observer/pkg/gelf_exporter/trace.go

package gelfexporter

import (
	"context"
	"maal/tracer/pkg/level"
	"sync"
	"time"

	"go.opentelemetry.io/otel/sdk/trace"
	"go.opentelemetry.io/otel/sdk/trace/tracetest"
	"gopkg.in/Graylog2/go-gelf.v2/gelf"
)

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
	}

	writer, err := gelf.NewUDPWriter(cfg.GelfUrl)
	if err != nil {
		return nil, err
	}

	return &Exporter{
		gelfWriter: writer,
	}, nil

}

type Exporter struct {
	timestamps bool
	gelfWriter *gelf.UDPWriter

	stoppedMu sync.RWMutex
	stopped   bool
}

func (e *Exporter) ExportSpans(ctx context.Context, spans []trace.ReadOnlySpan) error {
	if err := ctx.Err(); err != nil {
		return err
	}
	e.stoppedMu.RLock()
	stopped := e.stopped
	e.stoppedMu.RUnlock()
	if stopped {
		return nil
	}

	if len(spans) == 0 {
		return nil
	}

	stubs := tracetest.SpanStubsFromReadOnlySpans(spans)

	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
			}
		}

		// fmt.Printf("stub: %v\n", stub)

		Log(e.gelfWriter, GELFMessage{
			Host:         "test",
			ShortMessage: stub.Name,
			LongMessage:  "test",
			Timestamp:    stub.StartTime,
			Level:        level.DEBUG,
			ExtraFields:  make(map[string]interface{}),
		})

	}
	return nil
}

// Shutdown is called to stop the exporter, it performs no action.
func (e *Exporter) Shutdown(ctx context.Context) error {
	e.stoppedMu.Lock()
	e.stopped = true
	e.stoppedMu.Unlock()

	return nil
}

// // MarshalLog is the marshaling function used by the logging system to represent this Exporter.
// func (e *Exporter) MarshalLog() interface{} {
// 	return struct {
// 		Type           string
// 		WithTimestamps bool
// 	}{
// 		Type:           "stdout",
// 		WithTimestamps: e.timestamps,
// 	}
// }