Move global metric back to otel/metric/global for minor release (#3986)

* Revert "Remove the deprecated `otel/metric/global` pkg (#3829)"

This reverts commit 60f7d42d1eedae6381f1d6524374b57a274e1639.

* Revert "Support a global MeterProvider in `go.opentelemetry.io/otel` (#3818)"

This reverts commit 813936187e46d48924b717ed9f63767eef26f55a.

* Remove top level metric global

* Add change to changelog

CHANGELOG.md

@@ -24,6 +24,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Move No-Op implementation from `go.opentelemetry.io/otel/metric` into its own package `go.opentelemetry.io/otel/metric/noop`. (#3941)
   - `metric.NewNoopMeterProvider` is replaced with `noop.NewMeterProvider`
 - Wrap `UploadMetrics` error in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/` to improve error message when encountering generic grpc errors. (#3974)
+- Move global metric back to `go.opentelemetry.io/otel/metric/global` from `go.opentelemetry.io/otel`. (#3986)
 
 ### Fixed
 

bridge/opentracing/go.mod

@@ -18,8 +18,5 @@ require (
 	github.com/go-logr/logr v1.2.4 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
-
-replace go.opentelemetry.io/otel/metric => ../../metric

bridge/opentracing/test/go.mod

@@ -23,7 +23,6 @@ require (
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/trace v1.15.0-rc.2 // indirect
 	golang.org/x/net v0.8.0 // indirect
 	golang.org/x/sys v0.7.0 // indirect
@@ -32,5 +31,3 @@ require (
 	google.golang.org/protobuf v1.30.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
-
-replace go.opentelemetry.io/otel/metric => ../../../metric

example/fib/go.mod

@@ -12,7 +12,6 @@ require (
 require (
 	github.com/go-logr/logr v1.2.4 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 )
 
@@ -23,5 +22,3 @@ replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters
 replace go.opentelemetry.io/otel/sdk => ../../sdk
 
 replace go.opentelemetry.io/otel/trace => ../../trace
-
-replace go.opentelemetry.io/otel/metric => ../../metric

example/jaeger/go.mod

@@ -17,11 +17,8 @@ require (
 require (
 	github.com/go-logr/logr v1.2.4 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/trace v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 )
 
 replace go.opentelemetry.io/otel/trace => ../../trace
-
-replace go.opentelemetry.io/otel/metric => ../../metric

example/namedtracer/go.mod

@@ -17,12 +17,9 @@ require (
 
 require (
 	github.com/go-logr/logr v1.2.4 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 )
 
 replace go.opentelemetry.io/otel/trace => ../../trace
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
-
-replace go.opentelemetry.io/otel/metric => ../../metric

example/otel-collector/go.mod

@@ -23,7 +23,6 @@ require (
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/internal/retry v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.15.0-rc.2 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/proto/otlp v0.19.0 // indirect
 	golang.org/x/net v0.8.0 // indirect
 	golang.org/x/sys v0.7.0 // indirect
@@ -39,5 +38,3 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlptrace => ../../exporters/otl
 replace go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc => ../../exporters/otlp/otlptrace/otlptracegrpc
 
 replace go.opentelemetry.io/otel/exporters/otlp/internal/retry => ../../exporters/otlp/internal/retry
-
-replace go.opentelemetry.io/otel/metric => ../../metric

example/passthrough/go.mod

@@ -12,7 +12,6 @@ require (
 require (
 	github.com/go-logr/logr v1.2.4 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 )
 
@@ -23,5 +22,3 @@ replace (
 )
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
-
-replace go.opentelemetry.io/otel/metric => ../../metric

example/zipkin/go.mod

@@ -19,10 +19,7 @@ require (
 	github.com/go-logr/logr v1.2.4 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/openzipkin/zipkin-go v0.4.1 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 )
 
 replace go.opentelemetry.io/otel/trace => ../../trace
-
-replace go.opentelemetry.io/otel/metric => ../../metric

exporters/jaeger/go.mod

@@ -16,7 +16,6 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/stretchr/objx v0.5.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
@@ -26,5 +25,3 @@ replace go.opentelemetry.io/otel/trace => ../../trace
 replace go.opentelemetry.io/otel => ../..
 
