backend_impl.cc revision 46d4c2bc3267f3f028f39e7e311b0f89aba2e4fd 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "net/disk_cache/blockfile/backend_impl.h"
6
7#include "base/bind.h"
8#include "base/bind_helpers.h"
9#include "base/file_util.h"
10#include "base/files/file.h"
11#include "base/files/file_path.h"
12#include "base/hash.h"
13#include "base/message_loop/message_loop.h"
14#include "base/metrics/field_trial.h"
15#include "base/metrics/histogram.h"
16#include "base/metrics/stats_counters.h"
17#include "base/rand_util.h"
18#include "base/strings/string_util.h"
19#include "base/strings/stringprintf.h"
20#include "base/sys_info.h"
21#include "base/threading/thread_restrictions.h"
22#include "base/time/time.h"
23#include "base/timer/timer.h"
24#include "net/base/net_errors.h"
25#include "net/disk_cache/blockfile/disk_format.h"
26#include "net/disk_cache/blockfile/entry_impl.h"
27#include "net/disk_cache/blockfile/errors.h"
28#include "net/disk_cache/blockfile/experiments.h"
29#include "net/disk_cache/blockfile/file.h"
30#include "net/disk_cache/blockfile/histogram_macros.h"
31#include "net/disk_cache/blockfile/webfonts_histogram.h"
32#include "net/disk_cache/cache_util.h"
33
34// Provide a BackendImpl object to macros from histogram_macros.h.
35#define CACHE_UMA_BACKEND_IMPL_OBJ this
36
37using base::Time;
38using base::TimeDelta;
39using base::TimeTicks;
40
41namespace {
42
43const char* kIndexName = "index";
44
45// Seems like ~240 MB correspond to less than 50k entries for 99% of the people.
46// Note that the actual target is to keep the index table load factor under 55%
47// for most users.
48const int k64kEntriesStore = 240 * 1000 * 1000;
49const int kBaseTableLen = 64 * 1024;
50
51// Avoid trimming the cache for the first 5 minutes (10 timer ticks).
52const int kTrimDelay = 10;
53
54int DesiredIndexTableLen(int32 storage_size) {
55  if (storage_size <= k64kEntriesStore)
56    return kBaseTableLen;
57  if (storage_size <= k64kEntriesStore * 2)
58    return kBaseTableLen * 2;
59  if (storage_size <= k64kEntriesStore * 4)
60    return kBaseTableLen * 4;
61  if (storage_size <= k64kEntriesStore * 8)
62    return kBaseTableLen * 8;
63
64  // The biggest storage_size for int32 requires a 4 MB table.
65  return kBaseTableLen * 16;
66}
67
68int MaxStorageSizeForTable(int table_len) {
69  return table_len * (k64kEntriesStore / kBaseTableLen);
70}
71
72size_t GetIndexSize(int table_len) {
73  size_t table_size = sizeof(disk_cache::CacheAddr) * table_len;
74  return sizeof(disk_cache::IndexHeader) + table_size;
75}
76
77// ------------------------------------------------------------------------
78
79// Sets group for the current experiment. Returns false if the files should be
80// discarded.
81bool InitExperiment(disk_cache::IndexHeader* header, bool cache_created) {
82  if (header->experiment == disk_cache::EXPERIMENT_OLD_FILE1 ||
83      header->experiment == disk_cache::EXPERIMENT_OLD_FILE2) {
84    // Discard current cache.
85    return false;
86  }
87
88  if (base::FieldTrialList::FindFullName("SimpleCacheTrial") ==
89          "ExperimentControl") {
90    if (cache_created) {
91      header->experiment = disk_cache::EXPERIMENT_SIMPLE_CONTROL;
92      return true;
93    }
94    return header->experiment == disk_cache::EXPERIMENT_SIMPLE_CONTROL;
95  }
96
97  header->experiment = disk_cache::NO_EXPERIMENT;
98  return true;
99}
100
101// A callback to perform final cleanup on the background thread.
