/
tracer.go
161 lines (138 loc) · 5 KB
/
tracer.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package trace // import "go.opentelemetry.io/otel/sdk/trace"
import (
"context"
"time"
"go.opentelemetry.io/otel/sdk/instrumentation"
"go.opentelemetry.io/otel/trace"
)
type tracer struct {
provider *TracerProvider
instrumentationScope instrumentation.Scope
}
var _ trace.Tracer = &tracer{}
// Start starts a Span and returns it along with a context containing it.
//
// The Span is created with the provided name and as a child of any existing
// span context found in the passed context. The created Span will be
// configured appropriately by any SpanOption passed.
func (tr *tracer) Start(ctx context.Context, name string, options ...trace.SpanStartOption) (context.Context, trace.Span) {
config := trace.NewSpanStartConfig(options...)
if ctx == nil {
// Prevent trace.ContextWithSpan from panicking.
ctx = context.Background()
}
// For local spans created by this SDK, track child span count.
if p := trace.SpanFromContext(ctx); p != nil {
if sdkSpan, ok := p.(*recordingSpan); ok {
sdkSpan.addChild()
}
}
s := tr.newSpan(ctx, name, &config)
if rw, ok := s.(ReadWriteSpan); ok && s.IsRecording() {
sps := tr.provider.spanProcessors.Load().(spanProcessorStates)
for _, sp := range sps {
sp.sp.OnStart(ctx, rw)
}
}
if rtt, ok := s.(runtimeTracer); ok {
ctx = rtt.runtimeTrace(ctx)
}
return trace.ContextWithSpan(ctx, s), s
}
type runtimeTracer interface {
// runtimeTrace starts a "runtime/trace".Task for the span and
// returns a context containing the task.
runtimeTrace(ctx context.Context) context.Context
}
// newSpan returns a new configured span.
func (tr *tracer) newSpan(ctx context.Context, name string, config *trace.SpanConfig) trace.Span {
// If told explicitly to make this a new root use a zero value SpanContext
// as a parent which contains an invalid trace ID and is not remote.
var psc trace.SpanContext
if config.NewRoot() {
ctx = trace.ContextWithSpanContext(ctx, psc)
} else {
psc = trace.SpanContextFromContext(ctx)
}
// If there is a valid parent trace ID, use it to ensure the continuity of
// the trace. Always generate a new span ID so other components can rely
// on a unique span ID, even if the Span is non-recording.
var tid trace.TraceID
var sid trace.SpanID
if !psc.TraceID().IsValid() {
tid, sid = tr.provider.idGenerator.NewIDs(ctx)
} else {
tid = psc.TraceID()
sid = tr.provider.idGenerator.NewSpanID(ctx, tid)
}
samplingResult := tr.provider.sampler.ShouldSample(SamplingParameters{
ParentContext: ctx,
TraceID: tid,
Name: name,
Kind: config.SpanKind(),
Attributes: config.Attributes(),
Links: config.Links(),
})
scc := trace.SpanContextConfig{
TraceID: tid,
SpanID: sid,
TraceState: samplingResult.Tracestate,
}
if isSampled(samplingResult) {
scc.TraceFlags = psc.TraceFlags() | trace.FlagsSampled
} else {
scc.TraceFlags = psc.TraceFlags() &^ trace.FlagsSampled
}
sc := trace.NewSpanContext(scc)
if !isRecording(samplingResult) {
return tr.newNonRecordingSpan(sc)
}
return tr.newRecordingSpan(psc, sc, name, samplingResult, config)
}
// newRecordingSpan returns a new configured recordingSpan.
func (tr *tracer) newRecordingSpan(psc, sc trace.SpanContext, name string, sr SamplingResult, config *trace.SpanConfig) *recordingSpan {
startTime := config.Timestamp()
if startTime.IsZero() {
startTime = time.Now()
}
s := &recordingSpan{
// Do not pre-allocate the attributes slice here! Doing so will
// allocate memory that is likely never going to be used, or if used,
// will be over-sized. The default Go compiler has been tested to
// dynamically allocate needed space very well. Benchmarking has shown
// it to be more performant than what we can predetermine here,
// especially for the common use case of few to no added
// attributes.
parent: psc,
spanContext: sc,
spanKind: trace.ValidateSpanKind(config.SpanKind()),
name: name,
startTime: startTime,
events: newEvictedQueue(tr.provider.spanLimits.EventCountLimit),
links: newEvictedQueue(tr.provider.spanLimits.LinkCountLimit),
tracer: tr,
}
for _, l := range config.Links() {
s.addLink(l)
}
s.SetAttributes(sr.Attributes...)
s.SetAttributes(config.Attributes()...)
return s
}
// newNonRecordingSpan returns a new configured nonRecordingSpan.
func (tr *tracer) newNonRecordingSpan(sc trace.SpanContext) nonRecordingSpan {
return nonRecordingSpan{tracer: tr, sc: sc}
}