summaryrefslogtreecommitdiffstats
path: root/dom/storage/DOMStorageCache.cpp
blob: 34a50259ddc653caa40444b484262ffc5f5f918e (plain)
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
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "DOMStorageCache.h"

#include "DOMStorage.h"
#include "DOMStorageDBThread.h"
#include "DOMStorageIPC.h"
#include "DOMStorageManager.h"

#include "nsAutoPtr.h"
#include "nsDOMString.h"
#include "nsXULAppAPI.h"
#include "mozilla/Unused.h"
#include "nsProxyRelease.h"
#include "nsThreadUtils.h"

namespace mozilla {
namespace dom {

#define DOM_STORAGE_CACHE_KEEP_ALIVE_TIME_MS 20000

// static
DOMStorageDBBridge* DOMStorageCache::sDatabase = nullptr;
bool DOMStorageCache::sDatabaseDown = false;

namespace {

const uint32_t kDefaultSet = 0;
const uint32_t kPrivateSet = 1;
const uint32_t kSessionSet = 2;

inline uint32_t
GetDataSetIndex(bool aPrivate, bool aSessionOnly)
{
  if (aPrivate) {
    return kPrivateSet;
  }

  if (aSessionOnly) {
    return kSessionSet;
  }

  return kDefaultSet;
}

inline uint32_t
GetDataSetIndex(const DOMStorage* aStorage)
{
  return GetDataSetIndex(aStorage->IsPrivate(), aStorage->IsSessionOnly());
}

} // namespace

// DOMStorageCacheBridge

NS_IMPL_ADDREF(DOMStorageCacheBridge)

// Since there is no consumer of return value of Release, we can turn this 
// method to void to make implementation of asynchronous DOMStorageCache::Release
// much simpler.
NS_IMETHODIMP_(void) DOMStorageCacheBridge::Release(void)
{
  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
  nsrefcnt count = --mRefCnt;
  NS_LOG_RELEASE(this, count, "DOMStorageCacheBridge");
  if (0 == count) {
    mRefCnt = 1; /* stabilize */
    /* enable this to find non-threadsafe destructors: */
    /* NS_ASSERT_OWNINGTHREAD(_class); */
    delete (this);
  }
}

// DOMStorageCache

DOMStorageCache::DOMStorageCache(const nsACString* aOriginNoSuffix)
: mOriginNoSuffix(*aOriginNoSuffix)
, mMonitor("DOMStorageCache")
, mLoaded(false)
, mLoadResult(NS_OK)
, mInitialized(false)
, mPersistent(false)
, mSessionOnlyDataSetActive(false)
{
  MOZ_COUNT_CTOR(DOMStorageCache);
}

DOMStorageCache::~DOMStorageCache()
{
  if (mManager) {
    mManager->DropCache(this);
  }

  MOZ_COUNT_DTOR(DOMStorageCache);
}

NS_IMETHODIMP_(void)
DOMStorageCache::Release(void)
{
  // We must actually release on the main thread since the cache removes it
  // self from the manager's hash table.  And we don't want to lock access to
  // that hash table.
  if (NS_IsMainThread()) {
    DOMStorageCacheBridge::Release();
    return;
  }

  RefPtr<nsRunnableMethod<DOMStorageCacheBridge, void, false> > event =
    NewNonOwningRunnableMethod(static_cast<DOMStorageCacheBridge*>(this),
                               &DOMStorageCacheBridge::Release);

  nsresult rv = NS_DispatchToMainThread(event);
  if (NS_FAILED(rv)) {
    NS_WARNING("DOMStorageCache::Release() on a non-main thread");
    DOMStorageCacheBridge::Release();
  }
}

void
DOMStorageCache::Init(DOMStorageManager* aManager,
                      bool aPersistent,
                      nsIPrincipal* aPrincipal,
                      const nsACString& aQuotaOriginScope)
{
  if (mInitialized) {
    return;
  }

  mInitialized = true;
  mPrincipal = aPrincipal;
  BasePrincipal::Cast(aPrincipal)->OriginAttributesRef().CreateSuffix(mOriginSuffix);
  mPersistent = aPersistent;
  if (aQuotaOriginScope.IsEmpty()) {
    mQuotaOriginScope = Origin();
  } else {
    mQuotaOriginScope = aQuotaOriginScope;
  }

  if (mPersistent) {
    mManager = aManager;
    Preload();
  }

  // Check the quota string has (or has not) the identical origin suffix as
  // this storage cache is bound to.
  MOZ_ASSERT(StringBeginsWith(mQuotaOriginScope, mOriginSuffix));
  MOZ_ASSERT(mOriginSuffix.IsEmpty() != StringBeginsWith(mQuotaOriginScope, 
                                                         NS_LITERAL_CSTRING("^")));

  mUsage = aManager->GetOriginUsage(mQuotaOriginScope);
}

inline bool
DOMStorageCache::Persist(const DOMStorage* aStorage) const
{
  return mPersistent &&
         !aStorage->IsSessionOnly() &&
         !aStorage->IsPrivate();
}

const nsCString
DOMStorageCache::Origin() const
{
  return DOMStorageManager::CreateOrigin(mOriginSuffix, mOriginNoSuffix);
}