102void FinalCleanupCallback(disk_cache::BackendImpl* backend) {
103  backend->CleanupCache();
104}
105
106}  // namespace
107
108// ------------------------------------------------------------------------
109
110namespace disk_cache {
111
112BackendImpl::BackendImpl(const base::FilePath& path,
113                         base::MessageLoopProxy* cache_thread,
114                         net::NetLog* net_log)
115    : background_queue_(this, cache_thread),
116      path_(path),
117      block_files_(path),
118      mask_(0),
119      max_size_(0),
120      up_ticks_(0),
121      cache_type_(net::DISK_CACHE),
122      uma_report_(0),
123      user_flags_(0),
124      init_(false),
125      restarted_(false),
126      unit_test_(false),
127      read_only_(false),
128      disabled_(false),
129      new_eviction_(false),
130      first_timer_(true),
131      user_load_(false),
132      net_log_(net_log),
133      done_(true, false),
134      ptr_factory_(this) {
135}
136
137BackendImpl::BackendImpl(const base::FilePath& path,
138                         uint32 mask,
139                         base::MessageLoopProxy* cache_thread,
140                         net::NetLog* net_log)
141    : background_queue_(this, cache_thread),
142      path_(path),
143      block_files_(path),
144      mask_(mask),
145      max_size_(0),
146      up_ticks_(0),
147      cache_type_(net::DISK_CACHE),
148      uma_report_(0),
149      user_flags_(kMask),
150      init_(false),
151      restarted_(false),
152      unit_test_(false),
153      read_only_(false),
154      disabled_(false),
155      new_eviction_(false),
156      first_timer_(true),
157      user_load_(false),
158      net_log_(net_log),
159      done_(true, false),
160      ptr_factory_(this) {
161}
162
163BackendImpl::~BackendImpl() {
164  if (user_flags_ & kNoRandom) {
165    // This is a unit test, so we want to be strict about not leaking entries
166    // and completing all the work.
167    background_queue_.WaitForPendingIO();
168  } else {
169    // This is most likely not a test, so we want to do as little work as
170    // possible at this time, at the price of leaving dirty entries behind.
171    background_queue_.DropPendingIO();
172  }
173
174  if (background_queue_.BackgroundIsCurrentThread()) {
175    // Unit tests may use the same thread for everything.
176    CleanupCache();
177  } else {
178    background_queue_.background_thread()->PostTask(
179        FROM_HERE, base::Bind(&FinalCleanupCallback, base::Unretained(this)));
180    // http://crbug.com/74623
181    base::ThreadRestrictions::ScopedAllowWait allow_wait;
182    done_.Wait();
183  }
184}
185
186int BackendImpl::Init(const CompletionCallback& callback) {
187  background_queue_.Init(callback);
188  return net::ERR_IO_PENDING;
189}
190
191int BackendImpl::SyncInit() {
192#if defined(NET_BUILD_STRESS_CACHE)
193  // Start evictions right away.
194  up_ticks_ = kTrimDelay * 2;
195#endif
196  DCHECK(!init_);
197  if (init_)
198    return net::ERR_FAILED;
199
200  bool create_files = false;
201  if (!InitBackingStore(&create_files)) {
202    ReportError(ERR_STORAGE_ERROR);
203    return net::ERR_FAILED;
204  }
205
206  num_refs_ = num_pending_io_ = max_refs_ = 0;
207  entry_count_ = byte_count_ = 0;
208
209  bool should_create_timer = false;
210  if (!restarted_) {
211    buffer_bytes_ = 0;
212    trace_object_ = TraceObject::GetTraceObject();
213    should_create_timer = true;
214  }
215
216  init_ = true;
217  Trace("Init");
218
219  if (data_->header.experiment != NO_EXPERIMENT &&
220      cache_type_ != net::DISK_CACHE) {
221    // No experiment for other caches.
