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prometheus_quantile_summary.erl
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prometheus_quantile_summary.erl
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%% @doc
%% Summary metric, to track the size of events and report quantiles
%% Based on prometheus_summary
%%
%% Example use cases for Summaries:
%% - Response latency;
%% - Request size;
%% - Response size.
%%
%% Example:
%% <pre lang="erlang">
%% -module(my_proxy_instrumenter).
%%
%% setup() ->
%% prometheus_quantile_summary:declare([{name, request_size_bytes},
%% {help, "Request size in bytes."}]),
%% prometheus_quantile_summary:declare([{name, response_size_bytes},
%% {help, "Response size in bytes."}]).
%%
%% observe_request(Size) ->
%% prometheus_quantile_summary:observe(request_size_bytes, Size).
%%
%% observe_response(Size) ->
%% prometheus_quantile_summary:observe(response_size_bytes, Size).
%% </pre>
%%
%% Reports:
%% request_size_bytes_size
%% request_size_bytes_count
%% request_size_bytes{quantile="0.5"}
%% request_size_bytes{quantile="0.9"}
%% request_size_bytes{quantile="0.95"}
%% @end
-module(prometheus_quantile_summary).
%%% metric
-export([new/1,
declare/1,
deregister/1,
deregister/2,
set_default/2,
observe/2,
observe/3,
observe/4,
observe_duration/2,
observe_duration/3,
observe_duration/4,
remove/1,
remove/2,
remove/3,
reset/1,
reset/2,
reset/3,
value/1,
value/2,
value/3,
values/2]).
%%% collector
-export([deregister_cleanup/1,
collect_mf/2,
collect_metrics/2]).
-include("prometheus.hrl").
-include_lib("quantile_estimator/include/quantile_estimator.hrl").
-behaviour(prometheus_metric).
-behaviour(prometheus_collector).
%%====================================================================
%% Macros
%%====================================================================
-define(TABLE, ?PROMETHEUS_QUANTILE_SUMMARY_TABLE).
-define(SUM_POS, 3).
-define(COUNTER_POS, 2).
-define(QUANTILE_POS, 4).
-define(WIDTH, 16).
%%====================================================================
%% Metric API
%%====================================================================
%% @doc Creates a summary using `Spec'.
%%
%% Raises `{missing_metric_spec_key, Key, Spec}' error if required `Soec' key
%% is missing.<br/>
%% Raises `{invalid_metric_name, Name, Message}' error if metric `Name'
%% is invalid.<br/>
%% Raises `{invalid_metric_help, Help, Message}' error if metric `Help'
%% is invalid.<br/>
%% Raises `{invalid_metric_labels, Labels, Message}' error if `Labels'
%% isn't a list.<br/>
%% Raises `{invalid_label_name, Name, Message}' error if `Name' isn't a valid
%% label name.<br/>
%% Raises `{invalid_value_error, Value, Message}' error if `duration_unit' is
%% unknown or doesn't match metric name.<br/>
%% Raises `{mf_already_exists, {Registry, Name}, Message}' error if a summary
%% with the same `Spec' already exists.
%% @end
new(Spec) ->
Spec1 = validate_summary_spec(Spec),
prometheus_metric:insert_new_mf(?TABLE, ?MODULE, Spec1).
%% @doc Creates a summary using `Spec'.
%% If a summary with the same `Spec' exists returns `false'.
%%
%% Raises `{missing_metric_spec_key, Key, Spec}' error if required `Soec' key
%% is missing.<br/>
%% Raises `{invalid_metric_name, Name, Message}' error if metric `Name'
%% is invalid.<br/>
%% Raises `{invalid_metric_help, Help, Message}' error if metric `Help'
%% is invalid.<br/>
%% Raises `{invalid_metric_labels, Labels, Message}' error if `Labels'
%% isn't a list.<br/>
%% Raises `{invalid_label_name, Name, Message}' error if `Name' isn't a valid
%% label name.<br/>
%% Raises `{invalid_value_error, Value, MessagE}' error if `duration_unit' is
%% unknown or doesn't match metric name.<br/>
%% @end
declare(Spec) ->
Spec1 = validate_summary_spec(Spec),
prometheus_metric:insert_mf(?TABLE, ?MODULE, Spec1).
%% @equiv deregister(default, Name)
deregister(Name) ->
deregister(default, Name).
%% @doc
%% Removes all summary series with name `Name' and
%% removes Metric Family from `Registry'.
%%
%% After this call new/1 for `Name' and `Registry' will succeed.
%%
%% Returns `{true, _}' if `Name' was a registered summary.
%% Otherwise returns `{false, _}'.