DOMStorageCache::Data&
DOMStorageCache::DataSet(const DOMStorage* aStorage)
{
  uint32_t index = GetDataSetIndex(aStorage);

  if (index == kSessionSet && !mSessionOnlyDataSetActive) {
    // Session only data set is demanded but not filled with
    // current data set, copy to session only set now.

    WaitForPreload();

    Data& defaultSet = mData[kDefaultSet];
    Data& sessionSet = mData[kSessionSet];

    for (auto iter = defaultSet.mKeys.Iter(); !iter.Done(); iter.Next()) {
      sessionSet.mKeys.Put(iter.Key(), iter.UserData());
    }

    mSessionOnlyDataSetActive = true;

    // This updates sessionSet.mOriginQuotaUsage and also updates global usage
    // for all session only data
    ProcessUsageDelta(kSessionSet, defaultSet.mOriginQuotaUsage);
  }

  return mData[index];
}

bool
DOMStorageCache::ProcessUsageDelta(const DOMStorage* aStorage, int64_t aDelta)
{
  return ProcessUsageDelta(GetDataSetIndex(aStorage), aDelta);
}

bool
DOMStorageCache::ProcessUsageDelta(uint32_t aGetDataSetIndex, const int64_t aDelta)
{
  // Check limit per this origin
  Data& data = mData[aGetDataSetIndex];
  uint64_t newOriginUsage = data.mOriginQuotaUsage + aDelta;
  if (aDelta > 0 && newOriginUsage > DOMStorageManager::GetQuota()) {
    return false;
  }

  // Now check eTLD+1 limit
  if (mUsage && !mUsage->CheckAndSetETLD1UsageDelta(aGetDataSetIndex, aDelta)) {
    return false;
  }

  // Update size in our data set
  data.mOriginQuotaUsage = newOriginUsage;
  return true;
}

void
DOMStorageCache::Preload()
{
  if (mLoaded || !mPersistent) {
    return;
  }

  if (!StartDatabase()) {
    mLoaded = true;
    mLoadResult = NS_ERROR_FAILURE;
    return;
  }

  sDatabase->AsyncPreload(this);
}

namespace {

// This class is passed to timer as a tick observer.  It refers the cache
// and keeps it alive for a time.
class DOMStorageCacheHolder : public nsITimerCallback
{
  virtual ~DOMStorageCacheHolder() {}

  NS_DECL_ISUPPORTS

  NS_IMETHOD
  Notify(nsITimer* aTimer) override
  {
    mCache = nullptr;
    return NS_OK;
  }

  RefPtr<DOMStorageCache> mCache;

public:
  explicit DOMStorageCacheHolder(DOMStorageCache* aCache) : mCache(aCache) {}
};

NS_IMPL_ISUPPORTS(DOMStorageCacheHolder, nsITimerCallback)

} // namespace

void
DOMStorageCache::KeepAlive()
{
  // Missing reference back to the manager means the cache is not responsible
  // for its lifetime.  Used for keeping sessionStorage live forever.
  if (!mManager) {
    return;
  }

  if (!NS_IsMainThread()) {
    // Timer and the holder must be initialized on the main thread.
    NS_DispatchToMainThread(NewRunnableMethod(this, &DOMStorageCache::KeepAlive));
    return;
  }

  nsCOMPtr<nsITimer> timer = do_CreateInstance("@mozilla.org/timer;1");
  if (!timer) {
    return;
  }

  RefPtr<DOMStorageCacheHolder> holder = new DOMStorageCacheHolder(this);
  timer->InitWithCallback(holder, DOM_STORAGE_CACHE_KEEP_ALIVE_TIME_MS,
                          nsITimer::TYPE_ONE_SHOT);

  mKeepAliveTimer.swap(timer);
}

void
DOMStorageCache::WaitForPreload()
{
  if (!mPersistent) {
    return;
  }

  bool loaded = mLoaded;
  if (loaded) {
    return;
  }

  // If preload already started (i.e. we got some first data, but not all)
  // SyncPreload will just wait for it to finish rather then synchronously
  // read from the database.  It seems to me more optimal.

