-
Notifications
You must be signed in to change notification settings - Fork 19
/
garbageCollector.go
376 lines (353 loc) · 10.6 KB
/
garbageCollector.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
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
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
package scanner
import (
"bufio"
"encoding/gob"
"errors"
"io"
"os"
"path"
"time"
"github.com/Symantec/Dominator/lib/filesystem"
"github.com/Symantec/Dominator/lib/format"
"github.com/Symantec/Dominator/lib/fsutil"
"github.com/Symantec/Dominator/lib/hash"
"github.com/Symantec/Dominator/lib/image"
"github.com/Symantec/Dominator/lib/log"
)
var timeFormat string = "02 Jan 2006 15:04:05.99 MST"
type unreferencedObject struct {
Hash hash.Hash
Length uint64
Age time.Time
}
type unreferencedObjectsEntry struct {
object unreferencedObject
prev *unreferencedObjectsEntry
next *unreferencedObjectsEntry
}
type unreferencedObjectsList struct {
totalBytes uint64
oldest *unreferencedObjectsEntry
newest *unreferencedObjectsEntry
hashToEntry map[hash.Hash]*unreferencedObjectsEntry
lastRegeneratedTime time.Time
}
func loadUnreferencedObjects(fName string) (*unreferencedObjectsList, error) {
file, err := os.Open(fName)
if err != nil {
if !os.IsNotExist(err) {
return nil, err
}
return &unreferencedObjectsList{
hashToEntry: make(map[hash.Hash]*unreferencedObjectsEntry),
}, nil
}
defer file.Close()
reader := fsutil.NewChecksumReader(bufio.NewReader(file))
decoder := gob.NewDecoder(reader)
var length uint64
if err := decoder.Decode(&length); err != nil {
return nil, errors.New("error decoding list length: " + err.Error())
}
list := &unreferencedObjectsList{
hashToEntry: make(map[hash.Hash]*unreferencedObjectsEntry, length),
}
for count := uint64(0); count < length; count++ {
var object unreferencedObject
if err := decoder.Decode(&object); err != nil {
return nil, errors.New("error decoding object: " + err.Error())
}
entry := &unreferencedObjectsEntry{object: object}
list.addEntry(entry)
}
if err := reader.VerifyChecksum(); err != nil {
return nil, err
}
return list, nil
}
func (list *unreferencedObjectsList) write(w io.Writer,
logger log.Logger) error {
writer := fsutil.NewChecksumWriter(w)
encoder := gob.NewEncoder(writer)
if err := encoder.Encode(uint64(len(list.hashToEntry))); err != nil {
return err
}
nWritten := 0
for entry := list.oldest; entry != nil; entry = entry.next {
if err := encoder.Encode(entry.object); err != nil {
return err
}
nWritten++
}
if len(list.hashToEntry) != nWritten {
logger.Panicf("unref objects list length: %d != num entries: %d\n",
len(list.hashToEntry), nWritten)
}
return writer.WriteChecksum()
}
func (list *unreferencedObjectsList) addEntry(entry *unreferencedObjectsEntry) {
entry.prev = list.newest
if list.oldest == nil {
list.oldest = entry
} else {
list.newest.next = entry
}
list.newest = entry
list.hashToEntry[entry.object.Hash] = entry
list.totalBytes += entry.object.Length
}
// Returns true if object was added, else false if object was already on list.
func (list *unreferencedObjectsList) addObject(hashVal hash.Hash,
length uint64) bool {
if _, ok := list.hashToEntry[hashVal]; !ok {
object := unreferencedObject{hashVal, length, time.Now()}
list.addEntry(&unreferencedObjectsEntry{object: object})
return true
}
return false
}
func (list *unreferencedObjectsList) list() map[hash.Hash]uint64 {
objectsMap := make(map[hash.Hash]uint64, len(list.hashToEntry))
for entry := list.oldest; entry != nil; entry = entry.next {
objectsMap[entry.object.Hash] = entry.object.Length
}
return objectsMap
}
// Returns true if object was removed, else false (if not on list).