222    return net::ERR_FAILED;
223  }
224
225  if (!(user_flags_ & kNoRandom)) {
226    // The unit test controls directly what to test.
227    new_eviction_ = (cache_type_ == net::DISK_CACHE);
228  }
229
230  if (!CheckIndex()) {
231    ReportError(ERR_INIT_FAILED);
232    return net::ERR_FAILED;
233  }
234
235  if (!restarted_ && (create_files || !data_->header.num_entries))
236    ReportError(ERR_CACHE_CREATED);
237
238  if (!(user_flags_ & kNoRandom) && cache_type_ == net::DISK_CACHE &&
239      !InitExperiment(&data_->header, create_files)) {
240    return net::ERR_FAILED;
241  }
242
243  // We don't care if the value overflows. The only thing we care about is that
244  // the id cannot be zero, because that value is used as "not dirty".
245  // Increasing the value once per second gives us many years before we start
246  // having collisions.
247  data_->header.this_id++;
248  if (!data_->header.this_id)
249    data_->header.this_id++;
250
251  bool previous_crash = (data_->header.crash != 0);
252  data_->header.crash = 1;
253
254  if (!block_files_.Init(create_files))
255    return net::ERR_FAILED;
256
257  // We want to minimize the changes to cache for an AppCache.
258  if (cache_type() == net::APP_CACHE) {
259    DCHECK(!new_eviction_);
260    read_only_ = true;
261  } else if (cache_type() == net::SHADER_CACHE) {
262    DCHECK(!new_eviction_);
263  }
264
265  eviction_.Init(this);
266
267  // stats_ and rankings_ may end up calling back to us so we better be enabled.
268  disabled_ = false;
269  if (!InitStats())
270    return net::ERR_FAILED;
271
272  disabled_ = !rankings_.Init(this, new_eviction_);
273
274#if defined(STRESS_CACHE_EXTENDED_VALIDATION)
275  trace_object_->EnableTracing(false);
276  int sc = SelfCheck();
277  if (sc < 0 && sc != ERR_NUM_ENTRIES_MISMATCH)
278    NOTREACHED();
279  trace_object_->EnableTracing(true);
280#endif
281
282  if (previous_crash) {
283    ReportError(ERR_PREVIOUS_CRASH);
284  } else if (!restarted_) {
285    ReportError(ERR_NO_ERROR);
286  }
287
288  FlushIndex();
289
290  if (!disabled_ && should_create_timer) {
291    // Create a recurrent timer of 30 secs.
292    int timer_delay = unit_test_ ? 1000 : 30000;
293    timer_.reset(new base::RepeatingTimer<BackendImpl>());
294    timer_->Start(FROM_HERE, TimeDelta::FromMilliseconds(timer_delay), this,
295                  &BackendImpl::OnStatsTimer);
296  }
297
298  return disabled_ ? net::ERR_FAILED : net::OK;
299}
300
301void BackendImpl::CleanupCache() {
302  Trace("Backend Cleanup");
303  eviction_.Stop();
304  timer_.reset();
305
306  if (init_) {
307    StoreStats();
308    if (data_)
309      data_->header.crash = 0;
310
311    if (user_flags_ & kNoRandom) {
312      // This is a net_unittest, verify that we are not 'leaking' entries.