  // TODO place for A/B testing (force main thread load vs. let preload finish)

  // No need to check sDatabase for being non-null since preload is either
  // done before we've shut the DB down or when the DB could not start,
  // preload has not even be started.
  sDatabase->SyncPreload(this);
}

nsresult
DOMStorageCache::GetLength(const DOMStorage* aStorage, uint32_t* aRetval)
{
  if (Persist(aStorage)) {
    WaitForPreload();
    if (NS_FAILED(mLoadResult)) {
      return mLoadResult;
    }
  }

  *aRetval = DataSet(aStorage).mKeys.Count();
  return NS_OK;
}

nsresult
DOMStorageCache::GetKey(const DOMStorage* aStorage, uint32_t aIndex, nsAString& aRetval)
{
  // XXX: This does a linear search for the key at index, which would
  // suck if there's a large numer of indexes. Do we care? If so,
  // maybe we need to have a lazily populated key array here or
  // something?
  if (Persist(aStorage)) {
    WaitForPreload();
    if (NS_FAILED(mLoadResult)) {
      return mLoadResult;
    }
  }

  aRetval.SetIsVoid(true);
  for (auto iter = DataSet(aStorage).mKeys.Iter(); !iter.Done(); iter.Next()) {
    if (aIndex == 0) {
      aRetval = iter.Key();
      break;
    }
    aIndex--;
  }

  return NS_OK;
}

void
DOMStorageCache::GetKeys(const DOMStorage* aStorage, nsTArray<nsString>& aKeys)
{
  if (Persist(aStorage)) {
    WaitForPreload();
  }

  if (NS_FAILED(mLoadResult)) {
    return;
  }

  for (auto iter = DataSet(aStorage).mKeys.Iter(); !iter.Done(); iter.Next()) {
    aKeys.AppendElement(iter.Key());
  }
}

nsresult
DOMStorageCache::GetItem(const DOMStorage* aStorage, const nsAString& aKey,
                         nsAString& aRetval)
{
  if (Persist(aStorage)) {
    WaitForPreload();
    if (NS_FAILED(mLoadResult)) {
      return mLoadResult;
    }
  }

  // not using AutoString since we don't want to copy buffer to result
  nsString value;
  if (!DataSet(aStorage).mKeys.Get(aKey, &value)) {
    SetDOMStringToNull(value);
  }

  aRetval = value;

  return NS_OK;
}

nsresult
DOMStorageCache::SetItem(const DOMStorage* aStorage, const nsAString& aKey,
                         const nsString& aValue, nsString& aOld)
{
  // Size of the cache that will change after this action.
  int64_t delta = 0;

  if (Persist(aStorage)) {
    WaitForPreload();
    if (NS_FAILED(mLoadResult)) {
      return mLoadResult;
    }
  }

  Data& data = DataSet(aStorage);
  if (!data.mKeys.Get(aKey, &aOld)) {
    SetDOMStringToNull(aOld);

    // We only consider key size if the key doesn't exist before.
    delta += static_cast<int64_t>(aKey.Length());
  }

  delta += static_cast<int64_t>(aValue.Length()) -
           static_cast<int64_t>(aOld.Length());

  if (!ProcessUsageDelta(aStorage, delta)) {
    return NS_ERROR_DOM_QUOTA_REACHED;
  }

  if (aValue == aOld && DOMStringIsNull(aValue) == DOMStringIsNull(aOld)) {
    return NS_SUCCESS_DOM_NO_OPERATION;
  }

  data.mKeys.Put(aKey, aValue);

  if (Persist(aStorage)) {
    if (!sDatabase) {
      NS_ERROR("Writing to localStorage after the database has been shut down"
               ", data lose!");
      return NS_ERROR_NOT_INITIALIZED;
    }

    if (DOMStringIsNull(aOld)) {
      return sDatabase->AsyncAddItem(this, aKey, aValue);
    }

    return sDatabase->AsyncUpdateItem(this, aKey, aValue);
  }

  return NS_OK;
}

nsresult
DOMStorageCache::RemoveItem(const DOMStorage* aStorage, const nsAString& aKey,
                            nsString& aOld)
{
  if (Persist(aStorage)) {
    WaitForPreload();
    if (NS_FAILED(mLoadResult)) {
      return mLoadResult;
    }
  }

  Data& data = DataSet(aStorage);
  if (!data.mKeys.Get(aKey, &aOld)) {
    SetDOMStringToNull(aOld);
    return NS_SUCCESS_DOM_NO_OPERATION;
  }

