traefik/vendor/github.com/openzipkin-contrib/zipkin-go-opentracing/span.go
2019-04-05 11:58:06 +02:00

290 lines
7.1 KiB
Go

package zipkintracer
import (
"sync"
"time"
opentracing "github.com/opentracing/opentracing-go"
"github.com/opentracing/opentracing-go/ext"
"github.com/opentracing/opentracing-go/log"
otobserver "github.com/opentracing-contrib/go-observer"
"github.com/openzipkin-contrib/zipkin-go-opentracing/thrift/gen-go/zipkincore"
)
// Span provides access to the essential details of the span, for use
// by zipkintracer consumers. These methods may only be called prior
// to (*opentracing.Span).Finish().
type Span interface {
opentracing.Span
// Operation names the work done by this span instance
Operation() string
// Start indicates when the span began
Start() time.Time
}
// Implements the `Span` interface. Created via tracerImpl (see
// `zipkintracer.NewTracer()`).
type spanImpl struct {
tracer *tracerImpl
event func(SpanEvent)
observer otobserver.SpanObserver
sync.Mutex // protects the fields below
raw RawSpan
// The number of logs dropped because of MaxLogsPerSpan.
numDroppedLogs int
Endpoint *zipkincore.Endpoint
}
var spanPool = &sync.Pool{New: func() interface{} {
return &spanImpl{}
}}
func (s *spanImpl) reset() {
s.tracer, s.event = nil, nil
// Note: Would like to do the following, but then the consumer of RawSpan
// (the recorder) needs to make sure that they're not holding on to the
// baggage or logs when they return (i.e. they need to copy if they care):
//
// logs, baggage := s.raw.Logs[:0], s.raw.Baggage
// for k := range baggage {
// delete(baggage, k)
// }
// s.raw.Logs, s.raw.Baggage = logs, baggage
//
// That's likely too much to ask for. But there is some magic we should
// be able to do with `runtime.SetFinalizer` to reclaim that memory into
// a buffer pool when GC considers them unreachable, which should ease
// some of the load. Hard to say how quickly that would be in practice
// though.
s.raw = RawSpan{
Context: SpanContext{},
}
}
func (s *spanImpl) SetOperationName(operationName string) opentracing.Span {
if s.observer != nil {
s.observer.OnSetOperationName(operationName)
}
s.Lock()
defer s.Unlock()
s.raw.Operation = operationName
return s
}
func (s *spanImpl) trim() bool {
return !s.raw.Context.Sampled && s.tracer.options.trimUnsampledSpans
}
func (s *spanImpl) SetTag(key string, value interface{}) opentracing.Span {
defer s.onTag(key, value)
if s.observer != nil {
s.observer.OnSetTag(key, value)
}
s.Lock()
defer s.Unlock()
if key == string(ext.SamplingPriority) {
if v, ok := value.(uint16); ok {
s.raw.Context.Sampled = v != 0
return s
}
}
if s.trim() {
return s
}
if s.raw.Tags == nil {
s.raw.Tags = opentracing.Tags{}
}
s.raw.Tags[key] = value
return s
}
func (s *spanImpl) LogKV(keyValues ...interface{}) {
fields, err := log.InterleavedKVToFields(keyValues...)
if err != nil {
s.LogFields(log.Error(err), log.String("function", "LogKV"))
return
}
s.LogFields(fields...)
}
func (s *spanImpl) appendLog(lr opentracing.LogRecord) {
maxLogs := s.tracer.options.maxLogsPerSpan
if maxLogs == 0 || len(s.raw.Logs) < maxLogs {
s.raw.Logs = append(s.raw.Logs, lr)
return
}
// We have too many logs. We don't touch the first numOld logs; we treat the
// rest as a circular buffer and overwrite the oldest log among those.
