139 lines
4.1 KiB
Go
139 lines
4.1 KiB
Go
// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package refsvfs2
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import (
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"fmt"
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"gvisor.dev/gvisor/pkg/log"
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refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
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"gvisor.dev/gvisor/pkg/sync"
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)
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var (
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// liveObjects is a global map of reference-counted objects. Objects are
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// inserted when leak check is enabled, and they are removed when they are
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// destroyed. It is protected by liveObjectsMu.
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liveObjects map[CheckedObject]struct{}
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liveObjectsMu sync.Mutex
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)
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// CheckedObject represents a reference-counted object with an informative
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// leak detection message.
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type CheckedObject interface {
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// RefType is the type of the reference-counted object.
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RefType() string
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// LeakMessage supplies a warning to be printed upon leak detection.
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LeakMessage() string
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// LogRefs indicates whether reference-related events should be logged.
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LogRefs() bool
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}
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func init() {
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liveObjects = make(map[CheckedObject]struct{})
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}
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// leakCheckEnabled returns whether leak checking is enabled. The following
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// functions should only be called if it returns true.
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func leakCheckEnabled() bool {
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return refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking
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}
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// Register adds obj to the live object map.
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func Register(obj CheckedObject) {
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if leakCheckEnabled() {
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liveObjectsMu.Lock()
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if _, ok := liveObjects[obj]; ok {
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panic(fmt.Sprintf("Unexpected entry in leak checking map: reference %p already added", obj))
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}
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liveObjects[obj] = struct{}{}
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liveObjectsMu.Unlock()
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if leakCheckEnabled() && obj.LogRefs() {
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logEvent(obj, "registered")
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}
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}
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}
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// Unregister removes obj from the live object map.
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func Unregister(obj CheckedObject) {
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if leakCheckEnabled() {
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liveObjectsMu.Lock()
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defer liveObjectsMu.Unlock()
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if _, ok := liveObjects[obj]; !ok {
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panic(fmt.Sprintf("Expected to find entry in leak checking map for reference %p", obj))
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}
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delete(liveObjects, obj)
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if leakCheckEnabled() && obj.LogRefs() {
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logEvent(obj, "unregistered")
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}
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}
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}
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// LogIncRef logs a reference increment.
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func LogIncRef(obj CheckedObject, refs int64) {
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if leakCheckEnabled() && obj.LogRefs() {
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logEvent(obj, fmt.Sprintf("IncRef to %d", refs))
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}
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}
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// LogTryIncRef logs a successful TryIncRef call.
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func LogTryIncRef(obj CheckedObject, refs int64) {
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if leakCheckEnabled() && obj.LogRefs() {
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logEvent(obj, fmt.Sprintf("TryIncRef to %d", refs))
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}
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}
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// LogDecRef logs a reference decrement.
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func LogDecRef(obj CheckedObject, refs int64) {
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if leakCheckEnabled() && obj.LogRefs() {
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logEvent(obj, fmt.Sprintf("DecRef to %d", refs))
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}
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}
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// logEvent logs a message for the given reference-counted object.
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//
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// obj.LogRefs() should be checked before calling logEvent, in order to avoid
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// calling any text processing needed to evaluate msg.
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func logEvent(obj CheckedObject, msg string) {
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log.Infof("[%s %p] %s:\n%s", obj.RefType(), obj, msg, refs_vfs1.FormatStack(refs_vfs1.RecordStack()))
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}
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// checkOnce makes sure that leak checking is only done once. DoLeakCheck is
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// called from multiple places (which may overlap) to cover different sandbox
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// exit scenarios.
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var checkOnce sync.Once
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// DoLeakCheck iterates through the live object map and logs a message for each
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// object. It is called once no reference-counted objects should be reachable
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// anymore, at which point anything left in the map is considered a leak.
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func DoLeakCheck() {
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if leakCheckEnabled() {
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checkOnce.Do(func() {
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liveObjectsMu.Lock()
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defer liveObjectsMu.Unlock()
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leaked := len(liveObjects)
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if leaked > 0 {
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msg := fmt.Sprintf("Leak checking detected %d leaked objects:\n", leaked)
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for obj := range liveObjects {
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msg += obj.LeakMessage() + "\n"
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}
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log.Warningf(msg)
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}
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})
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}
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}
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