ready,1,0,0}, pool_call(Pid, status)).


pool_stats_disabled() ->
{ok, Pid} = new_pool(1, 0),
?assertMatch({error, disabled}, poolboy:stats(Pid)).

pool_stats_enabled() ->
{ok, Pid} = new_pool(1, 0, lifo, true),
?assertMatch({ok, 0.0}, poolboy:stats(Pid)),
Worker = poolboy:checkout(Pid),
timer:sleep(1000), %% emulating load?..
checkin_worker(Pid, Worker),
StatsRet = poolboy:stats(Pid),
?assertMatch({ok, Load} when Load > 0.5, StatsRet),
?assertNotMatch({ok, 0.0}, StatsRet),
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?assertMatch({ok, 0.0}, poolboy:stats(Pid)).

pool_startup() ->
%% Check basic pool operation.
{ok, Pid} = new_pool(10, 5),
Expand Down Expand Up @@ -546,5 +565,11 @@ new_pool(Size, MaxOverflow, Strategy) ->
{size, Size}, {max_overflow, MaxOverflow},
{strategy, Strategy}]).

new_pool(Size, MaxOverflow, Strategy, StatsEnabled) ->
poolboy:start_link([{name, {local, poolboy_test}},
{worker_module, poolboy_test_worker},
{size, Size}, {max_overflow, MaxOverflow},
{strategy, Strategy}, {stats, StatsEnabled}]).

pool_call(ServerRef, Request) ->
gen_server:call(ServerRef, Request).