%% @end
deregister(Registry, Name) ->
MFR = prometheus_metric:deregister_mf(?TABLE, Registry, Name),
NumDeleted = ets:select_delete(?TABLE, deregister_select(Registry, Name)),
{MFR, NumDeleted > 0}.
%% @private
set_default(Registry, Name) ->
Configuration = get_configuration(Registry, Name),
#{compress_limit := CompressLimit} = Configuration,
ets:insert_new(?TABLE, {
key(Registry, Name, []),
0,
0,
quantile(Configuration),
CompressLimit}).
%% @equiv observe(default, Name, [], Value)
observe(Name, Value) ->
observe(default, Name, [], Value).
%% @equiv observe(default, Name, LabelValues, Value)
observe(Name, LabelValues, Value) ->
observe(default, Name, LabelValues, Value).
%% @doc Observes the given `Value'.
%%
%% Raises `{invalid_value, Value, Message}' if `Value'
%% isn't an integer.<br/>
%% Raises `{unknown_metric, Registry, Name}' error if summary with named `Name'
%% can't be found in `Registry'.<br/>
%% Raises `{invalid_metric_arity, Present, Expected}' error if labels count
%% mismatch.
%% @end
observe(Registry, Name, LabelValues, Value) when is_number(Value) ->
Key = key(Registry, Name, LabelValues),
case ets:lookup(?TABLE, Key) of
[] -> insert_metric(Registry, Name, LabelValues, Value, fun observe/4);
[{Key, Count, S, Q, CompressLimit}] ->
ets:insert(?TABLE, {Key, Count + 1, S + Value, quantile_add(Q, Value, CompressLimit), CompressLimit})
end,
ok;
observe(_Registry, _Name, _LabelValues, Value) ->
erlang:error({invalid_value, Value, "observe accepts only numbers"}).
%% @equiv observe_duration(default, Name, [], Fun)
observe_duration(Name, Fun) ->
observe_duration(default, Name, [], Fun).
%% @equiv observe_duration(default, Name, LabelValues, Fun)
observe_duration(Name, LabelValues, Fun) ->
observe_duration(default, Name, LabelValues, Fun).
%% @doc Tracks the amount of time spent executing `Fun'.
%%
%% Raises `{unknown_metric, Registry, Name}' error if summary with named `Name'
%% can't be found in `Registry'.<br/>
%% Raises `{invalid_metric_arity, Present, Expected}' error if labels count
%% mismatch.
%% Raises `{invalid_value, Value, Message}' if `Fun'
%% isn't a function.<br/>
%% @end
observe_duration(Registry, Name, LabelValues, Fun) when is_function(Fun)->
Start = erlang:monotonic_time(),
try
Fun()
after
observe(Registry, Name, LabelValues, erlang:monotonic_time() - Start)
end;
observe_duration(_Regsitry, _Name, _LabelValues, Fun) ->
erlang:error({invalid_value, Fun, "observe_duration accepts only functions"}).
%% @equiv remove(default, Name, [])
remove(Name) ->
remove(default, Name, []).
%% @equiv remove(default, Name, LabelValues)
remove(Name, LabelValues) ->
remove(default, Name, LabelValues).
%% @doc Removes summary series identified by `Registry', `Name'
%% and `LabelValues'.
%%
%% Raises `{unknown_metric, Registry, Name}' error if summary with name `Name'
%% can't be found in `Registry'.<br/>
%% Raises `{invalid_metric_arity, Present, Expected}' error if labels count
%% mismatch.
%% @end
remove(Registry, Name, LabelValues) ->
prometheus_metric:check_mf_exists(?TABLE, Registry, Name, LabelValues),
case lists:flatten([ets:take(?TABLE,
{Registry, Name, LabelValues, Scheduler})
|| Scheduler <- schedulers_seq()]) of
[] -> false;
_ -> true
end.
%% @equiv reset(default, Name, [])
reset(Name) ->
reset(default, Name, []).
%% @equiv reset(default, Name, LabelValues)
reset(Name, LabelValues) ->
reset(default, Name, LabelValues).
%% @doc Resets the value of the summary identified by `Registry', `Name'
%% and `LabelValues'.
%%
%% Raises `{unknown_metric, Registry, Name}' error if summary with name `Name'
%% can't be found in `Registry'.<br/>
%% Raises `{invalid_metric_arity, Present, Expected}' error if labels count
%% mismatch.
%% @end
reset(Registry, Name, LabelValues) ->
MF = prometheus_metric:check_mf_exists(?TABLE, Registry, Name, LabelValues),
Configuration = prometheus_metric:mf_data(MF),
case lists:usort([ets:update_element(?TABLE,
{Registry, Name, LabelValues, Scheduler},
[{?COUNTER_POS, 0}, {?SUM_POS, 0}, {?QUANTILE_POS, quantile(Configuration)}])
|| Scheduler <- schedulers_seq()]) of
[_, _] -> true;
[true] -> true;
_ -> false
end.