 replace go.opentelemetry.io/otel/sdk => ../../sdk
-
-replace go.opentelemetry.io/otel/metric => ../../metric

exporters/otlp/otlpmetric/otlpmetricgrpc/example_test.go

@@ -17,8 +17,8 @@ package otlpmetricgrpc_test
 import (
 	"context"
 
-	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
+	"go.opentelemetry.io/otel/metric/global"
 	"go.opentelemetry.io/otel/sdk/metric"
 )
 
@@ -35,7 +35,7 @@ func Example() {
 			panic(err)
 		}
 	}()
-	otel.SetMeterProvider(meterProvider)
+	global.SetMeterProvider(meterProvider)
 
 	// From here, the meterProvider can be used by instrumentation to collect
 	// telemetry.

exporters/otlp/otlpmetric/otlpmetricgrpc/go.mod

@@ -9,6 +9,7 @@ require (
 	go.opentelemetry.io/otel v1.15.0-rc.2
 	go.opentelemetry.io/otel/exporters/otlp/internal/retry v1.15.0-rc.2
 	go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.38.0-rc.2
+	go.opentelemetry.io/otel/metric v1.15.0-rc.2
 	go.opentelemetry.io/otel/sdk/metric v0.38.0-rc.2
 	go.opentelemetry.io/proto/otlp v0.19.0
 	google.golang.org/genproto v0.0.0-20230110181048-76db0878b65f
@@ -25,7 +26,6 @@ require (
 	github.com/google/go-cmp v0.5.9 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/sdk v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/trace v1.15.0-rc.2 // indirect
 	golang.org/x/net v0.8.0 // indirect

exporters/otlp/otlpmetric/otlpmetrichttp/example_test.go

@@ -17,8 +17,8 @@ package otlpmetrichttp_test
 import (
 	"context"
 
-	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
+	"go.opentelemetry.io/otel/metric/global"
 	"go.opentelemetry.io/otel/sdk/metric"
 )
 
@@ -35,7 +35,7 @@ func Example() {
 			panic(err)
 		}
 	}()
-	otel.SetMeterProvider(meterProvider)
+	global.SetMeterProvider(meterProvider)
 
 	// From here, the meterProvider can be used by instrumentation to collect
 	// telemetry.

exporters/otlp/otlpmetric/otlpmetrichttp/go.mod

@@ -9,6 +9,7 @@ require (
 	go.opentelemetry.io/otel v1.15.0-rc.2
 	go.opentelemetry.io/otel/exporters/otlp/internal/retry v1.15.0-rc.2
 	go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.38.0-rc.2
+	go.opentelemetry.io/otel/metric v1.15.0-rc.2
 	go.opentelemetry.io/otel/sdk/metric v0.38.0-rc.2
 	go.opentelemetry.io/proto/otlp v0.19.0
 	google.golang.org/protobuf v1.30.0
@@ -23,7 +24,6 @@ require (
 	github.com/google/go-cmp v0.5.9 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/sdk v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/trace v1.15.0-rc.2 // indirect
 	golang.org/x/net v0.8.0 // indirect

exporters/otlp/otlptrace/go.mod

@@ -22,7 +22,6 @@ require (
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/net v0.8.0 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 	golang.org/x/text v0.8.0 // indirect
@@ -37,5 +36,3 @@ replace go.opentelemetry.io/otel/sdk => ../../../sdk
 replace go.opentelemetry.io/otel/trace => ../../../trace
 
 replace go.opentelemetry.io/otel/exporters/otlp/internal/retry => ../internal/retry
-
-replace go.opentelemetry.io/otel/metric => ../../../metric

exporters/otlp/otlptrace/otlptracegrpc/go.mod

@@ -23,7 +23,6 @@ require (
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	go.opentelemetry.io/otel/trace v1.15.0-rc.2 // indirect
 	golang.org/x/net v0.8.0 // indirect
 	golang.org/x/sys v0.7.0 // indirect
@@ -40,5 +39,3 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlptrace => ../
 replace go.opentelemetry.io/otel/trace => ../../../../trace
 