func (list *unreferencedObjectsList) removeObject(hashVal hash.Hash) bool {
entry := list.hashToEntry[hashVal]
if entry == nil {
return false
}
delete(list.hashToEntry, hashVal)
if entry.prev == nil {
list.oldest = entry.next
} else {
entry.prev.next = entry.next
}
if entry.next == nil {
list.newest = entry.prev
} else {
entry.next.prev = entry.prev
}
list.totalBytes -= entry.object.Length
return true
}
func (imdb *ImageDataBase) maybeAddToUnreferencedObjectsList(
fs *filesystem.FileSystem) {
// First get a list of objects in the image being deleted.
objects := fs.GetObjects()
// Scan all remaining images and remove their objects from the list.
for _, image := range imdb.imageMap {
image.ForEachObject(func(hashVal hash.Hash) error {
delete(objects, hashVal)
return nil
})
}
changed := false
for object, size := range objects {
if imdb.unreferencedObjects.addObject(object, size) {
changed = true
}
}
// Run garbage collector and save new list in the background.
unreferencedBytes := imdb.unreferencedObjects.totalBytes
go func() {
var bytesToDelete uint64
maxUnrefData := uint64(*imageServerMaxUnrefData)
if maxUnrefData > 0 && unreferencedBytes > maxUnrefData {
bytesToDelete = unreferencedBytes - maxUnrefData
}
var maxAge time.Time
if *imageServerMaxUnrefAge > 0 {
maxAge = time.Now().Add(-*imageServerMaxUnrefAge)
}
if bytesToDelete > 0 || !maxAge.IsZero() {
nDeleted, _ := imdb.collectGarbage(bytesToDelete, maxAge)
if nDeleted > 0 {
return // Garbage collector saved unreferenced objects list.
}
}
if changed {
imdb.saveUnreferencedObjectsList(true)
}
}()
}
func (imdb *ImageDataBase) removeFromUnreferencedObjectsListAndSave(
img *image.Image) {
if imdb.removeFromUnreferencedObjectsList(img) {
imdb.saveUnreferencedObjectsList(false)
}
}
func (imdb *ImageDataBase) removeFromUnreferencedObjectsList(
img *image.Image) bool {
changed := false
img.ForEachObject(func(hashVal hash.Hash) error {
if imdb.unreferencedObjects.removeObject(hashVal) {
changed = true
}
return nil
})
return changed
}
func (imdb *ImageDataBase) saveUnreferencedObjectsList(grabLock bool) {
if grabLock {
imdb.RLock()
defer imdb.RUnlock()
}
if err := imdb.writeUnreferencedObjectsList(); err != nil {
imdb.logger.Printf("Error writing unreferenced objects list: %s\n",
err)
}
}
func (imdb *ImageDataBase) writeUnreferencedObjectsList() error {
filename := path.Join(imdb.baseDir, unreferencedObjectsFile)
file, err := fsutil.CreateRenamingWriter(filename, filePerms)
if err != nil {
return err
}
defer file.Close()
writer := bufio.NewWriter(file)
defer writer.Flush()
return imdb.unreferencedObjects.write(writer, imdb.logger)
}
func (imdb *ImageDataBase) garbageCollector(bytesToDelete uint64) (
uint64, error) {
return imdb.collectGarbage(bytesToDelete, time.Time{})
}
// This grabs and releases the lock.
