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opentelemetry-go/exporters/stdout/stdouttrace/trace.go
Liz Fong-Jones 66fccc0be0
fix: lock accesses to encoder in json stdout exporter to prevent crash (#2265)
* lock accesses to encoder

fixes #2264

* move locking outside loop to avoid deadlock

* Update CHANGELOG.md
2021-09-30 15:58:26 -04:00

109 lines
2.4 KiB
Go

// 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 stdouttrace // import "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
import (
"context"
"encoding/json"
"sync"
"time"
"go.opentelemetry.io/otel/sdk/trace"
"go.opentelemetry.io/otel/sdk/trace/tracetest"
)
var zeroTime time.Time
var _ trace.SpanExporter = &Exporter{}
// New creates an Exporter with the passed options.
func New(options ...Option) (*Exporter, error) {
cfg, err := newConfig(options...)
if err != nil {
return nil, err
}
enc := json.NewEncoder(cfg.Writer)
if cfg.PrettyPrint {
enc.SetIndent("", "\t")
}
return &Exporter{
encoder: enc,
timestamps: cfg.Timestamps,
}, nil
}
// Exporter is an implementation of trace.SpanSyncer that writes spans to stdout.
type Exporter struct {
encoder *json.Encoder
encoderMu sync.Mutex
timestamps bool
stoppedMu sync.RWMutex
stopped bool
}
// ExportSpans writes spans in json format to stdout.
func (e *Exporter) ExportSpans(ctx context.Context, spans []trace.ReadOnlySpan) error {
e.stoppedMu.RLock()
stopped := e.stopped
e.stoppedMu.RUnlock()
if stopped {
return nil
}
if len(spans) == 0 {
return nil
}
stubs := tracetest.SpanStubsFromReadOnlySpans(spans)
e.encoderMu.Lock()
defer e.encoderMu.Unlock()
for i := range stubs {
stub := &stubs[i]
// Remove timestamps
if !e.timestamps {
stub.StartTime = zeroTime
stub.EndTime = zeroTime
for j := range stub.Events {
ev := &stub.Events[j]
ev.Time = zeroTime
}
}
// Encode span stubs, one by one
if err := e.encoder.Encode(stub); err != nil {
return err
}
}
return nil
}
// Shutdown is called to stop the exporter, it preforms no action.
func (e *Exporter) Shutdown(ctx context.Context) error {
e.stoppedMu.Lock()
e.stopped = true
e.stoppedMu.Unlock()
select {
case <-ctx.Done():
return ctx.Err()
default:
}
return nil
}