 replace go.opentelemetry.io/otel/exporters/otlp/internal/retry => ../../internal/retry
-
-replace go.opentelemetry.io/otel/metric => ../../../../metric

exporters/otlp/otlptrace/otlptracehttp/go.mod

@@ -21,7 +21,6 @@ require (
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/net v0.8.0 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 	golang.org/x/text v0.8.0 // indirect
@@ -39,5 +38,3 @@ replace go.opentelemetry.io/otel/sdk => ../../../../sdk
 replace go.opentelemetry.io/otel/trace => ../../../../trace
 
 replace go.opentelemetry.io/otel/exporters/otlp/internal/retry => ../../internal/retry
-
-replace go.opentelemetry.io/otel/metric => ../../../../metric

exporters/stdout/stdouttrace/go.mod

@@ -19,11 +19,8 @@ require (
 	github.com/go-logr/logr v1.2.4 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 
 replace go.opentelemetry.io/otel/trace => ../../../trace
-
-replace go.opentelemetry.io/otel/metric => ../../../metric

exporters/zipkin/go.mod

@@ -16,7 +16,6 @@ require (
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	golang.org/x/sys v0.7.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
@@ -26,5 +25,3 @@ replace go.opentelemetry.io/otel/trace => ../../trace
 replace go.opentelemetry.io/otel => ../..
 
 replace go.opentelemetry.io/otel/sdk => ../../sdk
-
-replace go.opentelemetry.io/otel/metric => ../../metric

go.mod

@@ -7,7 +7,6 @@ require (
 	github.com/go-logr/stdr v1.2.2
 	github.com/google/go-cmp v0.5.9
 	github.com/stretchr/testify v1.8.2
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2
 	go.opentelemetry.io/otel/trace v1.15.0-rc.2
 )
 
@@ -18,5 +17,3 @@ require (
 )
 
 replace go.opentelemetry.io/otel/trace => ./trace
-
-replace go.opentelemetry.io/otel/metric => ./metric

internal/global/state.go

@@ -19,7 +19,6 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -32,20 +31,14 @@ type (
 	propagatorsHolder struct {
 		tm propagation.TextMapPropagator
 	}
-
-	meterProviderHolder struct {
-		mp metric.MeterProvider
-	}
 )
 
 var (
-	globalTracer        = defaultTracerValue()
+	globalTracer      = defaultTracerValue()
-	globalPropagators   = defaultPropagatorsValue()
+	globalPropagators = defaultPropagatorsValue()
-	globalMeterProvider = defaultMeterProvider()
 
 	delegateTraceOnce             sync.Once
 	delegateTextMapPropagatorOnce sync.Once
-	delegateMeterOnce             sync.Once
 )
 
 // TracerProvider is the internal implementation for global.TracerProvider.
@@ -109,34 +102,6 @@ func SetTextMapPropagator(p propagation.TextMapPropagator) {
 	globalPropagators.Store(propagatorsHolder{tm: p})
 }
 
-// MeterProvider is the internal implementation for global.MeterProvider.
-func MeterProvider() metric.MeterProvider {
-	return globalMeterProvider.Load().(meterProviderHolder).mp
-}
-
-// SetMeterProvider is the internal implementation for global.SetMeterProvider.
-func SetMeterProvider(mp metric.MeterProvider) {
-	current := MeterProvider()
-	if _, cOk := current.(*meterProvider); cOk {
-		if _, mpOk := mp.(*meterProvider); mpOk && current == mp {
-			// Do not assign the default delegating MeterProvider to delegate
-			// to itself.
-			Error(
-				errors.New("no delegate configured in meter provider"),
-				"Setting meter provider to it's current value. No delegate will be configured",
-			)
-			return
-		}
-	}
-
-	delegateMeterOnce.Do(func() {
-		if def, ok := current.(*meterProvider); ok {
-			def.setDelegate(mp)
-		}
-	})
-	globalMeterProvider.Store(meterProviderHolder{mp: mp})
-}
-
 func defaultTracerValue() *atomic.Value {
 	v := &atomic.Value{}
 	v.Store(tracerProviderHolder{tp: &tracerProvider{}})
@@ -148,9 +113,3 @@ func defaultPropagatorsValue() *atomic.Value {
 	v.Store(propagatorsHolder{tm: newTextMapPropagator()})
 	return v
 }
-
-func defaultMeterProvider() *atomic.Value {
-	v := &atomic.Value{}
-	v.Store(meterProviderHolder{mp: &meterProvider{}})
-	return v
-}

