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opentelemetry-go/metric/example_test.go

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// 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 metric_test
import (
"context"
"fmt"
"runtime"
"time"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/metric"
)
func ExampleMeter_synchronous() {
// Create a histogram using the global MeterProvider.
workDuration, err := otel.Meter("go.opentelemetry.io/otel/metric#SyncExample").Int64Histogram(
"workDuration",
metric.WithUnit("ms"))
if err != nil {
fmt.Println("Failed to register instrument")
panic(err)
}
startTime := time.Now()
ctx := context.Background()
// Do work
// ...
workDuration.Record(ctx, time.Since(startTime).Milliseconds())
}
func ExampleMeter_asynchronous_single() {
meter := otel.Meter("go.opentelemetry.io/otel/metric#AsyncExample")
_, err := meter.Int64ObservableGauge(
"DiskUsage",
metric.WithUnit("By"),
metric.WithInt64Callback(func(_ context.Context, obsrv metric.Int64Observer) error {
// Do the real work here to get the real disk usage. For example,
//
// usage, err := GetDiskUsage(diskID)
// if err != nil {
// if retryable(err) {
// // Retry the usage measurement.
// } else {
// return err
// }
// }
//
// For demonstration purpose, a static value is used here.
usage := 75000
obsrv.Observe(int64(usage), metric.WithAttributes(attribute.Int("disk.id", 3)))
return nil
}),
)
if err != nil {
fmt.Println("failed to register instrument")
panic(err)
}
}
func ExampleMeter_asynchronous_multiple() {
meter := otel.Meter("go.opentelemetry.io/otel/metric#MultiAsyncExample")
// This is just a sample of memory stats to record from the Memstats
heapAlloc, _ := meter.Int64ObservableUpDownCounter("heapAllocs")
gcCount, _ := meter.Int64ObservableCounter("gcCount")
_, err := meter.RegisterCallback(
func(_ context.Context, o metric.Observer) error {
memStats := &runtime.MemStats{}
// This call does work
runtime.ReadMemStats(memStats)
o.ObserveInt64(heapAlloc, int64(memStats.HeapAlloc))
o.ObserveInt64(gcCount, int64(memStats.NumGC))
return nil
},
heapAlloc,
gcCount,
)
if err != nil {
fmt.Println("Failed to register callback")
panic(err)
}
}