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