internal/global/state_test.go

@@ -19,8 +19,6 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
-	"go.opentelemetry.io/otel/metric"
-	"go.opentelemetry.io/otel/metric/noop"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -31,12 +29,6 @@ type nonComparableTracerProvider struct {
 	nonComparable func() //nolint:structcheck,unused  // This is not called.
 }
 
-type nonComparableMeterProvider struct {
-	metric.MeterProvider
-
-	nonComparable func() //nolint:structcheck,unused  // This is not called.
-}
-
 func TestSetTracerProvider(t *testing.T) {
 	t.Run("Set With default is a noop", func(t *testing.T) {
 		ResetForTest(t)
@@ -133,53 +125,3 @@ func TestSetTextMapPropagator(t *testing.T) {
 		assert.NotPanics(t, func() { SetTextMapPropagator(prop) })
 	})
 }
-
-func TestSetMeterProvider(t *testing.T) {
-	t.Run("Set With default is a noop", func(t *testing.T) {
-		ResetForTest(t)
-
-		SetMeterProvider(MeterProvider())
-
-		mp, ok := MeterProvider().(*meterProvider)
-		if !ok {
-			t.Fatal("Global MeterProvider should be the default meter provider")
-		}
-
-		if mp.delegate != nil {
-			t.Fatal("meter provider should not delegate when setting itself")
-		}
-	})
-
-	t.Run("First Set() should replace the delegate", func(t *testing.T) {
-		ResetForTest(t)
-
-		SetMeterProvider(noop.NewMeterProvider())
-
-		_, ok := MeterProvider().(*meterProvider)
-		if ok {
-			t.Fatal("Global MeterProvider was not changed")
-		}
-	})
-
-	t.Run("Set() should delegate existing Meter Providers", func(t *testing.T) {
-		ResetForTest(t)
-
-		mp := MeterProvider()
-
-		SetMeterProvider(noop.NewMeterProvider())
-
-		dmp := mp.(*meterProvider)
-
-		if dmp.delegate == nil {
-			t.Fatal("The delegated meter providers should have a delegate")
-		}
-	})
-
-	t.Run("non-comparable types should not panic", func(t *testing.T) {
-		ResetForTest(t)
-
-		mp := nonComparableMeterProvider{}
-		SetMeterProvider(mp)
-		assert.NotPanics(t, func() { SetMeterProvider(mp) })
-	})
-}

internal/global/util_test.go

@@ -25,9 +25,7 @@ func ResetForTest(t testing.TB) {
 	t.Cleanup(func() {
 		globalTracer = defaultTracerValue()
 		globalPropagators = defaultPropagatorsValue()
-		globalMeterProvider = defaultMeterProvider()
 		delegateTraceOnce = sync.Once{}
 		delegateTextMapPropagatorOnce = sync.Once{}
-		delegateMeterOnce = sync.Once{}
 	})
 }

metric/example_test.go

@@ -20,15 +20,15 @@ import (
 	"runtime"
 	"time"
 
-	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/global"
 	"go.opentelemetry.io/otel/metric/instrument"
 )
 
 func ExampleMeter_synchronous() {
 	// Create a histogram using the global MeterProvider.
-	workDuration, err := otel.Meter("go.opentelemetry.io/otel/metric#SyncExample").Int64Histogram(
+	workDuration, err := global.Meter("go.opentelemetry.io/otel/metric#SyncExample").Int64Histogram(
 		"workDuration",
 		instrument.WithUnit("ms"))
 	if err != nil {
@@ -44,7 +44,7 @@ func ExampleMeter_synchronous() {
 }
 
 func ExampleMeter_asynchronous_single() {
-	meter := otel.Meter("go.opentelemetry.io/otel/metric#AsyncExample")
+	meter := global.Meter("go.opentelemetry.io/otel/metric#AsyncExample")
 
