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https://github.com/open-telemetry/opentelemetry-go.git
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312 lines
8.3 KiB
Go
312 lines
8.3 KiB
Go
// Copyright The OpenTelemetry Authors
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// SPDX-License-Identifier: Apache-2.0
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package metric_test
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import (
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"context"
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"database/sql"
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"fmt"
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"math/rand"
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"net/http"
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"runtime"
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"time"
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"go.opentelemetry.io/otel"
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"go.opentelemetry.io/otel/attribute"
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"go.opentelemetry.io/otel/metric"
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semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
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)
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var meter = otel.Meter("my-service-meter")
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func ExampleMeter_synchronous() {
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// Create a histogram using the global MeterProvider.
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workDuration, err := meter.Int64Histogram(
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"workDuration",
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metric.WithUnit("ms"))
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if err != nil {
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fmt.Println("Failed to register instrument")
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panic(err)
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}
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startTime := time.Now()
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ctx := context.Background()
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// Do work
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// ...
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workDuration.Record(ctx, time.Since(startTime).Milliseconds())
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}
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func ExampleMeter_asynchronous_single() {
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_, err := meter.Int64ObservableGauge(
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"DiskUsage",
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metric.WithUnit("By"),
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metric.WithInt64Callback(func(_ context.Context, obsrv metric.Int64Observer) error {
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// Do the real work here to get the real disk usage. For example,
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//
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// usage, err := GetDiskUsage(diskID)
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// if err != nil {
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// if retryable(err) {
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// // Retry the usage measurement.
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// } else {
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// return err
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// }
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// }
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//
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// For demonstration purpose, a static value is used here.
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usage := 75000
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obsrv.Observe(int64(usage), metric.WithAttributes(attribute.Int("disk.id", 3)))
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return nil
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}),
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)
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if err != nil {
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fmt.Println("failed to register instrument")
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panic(err)
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}
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}
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func ExampleMeter_asynchronous_multiple() {
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// This is just a sample of memory stats to record from the Memstats
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heapAlloc, err := meter.Int64ObservableUpDownCounter("heapAllocs")
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if err != nil {
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fmt.Println("failed to register updown counter for heapAllocs")
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panic(err)
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}
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gcCount, err := meter.Int64ObservableCounter("gcCount")
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if err != nil {
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fmt.Println("failed to register counter for gcCount")
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panic(err)
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}
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_, err = meter.RegisterCallback(
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func(_ context.Context, o metric.Observer) error {
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memStats := &runtime.MemStats{}
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// This call does work
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runtime.ReadMemStats(memStats)
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o.ObserveInt64(heapAlloc, int64(memStats.HeapAlloc))
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o.ObserveInt64(gcCount, int64(memStats.NumGC))
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return nil
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},
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heapAlloc,
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gcCount,
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)
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if err != nil {
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fmt.Println("Failed to register callback")
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panic(err)
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}
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}
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// Counters can be used to measure a non-negative, increasing value.
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//
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// Here's how you might report the number of calls for an HTTP handler.
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func ExampleMeter_counter() {
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apiCounter, err := meter.Int64Counter(
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"api.counter",
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metric.WithDescription("Number of API calls."),
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metric.WithUnit("{call}"),
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)
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if err != nil {
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panic(err)
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}
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http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
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apiCounter.Add(r.Context(), 1)
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// do some work in an API call
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})
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}
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// UpDown counters can increment and decrement, allowing you to observe
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// a cumulative value that goes up or down.
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//
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// Here's how you might report the number of items of some collection.
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func ExampleMeter_upDownCounter() {
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var err error
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itemsCounter, err := meter.Int64UpDownCounter(
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"items.counter",
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metric.WithDescription("Number of items."),
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metric.WithUnit("{item}"),
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)
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if err != nil {
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panic(err)
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}
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_ = func() {
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// code that adds an item to the collection
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itemsCounter.Add(context.Background(), 1)
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}
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_ = func() {
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// code that removes an item from the collection
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itemsCounter.Add(context.Background(), -1)
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}
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}
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// Gauges can be used to record non-additive values when changes occur.
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//
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// Here's how you might report the current speed of a cpu fan.
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func ExampleMeter_gauge() {
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speedGauge, err := meter.Int64Gauge(
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"cpu.fan.speed",
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metric.WithDescription("Speed of CPU fan"),
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metric.WithUnit("RPM"),
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)
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if err != nil {
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panic(err)
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}
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getCPUFanSpeed := func() int64 {
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// Generates a random fan speed for demonstration purpose.
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// In real world applications, replace this to get the actual fan speed.
