mirror of https://github.com/docker/cli.git
67 lines
1.9 KiB
Go
67 lines
1.9 KiB
Go
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// Copyright The OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package global // import "go.opentelemetry.io/otel/internal/metric/global"
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import (
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"sync"
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"sync/atomic"
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"go.opentelemetry.io/otel/metric"
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)
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type meterProviderHolder struct {
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mp metric.MeterProvider
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}
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var (
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globalMeter = defaultMeterValue()
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delegateMeterOnce sync.Once
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)
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// MeterProvider is the internal implementation for global.MeterProvider.
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func MeterProvider() metric.MeterProvider {
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return globalMeter.Load().(meterProviderHolder).mp
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}
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// SetMeterProvider is the internal implementation for global.SetMeterProvider.
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func SetMeterProvider(mp metric.MeterProvider) {
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delegateMeterOnce.Do(func() {
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current := MeterProvider()
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if current == mp {
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// Setting the provider to the prior default is nonsense, panic.
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// Panic is acceptable because we are likely still early in the
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// process lifetime.
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panic("invalid MeterProvider, the global instance cannot be reinstalled")
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} else if def, ok := current.(*meterProvider); ok {
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def.setDelegate(mp)
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}
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})
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globalMeter.Store(meterProviderHolder{mp: mp})
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}
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func defaultMeterValue() *atomic.Value {
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v := &atomic.Value{}
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v.Store(meterProviderHolder{mp: newMeterProvider()})
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return v
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}
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// ResetForTest restores the initial global state, for testing purposes.
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func ResetForTest() {
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globalMeter = defaultMeterValue()
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delegateMeterOnce = sync.Once{}
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}
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