 	_, err := meter.Int64ObservableGauge(
 		"DiskUsage",
@@ -74,7 +74,7 @@ func ExampleMeter_asynchronous_single() {
 }
 
 func ExampleMeter_asynchronous_multiple() {
-	meter := otel.Meter("go.opentelemetry.io/otel/metric#MultiAsyncExample")
+	meter := global.Meter("go.opentelemetry.io/otel/metric#MultiAsyncExample")
 
 	// This is just a sample of memory stats to record from the Memstats
 	heapAlloc, _ := meter.Int64ObservableUpDownCounter("heapAllocs")

metric/global/metric.go

@@ -12,11 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package otel // import "go.opentelemetry.io/otel"
+package global // import "go.opentelemetry.io/otel/metric/global"
 
 import (
-	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/internal/global"
 )
 
 // Meter returns a Meter from the global MeterProvider. The name must be the
@@ -32,18 +32,14 @@ import (
 // the new MeterProvider.
 //
 // This is short for GetMeterProvider().Meter(name).
-func Meter(name string, opts ...metric.MeterOption) metric.Meter {
+func Meter(instrumentationName string, opts ...metric.MeterOption) metric.Meter {
-	return GetMeterProvider().Meter(name, opts...)
+	return MeterProvider().Meter(instrumentationName, opts...)
 }
 
-// GetMeterProvider returns the registered global meter provider.
+// MeterProvider returns the registered global meter provider.
 //
-// If no global GetMeterProvider has been registered, a No-op GetMeterProvider
+// If no global MeterProvider has been registered, a No-op MeterProvider implementation is returned. When a global MeterProvider is registered for the first time, the returned MeterProvider, and all the Meters it has created or will create, are recreated automatically from the new MeterProvider.
-// implementation is returned. When a global GetMeterProvider is registered for
+func MeterProvider() metric.MeterProvider {
-// the first time, the returned GetMeterProvider, and all the Meters it has
-// created or will create, are recreated automatically from the new
-// GetMeterProvider.
-func GetMeterProvider() metric.MeterProvider {
 	return global.MeterProvider()
 }
 

metric/global/metric_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package otel // import "go.opentelemetry.io/otel"
+package global // import "go.opentelemetry.io/otel/metric/global"
 
 import (
 	"testing"
@@ -38,6 +38,6 @@ func TestMultipleGlobalMeterProvider(t *testing.T) {
 	SetMeterProvider(&p1)
 	SetMeterProvider(p2)
 
-	got := GetMeterProvider()
+	got := MeterProvider()
 	assert.Equal(t, p2, got)
 }

metric/internal/global/instruments.go

@@ -12,12 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package global // import "go.opentelemetry.io/otel/internal/global"
+package global // import "go.opentelemetry.io/otel/metric/internal/global"
 
 import (
 	"context"
 	"sync/atomic"
 
+	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/embedded"
@@ -45,7 +46,7 @@ var _ instrument.Float64ObservableCounter = (*afCounter)(nil)
 func (i *afCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64ObservableCounter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -74,7 +75,7 @@ var _ instrument.Float64ObservableUpDownCounter = (*afUpDownCounter)(nil)
 func (i *afUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64ObservableUpDownCounter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -103,7 +104,7 @@ var _ instrument.Float64ObservableGauge = (*afGauge)(nil)
 func (i *afGauge) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64ObservableGauge(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -132,7 +133,7 @@ var _ instrument.Int64ObservableCounter = (*aiCounter)(nil)
 func (i *aiCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64ObservableCounter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -161,7 +162,7 @@ var _ instrument.Int64ObservableUpDownCounter = (*aiUpDownCounter)(nil)
 func (i *aiUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64ObservableUpDownCounter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -190,7 +191,7 @@ var _ instrument.Int64ObservableGauge = (*aiGauge)(nil)
 func (i *aiGauge) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64ObservableGauge(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -218,7 +219,7 @@ var _ instrument.Float64Counter = (*sfCounter)(nil)
 func (i *sfCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64Counter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -244,7 +245,7 @@ var _ instrument.Float64UpDownCounter = (*sfUpDownCounter)(nil)
 func (i *sfUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64UpDownCounter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -270,7 +271,7 @@ var _ instrument.Float64Histogram = (*sfHistogram)(nil)
 func (i *sfHistogram) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64Histogram(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -296,7 +297,7 @@ var _ instrument.Int64Counter = (*siCounter)(nil)
 func (i *siCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64Counter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -322,7 +323,7 @@ var _ instrument.Int64UpDownCounter = (*siUpDownCounter)(nil)
 func (i *siUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64UpDownCounter(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -348,7 +349,7 @@ var _ instrument.Int64Histogram = (*siHistogram)(nil)
 func (i *siHistogram) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64Histogram(i.name, i.opts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)