313      File::WaitForPendingIO(&num_pending_io_);
314      DCHECK(!num_refs_);
315    } else {
316      File::DropPendingIO();
317    }
318  }
319  block_files_.CloseFiles();
320  FlushIndex();
321  index_ = NULL;
322  ptr_factory_.InvalidateWeakPtrs();
323  done_.Signal();
324}
325
326// ------------------------------------------------------------------------
327
328int BackendImpl::OpenPrevEntry(void** iter, Entry** prev_entry,
329                               const CompletionCallback& callback) {
330  DCHECK(!callback.is_null());
331  background_queue_.OpenPrevEntry(iter, prev_entry, callback);
332  return net::ERR_IO_PENDING;
333}
334
335int BackendImpl::SyncOpenEntry(const std::string& key, Entry** entry) {
336  DCHECK(entry);
337  *entry = OpenEntryImpl(key);
338  return (*entry) ? net::OK : net::ERR_FAILED;
339}
340
341int BackendImpl::SyncCreateEntry(const std::string& key, Entry** entry) {
342  DCHECK(entry);
343  *entry = CreateEntryImpl(key);
344  return (*entry) ? net::OK : net::ERR_FAILED;
345}
346
347int BackendImpl::SyncDoomEntry(const std::string& key) {
348  if (disabled_)
349    return net::ERR_FAILED;
350
351  EntryImpl* entry = OpenEntryImpl(key);
352  if (!entry)
353    return net::ERR_FAILED;
354
355  entry->DoomImpl();
356  entry->Release();
357  return net::OK;
358}
359
360int BackendImpl::SyncDoomAllEntries() {
361  // This is not really an error, but it is an interesting condition.
362  ReportError(ERR_CACHE_DOOMED);
363  stats_.OnEvent(Stats::DOOM_CACHE);
364  if (!num_refs_) {
365    RestartCache(false);
366    return disabled_ ? net::ERR_FAILED : net::OK;
367  } else {
368    if (disabled_)
369      return net::ERR_FAILED;
370
371    eviction_.TrimCache(true);
372    return net::OK;
373  }
374}
375
376int BackendImpl::SyncDoomEntriesBetween(const base::Time initial_time,
377                                        const base::Time end_time) {
378  DCHECK_NE(net::APP_CACHE, cache_type_);
379  if (end_time.is_null())
380    return SyncDoomEntriesSince(initial_time);
381
382  DCHECK(end_time >= initial_time);
383
384  if (disabled_)
385    return net::ERR_FAILED;
386
387  EntryImpl* node;
388  void* iter = NULL;
389  EntryImpl* next = OpenNextEntryImpl(&iter);
390  if (!next)
391    return net::OK;
392
393  while (next) {
394    node = next;
395    next = OpenNextEntryImpl(&iter);
396
397    if (node->GetLastUsed() >= initial_time &&
398        node->GetLastUsed() < end_time) {
399      node->DoomImpl();
400    } else if (node->GetLastUsed() < initial_time) {
401      if (next)
402        next->Release();
403      next = NULL;
404      SyncEndEnumeration(iter);
405    }
406
407    node->Release();
408  }
409
410  return net::OK;
411}
412
413// We use OpenNextEntryImpl to retrieve elements from the cache, until we get
414// entries that are too old.
415int BackendImpl::SyncDoomEntriesSince(const base::Time initial_time) {
416  DCHECK_NE(net::APP_CACHE, cache_type_);
417  if (disabled_)
418    return net::ERR_FAILED;
419
420  stats_.OnEvent(Stats::DOOM_RECENT);
421  for (;;) {
422    void* iter = NULL;
423    EntryImpl* entry = OpenNextEntryImpl(&iter);
424    if (!entry)
425      return net::OK;
426
427    if (initial_time > entry->GetLastUsed()) {
428      entry->Release();
429      SyncEndEnumeration(iter);
430      return net::OK;
431    }
432
433    entry->DoomImpl();
434    entry->Release();
