1 // Copyright The OpenTelemetry Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package trace // import "go.opentelemetry.io/otel/sdk/trace" 16 17 import ( 18 "context" 19 crand "crypto/rand" 20 "encoding/binary" 21 "math/rand" 22 "sync" 23 24 "go.opentelemetry.io/otel/trace" 25 ) 26 27 // IDGenerator allows custom generators for TraceID and SpanID. 28 type IDGenerator interface { 29 // DO NOT CHANGE: any modification will not be backwards compatible and 30 // must never be done outside of a new major release. 31 32 // NewIDs returns a new trace and span ID. 33 NewIDs(ctx context.Context) (trace.TraceID, trace.SpanID) 34 // DO NOT CHANGE: any modification will not be backwards compatible and 35 // must never be done outside of a new major release. 36 37 // NewSpanID returns a ID for a new span in the trace with traceID. 38 NewSpanID(ctx context.Context, traceID trace.TraceID) trace.SpanID 39 // DO NOT CHANGE: any modification will not be backwards compatible and 40 // must never be done outside of a new major release. 41 } 42 43 type randomIDGenerator struct { 44 sync.Mutex 45 randSource *rand.Rand 46 } 47 48 var _ IDGenerator = &randomIDGenerator{} 49 50 // NewSpanID returns a non-zero span ID from a randomly-chosen sequence. 51 func (gen *randomIDGenerator) NewSpanID(ctx context.Context, traceID trace.TraceID) trace.SpanID { 52 gen.Lock() 53 defer gen.Unlock() 54 sid := trace.SpanID{} 55 _, _ = gen.randSource.Read(sid[:]) 56 return sid 57 } 58 59 // NewIDs returns a non-zero trace ID and a non-zero span ID from a 60 // randomly-chosen sequence. 61 func (gen *randomIDGenerator) NewIDs(ctx context.Context) (trace.TraceID, trace.SpanID) { 62 gen.Lock() 63 defer gen.Unlock() 64 tid := trace.TraceID{} 65 _, _ = gen.randSource.Read(tid[:]) 66 sid := trace.SpanID{} 67 _, _ = gen.randSource.Read(sid[:]) 68 return tid, sid 69 } 70 71 func defaultIDGenerator() IDGenerator { 72 gen := &randomIDGenerator{} 73 var rngSeed int64 74 _ = binary.Read(crand.Reader, binary.LittleEndian, &rngSeed) 75 gen.randSource = rand.New(rand.NewSource(rngSeed)) 76 return gen 77 } 78