metric/internal/global/meter.go

@@ -12,13 +12,14 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package global // import "go.opentelemetry.io/otel/internal/global"
+package global // import "go.opentelemetry.io/otel/metric/internal/global"
 
 import (
 	"container/list"
 	"sync"
 	"sync/atomic"
 
+	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/embedded"
 	"go.opentelemetry.io/otel/metric/instrument"
@@ -37,6 +38,11 @@ type meterProvider struct {
 	delegate metric.MeterProvider
 }
 
+type il struct {
+	name    string
+	version string
+}
+
 // setDelegate configures p to delegate all MeterProvider functionality to
 // provider.
 //
@@ -335,7 +341,7 @@ func (c *registration) setDelegate(m metric.Meter) {
 
 	reg, err := m.RegisterCallback(c.function, insts...)
 	if err != nil {
-		GetErrorHandler().Handle(err)
+		otel.Handle(err)
 	}
 
 	c.unreg = reg.Unregister

metric/internal/global/meter_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package global // import "go.opentelemetry.io/otel/internal/global"
+package global // import "go.opentelemetry.io/otel/metric/internal/global"
 
 import (
 	"context"

metric/internal/global/meter_types_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package global // import "go.opentelemetry.io/otel/internal/global"
+package global // import "go.opentelemetry.io/otel/metric/internal/global"
 
 import (
 	"context"

metric/internal/global/state.go

@@ -0,0 +1,68 @@
+// 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
+//
+//     htmp://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 global // import "go.opentelemetry.io/otel/metric/internal/global"
+
+import (
+	"errors"
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel/internal/global"
+	"go.opentelemetry.io/otel/metric"
+)
+
+var (
+	globalMeterProvider = defaultMeterProvider()
+
+	delegateMeterOnce sync.Once
+)
+
+type meterProviderHolder struct {
+	mp metric.MeterProvider
+}
+
+// MeterProvider is the internal implementation for global.MeterProvider.
+func MeterProvider() metric.MeterProvider {
+	return globalMeterProvider.Load().(meterProviderHolder).mp
+}
+
+// SetMeterProvider is the internal implementation for global.SetMeterProvider.
+func SetMeterProvider(mp metric.MeterProvider) {
+	current := MeterProvider()
+	if _, cOk := current.(*meterProvider); cOk {
+		if _, mpOk := mp.(*meterProvider); mpOk && current == mp {
+			// Do not assign the default delegating MeterProvider to delegate
+			// to itself.
+			global.Error(
+				errors.New("no delegate configured in meter provider"),
+				"Setting meter provider to it's current value. No delegate will be configured",
+			)
+			return
+		}
+	}
+
+	delegateMeterOnce.Do(func() {
+		if def, ok := current.(*meterProvider); ok {
+			def.setDelegate(mp)
+		}
+	})
+	globalMeterProvider.Store(meterProviderHolder{mp: mp})
+}
+
+func defaultMeterProvider() *atomic.Value {
+	v := &atomic.Value{}
+	v.Store(meterProviderHolder{mp: &meterProvider{}})
+	return v
+}