435    SyncEndEnumeration(iter);  // Dooming the entry invalidates the iterator.
436  }
437}
438
439int BackendImpl::SyncOpenNextEntry(void** iter, Entry** next_entry) {
440  *next_entry = OpenNextEntryImpl(iter);
441  return (*next_entry) ? net::OK : net::ERR_FAILED;
442}
443
444int BackendImpl::SyncOpenPrevEntry(void** iter, Entry** prev_entry) {
445  *prev_entry = OpenPrevEntryImpl(iter);
446  return (*prev_entry) ? net::OK : net::ERR_FAILED;
447}
448
449void BackendImpl::SyncEndEnumeration(void* iter) {
450  scoped_ptr<Rankings::Iterator> iterator(
451      reinterpret_cast<Rankings::Iterator*>(iter));
452}
453
454void BackendImpl::SyncOnExternalCacheHit(const std::string& key) {
455  if (disabled_)
456    return;
457
458  uint32 hash = base::Hash(key);
459  bool error;
460  EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
461  if (cache_entry) {
462    if (ENTRY_NORMAL == cache_entry->entry()->Data()->state) {
463      UpdateRank(cache_entry, cache_type() == net::SHADER_CACHE);
464    }
465    cache_entry->Release();
466  }
467}
468
469EntryImpl* BackendImpl::OpenEntryImpl(const std::string& key) {
470  if (disabled_)
471    return NULL;
472
473  TimeTicks start = TimeTicks::Now();
474  uint32 hash = base::Hash(key);
475  Trace("Open hash 0x%x", hash);
476
477  bool error;
478  EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
479  if (cache_entry && ENTRY_NORMAL != cache_entry->entry()->Data()->state) {
480    // The entry was already evicted.
481    cache_entry->Release();
482    cache_entry = NULL;
483    web_fonts_histogram::RecordEvictedEntry(key);
484  } else if (!cache_entry) {
485    web_fonts_histogram::RecordCacheMiss(key);
486  }
487
488  int current_size = data_->header.num_bytes / (1024 * 1024);
489  int64 total_hours = stats_.GetCounter(Stats::TIMER) / 120;
490  int64 no_use_hours = stats_.GetCounter(Stats::LAST_REPORT_TIMER) / 120;
491  int64 use_hours = total_hours - no_use_hours;
492
493  if (!cache_entry) {
494    CACHE_UMA(AGE_MS, "OpenTime.Miss", 0, start);
495    CACHE_UMA(COUNTS_10000, "AllOpenBySize.Miss", 0, current_size);
496    CACHE_UMA(HOURS, "AllOpenByTotalHours.Miss", 0, total_hours);
497    CACHE_UMA(HOURS, "AllOpenByUseHours.Miss", 0, use_hours);
498    stats_.OnEvent(Stats::OPEN_MISS);
499    return NULL;
500  }
501
502  eviction_.OnOpenEntry(cache_entry);
503  entry_count_++;
504
505  Trace("Open hash 0x%x end: 0x%x", hash,
506        cache_entry->entry()->address().value());
507  CACHE_UMA(AGE_MS, "OpenTime", 0, start);
508  CACHE_UMA(COUNTS_10000, "AllOpenBySize.Hit", 0, current_size);
509  CACHE_UMA(HOURS, "AllOpenByTotalHours.Hit", 0, total_hours);
510  CACHE_UMA(HOURS, "AllOpenByUseHours.Hit", 0, use_hours);
511  stats_.OnEvent(Stats::OPEN_HIT);
512  web_fonts_histogram::RecordCacheHit(cache_entry);
513  SIMPLE_STATS_COUNTER("disk_cache.hit");
514  return cache_entry;
515}
516
517EntryImpl* BackendImpl::CreateEntryImpl(const std::string& key) {
518  if (disabled_ || key.empty())
519    return NULL;
520
521  TimeTicks start = TimeTicks::Now();
522  uint32 hash = base::Hash(key);
523  Trace("Create hash 0x%x", hash);
524
525  scoped_refptr<EntryImpl> parent;
526  Addr entry_address(data_->table[hash & mask_]);
527  if (entry_address.is_initialized()) {
528    // We have an entry already. It could be the one we are looking for, or just
529    // a hash conflict.
530    bool error;
531    EntryImpl* old_entry = MatchEntry(key, hash, false, Addr(), &error);
532    if (old_entry)
533      return ResurrectEntry(old_entry);
534
535    EntryImpl* parent_entry = MatchEntry(key, hash, true, Addr(), &error);
536    DCHECK(!error);
537    if (parent_entry) {
538      parent.swap(&parent_entry);
539    } else if (data_->table[hash & mask_]) {
540      // We should have corrected the problem.
