111 lines
2.6 KiB
Go
111 lines
2.6 KiB
Go
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package trace
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import (
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"strconv"
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"strings"
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"github.com/pkg/errors"
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)
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const (
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flagSampled = 0x01
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flagDebug = 0x02
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)
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var (
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errEmptyTracerString = errors.New("trace: cannot convert empty string to spancontext")
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errInvalidTracerString = errors.New("trace: string does not match spancontext string format")
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)
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// SpanContext implements opentracing.SpanContext
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type spanContext struct {
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// traceID represents globally unique ID of the trace.
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// Usually generated as a random number.
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traceID uint64
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// spanID represents span ID that must be unique within its trace,
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// but does not have to be globally unique.
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spanID uint64
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// parentID refers to the ID of the parent span.
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// Should be 0 if the current span is a root span.
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parentID uint64
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// flags is a bitmap containing such bits as 'sampled' and 'debug'.
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flags byte
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// probability
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probability float32
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// current level
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level int
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}
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func (c spanContext) isSampled() bool {
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return (c.flags & flagSampled) == flagSampled
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}
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func (c spanContext) isDebug() bool {
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return (c.flags & flagDebug) == flagDebug
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}
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// IsValid check spanContext valid
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func (c spanContext) IsValid() bool {
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return c.traceID != 0 && c.spanID != 0
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}
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// emptyContext emptyContext
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var emptyContext = spanContext{}
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// String convert spanContext to String
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// {TraceID}:{SpanID}:{ParentID}:{flags}:[extend...]
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// TraceID: uint64 base16
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// SpanID: uint64 base16
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// ParentID: uint64 base16
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// flags:
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// - :0 sampled flag
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// - :1 debug flag
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// extend:
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// sample-rate: s-{base16(BigEndian(float32))}
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func (c spanContext) String() string {
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base := make([]string, 4)
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base[0] = strconv.FormatUint(uint64(c.traceID), 16)
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base[1] = strconv.FormatUint(uint64(c.spanID), 16)
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base[2] = strconv.FormatUint(uint64(c.parentID), 16)
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base[3] = strconv.FormatUint(uint64(c.flags), 16)
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return strings.Join(base, ":")
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}
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// ContextFromString parse spanContext form string
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func contextFromString(value string) (spanContext, error) {
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if value == "" {
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return emptyContext, errEmptyTracerString
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}
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items := strings.Split(value, ":")
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if len(items) < 4 {
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return emptyContext, errInvalidTracerString
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}
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parseHexUint64 := func(hexs []string) ([]uint64, error) {
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rets := make([]uint64, len(hexs))
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var err error
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for i, hex := range hexs {
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rets[i], err = strconv.ParseUint(hex, 16, 64)
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if err != nil {
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break
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}
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}
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return rets, err
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}
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rets, err := parseHexUint64(items[0:4])
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if err != nil {
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return emptyContext, errInvalidTracerString
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}
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sctx := spanContext{
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traceID: rets[0],
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spanID: rets[1],
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parentID: rets[2],
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flags: byte(rets[3]),
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}
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return sctx, nil
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}
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