1 /*
2 * Copyright 2024 gRPC authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 17 package stats
18 19 import "maps"
20 21 // MetricSet is a set of metrics to record. Once created, MetricSet is immutable,
22 // however Add and Remove can make copies with specific metrics added or
23 // removed, respectively.
24 //
25 // Do not construct directly; use NewMetricSet instead.
26 type MetricSet struct {
27 // metrics are the set of metrics to initialize.
28 metrics map[string]bool
29 }
30 31 // NewMetricSet returns a MetricSet containing metricNames.
32 func NewMetricSet(metricNames ...string) *MetricSet {
33 newMetrics := make(map[string]bool)
34 for _, metric := range metricNames {
35 newMetrics[metric] = true
36 }
37 return &MetricSet{metrics: newMetrics}
38 }
39 40 // Metrics returns the metrics set. The returned map is read-only and must not
41 // be modified.
42 func (m *MetricSet) Metrics() map[string]bool {
43 return m.metrics
44 }
45 46 // Add adds the metricNames to the metrics set and returns a new copy with the
47 // additional metrics.
48 func (m *MetricSet) Add(metricNames ...string) *MetricSet {
49 newMetrics := make(map[string]bool)
50 for metric := range m.metrics {
51 newMetrics[metric] = true
52 }
53 54 for _, metric := range metricNames {
55 newMetrics[metric] = true
56 }
57 return &MetricSet{metrics: newMetrics}
58 }
59 60 // Join joins the metrics passed in with the metrics set, and returns a new copy
61 // with the merged metrics.
62 func (m *MetricSet) Join(metrics *MetricSet) *MetricSet {
63 newMetrics := make(map[string]bool)
64 maps.Copy(newMetrics, m.metrics)
65 maps.Copy(newMetrics, metrics.metrics)
66 return &MetricSet{metrics: newMetrics}
67 }
68 69 // Remove removes the metricNames from the metrics set and returns a new copy
70 // with the metrics removed.
71 func (m *MetricSet) Remove(metricNames ...string) *MetricSet {
72 newMetrics := make(map[string]bool)
73 for metric := range m.metrics {
74 newMetrics[metric] = true
75 }
76 77 for _, metric := range metricNames {
78 delete(newMetrics, metric)
79 }
80 return &MetricSet{metrics: newMetrics}
81 }
82