541      NOTREACHED();
542      return NULL;
543    }
544  }
545
546  // The general flow is to allocate disk space and initialize the entry data,
547  // followed by saving that to disk, then linking the entry though the index
548  // and finally through the lists. If there is a crash in this process, we may
549  // end up with:
550  // a. Used, unreferenced empty blocks on disk (basically just garbage).
551  // b. Used, unreferenced but meaningful data on disk (more garbage).
552  // c. A fully formed entry, reachable only through the index.
553  // d. A fully formed entry, also reachable through the lists, but still dirty.
554  //
555  // Anything after (b) can be automatically cleaned up. We may consider saving
556  // the current operation (as we do while manipulating the lists) so that we
557  // can detect and cleanup (a) and (b).
558
559  int num_blocks = EntryImpl::NumBlocksForEntry(key.size());
560  if (!block_files_.CreateBlock(BLOCK_256, num_blocks, &entry_address)) {
561    LOG(ERROR) << "Create entry failed " << key.c_str();
562    stats_.OnEvent(Stats::CREATE_ERROR);
563    return NULL;
564  }
565
566  Addr node_address(0);
567  if (!block_files_.CreateBlock(RANKINGS, 1, &node_address)) {
568    block_files_.DeleteBlock(entry_address, false);
569    LOG(ERROR) << "Create entry failed " << key.c_str();
570    stats_.OnEvent(Stats::CREATE_ERROR);
571    return NULL;
572  }
573
574  scoped_refptr<EntryImpl> cache_entry(
575      new EntryImpl(this, entry_address, false));
576  IncreaseNumRefs();
577
578  if (!cache_entry->CreateEntry(node_address, key, hash)) {
579    block_files_.DeleteBlock(entry_address, false);
580    block_files_.DeleteBlock(node_address, false);
581    LOG(ERROR) << "Create entry failed " << key.c_str();
582    stats_.OnEvent(Stats::CREATE_ERROR);
583    return NULL;
584  }
585
586  cache_entry->BeginLogging(net_log_, true);
587
588  // We are not failing the operation; let's add this to the map.
589  open_entries_[entry_address.value()] = cache_entry.get();
590
591  // Save the entry.
592  cache_entry->entry()->Store();
593  cache_entry->rankings()->Store();
594  IncreaseNumEntries();
595  entry_count_++;
596
597  // Link this entry through the index.
598  if (parent.get()) {
599    parent->SetNextAddress(entry_address);
600  } else {
601    data_->table[hash & mask_] = entry_address.value();
602  }
603
604  // Link this entry through the lists.
605  eviction_.OnCreateEntry(cache_entry.get());
606
607  CACHE_UMA(AGE_MS, "CreateTime", 0, start);
608  stats_.OnEvent(Stats::CREATE_HIT);
609  SIMPLE_STATS_COUNTER("disk_cache.miss");
610  Trace("create entry hit ");
611  FlushIndex();
612  cache_entry->AddRef();
613  return cache_entry.get();
614}
615
616EntryImpl* BackendImpl::OpenNextEntryImpl(void** iter) {
617  return OpenFollowingEntry(true, iter);
618}
619
620EntryImpl* BackendImpl::OpenPrevEntryImpl(void** iter) {
621  return OpenFollowingEntry(false, iter);
622}
623
624bool BackendImpl::SetMaxSize(int max_bytes) {
625  COMPILE_ASSERT(sizeof(max_bytes) == sizeof(max_size_), unsupported_int_model);
626  if (max_bytes < 0)
627    return false;
628
629  // Zero size means use the default.
630  if (!max_bytes)
631    return true;
632
633  // Avoid a DCHECK later on.
