Repository navigation
Expand file tree
/
Copy pathadmin-heal-ops.go
More file actions
776 lines (658 loc) · 21 KB
/
Copy pathadmin-heal-ops.go
File metadata and controls
776 lines (658 loc) · 21 KB
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
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
/*
* MinIO Cloud Storage, (C) 2017 MinIO, Inc.
*
* 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 cmd
import (
"context"
"encoding/json"
"fmt"
"net/http"
"strings"
"sync"
"time"
"github.com/minio/minio/cmd/logger"
"github.com/minio/minio/pkg/madmin"
)
// healStatusSummary - overall short summary of a healing sequence
type healStatusSummary string
// healStatusSummary constants
const (
healNotStartedStatus healStatusSummary = "not started"
healRunningStatus = "running"
healStoppedStatus = "stopped"
healFinishedStatus = "finished"
)
const (
// a heal sequence with this many un-consumed heal result
// items blocks until heal-status consumption resumes or is
// aborted due to timeout.
maxUnconsumedHealResultItems = 1000
// if no heal-results are consumed (via the heal-status API)
// for this timeout duration, the heal sequence is aborted.
healUnconsumedTimeout = 24 * time.Hour
// time-duration to keep heal sequence state after it
// completes.
keepHealSeqStateDuration = time.Minute * 10
)
var (
errHealIdleTimeout = fmt.Errorf("healing results were not consumed for too long")
errHealPushStopNDiscard = fmt.Errorf("heal push stopped due to heal stop signal")
errHealStopSignalled = fmt.Errorf("heal stop signaled")
errFnHealFromAPIErr = func(ctx context.Context, err error) error {
apiErr := toAPIError(ctx, err)
return fmt.Errorf("Heal internal error: %s: %s",
apiErr.Code, apiErr.Description)
}
)
// healSequenceStatus - accumulated status of the heal sequence
type healSequenceStatus struct {
// lock to update this structure as it is concurrently
// accessed
updateLock *sync.RWMutex
// summary and detail for failures
Summary healStatusSummary `json:"Summary"`
FailureDetail string `json:"Detail,omitempty"`
StartTime time.Time `json:"StartTime"`
// disk information
NumDisks int `json:"NumDisks"`
// settings for the heal sequence
HealSettings madmin.HealOpts `json:"Settings"`
// slice of available heal result records
Items []madmin.HealResultItem `json:"Items"`
}
// structure to hold state of all heal sequences in server memory
type allHealState struct {
sync.Mutex
// map of heal path to heal sequence
healSeqMap map[string]*healSequence
}
// initHealState - initialize healing apparatus
func initHealState() *allHealState {
healState := &allHealState{
healSeqMap: make(map[string]*healSequence),
}
go healState.periodicHealSeqsClean()
return healState
}
func (ahs *allHealState) periodicHealSeqsClean() {
// Launch clean-up routine to remove this heal sequence (after
// it ends) from the global state after timeout has elapsed.
ticker := time.NewTicker(time.Minute * 5)
defer ticker.Stop()
for {
select {
case <-ticker.C:
now := UTCNow()
ahs.Lock()
for path, h := range ahs.healSeqMap {
if h.hasEnded() && h.endTime.Add(keepHealSeqStateDuration).Before(now) {
delete(ahs.healSeqMap, path)
}
}
ahs.Unlock()
case <-GlobalServiceDoneCh:
// server could be restarting - need
// to exit immediately
return
}
}
}
// getHealSequenceByToken - Retrieve a heal sequence by token. The second
// argument returns if a heal sequence actually exists.
func (ahs *allHealState) getHealSequenceByToken(token string) (h *healSequence, exists bool) {
ahs.Lock()
defer ahs.Unlock()
for _, healSeq := range ahs.healSeqMap {
if healSeq.clientToken == token {
return healSeq, true
}
}
return nil, false
}
// getHealSequence - Retrieve a heal sequence by path. The second
// argument returns if a heal sequence actually exists.
