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-module(mongoose_instrument_prometheus). |
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-behaviour(mongoose_instrument). |
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-export([set_up/3, handle_event/4]). |
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%% Define Prometheus metric-related types, because the library has no type specs |
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-type spec() :: proplists:proplist(). |
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-type name() :: string(). |
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-type help() :: string(). |
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-spec set_up(mongoose_instrument:event_name(), mongoose_instrument:labels(), |
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mongoose_instrument:config()) -> boolean(). |
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set_up(EventName, Labels, #{metrics := Metrics}) -> |
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:-( |
maps:foreach(fun(MetricName, MetricType) -> |
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:-( |
set_up_metric(EventName, Labels, MetricName, MetricType) |
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end, Metrics), |
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:-( |
true; |
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set_up(_EventName, _Labels, #{}) -> |
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:-( |
false. |
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-spec handle_event(mongoose_instrument:event_name(), mongoose_instrument:labels(), |
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mongoose_instrument:config(), mongoose_instrument:measurements()) -> ok. |
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handle_event(EventName, Labels, #{metrics := Metrics}, Measurements) -> |
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:-( |
LabelValues = labels_to_values(Labels), |
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:-( |
maps:foreach(fun(MetricName, MetricType) -> |
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:-( |
handle_metric_event(EventName, LabelValues, MetricName, MetricType, Measurements) |
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end, Metrics). |
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-spec set_up_metric(mongoose_instrument:event_name(), mongoose_instrument:labels(), |
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mongoose_instrument:metric_name(), mongoose_instrument:metric_type()) -> |
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ok. |
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set_up_metric(EventName, Labels, MetricName, MetricType) -> |
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:-( |
LabelKeys = labels_to_keys(Labels), |
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:-( |
LabelValues = labels_to_values(Labels), |
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:-( |
MetricSpec = metric_spec(EventName, LabelKeys, MetricName), |
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:-( |
case declare_metric(MetricSpec, MetricType) of |
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:-( |
true -> ok; |
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:-( |
false -> reset_metric(proplists:get_value(name, MetricSpec), LabelValues, MetricType) |
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end. |
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-spec declare_metric(proplists:proplist(), mongoose_instrument:metric_type()) -> boolean(). |
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declare_metric(MetricSpec, spiral) -> |
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:-( |
prometheus_counter:declare(MetricSpec); |
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declare_metric(MetricSpec, histogram) -> |
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:-( |
prometheus_histogram:declare([{buckets, histogram_buckets()} | MetricSpec]). |
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-spec reset_metric(name(), [mongoose_instrument:label_value()], |
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mongoose_instrument:metric_type()) -> ok. |
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reset_metric(Name, LabelValues, spiral) -> |
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:-( |
prometheus_counter:reset(Name, LabelValues), |
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:-( |
prometheus_counter:inc(Name, LabelValues, 0); |
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reset_metric(Name, LabelValues, histogram) -> |
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:-( |
prometheus_histogram:reset(Name, LabelValues), |
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:-( |
ok. |
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-spec metric_spec(mongoose_instrument:event_name(), [mongoose_instrument:label_key()], |
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mongoose_instrument:metric_name()) -> spec(). |
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metric_spec(EventName, LabelKeys, MetricName) -> |
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:-( |
[{name, full_metric_name(EventName, MetricName)}, |
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{help, metric_help(EventName, MetricName)}, |
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{labels, LabelKeys}]. |
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-spec histogram_buckets() -> [integer()]. |
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histogram_buckets() -> |
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:-( |
histogram_buckets([], 1 bsl 30). % ~1.07 * 10^9 |
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histogram_buckets(AccBuckets, Val) when Val > 0 -> |
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:-( |
histogram_buckets([Val | AccBuckets], Val bsr 1); |
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histogram_buckets(AccBuckets, _Val) -> |
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:-( |
AccBuckets. |
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-spec handle_metric_event(mongoose_instrument:event_name(), [mongoose_instrument:label_value()], |
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mongoose_instrument:metric_name(), mongoose_instrument:metric_type(), |
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mongoose_instrument:measurements()) -> ok. |
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handle_metric_event(EventName, LabelValues, MetricName, MetricType, Measurements) -> |
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:-( |
case Measurements of |
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#{MetricName := MetricValue} -> |
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:-( |
FullName = full_metric_name(EventName, MetricName), |
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:-( |
update_metric(FullName, LabelValues, MetricType, MetricValue); |
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#{} -> |
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:-( |
ok |
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end. |
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-spec metric_help(mongoose_instrument:event_name(), mongoose_instrument:metric_name()) -> help(). |
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metric_help(EventName, MetricName) -> |
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:-( |
lists:flatten(io_lib:format("Event: ~p, Metric: ~p", [EventName, MetricName])). |
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-spec full_metric_name(mongoose_instrument:event_name(), mongoose_instrument:metric_name()) -> |
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name(). |
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full_metric_name(EventName, MetricName) -> |
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:-( |
atom_to_list(EventName) ++ "_" ++ atom_to_list(MetricName). |
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-spec labels_to_keys(mongoose_instrument:labels()) -> [mongoose_instrument:label_key()]. |
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labels_to_keys(Labels) -> |
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:-( |
lists:sort(maps:keys(Labels)). |
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-spec labels_to_values(mongoose_instrument:labels()) -> [mongoose_instrument:label_value()]. |
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labels_to_values(Labels) -> |
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:-( |
[V || {_K, V} <- lists:keysort(1, maps:to_list(Labels))]. |
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-spec update_metric(name(), [mongoose_instrument:label_value()], |
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mongoose_instrument:metric_type(), integer()) -> ok. |
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update_metric(Name, Labels, spiral, Value) when is_integer(Value), Value >= 0 -> |
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:-( |
ok = prometheus_counter:inc(Name, Labels, Value); |
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update_metric(Name, Labels, histogram, Value) when is_integer(Value) -> |
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:-( |
ok = prometheus_histogram:observe(Name, Labels, Value). |