istio

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// Copyright Istio Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//     http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package monitoring
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import (
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	"context"
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	api "go.opentelemetry.io/otel/metric"
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	"istio.io/istio/pkg/log"
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)
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type distribution struct {
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	baseMetric
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	d api.Float64Histogram
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	// precomputedRecordOption is just a precomputation to avoid allocations on each record call
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	precomputedRecordOption []api.RecordOption
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}
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var _ Metric = &distribution{}
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func newDistribution(o options) *distribution {
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	d, err := meter().Float64Histogram(o.name,
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		api.WithDescription(o.description),
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		api.WithUnit(string(o.unit)))
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	if err != nil {
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		log.Fatalf("failed to create distribution: %v", err)
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	}
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	r := &distribution{d: d}
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	r.baseMetric = baseMetric{
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		name: o.name,
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		rest: r,
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	}
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	return r
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}
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func (f *distribution) Record(value float64) {
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	f.runRecordHook(value)
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	if f.precomputedRecordOption != nil {
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		f.d.Record(context.Background(), value, f.precomputedRecordOption...)
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	} else {
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		f.d.Record(context.Background(), value)
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	}
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}
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func (f *distribution) With(labelValues ...LabelValue) Metric {
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	attrs, set := rebuildAttributes(f.baseMetric, labelValues)
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	nm := &distribution{
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		d:                       f.d,
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		precomputedRecordOption: []api.RecordOption{api.WithAttributeSet(set)},
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	}
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	nm.baseMetric = baseMetric{
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		name:  f.name,
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		attrs: attrs,
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		rest:  nm,
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	}
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	return nm
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}
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