func (ahs *allHealState) getHealSequence(path string) (h *healSequence, exists bool) {
ahs.Lock()
defer ahs.Unlock()
h, exists = ahs.healSeqMap[path]
return h, exists
}
func (ahs *allHealState) stopHealSequence(path string) ([]byte, APIError) {
var hsp madmin.HealStopSuccess
he, exists := ahs.getHealSequence(path)
if !exists {
hsp = madmin.HealStopSuccess{
ClientToken: "invalid",
StartTime: UTCNow(),
}
} else {
hsp = madmin.HealStopSuccess{
ClientToken: he.clientToken,
ClientAddress: he.clientAddress,
StartTime: he.startTime,
}
he.stop()
for !he.hasEnded() {
time.Sleep(1 * time.Second)
}
ahs.Lock()
defer ahs.Unlock()
// Heal sequence explicitly stopped, remove it.
delete(ahs.healSeqMap, path)
}
b, err := json.Marshal(&hsp)
return b, toAdminAPIErr(context.Background(), err)
}
// LaunchNewHealSequence - launches a background routine that performs
// healing according to the healSequence argument. For each heal
// sequence, state is stored in the `globalAllHealState`, which is a
// map of the heal path to `healSequence` which holds state about the
// heal sequence.
//
// Heal results are persisted in server memory for
// `keepHealSeqStateDuration`. This function also launches a
// background routine to clean up heal results after the
// aforementioned duration.
func (ahs *allHealState) LaunchNewHealSequence(h *healSequence) (
respBytes []byte, apiErr APIError, errMsg string) {
existsAndLive := false
he, exists := ahs.getHealSequence(h.path)
if exists {
if !he.hasEnded() || len(he.currentStatus.Items) > 0 {
existsAndLive = true
}
}
if existsAndLive {
// A heal sequence exists on the given path.
if h.forceStarted {
// stop the running heal sequence - wait for it to finish.
he.stop()
for !he.hasEnded() {
time.Sleep(1 * time.Second)
}
} else {
errMsg = "Heal is already running on the given path " +
"(use force-start option to stop and start afresh). " +
fmt.Sprintf("The heal was started by IP %s at %s, token is %s",
h.clientAddress, h.startTime.Format(http.TimeFormat), h.clientToken)
return nil, errorCodes.ToAPIErr(ErrHealAlreadyRunning), errMsg
}
}
ahs.Lock()
defer ahs.Unlock()
// Check if new heal sequence to be started overlaps with any
// existing, running sequence
for k, hSeq := range ahs.healSeqMap {
if !hSeq.hasEnded() && (strings.HasPrefix(k, h.path) ||
strings.HasPrefix(h.path, k)) {
errMsg = "The provided heal sequence path overlaps with an existing " +
fmt.Sprintf("heal path: %s", k)
return nil, errorCodes.ToAPIErr(ErrHealOverlappingPaths), errMsg
}
}
// Add heal state and start sequence
ahs.healSeqMap[h.path] = h
// Launch top-level background heal go-routine
go h.healSequenceStart()
b, err := json.Marshal(madmin.HealStartSuccess{
ClientToken: h.clientToken,
ClientAddress: h.clientAddress,
StartTime: h.startTime,
})
if err != nil {
logger.LogIf(h.ctx, err)
return nil, toAPIError(h.ctx, err), ""
}
return b, noError, ""
}
// PopHealStatusJSON - Called by heal-status API. It fetches the heal
// status results from global state and returns its JSON
// representation. The clientToken helps ensure there aren't
// conflicting clients fetching status.
func (ahs *allHealState) PopHealStatusJSON(path string,
clientToken string) ([]byte, APIErrorCode) {
// fetch heal state for given path
h, exists := ahs.getHealSequence(path)
if !exists {
// If there is no such heal sequence, return error.
return nil, ErrHealNoSuchProcess
}
// Check if client-token is valid
if clientToken != h.clientToken {
return nil, ErrHealInvalidClientToken
}
// Take lock to access and update the heal-sequence
h.currentStatus.updateLock.Lock()
defer h.currentStatus.updateLock.Unlock()
numItems := len(h.currentStatus.Items)
// calculate index of most recently available heal result
// record.
lastResultIndex := h.lastSentResultIndex
if numItems > 0 {
lastResultIndex = h.currentStatus.Items[numItems-1].ResultIndex
}
// After sending status to client, and before relinquishing
// the updateLock, reset Item to nil and record the result
// index sent to the client.
defer func(i int64) {
h.lastSentResultIndex = i
h.currentStatus.Items = nil
}(lastResultIndex)
jbytes, err := json.Marshal(h.currentStatus)
if err != nil {
logger.LogIf(h.ctx, err)
return nil, ErrInternalError
}
return jbytes, ErrNone
}
// healSequence - state for each heal sequence initiated on the
// server.
