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// 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 refsvfs2
import (
"fmt"
"inet.af/netstack/log"
refs_vfs1 "inet.af/netstack/refs"
"inet.af/netstack/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 {
return refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking
}
// 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, refs_vfs1.FormatStack(refs_vfs1.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 is called once no reference-counted objects should be reachable
// anymore, at which point anything left in the map is considered a leak.
func DoLeakCheck() {
if leakCheckEnabled() {
checkOnce.Do(func() {
liveObjectsMu.Lock()
defer liveObjectsMu.Unlock()
leaked := len(liveObjects)
if leaked > 0 {
msg := fmt.Sprintf("Leak checking detected %d leaked objects:\n", leaked)
for obj := range liveObjects {
msg += obj.LeakMessage() + "\n"
}
log.Warningf(msg)
}
})
}
}
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