/
state.go
58 lines (49 loc) · 1.62 KB
/
state.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
//
// 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 (
"sync"
"sync/atomic"
"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) {
delegateMeterOnce.Do(func() {
current := MeterProvider()
if current == mp {
// Setting the provider to the prior default results in a noop. Return
// early.
return
} else 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
}