traefik/vendor/github.com/instana/go-sensor/tracer_options.go

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2019-02-18 15:52:04 +00:00
package instana
import (
bt "github.com/opentracing/basictracer-go"
opentracing "github.com/opentracing/opentracing-go"
)
// Tracer extends the opentracing.Tracer interface
type Tracer interface {
opentracing.Tracer
// Options gets the Options used in New() or NewWithOptions().
Options() TracerOptions
}
// TracerOptions allows creating a customized Tracer via NewWithOptions. The object
// must not be updated when there is an active tracer using it.
type TracerOptions struct {
// ShouldSample is a function which is called when creating a new Span and
// determines whether that Span is sampled. The randomized TraceID is supplied
// to allow deterministic sampling decisions to be made across different nodes.
// For example,
//
// func(traceID uint64) { return traceID % 64 == 0 }
//
// samples every 64th trace on average.
ShouldSample func(traceID int64) bool
// TrimUnsampledSpans turns potentially expensive operations on unsampled
// Spans into no-ops. More precisely, tags and log events are silently
// discarded. If NewSpanEventListener is set, the callbacks will still fire.
TrimUnsampledSpans bool
// Recorder receives Spans which have been finished.
Recorder SpanRecorder
// NewSpanEventListener can be used to enhance the tracer by effectively
// attaching external code to trace events. See NetTraceIntegrator for a
// practical example, and event.go for the list of possible events.
NewSpanEventListener func() func(bt.SpanEvent)
// DropAllLogs turns log events on all Spans into no-ops.
// If NewSpanEventListener is set, the callbacks will still fire.
DropAllLogs bool
// MaxLogsPerSpan limits the number of Logs in a span (if set to a nonzero
// value). If a span has more logs than this value, logs are dropped as
// necessary (and replaced with a log describing how many were dropped).
//
// About half of the MaxLogPerSpan logs kept are the oldest logs, and about
// half are the newest logs.
//
// If NewSpanEventListener is set, the callbacks will still fire for all log
// events. This value is ignored if DropAllLogs is true.
MaxLogsPerSpan int
// DebugAssertSingleGoroutine internally records the ID of the goroutine
// creating each Span and verifies that no operation is carried out on
// it on a different goroutine.
// Provided strictly for development purposes.
// Passing Spans between goroutine without proper synchronization often
// results in use-after-Finish() errors. For a simple example, consider the
// following pseudocode:
//
// func (s *Server) Handle(req http.Request) error {
// sp := s.StartSpan("server")
// defer sp.Finish()
// wait := s.queueProcessing(opentracing.ContextWithSpan(context.Background(), sp), req)
// select {
// case resp := <-wait:
// return resp.Error
// case <-time.After(10*time.Second):
// sp.LogEvent("timed out waiting for processing")
// return ErrTimedOut
// }
// }
//
// This looks reasonable at first, but a request which spends more than ten
// seconds in the queue is abandoned by the main goroutine and its trace
// finished, leading to use-after-finish when the request is finally
// processed. Note also that even joining on to a finished Span via
// StartSpanWithOptions constitutes an illegal operation.
//
// Code bases which do not require (or decide they do not want) Spans to
// be passed across goroutine boundaries can run with this flag enabled in
// tests to increase their chances of spotting wrong-doers.
DebugAssertSingleGoroutine bool
// DebugAssertUseAfterFinish is provided strictly for development purposes.
// When set, it attempts to exacerbate issues emanating from use of Spans
// after calling Finish by running additional assertions.
DebugAssertUseAfterFinish bool
// EnableSpanPool enables the use of a pool, so that the tracer reuses spans
// after Finish has been called on it. Adds a slight performance gain as it
// reduces allocations. However, if you have any use-after-finish race
// conditions the code may panic.
EnableSpanPool bool
}