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opentelemetry-go/api/global/internal/state.go

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package internal
import (
"sync"
"sync/atomic"
"go.opentelemetry.io/otel/api/metric"
"go.opentelemetry.io/otel/api/trace"
)
type (
traceProviderHolder struct {
tp trace.Provider
}
meterProviderHolder struct {
mp metric.Provider
}
)
var (
globalTracer = defaultTracerValue()
globalMeter = defaultMeterValue()
delegateMeterOnce sync.Once
delegateTraceOnce sync.Once
)
// TraceProvider is the internal implementation for global.TraceProvider.
func TraceProvider() trace.Provider {
return globalTracer.Load().(traceProviderHolder).tp
}
// SetTraceProvider is the internal implementation for global.SetTraceProvider.
func SetTraceProvider(tp trace.Provider) {
delegateTraceOnce.Do(func() {
current := TraceProvider()
if current == tp {
// Setting the provider to the prior default is nonsense, panic.
// Panic is acceptable because we are likely still early in the
// process lifetime.
panic("invalid Provider, the global instance cannot be reinstalled")
} else if def, ok := current.(*traceProvider); ok {
def.setDelegate(tp)
}
})
globalTracer.Store(traceProviderHolder{tp: tp})
}
// MeterProvider is the internal implementation for global.MeterProvider.
func MeterProvider() metric.Provider {
return globalMeter.Load().(meterProviderHolder).mp
}
// SetMeterProvider is the internal implementation for global.SetMeterProvider.
func SetMeterProvider(mp metric.Provider) {
delegateMeterOnce.Do(func() {
current := MeterProvider()
if current == mp {
// Setting the provider to the prior default is nonsense, panic.
// Panic is acceptable because we are likely still early in the
// process lifetime.
panic("invalid Provider, the global instance cannot be reinstalled")
} else if def, ok := current.(*meterProvider); ok {
def.setDelegate(mp)
}
})
globalMeter.Store(meterProviderHolder{mp: mp})
}
func defaultTracerValue() *atomic.Value {
v := &atomic.Value{}
v.Store(traceProviderHolder{tp: &traceProvider{}})
return v
}
func defaultMeterValue() *atomic.Value {
v := &atomic.Value{}
v.Store(meterProviderHolder{mp: &meterProvider{}})
return v
}
// ResetForTest restores the initial global state, for testing purposes.
func ResetForTest() {
globalTracer = defaultTracerValue()
globalMeter = defaultMeterValue()
delegateMeterOnce = sync.Once{}
delegateTraceOnce = sync.Once{}
}