79 lines
1.7 KiB
Go
79 lines
1.7 KiB
Go
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package zipkintracer
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import (
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"bytes"
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"fmt"
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"runtime"
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"strconv"
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"sync"
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)
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const debugGoroutineIDTag = "_initial_goroutine"
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type errAssertionFailed struct {
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span *spanImpl
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msg string
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}
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// Error implements the error interface.
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func (err *errAssertionFailed) Error() string {
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return fmt.Sprintf("%s:\n%+v", err.msg, err.span)
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}
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func (s *spanImpl) Lock() {
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s.Mutex.Lock()
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s.maybeAssertSanityLocked()
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}
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func (s *spanImpl) maybeAssertSanityLocked() {
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if s.tracer == nil {
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s.Mutex.Unlock()
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panic(&errAssertionFailed{span: s, msg: "span used after call to Finish()"})
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}
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if s.tracer.options.debugAssertSingleGoroutine {
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startID := curGoroutineID()
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curID, ok := s.raw.Tags[debugGoroutineIDTag].(uint64)
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if !ok {
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// This is likely invoked in the context of the SetTag which sets
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// debugGoroutineTag.
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return
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}
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if startID != curID {
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s.Mutex.Unlock()
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panic(&errAssertionFailed{
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span: s,
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msg: fmt.Sprintf("span started on goroutine %d, but now running on %d", startID, curID),
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})
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}
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}
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}
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var goroutineSpace = []byte("goroutine ")
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var littleBuf = sync.Pool{
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New: func() interface{} {
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buf := make([]byte, 64)
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return &buf
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},
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}
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// Credit to @bradfitz:
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// https://github.com/golang/net/blob/master/http2/gotrack.go#L51
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func curGoroutineID() uint64 {
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bp := littleBuf.Get().(*[]byte)
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defer littleBuf.Put(bp)
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b := *bp
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b = b[:runtime.Stack(b, false)]
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// Parse the 4707 out of "goroutine 4707 ["
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b = bytes.TrimPrefix(b, goroutineSpace)
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i := bytes.IndexByte(b, ' ')
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if i < 0 {
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panic(fmt.Sprintf("No space found in %q", b))
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}
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b = b[:i]
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n, err := strconv.ParseUint(string(b), 10, 64)
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if err != nil {
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panic(fmt.Sprintf("Failed to parse goroutine ID out of %q: %v", b, err))
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}
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return n
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}
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