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% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(couch_stats).
-export([
start/0,
stop/0,
fetch/0,
reload/0,
sample/1,
new/2,
delete/1,
list/0,
increment_counter/1,
increment_counter/2,
decrement_counter/1,
decrement_counter/2,
update_histogram/2,
update_gauge/2
]).
-include("couch_stats.hrl").
-type response() :: ok | {error, unknown_metric}.
-type stat() :: {any(), [{atom(), any()}]}.
start() ->
application:start(couch_stats).
stop() ->
application:stop(couch_stats).
fetch() ->
couch_stats_aggregator:fetch().
reload() ->
couch_stats_aggregator:reload().
-spec sample(any()) -> stat().
sample(Name) ->
[{Name, Info}] = folsom_metrics:get_metric_info(Name),
sample_type(Name, proplists:get_value(type, Info)).
-spec new(atom(), any()) -> ok | {error, metric_exists | unsupported_type}.
new(counter, Name) ->
case folsom_metrics:new_counter(Name) of
ok -> ok;
{error, Name, metric_already_exists} -> {error, metric_exists}
end;
new(histogram, Name) ->
Time = config:get_integer("stats", "interval", ?DEFAULT_INTERVAL),
case folsom_metrics:new_histogram(Name, slide_uniform, {Time, 1024}) of
ok -> ok;
{error, Name, metric_already_exists} -> {error, metric_exists}
end;
new(gauge, Name) ->
case folsom_metrics:new_gauge(Name) of
ok -> ok;
{error, Name, metric_already_exists} -> {error, metric_exists}
end;
new(_, _) ->
{error, unsupported_type}.
delete(Name) ->
folsom_metrics:delete_metric(Name).
list() ->
folsom_metrics:get_metrics_info().
-spec increment_counter(any()) -> response().
increment_counter(Name) ->
notify_existing_metric(Name, {inc, 1}, counter).
-spec increment_counter(any(), pos_integer()) -> response().
increment_counter(Name, Value) ->
notify_existing_metric(Name, {inc, Value}, counter).
-spec decrement_counter(any()) -> response().
decrement_counter(Name) ->
notify_existing_metric(Name, {dec, 1}, counter).
-spec decrement_counter(any(), pos_integer()) -> response().
decrement_counter(Name, Value) ->
notify_existing_metric(Name, {dec, Value}, counter).
-spec update_histogram
(any(), number()) -> response();
(any(), function()) -> any().
update_histogram(Name, Fun) when is_function(Fun, 0) ->
Begin = os:timestamp(),
Result = Fun(),
Duration = timer:now_diff(os:timestamp(), Begin) div 1000,
case notify_existing_metric(Name, Duration, histogram) of
ok ->
Result;
{error, unknown_metric} ->
throw({unknown_metric, Name})
end;
update_histogram(Name, Value) when is_number(Value) ->
notify_existing_metric(Name, Value, histogram).
-spec update_gauge(any(), number()) -> response().
update_gauge(Name, Value) ->
notify_existing_metric(Name, Value, gauge).
-spec notify_existing_metric(any(), any(), any()) -> response().
notify_existing_metric(Name, Op, Type) ->
try
ok = folsom_metrics:notify_existing_metric(Name, Op, Type)
catch
_:_ ->
error_logger:error_msg("unknown metric: ~p", [Name]),
{error, unknown_metric}
end.
-spec sample_type(any(), atom()) -> stat().
sample_type(Name, histogram) ->
folsom_metrics:get_histogram_statistics(Name);
sample_type(Name, _) ->
folsom_metrics:get_metric_value(Name).
|
