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opentelemetry-go/sdk/trace/span_processor.go
Artem Kartasov ffbef6a007 SDK: Multiple Unregister should not trigger multiple shutdown call (#176)
* SDK: Multiple Unregister should not trigger multiple shutdown call

* fix a data race: waitGroup.Add() should be outside of a goroutine
2019-10-08 23:31:29 -07:00

82 lines
2.2 KiB
Go

// Copyright 2019, 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 trace
import (
"sync"
"sync/atomic"
"go.opentelemetry.io/sdk/export"
)
// SpanProcessor is interface to add hooks to start and end method invocations.
type SpanProcessor interface {
// OnStart method is invoked when span is started. It is a synchronous call
// and hence should not block.
OnStart(sd *export.SpanData)
// OnEnd method is invoked when span is finished. It is a synchronous call
// and hence should not block.
OnEnd(sd *export.SpanData)
// Shutdown is invoked when SDK shutsdown. Use this call to cleanup any processor
// data. No calls to OnStart and OnEnd method is invoked after Shutdown call is
// made. It should not be blocked indefinitely.
Shutdown()
}
type spanProcessorMap map[SpanProcessor]*sync.Once
var (
mu sync.Mutex
spanProcessors atomic.Value
)
// RegisterSpanProcessor adds to the list of SpanProcessors that will receive sampled
// trace spans.
func RegisterSpanProcessor(e SpanProcessor) {
mu.Lock()
defer mu.Unlock()
new := make(spanProcessorMap)
if old, ok := spanProcessors.Load().(spanProcessorMap); ok {
for k, v := range old {
new[k] = v
}
}
new[e] = &sync.Once{}
spanProcessors.Store(new)
}
// UnregisterSpanProcessor removes from the list of SpanProcessors the SpanProcessor that was
// registered with the given name.
func UnregisterSpanProcessor(s SpanProcessor) {
mu.Lock()
defer mu.Unlock()
new := make(spanProcessorMap)
if old, ok := spanProcessors.Load().(spanProcessorMap); ok {
for k, v := range old {
new[k] = v
}
}
if stopOnce, ok := new[s]; ok && stopOnce != nil {
stopOnce.Do(func() {
s.Shutdown()
})
}
delete(new, s)
spanProcessors.Store(new)
}