1
0
mirror of https://github.com/open-telemetry/opentelemetry-go.git synced 2024-12-30 21:20:04 +02:00

Add delegating global propagator (#1258)

* Add delegating global propagator

* Add Changes to CHANGELOG

* Add PR number to CHANGELOG

* Add tests using new test framework

* Revert "Add tests using new test framework"

This reverts commit af7ae17436.
This commit is contained in:
Tyler Yahn 2020-10-15 10:35:47 -07:00 committed by GitHub
parent 8fd4b26655
commit 786a78ea36
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 107 additions and 9 deletions

View File

@ -32,6 +32,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
- The `ErrInvalidHexID`, `ErrInvalidTraceIDLength`, `ErrInvalidSpanIDLength`, `ErrInvalidSpanIDLength`, or `ErrNilSpanID` from the `go.opentelemetry.io/otel` package are unexported now. (#1243)
### Fixed
- The `go.opentelemetry.io/otel/api/global` packages global TextMapPropagator now delegates functionality to a globally set delegate for all previously returned propagators. (#1258)
## [0.13.0] - 2020-10-08
### Added

View File

@ -0,0 +1,86 @@
// 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 internal
import (
"context"
"sync"
"go.opentelemetry.io/otel"
)
// textMapPropagator is a default TextMapPropagator that delegates calls to a
// registered delegate if one is set, otherwise it defaults to delegating the
// calls to a the default no-op otel.TextMapPropagator.
type textMapPropagator struct {
mtx sync.Mutex
once sync.Once
delegate otel.TextMapPropagator
noop otel.TextMapPropagator
}
// Compile-time guarantee that textMapPropagator implements the
// otel.TextMapPropagator interface.
var _ otel.TextMapPropagator = (*textMapPropagator)(nil)
func newTextMapPropagator() *textMapPropagator {
return &textMapPropagator{
noop: otel.NewCompositeTextMapPropagator(),
}
}
// SetDelegate sets a delegate otel.TextMapPropagator that all calls are
// forwarded to. Delegation can only be performed once, all subsequent calls
// perform no delegation.
func (p *textMapPropagator) SetDelegate(delegate otel.TextMapPropagator) {
if delegate == nil {
return
}
p.mtx.Lock()
p.once.Do(func() { p.delegate = delegate })
p.mtx.Unlock()
}
// HasDelegate returns if a delegate is set for p.
func (p *textMapPropagator) HasDelegate() bool {
p.mtx.Lock()
defer p.mtx.Unlock()
return p.delegate != nil
}
// Inject set cross-cutting concerns from the Context into the carrier.
func (p *textMapPropagator) Inject(ctx context.Context, carrier otel.TextMapCarrier) {
if p.HasDelegate() {
p.delegate.Inject(ctx, carrier)
}
p.noop.Inject(ctx, carrier)
}
// Extract reads cross-cutting concerns from the carrier into a Context.
func (p *textMapPropagator) Extract(ctx context.Context, carrier otel.TextMapCarrier) context.Context {
if p.HasDelegate() {
return p.delegate.Extract(ctx, carrier)
}
return p.noop.Extract(ctx, carrier)
}
// Fields returns the keys who's values are set with Inject.
func (p *textMapPropagator) Fields() []string {
if p.HasDelegate() {
return p.delegate.Fields()
}
return p.noop.Fields()
}

View File

@ -41,8 +41,9 @@ var (
globalMeter = defaultMeterValue()
globalPropagators = defaultPropagatorsValue()
delegateMeterOnce sync.Once
delegateTraceOnce sync.Once
delegateMeterOnce sync.Once
delegateTraceOnce sync.Once
delegateTextMapPropagatorOnce sync.Once
)
// TracerProvider is the internal implementation for global.TracerProvider.
@ -96,6 +97,19 @@ func TextMapPropagator() otel.TextMapPropagator {
// SetTextMapPropagator is the internal implementation for global.SetTextMapPropagator.
func SetTextMapPropagator(p otel.TextMapPropagator) {
// For the textMapPropagator already returned by TextMapPropagator
// delegate to p.
delegateTextMapPropagatorOnce.Do(func() {
if current := TextMapPropagator(); current == p {
// 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 TextMapPropagator, the global instance cannot be reinstalled")
} else if def, ok := current.(*textMapPropagator); ok {
def.SetDelegate(p)
}
})
// Return p when subsequent calls to TextMapPropagator are made.
globalPropagators.Store(propagatorsHolder{tm: p})
}
@ -113,16 +127,10 @@ func defaultMeterValue() *atomic.Value {
func defaultPropagatorsValue() *atomic.Value {
v := &atomic.Value{}
v.Store(propagatorsHolder{tm: getDefaultTextMapPropagator()})
v.Store(propagatorsHolder{tm: newTextMapPropagator()})
return v
}
// getDefaultTextMapPropagator returns the default TextMapPropagator,
// configured with W3C trace and baggage propagation.
func getDefaultTextMapPropagator() otel.TextMapPropagator {
return otel.NewCompositeTextMapPropagator()
}
// ResetForTest restores the initial global state, for testing purposes.
func ResetForTest() {
globalTracer = defaultTracerValue()