type healSequence struct {
// bucket, and prefix on which heal seq. was initiated
bucket, objPrefix string
// path is just pathJoin(bucket, objPrefix)
path string
// List of entities (format, buckets, objects) to heal
sourceCh chan string
// Report healing progress, false if this is a background
// healing since currently there is no entity which will
// receive realtime healing status
reportProgress bool
// time at which heal sequence was started
startTime time.Time
// time at which heal sequence has ended
endTime time.Time
// Heal client info
clientToken, clientAddress string
// was this heal sequence force started?
forceStarted bool
// heal settings applied to this heal sequence
settings madmin.HealOpts
// current accumulated status of the heal sequence
currentStatus healSequenceStatus
// channel signaled by background routine when traversal has
// completed
traverseAndHealDoneCh chan error
// channel to signal heal sequence to stop (e.g. from the
// heal-stop API)
stopSignalCh chan struct{}
// the last result index sent to client
lastSentResultIndex int64
// Number of total items scanned
scannedItemsCount int64
// The time of the last scan/heal activity
lastHealActivity time.Time
// Holds the request-info for logging
ctx context.Context
}
// NewHealSequence - creates healSettings, assumes bucket and
// objPrefix are already validated.
func newHealSequence(bucket, objPrefix, clientAddr string,
numDisks int, hs madmin.HealOpts, forceStart bool) *healSequence {
reqInfo := &logger.ReqInfo{RemoteHost: clientAddr, API: "Heal", BucketName: bucket}
reqInfo.AppendTags("prefix", objPrefix)
ctx := logger.SetReqInfo(context.Background(), reqInfo)
return &healSequence{
bucket: bucket,
objPrefix: objPrefix,
path: pathJoin(bucket, objPrefix),
reportProgress: true,
startTime: UTCNow(),
clientToken: mustGetUUID(),
clientAddress: clientAddr,
forceStarted: forceStart,
settings: hs,
currentStatus: healSequenceStatus{
Summary: healNotStartedStatus,
HealSettings: hs,
NumDisks: numDisks,
updateLock: &sync.RWMutex{},
},
traverseAndHealDoneCh: make(chan error),
stopSignalCh: make(chan struct{}),
ctx: ctx,
}
}
// isQuitting - determines if the heal sequence is quitting (due to an
// external signal)
func (h *healSequence) isQuitting() bool {
select {
case <-h.stopSignalCh:
return true
default:
return false
}
}
// check if the heal sequence has ended
func (h *healSequence) hasEnded() bool {
h.currentStatus.updateLock.RLock()
summary := h.currentStatus.Summary
h.currentStatus.updateLock.RUnlock()
return summary == healStoppedStatus || summary == healFinishedStatus
}
// stops the heal sequence - safe to call multiple times.
func (h *healSequence) stop() {
select {
case <-h.stopSignalCh:
default:
close(h.stopSignalCh)
}
}
// pushHealResultItem - pushes a heal result item for consumption in
// the heal-status API. It blocks if there are
// maxUnconsumedHealResultItems. When it blocks, the heal sequence
// routine is effectively paused - this happens when the server has
// accumulated the maximum number of heal records per heal
// sequence. When the client consumes further records, the heal
// sequence automatically resumes. The return value indicates if the
// operation succeeded.
func (h *healSequence) pushHealResultItem(r madmin.HealResultItem) error {
// start a timer to keep an upper time limit to find an empty
// slot to add the given heal result - if no slot is found it
// means that the server is holding the maximum amount of
// heal-results in memory and the client has not consumed it
// for too long.
unconsumedTimer := time.NewTimer(healUnconsumedTimeout)
defer func() {
// stop the timeout timer so it is garbage collected.
if !unconsumedTimer.Stop() {
<-unconsumedTimer.C
}
}()
var itemsLen int
for {
h.currentStatus.updateLock.Lock()
itemsLen = len(h.currentStatus.Items)
if itemsLen == maxUnconsumedHealResultItems {
// unlock and wait to check again if we can push
h.currentStatus.updateLock.Unlock()
// wait for a second, or quit if an external
// stop signal is received or the
// unconsumedTimer fires.
