1 files changed, 354 insertions, 0 deletions
diff --git a/vendor/go.opentelemetry.io/otel/internal/global/meter.go b/vendor/go.opentelemetry.io/otel/internal/global/meter.go
new file mode 100644
index 000000000..0097db478
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/internal/global/meter.go
@@ -0,0 +1,354 @@
+// 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/internal/global"
+
+import (
+	"container/list"
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/embedded"
+)
+
+// meterProvider is a placeholder for a configured SDK MeterProvider.
+//
+// All MeterProvider functionality is forwarded to a delegate once
+// configured.
+type meterProvider struct {
+	embedded.MeterProvider
+
+	mtx    sync.Mutex
+	meters map[il]*meter
+
+	delegate metric.MeterProvider
+}
+
+// setDelegate configures p to delegate all MeterProvider functionality to
+// provider.
+//
+// All Meters provided prior to this function call are switched out to be
+// Meters provided by provider. All instruments and callbacks are recreated and
+// delegated.
+//
+// It is guaranteed by the caller that this happens only once.
+func (p *meterProvider) setDelegate(provider metric.MeterProvider) {
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+
+	p.delegate = provider
+
+	if len(p.meters) == 0 {
+		return
+	}
+
+	for _, meter := range p.meters {
+		meter.setDelegate(provider)
+	}
+
+	p.meters = nil
+}
+
+// Meter implements MeterProvider.
+func (p *meterProvider) Meter(name string, opts ...metric.MeterOption) metric.Meter {
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+
+	if p.delegate != nil {
+		return p.delegate.Meter(name, opts...)
+	}
+
+	// At this moment it is guaranteed that no sdk is installed, save the meter in the meters map.
+
+	c := metric.NewMeterConfig(opts...)
+	key := il{
+		name:    name,
+		version: c.InstrumentationVersion(),
+	}
+
+	if p.meters == nil {
+		p.meters = make(map[il]*meter)
+	}
+
+	if val, ok := p.meters[key]; ok {
+		return val
+	}
+
+	t := &meter{name: name, opts: opts}
+	p.meters[key] = t
+	return t
+}
+
+// meter is a placeholder for a metric.Meter.
+//
+// All Meter functionality is forwarded to a delegate once configured.
+// Otherwise, all functionality is forwarded to a NoopMeter.
+type meter struct {
+	embedded.Meter
+
+	name string
+	opts []metric.MeterOption
+
+	mtx         sync.Mutex
+	instruments []delegatedInstrument
+
+	registry list.List
+
+	delegate atomic.Value // metric.Meter
+}
+
+type delegatedInstrument interface {
+	setDelegate(metric.Meter)
+}
+
+// setDelegate configures m to delegate all Meter functionality to Meters
+// created by provider.
+//
+// All subsequent calls to the Meter methods will be passed to the delegate.
+//
+// It is guaranteed by the caller that this happens only once.
+func (m *meter) setDelegate(provider metric.MeterProvider) {
+	meter := provider.Meter(m.name, m.opts...)
+	m.delegate.Store(meter)
+
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+
+	for _, inst := range m.instruments {
+		inst.setDelegate(meter)
+	}
+
+	for e := m.registry.Front(); e != nil; e = e.Next() {
+		r := e.Value.(*registration)
+		r.setDelegate(meter)
+		m.registry.Remove(e)
+	}
+
+	m.instruments = nil
+	m.registry.Init()
+}
+
+func (m *meter) Int64Counter(name string, options ...metric.Int64CounterOption) (metric.Int64Counter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Int64Counter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &siCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Int64UpDownCounter(name string, options ...metric.Int64UpDownCounterOption) (metric.Int64UpDownCounter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Int64UpDownCounter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &siUpDownCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Int64Histogram(name string, options ...metric.Int64HistogramOption) (metric.Int64Histogram, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Int64Histogram(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &siHistogram{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Int64ObservableCounter(name string, options ...metric.Int64ObservableCounterOption) (metric.Int64ObservableCounter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Int64ObservableCounter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &aiCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Int64ObservableUpDownCounter(name string, options ...metric.Int64ObservableUpDownCounterOption) (metric.Int64ObservableUpDownCounter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Int64ObservableUpDownCounter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &aiUpDownCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Int64ObservableGauge(name string, options ...metric.Int64ObservableGaugeOption) (metric.Int64ObservableGauge, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Int64ObservableGauge(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &aiGauge{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Float64Counter(name string, options ...metric.Float64CounterOption) (metric.Float64Counter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Float64Counter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &sfCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Float64UpDownCounter(name string, options ...metric.Float64UpDownCounterOption) (metric.Float64UpDownCounter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Float64UpDownCounter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &sfUpDownCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Float64Histogram(name string, options ...metric.Float64HistogramOption) (metric.Float64Histogram, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Float64Histogram(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &sfHistogram{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Float64ObservableCounter(name string, options ...metric.Float64ObservableCounterOption) (metric.Float64ObservableCounter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Float64ObservableCounter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &afCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Float64ObservableUpDownCounter(name string, options ...metric.Float64ObservableUpDownCounterOption) (metric.Float64ObservableUpDownCounter, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Float64ObservableUpDownCounter(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &afUpDownCounter{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+func (m *meter) Float64ObservableGauge(name string, options ...metric.Float64ObservableGaugeOption) (metric.Float64ObservableGauge, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		return del.Float64ObservableGauge(name, options...)
+	}
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	i := &afGauge{name: name, opts: options}
+	m.instruments = append(m.instruments, i)
+	return i, nil
+}
+
+// RegisterCallback captures the function that will be called during Collect.
+func (m *meter) RegisterCallback(f metric.Callback, insts ...metric.Observable) (metric.Registration, error) {
+	if del, ok := m.delegate.Load().(metric.Meter); ok {
+		insts = unwrapInstruments(insts)
+		return del.RegisterCallback(f, insts...)
+	}
+
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+
+	reg := &registration{instruments: insts, function: f}
+	e := m.registry.PushBack(reg)
+	reg.unreg = func() error {
+		m.mtx.Lock()
+		_ = m.registry.Remove(e)
+		m.mtx.Unlock()
+		return nil
+	}
+	return reg, nil
+}
+
+type wrapped interface {
+	unwrap() metric.Observable
+}
+
+func unwrapInstruments(instruments []metric.Observable) []metric.Observable {
+	out := make([]metric.Observable, 0, len(instruments))
+
+	for _, inst := range instruments {
+		if in, ok := inst.(wrapped); ok {
+			out = append(out, in.unwrap())
+		} else {
+			out = append(out, inst)
+		}
+	}
+
+	return out
+}
+
+type registration struct {
+	embedded.Registration
+
+	instruments []metric.Observable
+	function    metric.Callback
+
+	unreg   func() error
+	unregMu sync.Mutex
+}
+
+func (c *registration) setDelegate(m metric.Meter) {
+	insts := unwrapInstruments(c.instruments)
+
+	c.unregMu.Lock()
+	defer c.unregMu.Unlock()
+
+	if c.unreg == nil {
+		// Unregister already called.
+		return
+	}
+
+	reg, err := m.RegisterCallback(c.function, insts...)
+	if err != nil {
+		GetErrorHandler().Handle(err)
+	}
+
+	c.unreg = reg.Unregister
+}
+
+func (c *registration) Unregister() error {
+	c.unregMu.Lock()
+	defer c.unregMu.Unlock()
+	if c.unreg == nil {
+		// Unregister already called.
+		return nil
+	}
+
+	var err error
+	err, c.unreg = c.unreg(), nil
+	return err
+}