%% @equiv value(default, Name, [])
value(Name) ->
value(default, Name, []).
%% @equiv value(default, Name, LabelValues)
value(Name, LabelValues) ->
value(default, Name, LabelValues).
%% @doc Returns the value of the summary identified by `Registry', `Name'
%% and `LabelValues'. If there is no summary for `LabelValues',
%% returns `undefined'.
%%
%% If duration unit set, sum will be converted to the duration unit.
%% {@link prometheus_time. Read more here.}
%%
%% Raises `{unknown_metric, Registry, Name}' error if summary named `Name'
%% can't be found in `Registry'.<br/>
%% Raises `{invalid_metric_arity, Present, Expected}' error if labels count
%% mismatch.
%% @end
value(Registry, Name, LabelValues) ->
MF = prometheus_metric:check_mf_exists(?TABLE, Registry, Name, LabelValues),
DU = prometheus_metric:mf_duration_unit(MF),
#{quantiles := QNs} = prometheus_metric:mf_data(MF),
case ets:select(?TABLE, [{{{Registry, Name, LabelValues, '_'}, '$1', '$2', '$3', '_'},
[],
['$$']}]) of
[] -> undefined;
Values -> {Count, Sum, QE} = reduce_values(Values),
{Count, prometheus_time:maybe_convert_to_du(DU, Sum), quantile_values(QE, QNs)}
end.
values(Registry, Name) ->
case prometheus_metric:check_mf_exists(?TABLE, Registry, Name) of
false -> [];
MF ->
DU = prometheus_metric:mf_duration_unit(MF),
Labels = prometheus_metric:mf_labels(MF),
#{quantiles := QNs} = Configuration = prometheus_metric:mf_data(MF),
MFValues = load_all_values(Registry, Name),
ReducedMap = lists:foldl(
fun([L, C, S, QE], ResAcc) ->
{PrevCount, PrevSum, PrevQE} = maps:get(L, ResAcc, {0, 0, quantile(Configuration)}),
ResAcc#{L => {PrevCount + C, PrevSum + S, quantile_merge(PrevQE, QE)}}
end,
#{},
MFValues),
ReducedMapList = lists:sort(maps:to_list(ReducedMap)),
lists:foldr(
fun({LabelValues, {Count, Sum, QE}}, Acc) ->
[{lists:zip(Labels, LabelValues), Count,
prometheus_time:maybe_convert_to_du(DU, Sum),
quantile_values(QE, QNs)} | Acc]
end,
[],
ReducedMapList)
end.
%%====================================================================
%% Collector API
%%====================================================================
%% @private
deregister_cleanup(Registry) ->
prometheus_metric:deregister_mf(?TABLE, Registry),
true = ets:match_delete(?TABLE, {{Registry, '_', '_', '_'}, '_', '_', '_', '_'}),
ok.
%% @private
collect_mf(Registry, Callback) ->
[Callback(create_summary(Name, Help, {CLabels, Labels, Registry, DU, Data})) ||
[Name, {Labels, Help}, CLabels, DU, Data] <- prometheus_metric:metrics(?TABLE,
Registry)],
ok.
%% @private
collect_metrics(Name, {CLabels, Labels, Registry, DU, Configuration}) ->
#{quantiles := QNs} = Configuration,
MFValues = load_all_values(Registry, Name),
ReducedMap = lists:foldl(
fun([L, C, S, QE], ResAcc) ->
{PrevCount, PrevSum, PrevQE} = maps:get(L, ResAcc, {0, 0, quantile(Configuration)}),
ResAcc#{L => {PrevCount + C, PrevSum + S, quantile_merge(PrevQE, QE)}}
end,
#{},
MFValues),
ReducedMapList = lists:sort(maps:to_list(ReducedMap)),
lists:foldr(
fun({LabelValues, {Count, Sum, QE}}, Acc) ->
[prometheus_model_helpers:summary_metric(
CLabels ++ lists:zip(Labels, LabelValues), Count,
prometheus_time:maybe_convert_to_du(DU, Sum),
quantile_values(QE, QNs)) | Acc]
end,
[],
ReducedMapList).