select {
// Check after a second
case <-time.After(time.Second):
continue
case <-h.stopSignalCh:
// discard result and return.
return errHealPushStopNDiscard
// Timeout if no results consumed for too
// long.
case <-unconsumedTimer.C:
return errHealIdleTimeout
}
}
break
}
// Set the correct result index for the new result item
if itemsLen > 0 {
r.ResultIndex = 1 + h.currentStatus.Items[itemsLen-1].ResultIndex
} else {
r.ResultIndex = 1 + h.lastSentResultIndex
}
// append to results
h.currentStatus.Items = append(h.currentStatus.Items, r)
// release lock
h.currentStatus.updateLock.Unlock()
// This is a "safe" point for the heal sequence to quit if
// signaled externally.
if h.isQuitting() {
return errHealStopSignalled
}
return nil
}
// healSequenceStart - this is the top-level background heal
// routine. It launches another go-routine that actually traverses
// on-disk data, checks and heals according to the selected
// settings. This go-routine itself, (1) monitors the traversal
// routine for completion, and (2) listens for external stop
// signals. When either event happens, it sets the finish status for
// the heal-sequence.
func (h *healSequence) healSequenceStart() {
// Set status as running
h.currentStatus.updateLock.Lock()
h.currentStatus.Summary = healRunningStatus
h.currentStatus.StartTime = UTCNow()
h.currentStatus.updateLock.Unlock()
if h.sourceCh == nil {
go h.traverseAndHeal()
} else {
go h.healFromSourceCh()
}
select {
case err, ok := <-h.traverseAndHealDoneCh:
h.endTime = UTCNow()
h.currentStatus.updateLock.Lock()
defer h.currentStatus.updateLock.Unlock()
// Heal traversal is complete.
if ok {
// heal traversal had an error.
h.currentStatus.Summary = healStoppedStatus
h.currentStatus.FailureDetail = err.Error()
} else {
// heal traversal succeeded.
h.currentStatus.Summary = healFinishedStatus
}
case <-h.stopSignalCh:
h.endTime = UTCNow()
h.currentStatus.updateLock.Lock()
h.currentStatus.Summary = healStoppedStatus
h.currentStatus.FailureDetail = errHealStopSignalled.Error()
h.currentStatus.updateLock.Unlock()
// drain traverse channel so the traversal
// go-routine does not leak.
go func() {
// Eventually the traversal go-routine closes
// the channel and returns, so this go-routine
// itself will not leak.
<-h.traverseAndHealDoneCh
}()
}
}
func (h *healSequence) queueHealTask(path string, healType madmin.HealItemType) error {
var respCh = make(chan healResult)
defer close(respCh)
// Send heal request
globalBackgroundHealing.queueHealTask(healTask{path: path, responseCh: respCh, opts: h.settings})
// Wait for answer and push result to the client
res := <-respCh
if !h.reportProgress {
return nil
}
res.result.Type = healType
if res.err != nil {
// Object might have been deleted, by the time heal
// was attempted, we should ignore this object and return success.
if isErrObjectNotFound(res.err) {
return nil
}
// Only report object error
if healType != madmin.HealItemObject {
return res.err
}
res.result.Detail = res.err.Error()
}
return h.pushHealResultItem(res.result)
}
func (
F2C2
h *healSequence) healItemsFromSourceCh() error {
h.lastHealActivity = UTCNow()
// Start healing the config prefix.
if err := h.healMinioSysMeta(minioConfigPrefix)(); err != nil {
logger.LogIf(h.ctx, err)
}
// Start healing the bucket config prefix.
if err := h.healMinioSysMeta(bucketConfigPrefix)(); err != nil {
logger.LogIf(h.ctx, err)
}
for path := range h.sourceCh {
var itemType madmin.HealItemType
switch {
case path == "/":
itemType = madmin.HealItemMetadata
case !strings.Contains(path, "/"):
itemType = madmin.HealItemBucket
default:
itemType = madmin.HealItemObject
}
if err := h.queueHealTask(path, itemType); err != nil {
logger.LogIf(h.ctx, err)
}
h.scannedItemsCount++
h.lastHealActivity = UTCNow()
}
return nil
}
func (h *healSequence) healFromSourceCh() {
if err := h.healItemsFromSourceCh(); err != nil {
h.traverseAndHealDoneCh <- err
}
close(h.traverseAndHealDoneCh)
}
func (h *healSequence) healItems() error {
// Start with format healing
if err := h.healDiskFormat(); err != nil {
return err
}
// Start healing the config prefix.
