Remove the deprecated otel/metric/global pkg (#3829)

* Remove the deprecated `otel/metric/global` pkg

* Add changelog entry

* Update PR number in changelog

* Fix lint

---------

Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>

CHANGELOG.md

@@ -12,6 +12,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - Avoid creating new objects on all calls to `WithDeferredSetup` and `SkipContextSetup` in OpenTracing bridge. (#3833)
 
+### Removed
+
+- The deprecated `go.opentelemetry.io/otel/metric/global` package is removed. (#3829)
+
 ## [1.15.0-rc.1/0.38.0-rc.1] 2023-03-01
 
 This is a release candidate for the v1.15.0/v0.38.0 release.

metric/internal/global/instruments.go → internal/global/instruments.go

@@ -12,14 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package global // import "go.opentelemetry.io/otel/metric/internal/global"
+package global // import "go.opentelemetry.io/otel/internal/global"
 
 import (
 	"context"
 	"sync/atomic"
 
 	"go.opentelemetry.io/otel/attribute"
-	oGlob "go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/instrument"
 )
@@ -44,7 +43,7 @@ var _ instrument.Float64ObservableCounter = (*afCounter)(nil)
 func (i *afCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64ObservableCounter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -72,7 +71,7 @@ var _ instrument.Float64ObservableUpDownCounter = (*afUpDownCounter)(nil)
 func (i *afUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64ObservableUpDownCounter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -100,7 +99,7 @@ var _ instrument.Float64ObservableGauge = (*afGauge)(nil)
 func (i *afGauge) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64ObservableGauge(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -128,7 +127,7 @@ var _ instrument.Int64ObservableCounter = (*aiCounter)(nil)
 func (i *aiCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64ObservableCounter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -156,7 +155,7 @@ var _ instrument.Int64ObservableUpDownCounter = (*aiUpDownCounter)(nil)
 func (i *aiUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64ObservableUpDownCounter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -184,7 +183,7 @@ var _ instrument.Int64ObservableGauge = (*aiGauge)(nil)
 func (i *aiGauge) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64ObservableGauge(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -212,7 +211,7 @@ var _ instrument.Float64Counter = (*sfCounter)(nil)
 func (i *sfCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64Counter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -238,7 +237,7 @@ var _ instrument.Float64UpDownCounter = (*sfUpDownCounter)(nil)
 func (i *sfUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64UpDownCounter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -264,7 +263,7 @@ var _ instrument.Float64Histogram = (*sfHistogram)(nil)
 func (i *sfHistogram) setDelegate(m metric.Meter) {
 	ctr, err := m.Float64Histogram(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -290,7 +289,7 @@ var _ instrument.Int64Counter = (*siCounter)(nil)
 func (i *siCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64Counter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -316,7 +315,7 @@ var _ instrument.Int64UpDownCounter = (*siUpDownCounter)(nil)
 func (i *siUpDownCounter) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64UpDownCounter(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)
@@ -342,7 +341,7 @@ var _ instrument.Int64Histogram = (*siHistogram)(nil)
 func (i *siHistogram) setDelegate(m metric.Meter) {
 	ctr, err := m.Int64Histogram(i.name, i.opts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 		return
 	}
 	i.delegate.Store(ctr)

metric/internal/global/meter.go → internal/global/meter.go

@@ -12,14 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package global // import "go.opentelemetry.io/otel/metric/internal/global"
+package global // import "go.opentelemetry.io/otel/internal/global"
 
 import (
 	"container/list"
 	"sync"
 	"sync/atomic"
 
-	oGlob "go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/instrument"
 )
@@ -35,11 +34,6 @@ type meterProvider struct {
 	delegate metric.MeterProvider
 }
 
-type il struct {
-	name    string
-	version string
-}
-
 // setDelegate configures p to delegate all MeterProvider functionality to
 // provider.
 //
@@ -334,7 +328,7 @@ func (c *registration) setDelegate(m metric.Meter) {
 
 	reg, err := m.RegisterCallback(c.function, insts...)
 	if err != nil {
-		oGlob.GetErrorHandler().Handle(err)
+		GetErrorHandler().Handle(err)
 	}
 
 	c.unreg = reg.Unregister

metric/internal/global/meter_test.go → 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/metric/internal/global"
+package global // import "go.opentelemetry.io/otel/internal/global"
 
 import (
 	"context"

metric/internal/global/meter_types_test.go → 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/metric/internal/global"
+package global // import "go.opentelemetry.io/otel/internal/global"
 
 import (
 	"context"

internal/global/state.go

@@ -19,6 +19,7 @@ import (
 	"sync"
 	"sync/atomic"
 
+	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -31,14 +32,20 @@ type (
 	propagatorsHolder struct {
 		tm propagation.TextMapPropagator
 	}
+
+	meterProviderHolder struct {
+		mp metric.MeterProvider
+	}
 )
 
 var (
-	globalTracer      = defaultTracerValue()
-	globalPropagators = defaultPropagatorsValue()
+	globalTracer        = defaultTracerValue()
+	globalPropagators   = defaultPropagatorsValue()
+	globalMeterProvider = defaultMeterProvider()
 
 	delegateTraceOnce             sync.Once
 	delegateTextMapPropagatorOnce sync.Once
+	delegateMeterOnce             sync.Once
 )
 
 // TracerProvider is the internal implementation for global.TracerProvider.
@@ -102,6 +109,34 @@ 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{}})
@@ -113,3 +148,9 @@ 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

@@ -19,6 +19,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
+	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -29,6 +30,12 @@ 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)
@@ -125,3 +132,53 @@ 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(metric.NewNoopMeterProvider())
+
+		_, 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(metric.NewNoopMeterProvider())
+
+		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

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

metric.go

@@ -15,10 +15,8 @@
 package otel // import "go.opentelemetry.io/otel"
 
 import (
+	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/metric"
-	// TODO (#3819): Remove this disablement.
-	// nolint: staticcheck  // Temporary, while metric/global is deprecated.
-	"go.opentelemetry.io/otel/metric/global"
 )
 
 // Meter returns a Meter from the global MeterProvider. The name must be the
@@ -35,8 +33,6 @@ import (
 //
 // This is short for GetMeterProvider().Meter(name).
 func Meter(name string, opts ...metric.MeterOption) metric.Meter {
-	// TODO (#3819): Remove this disablement.
-	// nolint: staticcheck  // Temporary, while metric/global is deprecated.
 	return GetMeterProvider().Meter(name, opts...)
 }
 
@@ -48,14 +44,10 @@ func Meter(name string, opts ...metric.MeterOption) metric.Meter {
 // created or will create, are recreated automatically from the new
 // GetMeterProvider.
 func GetMeterProvider() metric.MeterProvider {
-	// TODO (#3819): Remove this disablement.
-	// nolint: staticcheck  // Temporary, while metric/global is deprecated.
 	return global.MeterProvider()
 }
 
 // SetMeterProvider registers mp as the global MeterProvider.
 func SetMeterProvider(mp metric.MeterProvider) {
-	// TODO (#3819): Remove this disablement.
-	// nolint: staticcheck  // Temporary, while metric/global is deprecated.
 	global.SetMeterProvider(mp)
 }