Make registration of callback for async metric always optional (open-…

…telemetry#12204)

This PR also solves one more issues with the new interface, which is the
ability to record multiple observations for a single async metric using
one callback.

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

.chloggen/all-optional-async.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: All register callbacks to async instruments can now be unregistered by calling `metadata.TelemetryBuilder.Shutdown()`
+
+# One or more tracking issues or pull requests related to the change
+issues: [12204]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [api]

.chloggen/deprecate-optional-async.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: deprecation
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Make registration of callback for async metric always optional.
+
+# One or more tracking issues or pull requests related to the change
+issues: [12204]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: Deprecate `metadata.TelemetryBuilder.Init*` and `metadata.With*Callback` in favor of `metadata.TelemetryBuilder.Register*Callback`
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [api]

cmd/mdatagen/internal/command_test.go

@@ -601,10 +601,10 @@ package metadata
 
 import (
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/embedded"
 	"go.opentelemetry.io/otel/trace"
 
 	"go.opentelemetry.io/collector/component"
-	"go.opentelemetry.io/collector/config/configtelemetry"
 )
 
 func Meter(settings component.TelemetrySettings) metric.Meter {
@@ -634,10 +634,10 @@ package metadata
 
 import (
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/embedded"
 	"go.opentelemetry.io/otel/trace"
 
 	"go.opentelemetry.io/collector/component"
-	"go.opentelemetry.io/collector/config/configtelemetry"
 )
 
 func Meter(settings component.TelemetrySettings) metric.Meter {

cmd/mdatagen/internal/samplereceiver/factory.go

@@ -6,6 +6,8 @@ package samplereceiver // import "go.opentelemetry.io/collector/cmd/mdatagen/int
 import (
 	"context"
 
+	"go.opentelemetry.io/otel/metric"
+
 	"go.opentelemetry.io/collector/cmd/mdatagen/internal/samplereceiver/internal/metadata"
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/consumer"
@@ -27,10 +29,18 @@ func createTraces(context.Context, receiver.Settings, component.Config, consumer
 }
 
 func createMetrics(ctx context.Context, set receiver.Settings, _ component.Config, _ consumer.Metrics) (receiver.Metrics, error) {
-	telemetryBuilder, err := metadata.NewTelemetryBuilder(set.TelemetrySettings, metadata.WithProcessRuntimeTotalAllocBytesCallback(func() int64 { return 2 }))
+	telemetryBuilder, err := metadata.NewTelemetryBuilder(set.TelemetrySettings)
+	if err != nil {
+		return nil, err
+	}
+	err = telemetryBuilder.RegisterProcessRuntimeTotalAllocBytesCallback(func(_ context.Context, observer metric.Int64Observer) error {
+		observer.Observe(2)
+		return nil
+	})
 	if err != nil {
 		return nil, err
 	}
+
 	telemetryBuilder.BatchSizeTriggerSend.Add(ctx, 1)
 	return nopReceiver{telemetryBuilder: telemetryBuilder}, nil
 }
@@ -43,10 +53,20 @@ var nopInstance = &nopReceiver{}
 
 type nopReceiver struct {
 	component.StartFunc
-	component.ShutdownFunc
 	telemetryBuilder *metadata.TelemetryBuilder
 }
 
 func (r nopReceiver) initOptionalMetric() {
-	_, _ = r.telemetryBuilder.InitQueueLength(func() int64 { return 1 })
+	_ = r.telemetryBuilder.RegisterQueueLengthCallback(func(_ context.Context, observer metric.Int64Observer) error {
+		observer.Observe(3)
+		return nil
+	})
+}
+
+// Shutdown shuts down the component.
+func (r nopReceiver) Shutdown(context.Context) error {
+	if r.telemetryBuilder != nil {
+		r.telemetryBuilder.Shutdown()
+	}
+	return nil
 }