if err := h.healMinioSysMeta(minioConfigPrefix)(); err != nil {
return err
}
// Start healing the bucket config prefix.
if err := h.healMinioSysMeta(bucketConfigPrefix)(); err != nil {
return err
}
// Heal buckets and objects
return h.healBuckets()
}
// traverseAndHeal - traverses on-disk data and performs healing
// according to settings. At each "safe" point it also checks if an
// external quit signal has been received and quits if so. Since the
// healing traversal may be mutating on-disk data when an external
// quit signal is received, this routine cannot quit immediately and
// has to wait until a safe point is reached, such as between scanning
// two objects.
func (h *healSequence) traverseAndHeal() {
if err := h.healItems(); err != nil {
if h.isQuitting() {
err = errHealStopSignalled
}
h.traverseAndHealDoneCh <- err
}
close(h.traverseAndHealDoneCh)
}
// healMinioSysMeta - heals all files under a given meta prefix, returns a function
// which in-turn heals the respective meta directory path and any files in int.
func (h *healSequence) healMinioSysMeta(metaPrefix string) func() error {
return func() error {
// Get current object layer instance.
objectAPI := newObjectLayerFn()
if objectAPI == nil {
return errServerNotInitialized
}
// NOTE: Healing on meta is run regardless
// of any bucket being selected, this is to ensure that
// meta are always upto date and correct.
return objectAPI.HealObjects(h.ctx, minioMetaBucket, metaPrefix, func(bucket string, object string) error {
if h.isQuitting() {
return errHealStopSignalled
}
herr := h.queueHealTask(pathJoin(bucket, object), madmin.HealItemBucketMetadata)
// Object might have been deleted, by the time heal
// was attempted we ignore this object an move on.
if isErrObjectNotFound(herr) {
return nil
}
return herr
})
}
}
// healDiskFormat - heals format.json, return value indicates if a
// failure error occurred.
func (h *healSequence) healDiskFormat() error {
if h.isQuitting() {
return errHealStopSignalled
}
// Get current object layer instance.
objectAPI := newObjectLayerFn()
if objectAPI == nil {
return errServerNotInitialized
}
return h.queueHealTask("/", madmin.HealItemMetadata)
}
// healBuckets - check for all buckets heal or just particular bucket.
func (h *healSequence) healBuckets() error {
if h.isQuitting() {
return errHealStopSignalled
}
// 1. If a bucket was specified, heal only the bucket.
if h.bucket != "" {
return h.healBucket(h.bucket)
}
// Get current object layer instance.
objectAPI := newObjectLayerFn()
if objectAPI == nil {
return errServerNotInitialized
}
buckets, err := objectAPI.ListBucketsHeal(h.ctx)
if err != nil {
return errFnHealFromAPIErr(h.ctx, err)
}
for _, bucket := range buckets {
if err = h.healBucket(bucket.Name); err != nil {
return err
}
}
return nil
}
// healBucket - traverses and heals given bucket
func (h *healSequence) healBucket(bucket string) error {
// Get current object layer instance.
objectAPI := newObjectLayerFn()
if objectAPI == nil {
return errServerNotInitialized
}
if err := h.queueHealTask(bucket, madmin.HealItemBucket); err != nil {
return err
}
if !h.settings.Recursive {
if h.objPrefix != "" {
// Check if an object named as the objPrefix exists,
// and if so heal it.
_, err := objectAPI.GetObjectInfo(h.ctx, bucket, h.objPrefix, ObjectOptions{})
if err == nil {
if err = h.healObject(bucket, h.objPrefix); err != nil {
return err
}
}
}
return nil
}
if err := objectAPI.HealObjects(h.ctx, bucket, h.objPrefix, h.healObject); err != nil {
return errFnHealFromAPIErr(h.ctx, err)
}
return nil
}
// healObject - heal the given object and record result
func (h *healSequence) healObject(bucket, object string) error {
if h.isQuitting() {
return errHealStopSignalled
}
// Get current object layer instance.
objectAPI := newObjectLayerFn()
if objectAPI == nil {
return errServerNotInitialized
}
return h.queueHealTask(pathJoin(bucket, object), madmin.HealItemObject)
}