| 1 | // Copyright 2019 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package export |
| 6 | |
| 7 | import ( |
| 8 | crand "crypto/rand" |
| 9 | "encoding/binary" |
| 10 | "fmt" |
| 11 | "math/rand" |
| 12 | "sync" |
| 13 | "sync/atomic" |
| 14 | ) |
| 15 | |
| 16 | type TraceID [16]byte |
| 17 | type SpanID [8]byte |
| 18 | |
| 19 | func (t TraceID) String() string { |
| 20 | return fmt.Sprintf("%02x", t[:]) |
| 21 | } |
| 22 | |
| 23 | func (s SpanID) String() string { |
| 24 | return fmt.Sprintf("%02x", s[:]) |
| 25 | } |
| 26 | |
| 27 | func (s SpanID) IsValid() bool { |
| 28 | return s != SpanID{} |
| 29 | } |
| 30 | |
| 31 | var ( |
| 32 | generationMu sync.Mutex |
| 33 | nextSpanID uint64 |
| 34 | spanIDInc uint64 |
| 35 | |
| 36 | traceIDAdd [2]uint64 |
| 37 | traceIDRand *rand.Rand |
| 38 | ) |
| 39 | |
| 40 | func initGenerator() { |
| 41 | var rngSeed int64 |
| 42 | for _, p := range []interface{}{ |
| 43 | &rngSeed, &traceIDAdd, &nextSpanID, &spanIDInc, |
| 44 | } { |
| 45 | binary.Read(crand.Reader, binary.LittleEndian, p) |
| 46 | } |
| 47 | traceIDRand = rand.New(rand.NewSource(rngSeed)) |
| 48 | spanIDInc |= 1 |
| 49 | } |
| 50 | |
| 51 | func newTraceID() TraceID { |
| 52 | generationMu.Lock() |
| 53 | defer generationMu.Unlock() |
| 54 | if traceIDRand == nil { |
| 55 | initGenerator() |
| 56 | } |
| 57 | var tid [16]byte |
| 58 | binary.LittleEndian.PutUint64(tid[0:8], traceIDRand.Uint64()+traceIDAdd[0]) |
| 59 | binary.LittleEndian.PutUint64(tid[8:16], traceIDRand.Uint64()+traceIDAdd[1]) |
| 60 | return tid |
| 61 | } |
| 62 | |
| 63 | func newSpanID() SpanID { |
| 64 | var id uint64 |
| 65 | for id == 0 { |
| 66 | id = atomic.AddUint64(&nextSpanID, spanIDInc) |
| 67 | } |
| 68 | var sid [8]byte |
| 69 | binary.LittleEndian.PutUint64(sid[:], id) |
| 70 | return sid |
| 71 | } |
| 72 |
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