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
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
|
// Copyright 2020 The gVisor 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 refs
import (
"fmt"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sync"
)
var (
// liveObjects is a global map of reference-counted objects. Objects are
// inserted when leak check is enabled, and they are removed when they are
// destroyed. It is protected by liveObjectsMu.
liveObjects map[CheckedObject]struct{}
liveObjectsMu sync.Mutex
)
// CheckedObject represents a reference-counted object with an informative
// leak detection message.
type CheckedObject interface {
// RefType is the type of the reference-counted object.
RefType() string
// LeakMessage supplies a warning to be printed upon leak detection.
LeakMessage() string
// LogRefs indicates whether reference-related events should be logged.
LogRefs() bool
}
func init() {
liveObjects = make(map[CheckedObject]struct{})
}
// LeakCheckEnabled returns whether leak checking is enabled. The following
// functions should only be called if it returns true.
func LeakCheckEnabled() bool {
mode := GetLeakMode()
return mode != NoLeakChecking
}
// leakCheckPanicEnabled returns whether DoLeakCheck() should panic when leaks
// are detected.
func leakCheckPanicEnabled() bool {
return GetLeakMode() == LeaksPanic
}
// Register adds obj to the live object map.
func Register(obj CheckedObject) {
if LeakCheckEnabled() {
liveObjectsMu.Lock()
if _, ok := liveObjects[obj]; ok {
panic(fmt.Sprintf("Unexpected entry in leak checking map: reference %p already added", obj))
}
liveObjects[obj] = struct{}{}
liveObjectsMu.Unlock()
if LeakCheckEnabled() && obj.LogRefs() {
logEvent(obj, "registered")
}
}
}
// Unregister removes obj from the live object map.
func Unregister(obj CheckedObject) {
if LeakCheckEnabled() {
liveObjectsMu.Lock()
defer liveObjectsMu.Unlock()
if _, ok := liveObjects[obj]; !ok {
panic(fmt.Sprintf("Expected to find entry in leak checking map for reference %p", obj))
}
delete(liveObjects, obj)
if LeakCheckEnabled() && obj.LogRefs() {
logEvent(obj, "unregistered")
}
}
}
// LogIncRef logs a reference increment.
func LogIncRef(obj CheckedObject, refs int64) {
if LeakCheckEnabled() && obj.LogRefs() {
logEvent(obj, fmt.Sprintf("IncRef to %d", refs))
}
}
// LogTryIncRef logs a successful TryIncRef call.
func LogTryIncRef(obj CheckedObject, refs int64) {
if LeakCheckEnabled() && obj.LogRefs() {
logEvent(obj, fmt.Sprintf("TryIncRef to %d", refs))
}
}
// LogDecRef logs a reference decrement.
func LogDecRef(obj CheckedObject, refs int64) {
if LeakCheckEnabled() && obj.LogRefs() {
logEvent(obj, fmt.Sprintf("DecRef to %d", refs))
}
}
// logEvent logs a message for the given reference-counted object.
//
// obj.LogRefs() should be checked before calling logEvent, in order to avoid
// calling any text processing needed to evaluate msg.
func logEvent(obj CheckedObject, msg string) {
log.Infof("[%s %p] %s:\n%s", obj.RefType(), obj, msg, FormatStack(RecordStack()))
}
// checkOnce makes sure that leak checking is only done once. DoLeakCheck is
// called from multiple places (which may overlap) to cover different sandbox
// exit scenarios.
var checkOnce sync.Once
// DoLeakCheck iterates through the live object map and logs a message for each
// object. It should be called when no reference-counted objects are reachable
// anymore, at which point anything left in the map is considered a leak. On
// multiple calls, only the first call will perform the leak check.
func DoLeakCheck() {
if LeakCheckEnabled() {
checkOnce.Do(doLeakCheck)
}
}
// DoRepeatedLeakCheck is the same as DoLeakCheck except that it can be called
// multiple times by the caller to incrementally perform leak checking.
func DoRepeatedLeakCheck() {
if LeakCheckEnabled() {
doLeakCheck()
}
}
type leakCheckDisabled interface {
LeakCheckDisabled() bool
}
// CleanupSync is used to wait for async cleanup actions.
var CleanupSync sync.WaitGroup
func doLeakCheck() {
CleanupSync.Wait()
liveObjectsMu.Lock()
defer liveObjectsMu.Unlock()
leaked := len(liveObjects)
if leaked > 0 {
n := 0
msg := fmt.Sprintf("Leak checking detected %d leaked objects:\n", leaked)
for obj := range liveObjects {
skip := false
if o, ok := obj.(leakCheckDisabled); ok {
skip = o.LeakCheckDisabled()
}
if skip {
log.Debugf(obj.LeakMessage())
continue
}
msg += obj.LeakMessage() + "\n"
n++
}
if n == 0 {
return
}
if leakCheckPanicEnabled() {
panic(msg)
}
log.Warningf(msg)
}
}
|
