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本文主要研究一下dapr的metrics_utils
NewMeasureView
dapr/pkg/diagnostics/utils/metrics_utils.go
// NewMeasureView creates opencensus View instance using stats.Measure
func NewMeasureView(measure stats.Measure, keys []tag.Key, aggregation *view.Aggregation) *view.View {
return &view.View{
Name: measure.Name(),
Description: measure.Description(),
Measure: measure,
TagKeys: keys,
Aggregation: aggregation,
}
}
NewMeasureView根据measure、tag、aggregation来创建view
WithTags
dapr/pkg/diagnostics/utils/metrics_utils.go
// WithTags converts tag key and value pairs to tag.Mutator array.
// WithTags(key1, value1, key2, value2) returns
// []tag.Mutator{tag.Upsert(key1, value1), tag.Upsert(key2, value2)}
func WithTags(opts ...interface{}) []tag.Mutator {
tagMutators := []tag.Mutator{}
for i := 0; i < len(opts)-1; i += 2 {
key, ok := opts[i].(tag.Key)
if !ok {
break
}
value, ok := opts[i+1].(string)
if !ok {
break
}
// skip if value is empty
if value != "" {
tagMutators = append(tagMutators, tag.Upsert(key, value))
}
}
return tagMutators
}
WithTags方法支持变长的tag.Key类型,支持将tag.Key转换为tag.Mutator
AddTagKeyToCtx
dapr/pkg/diagnostics/utils/metrics_utils.go
// AddTagKeyToCtx assigns opencensus tag key value to context
func AddTagKeyToCtx(ctx context.Context, key tag.Key, value string) context.Context {
// return if value is not given
if value == "" {
return ctx
}
newCtx, err := tag.New(ctx, tag.Upsert(key, value))
if err != nil {
// return original if adding tagkey is failed.
return ctx
}
return newCtx
}
AddTagKeyToCtx方法将key和value添加新的context中
AddNewTagKey
dapr/pkg/diagnostics/utils/metrics_utils.go
// AddNewTagKey adds new tag keys to existing view
func AddNewTagKey(views []*view.View, key *tag.Key) []*view.View {
for _, v := range views {
v.TagKeys = append(v.TagKeys, *key)
}
return views
}
AddNewTagKey方法遍历views将指定key追加到view的TagKeys中
实例
dapr/pkg/diagnostics/utils/metrics_utils_test.go
func TestWithTags(t *testing.T) {
t.Run("one tag", func(t *testing.T) {
appKey := tag.MustNewKey("app_id")
mutators := WithTags(appKey, "test")
assert.Equal(t, 1, len(mutators))
})
t.Run("two tags", func(t *testing.T) {
appKey := tag.MustNewKey("app_id")
operationKey := tag.MustNewKey("operation")
mutators := WithTags(appKey, "test", operationKey, "op")
assert.Equal(t, 2, len(mutators))
})
t.Run("three tags", func(t *testing.T) {
appKey := tag.MustNewKey("app_id")
operationKey := tag.MustNewKey("operation")
methodKey := tag.MustNewKey("method")
mutators := WithTags(appKey, "test", operationKey, "op", methodKey, "method")
assert.Equal(t, 3, len(mutators))
})
t.Run("two tags with wrong value type", func(t *testing.T) {
appKey := tag.MustNewKey("app_id")
operationKey := tag.MustNewKey("operation")
mutators := WithTags(appKey, "test", operationKey, 1)
assert.Equal(t, 1, len(mutators))
})
t.Run("skip empty value key", func(t *testing.T) {
appKey := tag.MustNewKey("app_id")
operationKey := tag.MustNewKey("operation")
methodKey := tag.MustNewKey("method")
mutators := WithTags(appKey, "", operationKey, "op", methodKey, "method")
assert.Equal(t, 2, len(mutators))
})
}
小结
dapr的metrics_utils基于opencensus的stats及tag提供了NewMeasureView、WithTags、AddTagKeyToCtx、AddNewTagKey方法。
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