%%====================================================================
%% Private Parts
%%====================================================================
deregister_select(Registry, Name) ->
[{{{Registry, Name, '_', '_'}, '_', '_', '_', '_'}, [], [true]}].
validate_summary_spec(Spec) ->
Labels = prometheus_metric_spec:labels(Spec),
validate_summary_labels(Labels),
{Invariant, QNs} = invariant_and_quantiles_from_spec(Spec),
CompressLimit = compress_limit_from_spec(Spec),
[
{data,
#{quantiles => QNs,
invariant => Invariant,
compress_limit => CompressLimit}}
| Spec
].
validate_summary_labels(Labels) ->
[raise_error_if_quantile_label_found(Label) || Label <- Labels].
raise_error_if_quantile_label_found("quantile") ->
erlang:error({invalid_metric_label_name, "quantile",
"summary cannot have a label named \"quantile\""});
raise_error_if_quantile_label_found(Label) ->
Label.
insert_metric(Registry, Name, LabelValues, Value, ConflictCB) ->
MF = prometheus_metric:check_mf_exists(?TABLE, Registry, Name, LabelValues),
Configuration = prometheus_metric:mf_data(MF),
#{compress_limit := CompressLimit} = Configuration,
Quantile = quantile(Configuration, Value),
case ets:insert_new(?TABLE, {key(Registry, Name, LabelValues), 1, Value, Quantile, CompressLimit}) of
false -> %% some sneaky process already inserted
ConflictCB(Registry, Name, LabelValues, Value);
true ->
ok
end.
load_all_values(Registry, Name) ->
ets:match(?TABLE, {{Registry, Name, '$1', '_'}, '$2', '$3', '$4', '_'}).
get_configuration(Registry, Name) ->
MF = prometheus_metric:check_mf_exists(?TABLE, Registry, Name),
prometheus_metric:mf_data(MF).
schedulers_seq() ->
lists:seq(0, ?WIDTH-1).
key(Registry, Name, LabelValues) ->
X = erlang:system_info(scheduler_id),
Rnd = X band (?WIDTH-1),
{Registry, Name, LabelValues, Rnd}.
reduce_values(Values) ->
{lists:sum([C || [C, _, _] <- Values]),
lists:sum([S || [_, S, _] <- Values]),
fold_quantiles([Q || [_C, _S, Q] <- Values])}.
create_summary(Name, Help, Data) ->
prometheus_model_helpers:create_mf(Name, Help, summary, ?MODULE, Data).
default_compress_limit() -> 100.
invariant_and_quantiles_from_spec(Spec) ->
Targets = prometheus_metric_spec:get_value(targets, Spec, default_targets()),
validate_targets(Targets),
{QNs, _} = lists:unzip(Targets),
Invariant = quantile_estimator:f_targeted(Targets),
{Invariant, QNs}.
compress_limit_from_spec(Spec) ->
prometheus_metric_spec:get_value(compress_limit, Spec, default_compress_limit()).
validate_targets(Targets) when is_list(Targets) ->
lists:foreach(
fun
({Q, _E}) when not is_float(Q) ->
erlang:error({invalid_targets, "target quantile value should be float"});
({_Q, E}) when not is_float(E) ->
erlang:error({invalid_targets, "target error value should be float"});
({_, _}) ->
ok;
(_) ->
erlang:error({invalid_targets, "targets should be tuples of quantile and error"})
end,
Targets);
validate_targets(_Targets) ->
erlang:error({invalid_targets, "targets should be a list of tuples"}).
default_targets() ->
[{0.5, 0.02}, {0.9, 0.01}, {0.95, 0.005}].
quantile(#{invariant := Invariant}) ->
quantile_estimator:new(Invariant).
quantile(Configuration, Val) ->
quantile_estimator:insert(Val, quantile(Configuration)).
quantile_add(Q = #quantile_estimator{inserts_since_compression = ISS}, Val, CompressLimit) ->
Q1 = case ISS > CompressLimit of
true -> quantile_estimator:compress(Q);
false -> Q
end,
quantile_estimator:insert(Val, Q1).
%% Quantile estimator throws on empty stats
quantile_values(#quantile_estimator{data = []}, _QNs) ->
[];
quantile_values(Q, QNs) ->
[{QN, quantile_estimator:quantile(QN, Q)} || QN <- QNs].
fold_quantiles(QList) ->
lists:foldl(
fun
(Q, init) -> Q;
(Q1, Q2) -> quantile_merge(Q1, Q2)
end,
init,
QList).
quantile_merge(QE1, QE2) ->
#quantile_estimator{samples_count = N1, data = Data1, invariant = Invariant} = QE1,
#quantile_estimator{samples_count = N2, data = Data2} = QE2,
quantile_estimator:compress(#quantile_estimator{
samples_count = N1 + N2,
data = Data1 ++ Data2,
invariant = Invariant,
data_count = 0,
inserts_since_compression = 0
}).