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return int64(1500 + rand.Intn(1000))
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}
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fanSpeedSubscription := make(chan int64, 1)
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go func() {
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defer close(fanSpeedSubscription)
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for idx := 0; idx < 5; idx++ {
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// Synchronous gauges are used when the measurement cycle is
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// synchronous to an external change.
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// Simulate that external cycle here.
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time.Sleep(time.Duration(rand.Intn(3)) * time.Second)
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fanSpeed := getCPUFanSpeed()
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fanSpeedSubscription <- fanSpeed
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}
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}()
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ctx := context.Background()
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for fanSpeed := range fanSpeedSubscription {
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speedGauge.Record(ctx, fanSpeed)
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}
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}
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// Histograms are used to measure a distribution of values over time.
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//
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// Here's how you might report a distribution of response times for an HTTP handler.
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func ExampleMeter_histogram() {
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histogram, err := meter.Float64Histogram(
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"task.duration",
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metric.WithDescription("The duration of task execution."),
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metric.WithUnit("s"),
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metric.WithExplicitBucketBoundaries(.005, .01, .025, .05, .075, .1, .25, .5, .75, 1, 2.5, 5, 7.5, 10),
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)
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if err != nil {
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panic(err)
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}
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http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
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start := time.Now()
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// do some work in an API call
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duration := time.Since(start)
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histogram.Record(r.Context(), duration.Seconds())
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})
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}
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// Observable counters can be used to measure an additive, non-negative,
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// monotonically increasing value.
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//
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// Here's how you might report time since the application started.
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func ExampleMeter_observableCounter() {
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start := time.Now()
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if _, err := meter.Float64ObservableCounter(
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"uptime",
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metric.WithDescription("The duration since the application started."),
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metric.WithUnit("s"),
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metric.WithFloat64Callback(func(_ context.Context, o metric.Float64Observer) error {
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o.Observe(float64(time.Since(start).Seconds()))
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return nil
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}),
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); err != nil {
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panic(err)
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}
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}
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// Observable UpDown counters can increment and decrement, allowing you to measure
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// an additive, non-negative, non-monotonically increasing cumulative value.
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//
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// Here's how you might report some database metrics.
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func ExampleMeter_observableUpDownCounter() {
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// The function registers asynchronous metrics for the provided db.
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// Make sure to unregister metric.Registration before closing the provided db.
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_ = func(db *sql.DB, meter metric.Meter, poolName string) (metric.Registration, error) {
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max, err := meter.Int64ObservableUpDownCounter(
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"db.client.connections.max",
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metric.WithDescription("The maximum number of open connections allowed."),
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metric.WithUnit("{connection}"),
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)
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if err != nil {
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return nil, err
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}
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waitTime, err := meter.Int64ObservableUpDownCounter(
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"db.client.connections.wait_time",
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metric.WithDescription("The time it took to obtain an open connection from the pool."),
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metric.WithUnit("ms"),
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)
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if err != nil {
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return nil, err
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}
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reg, err := meter.RegisterCallback(
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func(_ context.Context, o metric.Observer) error {
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stats := db.Stats()
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o.ObserveInt64(max, int64(stats.MaxOpenConnections))
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o.ObserveInt64(waitTime, int64(stats.WaitDuration))
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return nil
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},
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max,
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waitTime,
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)
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if err != nil {
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return nil, err
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}
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return reg, nil
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}
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}
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// Observable Gauges should be used to measure non-additive values.
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//
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// Here's how you might report memory usage of the heap objects used
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// in application.
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func ExampleMeter_observableGauge() {
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if _, err := meter.Int64ObservableGauge(
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"memory.heap",
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metric.WithDescription(
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"Memory usage of the allocated heap objects.",
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),
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metric.WithUnit("By"),
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metric.WithInt64Callback(func(_ context.Context, o metric.Int64Observer) error {
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var m runtime.MemStats
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runtime.ReadMemStats(&m)
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o.Observe(int64(m.HeapAlloc))
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return nil
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}),
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); err != nil {
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panic(err)
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}
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}
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// You can add Attributes by using the [WithAttributeSet] and [WithAttributes] options.
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//
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// Here's how you might add the HTTP status code attribute to your recordings.
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func ExampleMeter_attributes() {
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apiCounter, err := meter.Int64UpDownCounter(
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"api.finished.counter",
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metric.WithDescription("Number of finished API calls."),
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metric.WithUnit("{call}"),
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)
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if err != nil {
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panic(err)
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}
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http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
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// do some work in an API call and set the response HTTP status code
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statusCode := http.StatusOK
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apiCounter.Add(r.Context(), 1,
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metric.WithAttributes(semconv.HTTPResponseStatusCode(statusCode)))
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})
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}
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