exporter_test.go

Documentation: go.opencensus.io/metric/test

     1  package test
     2  
     3  import (
     4  	"context"
     5  	"fmt"
     6  
     7  	"go.opencensus.io/metric"
     8  	"go.opencensus.io/metric/metricdata"
     9  	"go.opencensus.io/metric/metricexport"
    10  	"go.opencensus.io/stats"
    11  	"go.opencensus.io/stats/view"
    12  	"go.opencensus.io/tag"
    13  )
    14  
    15  var (
    16  	myTag    = tag.MustNewKey("my_label")
    17  	myMetric = stats.Int64("my_metric", "description", stats.UnitDimensionless)
    18  )
    19  
    20  func init() {
    21  	if err := view.Register(
    22  		&view.View{
    23  			Measure:     myMetric,
    24  			TagKeys:     []tag.Key{myTag},
    25  			Aggregation: view.Sum(),
    26  		},
    27  	); err != nil {
    28  		panic(err)
    29  	}
    30  }
    31  
    32  func ExampleExporter_stats() {
    33  	metricReader := metricexport.NewReader()
    34  	metrics := NewExporter(metricReader)
    35  	metrics.ReadAndExport()
    36  	metricBase := getCounter(metrics, myMetric.Name(), newMetricKey("label1"))
    37  
    38  	for i := 1; i <= 3; i++ {
    39  		// The code under test begins here.
    40  		stats.RecordWithTags(context.Background(),
    41  			[]tag.Mutator{tag.Upsert(myTag, "label1")},
    42  			myMetric.M(int64(i)))
    43  		// The code under test ends here.
    44  
    45  		metrics.ReadAndExport()
    46  		metricValue := getCounter(metrics, myMetric.Name(), newMetricKey("label1"))
    47  		fmt.Printf("increased by %d\n", metricValue-metricBase)
    48  	}
    49  	// Output:
    50  	// increased by 1
    51  	// increased by 3
    52  	// increased by 6
    53  }
    54  
    55  type derivedMetric struct {
    56  	i int64
    57  }
    58  
    59  func (m *derivedMetric) ToInt64() int64 {
    60  	return m.i
    61  }
    62  
    63  func ExampleExporter_metric() {
    64  	metricReader := metricexport.NewReader()
    65  	metrics := NewExporter(metricReader)
    66  	m := derivedMetric{}
    67  	r := metric.NewRegistry()
    68  	g, _ := r.AddInt64DerivedCumulative("derived", metric.WithLabelKeys(myTag.Name()))
    69  	g.UpsertEntry(m.ToInt64, metricdata.NewLabelValue("l1"))
    70  	for i := 1; i <= 3; i++ {
    71  		// The code under test begins here.
    72  		m.i = int64(i)
    73  		// The code under test ends here.
    74  
    75  		metrics.ExportMetrics(context.Background(), r.Read())
    76  		metricValue := getCounter(metrics, "derived", newMetricKey("l1"))
    77  		fmt.Println(metricValue)
    78  	}
    79  	// Output:
    80  	// 1
    81  	// 2
    82  	// 3
    83  }
    84  
    85  func newMetricKey(v string) map[string]string {
    86  	return map[string]string{myTag.Name(): v}
    87  }
    88  
    89  func getCounter(metrics *Exporter, metricName string, metricKey map[string]string) int64 {
    90  	p, ok := metrics.GetPoint(metricName, metricKey)
    91  	if !ok {
    92  		// This is expected before the metric is recorded the first time.
    93  		return 0
    94  	}
    95  	return p.Value.(int64)
    96  }
    97
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