  // Recalculate the cached data size
  const int64_t delta = -(static_cast<int64_t>(aOld.Length()) +
                          static_cast<int64_t>(aKey.Length()));
  Unused << ProcessUsageDelta(aStorage, delta);
  data.mKeys.Remove(aKey);

  if (Persist(aStorage)) {
    if (!sDatabase) {
      NS_ERROR("Writing to localStorage after the database has been shut down"
               ", data lose!");
      return NS_ERROR_NOT_INITIALIZED;
    }

    return sDatabase->AsyncRemoveItem(this, aKey);
  }

  return NS_OK;
}

nsresult
DOMStorageCache::Clear(const DOMStorage* aStorage)
{
  bool refresh = false;
  if (Persist(aStorage)) {
    // We need to preload all data (know the size) before we can proceeed
    // to correctly decrease cached usage number.
    // XXX as in case of unload, this is not technically needed now, but
    // after super-scope quota introduction we have to do this.
    WaitForPreload();
    if (NS_FAILED(mLoadResult)) {
      // When we failed to load data from the database, force delete of the
      // scope data and make use of the storage possible again.
      refresh = true;
      mLoadResult = NS_OK;
    }
  }

  Data& data = DataSet(aStorage);
  bool hadData = !!data.mKeys.Count();

  if (hadData) {
    Unused << ProcessUsageDelta(aStorage, -data.mOriginQuotaUsage);
    data.mKeys.Clear();
  }

  if (Persist(aStorage) && (refresh || hadData)) {
    if (!sDatabase) {
      NS_ERROR("Writing to localStorage after the database has been shut down"
               ", data lose!");
      return NS_ERROR_NOT_INITIALIZED;
    }

    return sDatabase->AsyncClear(this);
  }

  return hadData ? NS_OK : NS_SUCCESS_DOM_NO_OPERATION;
}

void
DOMStorageCache::CloneFrom(const DOMStorageCache* aThat)
{
  // This will never be called on anything else than SessionStorage.
  // This means mData will never be touched on any other thread than
  // the main thread and it never went through the loading process.
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(!mPersistent);
  MOZ_ASSERT(!(bool)aThat->mLoaded);

  mLoaded = false;
  mInitialized = aThat->mInitialized;
  mPersistent = false;
  mSessionOnlyDataSetActive = aThat->mSessionOnlyDataSetActive;

  for (uint32_t i = 0; i < kDataSetCount; ++i) {
    for (auto it = aThat->mData[i].mKeys.ConstIter(); !it.Done(); it.Next()) {
      mData[i].mKeys.Put(it.Key(), it.UserData());
    }
    ProcessUsageDelta(i, aThat->mData[i].mOriginQuotaUsage);
  }
}

// Defined in DOMStorageManager.cpp
extern bool
PrincipalsEqual(nsIPrincipal* aObjectPrincipal, nsIPrincipal* aSubjectPrincipal);

bool
DOMStorageCache::CheckPrincipal(nsIPrincipal* aPrincipal) const
{
  return PrincipalsEqual(mPrincipal, aPrincipal);
}

void
DOMStorageCache::UnloadItems(uint32_t aUnloadFlags)
{
  if (aUnloadFlags & kUnloadDefault) {
    // Must wait for preload to pass correct usage to ProcessUsageDelta
    // XXX this is not technically needed right now since there is just
    // per-origin isolated quota handling, but when we introduce super-
    // -scope quotas, we have to do this.
    WaitForPreload();

    mData[kDefaultSet].mKeys.Clear();
    ProcessUsageDelta(kDefaultSet, -mData[kDefaultSet].mOriginQuotaUsage);
  }

  if (aUnloadFlags & kUnloadPrivate) {
    mData[kPrivateSet].mKeys.Clear();
    ProcessUsageDelta(kPrivateSet, -mData[kPrivateSet].mOriginQuotaUsage);
  }

  if (aUnloadFlags & kUnloadSession) {
    mData[kSessionSet].mKeys.Clear();
    ProcessUsageDelta(kSessionSet, -mData[kSessionSet].mOriginQuotaUsage);
    mSessionOnlyDataSetActive = false;
  }

#ifdef DOM_STORAGE_TESTS
  if (aUnloadFlags & kTestReload) {
    WaitForPreload();

    mData[kDefaultSet].mKeys.Clear();
    mLoaded = false; // This is only used in testing code
    Preload();
  }
#endif
}