numOld := (maxLogs - 1) / 2
numNew := maxLogs - numOld
s.raw.Logs[numOld+s.numDroppedLogs%numNew] = lr
s.numDroppedLogs++
}
func (s *spanImpl) LogFields(fields ...log.Field) {
lr := opentracing.LogRecord{
Fields: fields,
}
defer s.onLogFields(lr)
s.Lock()
defer s.Unlock()
if s.trim() || s.tracer.options.dropAllLogs {
return
}
if lr.Timestamp.IsZero() {
lr.Timestamp = time.Now()
}
s.appendLog(lr)
}
func (s *spanImpl) LogEvent(event string) {
s.Log(opentracing.LogData{
Event: event,
})
}
func (s *spanImpl) LogEventWithPayload(event string, payload interface{}) {
s.Log(opentracing.LogData{
Event: event,
Payload: payload,
})
}
func (s *spanImpl) Log(ld opentracing.LogData) {
defer s.onLog(ld)
s.Lock()
defer s.Unlock()
if s.trim() || s.tracer.options.dropAllLogs {
return
}
if ld.Timestamp.IsZero() {
ld.Timestamp = time.Now()
}
s.appendLog(ld.ToLogRecord())
}
func (s *spanImpl) Finish() {
s.FinishWithOptions(opentracing.FinishOptions{})
}
// rotateLogBuffer rotates the records in the buffer: records 0 to pos-1 move at
// the end (i.e. pos circular left shifts).
func rotateLogBuffer(buf []opentracing.LogRecord, pos int) {
// This algorithm is described in:
// http://www.cplusplus.com/reference/algorithm/rotate
for first, middle, next := 0, pos, pos; first != middle; {
buf[first], buf[next] = buf[next], buf[first]
first++
next++
if next == len(buf) {
next = middle
} else if first == middle {
middle = next
}
}
}
func (s *spanImpl) FinishWithOptions(opts opentracing.FinishOptions) {
finishTime := opts.FinishTime
if finishTime.IsZero() {
finishTime = time.Now()
}
duration := finishTime.Sub(s.raw.Start)
if s.observer != nil {
s.observer.OnFinish(opts)
}
s.Lock()
defer s.Unlock()
for _, lr := range opts.LogRecords {
s.appendLog(lr)
}
for _, ld := range opts.BulkLogData {
s.appendLog(ld.ToLogRecord())
}
if s.numDroppedLogs > 0 {
// We dropped some log events, which means that we used part of Logs as a
// circular buffer (see appendLog). De-circularize it.
numOld := (len(s.raw.Logs) - 1) / 2
numNew := len(s.raw.Logs) - numOld
rotateLogBuffer(s.raw.Logs[numOld:], s.numDroppedLogs%numNew)
// Replace the log in the middle (the oldest "new" log) with information
// about the dropped logs. This means that we are effectively dropping one
// more "new" log.
numDropped := s.numDroppedLogs + 1
s.raw.Logs[numOld] = opentracing.LogRecord{
// Keep the timestamp of the last dropped event.
Timestamp: s.raw.Logs[numOld].Timestamp,
Fields: []log.Field{
log.String("event", "dropped Span logs"),
log.Int("dropped_log_count", numDropped),
log.String("component", "zipkintracer"),
},
}
}
s.raw.Duration = duration
s.onFinish(s.raw)
s.tracer.options.recorder.RecordSpan(s.raw)
// Last chance to get options before the span is possibly reset.
poolEnabled := s.tracer.options.enableSpanPool
if s.tracer.options.debugAssertUseAfterFinish {
// This makes it much more likely to catch a panic on any subsequent
// operation since s.tracer is accessed on every call to `Lock`.
// We don't call `reset()` here to preserve the logs in the Span
// which are printed when the assertion triggers.
s.tracer = nil
}
if poolEnabled {
spanPool.Put(s)
}
}
func (s *spanImpl) Tracer() opentracing.Tracer {
return s.tracer
}
func (s *spanImpl) Context() opentracing.SpanContext {
return s.raw.Context
}
func (s *spanImpl) SetBaggageItem(key, val string) opentracing.Span {
s.onBaggage(key, val)
if s.trim() {
return s
}
s.Lock()
defer s.Unlock()
s.raw.Context = s.raw.Context.WithBaggageItem(key, val)
return s
}
func (s *spanImpl) BaggageItem(key string) string {
s.Lock()
defer s.Unlock()
return s.raw.Context.Baggage[key]
}
func (s *spanImpl) Operation() string {
return s.raw.Operation
}
func (s *spanImpl) Start() time.Time {
return s.raw.Start
}