forked from jaegertracing/jaeger
-
Notifications
You must be signed in to change notification settings - Fork 5
/
mutex.go
88 lines (75 loc) · 2.75 KB
/
mutex.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
// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package tracing
import (
"context"
"fmt"
"sync"
"github.com/opentracing/opentracing-go"
"github.com/opentracing/opentracing-go/log"
)
// Mutex is just like the standard sync.Mutex, except that it is aware of the Context
// and logs some diagnostic information into the current span.
type Mutex struct {
SessionBaggageKey string
realLock sync.Mutex
holder string
waiters []string
waitersLock sync.Mutex
}
// Lock acquires an exclusive lock.
func (sm *Mutex) Lock(ctx context.Context) {
var session string
activeSpan := opentracing.SpanFromContext(ctx)
if activeSpan != nil {
session = activeSpan.BaggageItem(sm.SessionBaggageKey)
activeSpan.SetTag(sm.SessionBaggageKey, session)
}
sm.waitersLock.Lock()
if waiting := len(sm.waiters); waiting > 0 && activeSpan != nil {
activeSpan.LogFields(
log.String("event", fmt.Sprintf("Waiting for lock behind %d transactions", waiting)),
log.String("blockers", fmt.Sprintf("%v", sm.waiters))) // avoid deferred slice.String()
fmt.Printf("%s Waiting for lock behind %d transactions: %v\n", session, waiting, sm.waiters)
}
sm.waiters = append(sm.waiters, session)
sm.waitersLock.Unlock()
sm.realLock.Lock()
sm.holder = session
sm.waitersLock.Lock()
behindLen := len(sm.waiters) - 1
sm.waitersLock.Unlock()
if activeSpan != nil {
activeSpan.LogEvent(
fmt.Sprintf("Acquired lock with %d transactions waiting behind", behindLen))
}
}
// Unlock releases the lock.
func (sm *Mutex) Unlock() {
sm.waitersLock.Lock()
for i, v := range sm.waiters {
if v == sm.holder {
sm.waiters = append(sm.waiters[0:i], sm.waiters[i+1:]...)
break
}
}
sm.waitersLock.Unlock()
sm.realLock.Unlock()
}