// DOMStorageCacheBridge

uint32_t
DOMStorageCache::LoadedCount()
{
  MonitorAutoLock monitor(mMonitor);
  Data& data = mData[kDefaultSet];
  return data.mKeys.Count();
}

bool
DOMStorageCache::LoadItem(const nsAString& aKey, const nsString& aValue)
{
  MonitorAutoLock monitor(mMonitor);
  if (mLoaded) {
    return false;
  }

  Data& data = mData[kDefaultSet];
  if (data.mKeys.Get(aKey, nullptr)) {
    return true; // don't stop, just don't override
  }

  data.mKeys.Put(aKey, aValue);
  data.mOriginQuotaUsage += aKey.Length() + aValue.Length();
  return true;
}

void
DOMStorageCache::LoadDone(nsresult aRv)
{
  // Keep the preloaded cache alive for a time
  KeepAlive();

  MonitorAutoLock monitor(mMonitor);
  mLoadResult = aRv;
  mLoaded = true;
  monitor.Notify();
}

void
DOMStorageCache::LoadWait()
{
  MonitorAutoLock monitor(mMonitor);
  while (!mLoaded) {
    monitor.Wait();
  }
}

// DOMStorageUsage

DOMStorageUsage::DOMStorageUsage(const nsACString& aOriginScope)
  : mOriginScope(aOriginScope)
{
  mUsage[kDefaultSet] = mUsage[kPrivateSet] = mUsage[kSessionSet] = 0LL;
}

namespace {

class LoadUsageRunnable : public Runnable
{
public:
  LoadUsageRunnable(int64_t* aUsage, const int64_t aDelta)
    : mTarget(aUsage)
    , mDelta(aDelta)
  {}

private:
  int64_t* mTarget;
  int64_t mDelta;

  NS_IMETHOD Run() override { *mTarget = mDelta; return NS_OK; }
};

} // namespace

void
DOMStorageUsage::LoadUsage(const int64_t aUsage)
{
  // Using kDefaultSet index since it is the index for the persitent data
  // stored in the database we have just loaded usage for.
  if (!NS_IsMainThread()) {
    // In single process scenario we get this call from the DB thread
    RefPtr<LoadUsageRunnable> r =
      new LoadUsageRunnable(mUsage + kDefaultSet, aUsage);
    NS_DispatchToMainThread(r);
  } else {
    // On a child process we get this on the main thread already
    mUsage[kDefaultSet] += aUsage;
  }
}

bool
DOMStorageUsage::CheckAndSetETLD1UsageDelta(uint32_t aDataSetIndex, const int64_t aDelta)
{
  MOZ_ASSERT(NS_IsMainThread());

  int64_t newUsage = mUsage[aDataSetIndex] + aDelta;
  if (aDelta > 0 && newUsage > DOMStorageManager::GetQuota()) {
    return false;
  }

  mUsage[aDataSetIndex] = newUsage;
  return true;
}


// static
DOMStorageDBBridge*
DOMStorageCache::StartDatabase()
{
  if (sDatabase || sDatabaseDown) {
    // When sDatabaseDown is at true, sDatabase is null.
    // Checking sDatabaseDown flag here prevents reinitialization of
    // the database after shutdown.
    return sDatabase;
  }

  if (XRE_IsParentProcess()) {
    nsAutoPtr<DOMStorageDBThread> db(new DOMStorageDBThread());

    nsresult rv = db->Init();
    if (NS_FAILED(rv)) {
      return nullptr;
    }

    sDatabase = db.forget();
  } else {
    // Use DOMLocalStorageManager::Ensure in case we're called from
    // DOMSessionStorageManager's initializer and we haven't yet initialized the
    // local storage manager.
    RefPtr<DOMStorageDBChild> db = new DOMStorageDBChild(
        DOMLocalStorageManager::Ensure());

    nsresult rv = db->Init();
    if (NS_FAILED(rv)) {
      return nullptr;
    }

    db.forget(&sDatabase);
  }

  return sDatabase;
}

// static
DOMStorageDBBridge*
DOMStorageCache::GetDatabase()
{
  return sDatabase;
}

// static
nsresult
DOMStorageCache::StopDatabase()
{
  if (!sDatabase) {
    return NS_OK;
  }

  sDatabaseDown = true;

  nsresult rv = sDatabase->Shutdown();
  if (XRE_IsParentProcess()) {
    delete sDatabase;
  } else {
    DOMStorageDBChild* child = static_cast<DOMStorageDBChild*>(sDatabase);
    NS_RELEASE(child);
  }

  sDatabase = nullptr;
  return rv;
}

} // namespace dom
} // namespace mozilla