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0.1.0
Prometheus.io client in Erlang
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Files
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Files
src/prometheus_buckets.erl
-module(prometheus_buckets).
-export([default/0,
linear/3,
exponential/3]).
-export_type([bucket_bound/0,
buckets/0]).
%%====================================================================
%% Types
%%====================================================================
-type bucket_bound() :: number() | infinity.
-type buckets() :: [bucket_bound(), ...].
%%====================================================================
%% Public API
%%====================================================================
-spec default() -> buckets().
default() -> [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10].
-spec linear(integer(), pos_integer(), pos_integer()) -> buckets().
linear(_Start, _Step, Count) when Count < 1 ->
erlang:error({invalid_value, Count, "Buckets count should be positive"});
linear(Start, Step, Count) ->
Bounds = lists:seq(Start, Start + Step*(Count - 1), Step),
[try_to_maintain_integer_bounds(Bound) || Bound <- Bounds].
-spec exponential(number(), number(), pos_integer()) -> buckets().
exponential(_Start, _Factor, Count) when Count < 1 ->
erlang:error({invalid_value, Count, "Buckets count should be positive"});
exponential(Start, _Factor, _Count) when Start =< 0 ->
erlang:error({invalid_value, Start, "Buckets start should be positive"});
exponential(_Start, Factor, _Count) when Factor =< 1 ->
erlang:error({invalid_value, Factor,
"Buckets factor should be greater than 1"});
exponential(Start, Factor, Count) ->
[try_to_maintain_integer_bounds(Start*math:pow(Factor, I)) ||
I <- lists:seq(0, Count-1)].
%%====================================================================
%% Private Parts
%%====================================================================
-spec try_to_maintain_integer_bounds(integer()) -> integer();
(float()) -> integer() | float().
try_to_maintain_integer_bounds(Bound) when is_integer(Bound) -> Bound;
try_to_maintain_integer_bounds(Bound) when is_float(Bound) ->
TBound = trunc(Bound),
case TBound == Bound of
true -> TBound;
false -> Bound
end.