/
filter.go
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/
filter.go
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// Copyright The OpenTelemetry Authors
//
// 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.
package internal // import "go.opentelemetry.io/otel/sdk/metric/internal"
import (
"sync"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/sdk/metric/metricdata"
)
// filter is an aggregator that applies attribute filter when Aggregating. filters
// do not have any backing memory, and must be constructed with a backing Aggregator.
type filter[N int64 | float64] struct {
filter func(attribute.Set) attribute.Set
aggregator Aggregator[N]
sync.Mutex
seen map[attribute.Set]attribute.Set
}
// NewFilter wraps an Aggregator with an attribute filtering function.
func NewFilter[N int64 | float64](agg Aggregator[N], fn func(attribute.Set) attribute.Set) Aggregator[N] {
if fn == nil {
return agg
}
return &filter[N]{
filter: fn,
aggregator: agg,
seen: map[attribute.Set]attribute.Set{},
}
}
// Aggregate records the measurement, scoped by attr, and aggregates it
// into an aggregation.
func (f *filter[N]) Aggregate(measurement N, attr attribute.Set) {
// TODO (#3006): drop stale attributes from seen.
f.Lock()
defer f.Unlock()
fAttr, ok := f.seen[attr]
if !ok {
fAttr = f.filter(attr)
f.seen[attr] = fAttr
}
f.aggregator.Aggregate(measurement, fAttr)
}
// Aggregation returns an Aggregation, for all the aggregated
// measurements made and ends an aggregation cycle.
func (f *filter[N]) Aggregation() metricdata.Aggregation {
return f.aggregator.Aggregation()
}