1// Copyright 2017, OpenCensus 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
15package trace
16
17import (
18	"sync"
19	"sync/atomic"
20	"time"
21)
22
23// Exporter is a type for functions that receive sampled trace spans.
24//
25// The ExportSpan method should be safe for concurrent use and should return
26// quickly; if an Exporter takes a significant amount of time to process a
27// SpanData, that work should be done on another goroutine.
28//
29// The SpanData should not be modified, but a pointer to it can be kept.
30type Exporter interface {
31	ExportSpan(s *SpanData)
32}
33
34type exportersMap map[Exporter]struct{}
35
36var (
37	exporterMu sync.Mutex
38	exporters  atomic.Value
39)
40
41// RegisterExporter adds to the list of Exporters that will receive sampled
42// trace spans.
43//
44// Binaries can register exporters, libraries shouldn't register exporters.
45func RegisterExporter(e Exporter) {
46	exporterMu.Lock()
47	new := make(exportersMap)
48	if old, ok := exporters.Load().(exportersMap); ok {
49		for k, v := range old {
50			new[k] = v
51		}
52	}
53	new[e] = struct{}{}
54	exporters.Store(new)
55	exporterMu.Unlock()
56}
57
58// UnregisterExporter removes from the list of Exporters the Exporter that was
59// registered with the given name.
60func UnregisterExporter(e Exporter) {
61	exporterMu.Lock()
62	new := make(exportersMap)
63	if old, ok := exporters.Load().(exportersMap); ok {
64		for k, v := range old {
65			new[k] = v
66		}
67	}
68	delete(new, e)
69	exporters.Store(new)
70	exporterMu.Unlock()
71}
72
73// SpanData contains all the information collected by a Span.
74type SpanData struct {
75	SpanContext
76	ParentSpanID SpanID
77	SpanKind     int
78	Name         string
79	StartTime    time.Time
80	// The wall clock time of EndTime will be adjusted to always be offset
81	// from StartTime by the duration of the span.
82	EndTime time.Time
83	// The values of Attributes each have type string, bool, or int64.
84	Attributes    map[string]interface{}
85	Annotations   []Annotation
86	MessageEvents []MessageEvent
87	Status
88	Links                    []Link
89	HasRemoteParent          bool
90	DroppedAttributeCount    int
91	DroppedAnnotationCount   int
92	DroppedMessageEventCount int
93	DroppedLinkCount         int
94
95	// ChildSpanCount holds the number of child span created for this span.
96	ChildSpanCount int
97}
98