func (imdb *ImageDataBase) collectGarbage(bytesToDelete uint64,
deleteBefore time.Time) (uint64, error) {
if bytesToDelete < 1 && deleteBefore.IsZero() {
return 0, nil
}
if deleteBefore.IsZero() {
imdb.logger.Printf("Garbage collector deleting: %s\n",
format.FormatBytes(bytesToDelete))
} else {
imdb.logger.Printf("Garbage collector deleting: %s or before: %s\n",
format.FormatBytes(bytesToDelete), deleteBefore.Format(timeFormat))
}
imdb.Lock()
var firstEntryToDelete *unreferencedObjectsEntry
entry := imdb.unreferencedObjects.oldest
var nObjectsDeleted uint64
var nBytesDeleted uint64
for ; entry != nil && (nBytesDeleted < bytesToDelete ||
entry.object.Age.Before(deleteBefore)); entry = entry.next {
firstEntryToDelete = imdb.unreferencedObjects.oldest
delete(imdb.unreferencedObjects.hashToEntry, entry.object.Hash)
nObjectsDeleted++
nBytesDeleted += entry.object.Length
}
imdb.unreferencedObjects.totalBytes -= nBytesDeleted
imdb.unreferencedObjects.oldest = entry
if entry == nil {
imdb.unreferencedObjects.newest = nil
} else if entry.prev != nil {
entry.prev.next = nil
entry.prev = nil
}
imdb.Unlock()
if firstEntryToDelete == nil {
imdb.logger.Println("Garbage collector: nothing to delete")
return 0, nil
}
nBytesDeleted = 0
var err error
for entry := firstEntryToDelete; entry != nil; entry = entry.next {
if e := imdb.objectServer.DeleteObject(entry.object.Hash); e != nil {
if err == nil {
err = e
}
} else {
nBytesDeleted += entry.object.Length
}
}
imdb.saveUnreferencedObjectsList(true)
imdb.logger.Printf("Garbage collector deleted: %s in: %d objects\n",
format.FormatBytes(nBytesDeleted), nObjectsDeleted)
return nBytesDeleted, err
}
// This grabs and releases the lock.
func (imdb *ImageDataBase) maybeRegenerateUnreferencedObjectsList() {
imdb.RLock()
lastRegeneratedTime := imdb.unreferencedObjects.lastRegeneratedTime
imdb.RUnlock()
lastMutationTime := imdb.objectServer.LastMutationTime()
if lastMutationTime.After(lastRegeneratedTime) {
imdb.regenerateUnreferencedObjectsList()
}
}
// This grabs and releases the lock.
func (imdb *ImageDataBase) regenerateUnreferencedObjectsList() {
scanTime := time.Now()
// First generate list of currently unused objects.
objectsMap := imdb.objectServer.ListObjectSizes()
imdb.Lock()
defer imdb.Unlock()
for _, image := range imdb.imageMap {
image.ForEachObject(func(hashVal hash.Hash) error {
delete(objectsMap, hashVal)
return nil
})
}
changed := false
// Now add unused objects to cached list.
for hashVal, length := range objectsMap {
if imdb.unreferencedObjects.addObject(hashVal, length) {
changed = true
}
}
// Finally remove objects from cached list which are no longer unreferenced.
for entry := imdb.unreferencedObjects.oldest; entry != nil; {
hashVal := entry.object.Hash
entry = entry.next
if _, ok := objectsMap[hashVal]; !ok {
if imdb.unreferencedObjects.removeObject(hashVal) {
changed = true
}
}
}
if changed {
imdb.saveUnreferencedObjectsList(false)
}
imdb.unreferencedObjects.lastRegeneratedTime = scanTime
}
// This grabs and releases the lock.
func (imdb *ImageDataBase) garbageCollectorAddCallback(hashVal hash.Hash,
length uint64, isNew bool) {
imdb.Lock()
defer imdb.Unlock()
// Move added objects (whether new or old) to the back of the unreferenced
// list if they are unreferenced, as they are likely to be referenced soon.
if imdb.unreferencedObjects.removeObject(hashVal) {
imdb.unreferencedObjects.addObject(hashVal, length)
}
}
func (imdb *ImageDataBase) periodicGarbageCollector() {
if *imageServerMaxUnrefData < 1 && *imageServerMaxUnrefAge < 1 {
return
}
maxUnrefData := uint64(*imageServerMaxUnrefData)
for ; ; time.Sleep(time.Minute) {
var bytesToDelete uint64
var maxAge time.Time
imdb.RLock()
unreferencedBytes := imdb.unreferencedObjects.totalBytes
if maxUnrefData > 0 && unreferencedBytes > maxUnrefData {
bytesToDelete = unreferencedBytes - maxUnrefData
}
if *imageServerMaxUnrefAge > 0 &&
imdb.unreferencedObjects.oldest != nil {
ageLimit := time.Now().Add(-*imageServerMaxUnrefAge)
if imdb.unreferencedObjects.oldest.object.Age.Before(ageLimit) {
maxAge = ageLimit
}
}
imdb.RUnlock()
if bytesToDelete > 0 || !maxAge.IsZero() {
imdb.collectGarbage(bytesToDelete, maxAge)
}
}
}