1 files changed, 53 insertions, 0 deletions
diff --git a/vendor/go.opentelemetry.io/otel/sdk/metric/internal/aggregate/limit.go b/vendor/go.opentelemetry.io/otel/sdk/metric/internal/aggregate/limit.go
new file mode 100644
index 000000000..d3de84272
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/sdk/metric/internal/aggregate/limit.go
@@ -0,0 +1,53 @@
+// 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 aggregate // import "go.opentelemetry.io/otel/sdk/metric/internal/aggregate"
+
+import "go.opentelemetry.io/otel/attribute"
+
+// overflowSet is the attribute set used to record a measurement when adding
+// another distinct attribute set to the aggregate would exceed the aggregate
+// limit.
+var overflowSet = attribute.NewSet(attribute.Bool("otel.metric.overflow", true))
+
+// limiter limits aggregate values.
+type limiter[V any] struct {
+	// aggLimit is the maximum number of metric streams that can be aggregated.
+	//
+	// Any metric stream with attributes distinct from any set already
+	// aggregated once the aggLimit will be meet will instead be aggregated
+	// into an "overflow" metric stream. That stream will only contain the
+	// "otel.metric.overflow"=true attribute.
+	aggLimit int
+}
+
+// newLimiter returns a new Limiter with the provided aggregation limit.
+func newLimiter[V any](aggregation int) limiter[V] {
+	return limiter[V]{aggLimit: aggregation}
+}
+
+// Attributes checks if adding a measurement for attrs will exceed the
+// aggregation cardinality limit for the existing measurements. If it will,
+// overflowSet is returned. Otherwise, if it will not exceed the limit, or the
+// limit is not set (limit <= 0), attr is returned.
+func (l limiter[V]) Attributes(attrs attribute.Set, measurements map[attribute.Set]V) attribute.Set {
+	if l.aggLimit > 0 {
+		_, exists := measurements[attrs]
+		if !exists && len(measurements) >= l.aggLimit-1 {
+			return overflowSet
+		}
+	}
+
+	return attrs
+}