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
|
/**
* Copyright (C) 2021-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <memory>
#include <string>
#include <boost/optional.hpp>
#include "mongo/bson/bsonobj.h"
#include "mongo/util/tick_source.h"
namespace mongo {
/**
* Handles span creation and provides a compatible interface to `opentelemetry::trace::Tracer`.
* This class does not support concurrent accesses, and should not be used in production.
*
* Spans are organized in a hierarchy. Once a new span is created, through calling `startSpan()`,
* it will be added as a child to the active span, and replaces its parent as the new active span.
* When there is no active span, the newly created span is considered as the root span.
*
* Once the root span goes out of scope, the collected trace is serialized into a BSON object, and
* may be retrieved through `getLatestTrace()`. The trace object remains valid until a new root span
* is created. This interface is not compatible with `opentelemetry::trace::Tracer`, and fills the
* gap for `opentelemetry` exporters.
*
* Here is an example on how to create spans and retrieve traces:
* ```
* void f1(std::shared_ptr<Tracer> tracer) {
* auto root = tracer->startSpan("root");
* sleepFor(Milliseconds(1));
* {
* auto child = tracer->startSpan("child");
* sleepFor(Milliseconds(2));
* }
* }
*
* void f2() {
* auto tracer = TracerProvider::get().getTracer("myTracer");
* f1(tracer);
* BSONObj trace = tracer->getLatestTrace();
* }
* ```
*
* The above code will produce the following `BSONObj`:
* ```
* {
* "tracer": "myTracer",
* "root": {
* "startedMicros": 0,
* "spans": {
* "child": {
* "startedMicros": 1,
* "stoppedMicros": 3,
* },
* },
* "stoppedMicros": 3,
* },
* }
* ```
*/
class Tracer : public std::enable_shared_from_this<Tracer> {
public:
class Span {
public:
virtual ~Span() = default;
};
using ScopedSpan = std::unique_ptr<Span, std::function<void(Span*)>>;
class Factory {
public:
virtual ~Factory() = default;
virtual ScopedSpan startSpan(std::string) = 0;
virtual boost::optional<BSONObj> getLatestTrace() const = 0;
};
Tracer(std::string name,
TickSource* tickSource,
std::function<std::unique_ptr<Factory>(std::string, Tracer*)> maker);
ScopedSpan startSpan(std::string name) {
return _factory->startSpan(std::move(name));
}
boost::optional<BSONObj> getLatestTrace() const {
return _factory->getLatestTrace();
}
TickSource* getTickSource() {
return _tickSource;
}
private:
TickSource* const _tickSource;
std::unique_ptr<Factory> _factory;
};
/**
* The factory class for constructing instances of `Tracer`.
* Consider the following before using this class:
* Must be initialized first by calling `initialize()`, and implements the singleton pattern.
* Once initialized, multiple threads my concurrently call into `get()` and `getTracer()`.
*/
class TracerProvider {
public:
explicit TracerProvider(std::unique_ptr<TickSource> tickSource)
: _tickSource(std::move(tickSource)) {}
static void initialize(std::unique_ptr<TickSource> tickSource);
static TracerProvider& get();
std::shared_ptr<Tracer> getTracer(std::string name);
/**
* Get a tracer that outputs Chrome's Trace Event Format
*/
std::shared_ptr<Tracer> getEventTracer(std::string name);
private:
std::unique_ptr<TickSource> _tickSource;
};
} // namespace mongo
|
