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opentelemetry-go/sdk/metric/processor/reducer/reducer.go
Joshua MacDonald 5d1dd4ee23
Add a dimensionality-reducing metric Processor (#1057)
* Add a dimensionality-reducing metric processor

* Precommit

* Add package docs

* Remove dead code
2020-08-13 15:47:17 -07:00

68 lines
2.0 KiB
Go

// 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 reducer // import "go.opentelemetry.io/otel/sdk/metric/processor/reducer"
import (
"go.opentelemetry.io/otel/api/label"
"go.opentelemetry.io/otel/api/metric"
export "go.opentelemetry.io/otel/sdk/export/metric"
)
type (
// Processor implements "dimensionality reduction" by
// filtering keys from export label sets.
Processor struct {
export.Checkpointer
filterSelector LabelFilterSelector
}
// LabelFilterSelector is the interface used to configure a
// specific Filter to an instrument.
LabelFilterSelector interface {
LabelFilterFor(*metric.Descriptor) label.Filter
}
)
var _ export.Processor = &Processor{}
var _ export.Checkpointer = &Processor{}
// New returns a dimensionality-reducing Processor that passes data to
// the next stage in an export pipeline.
func New(filterSelector LabelFilterSelector, ckpter export.Checkpointer) *Processor {
return &Processor{
Checkpointer: ckpter,
filterSelector: filterSelector,
}
}
// Process implements export.Processor.
func (p *Processor) Process(accum export.Accumulation) error {
// Note: the removed labels are returned and ignored here.
// Conceivably these inputs could be useful to a sampler.
reduced, _ := accum.Labels().Filter(
p.filterSelector.LabelFilterFor(
accum.Descriptor(),
),
)
return p.Checkpointer.Process(
export.NewAccumulation(
accum.Descriptor(),
&reduced,
accum.Resource(),
accum.Aggregator(),
),
)
}