metric/internal/global/state_test.go

@@ -0,0 +1,87 @@
+// 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 global // import "go.opentelemetry.io/otel/metric/internal/global"
+
+import (
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/noop"
+)
+
+func resetGlobalMeterProvider() {
+	globalMeterProvider = defaultMeterProvider()
+	delegateMeterOnce = sync.Once{}
+}
+
+type nonComparableMeterProvider struct {
+	metric.MeterProvider
+
+	nonComparable func() //nolint:structcheck,unused  // This is not called.
+}
+
+func TestSetMeterProvider(t *testing.T) {
+	t.Cleanup(resetGlobalMeterProvider)
+
+	t.Run("Set With default is a noop", func(t *testing.T) {
+		resetGlobalMeterProvider()
+		SetMeterProvider(MeterProvider())
+
+		mp, ok := MeterProvider().(*meterProvider)
+		if !ok {
+			t.Fatal("Global MeterProvider should be the default meter provider")
+		}
+
+		if mp.delegate != nil {
+			t.Fatal("meter provider should not delegate when setting itself")
+		}
+	})
+
+	t.Run("First Set() should replace the delegate", func(t *testing.T) {
+		resetGlobalMeterProvider()
+
+		SetMeterProvider(noop.NewMeterProvider())
+
+		_, ok := MeterProvider().(*meterProvider)
+		if ok {
+			t.Fatal("Global MeterProvider was not changed")
+		}
+	})
+
+	t.Run("Set() should delegate existing Meter Providers", func(t *testing.T) {
+		resetGlobalMeterProvider()
+
+		mp := MeterProvider()
+
+		SetMeterProvider(noop.NewMeterProvider())
+
+		dmp := mp.(*meterProvider)
+
+		if dmp.delegate == nil {
+			t.Fatal("The delegated meter providers should have a delegate")
+		}
+	})
+
+	t.Run("non-comparable types should not panic", func(t *testing.T) {
+		resetGlobalMeterProvider()
+
+		mp := nonComparableMeterProvider{}
+		SetMeterProvider(mp)
+		assert.NotPanics(t, func() { SetMeterProvider(mp) })
+	})
+}

sdk/go.mod

@@ -17,10 +17,7 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.opentelemetry.io/otel/metric v1.15.0-rc.2 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 
 replace go.opentelemetry.io/otel/trace => ../trace
-
-replace go.opentelemetry.io/otel/metric => ../metric

sdk/metric/example_test.go

@@ -18,7 +18,7 @@ import (
 	"context"
 	"log"
 
-	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/metric/global"
 	"go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/resource"
 	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
@@ -42,7 +42,7 @@ func Example() {
 		metric.WithResource(res),
 		metric.WithReader(reader),
 	)
-	otel.SetMeterProvider(meterProvider)
+	global.SetMeterProvider(meterProvider)
 	defer func() {
 		err := meterProvider.Shutdown(context.Background())
 		if err != nil {

sdk/metric/meter_test.go

@@ -29,6 +29,7 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/global"
 	"go.opentelemetry.io/otel/metric/instrument"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/metric/aggregation"
@@ -629,7 +630,7 @@ func TestGlobalInstRegisterCallback(t *testing.T) {
 	otel.SetLogger(logr.New(l))
 
 	const mtrName = "TestGlobalInstRegisterCallback"
-	preMtr := otel.Meter(mtrName)
+	preMtr := global.Meter(mtrName)
 	preInt64Ctr, err := preMtr.Int64ObservableCounter("pre.int64.counter")
 	require.NoError(t, err)
 	preFloat64Ctr, err := preMtr.Float64ObservableCounter("pre.float64.counter")
@@ -637,9 +638,9 @@ func TestGlobalInstRegisterCallback(t *testing.T) {
 
 	rdr := NewManualReader()
 	mp := NewMeterProvider(WithReader(rdr), WithResource(resource.Empty()))
-	otel.SetMeterProvider(mp)
+	global.SetMeterProvider(mp)
 
-	postMtr := otel.Meter(mtrName)
+	postMtr := global.Meter(mtrName)
 	postInt64Ctr, err := postMtr.Int64ObservableCounter("post.int64.counter")
 	require.NoError(t, err)
 	postFloat64Ctr, err := postMtr.Float64ObservableCounter("post.float64.counter")

trace/go.mod

@@ -15,5 +15,3 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
-
-replace go.opentelemetry.io/otel/metric => ../metric