634  if (max_bytes >= kint32max - kint32max / 10)
635    max_bytes = kint32max - kint32max / 10 - 1;
636
637  user_flags_ |= kMaxSize;
638  max_size_ = max_bytes;
639  return true;
640}
641
642void BackendImpl::SetType(net::CacheType type) {
643  DCHECK_NE(net::MEMORY_CACHE, type);
644  cache_type_ = type;
645}
646
647base::FilePath BackendImpl::GetFileName(Addr address) const {
648  if (!address.is_separate_file() || !address.is_initialized()) {
649    NOTREACHED();
650    return base::FilePath();
651  }
652
653  std::string tmp = base::StringPrintf("f_%06x", address.FileNumber());
654  return path_.AppendASCII(tmp);
655}
656
657MappedFile* BackendImpl::File(Addr address) {
658  if (disabled_)
659    return NULL;
660  return block_files_.GetFile(address);
661}
662
663base::WeakPtr<InFlightBackendIO> BackendImpl::GetBackgroundQueue() {
664  return background_queue_.GetWeakPtr();
665}
666
667bool BackendImpl::CreateExternalFile(Addr* address) {
668  int file_number = data_->header.last_file + 1;
669  Addr file_address(0);
670  bool success = false;
671  for (int i = 0; i < 0x0fffffff; i++, file_number++) {
672    if (!file_address.SetFileNumber(file_number)) {
673      file_number = 1;
674      continue;
675    }
676    base::FilePath name = GetFileName(file_address);
677    int flags = base::File::FLAG_READ | base::File::FLAG_WRITE |
678                base::File::FLAG_CREATE | base::File::FLAG_EXCLUSIVE_WRITE;
679    base::File file(name, flags);
680    if (!file.IsValid()) {
681      base::File::Error error = file.error_details();
682      if (error != base::File::FILE_ERROR_EXISTS) {
683        LOG(ERROR) << "Unable to create file: " << error;
684        return false;
685      }
686      continue;
687    }
688
689    success = true;
690    break;
691  }
692
693  DCHECK(success);
694  if (!success)
695    return false;
696
697  data_->header.last_file = file_number;
698  address->set_value(file_address.value());
699  return true;
700}
701
702bool BackendImpl::CreateBlock(FileType block_type, int block_count,
703                             Addr* block_address) {
704  return block_files_.CreateBlock(block_type, block_count, block_address);
705}
706
707void BackendImpl::DeleteBlock(Addr block_address, bool deep) {
708  block_files_.DeleteBlock(block_address, deep);
709}
710
711LruData* BackendImpl::GetLruData() {
712  return &data_->header.lru;
713}
714
715void BackendImpl::UpdateRank(EntryImpl* entry, bool modified) {
716  if (read_only_ || (!modified && cache_type() == net::SHADER_CACHE))
717    return;
718  eviction_.UpdateRank(entry, modified);
719}
720
721void BackendImpl::RecoveredEntry(CacheRankingsBlock* rankings) {
722  Addr address(rankings->Data()->contents);
723  EntryImpl* cache_entry = NULL;
724  if (NewEntry(address, &cache_entry)) {
725    STRESS_NOTREACHED();
726    return;
727  }
728
729  uint32 hash = cache_entry->GetHash();
730  cache_entry->Release();
731
732  // Anything on the table means that this entry is there.
733  if (data_->table[hash & mask_])
734    return;
735
736  data_->table[hash & mask_] = address.value();
737  FlushIndex();
738}
739
740void BackendImpl::InternalDoomEntry(EntryImpl* entry) {
741  uint32 hash = entry->GetHash();
742  std::string key = entry->GetKey();
743  Addr entry_addr = entry->entry()->address();
744  bool error;
745  EntryImpl* parent_entry = MatchEntry(key, hash, true, entry_addr, &error);
746  CacheAddr child(entry->GetNextAddress());
747
748  Trace("Doom entry 0x%p", entry);
749
750  if (!entry->doomed()) {
751    // We may have doomed this entry from within MatchEntry.
752    eviction_.OnDoomEntry(entry);
753    entry->InternalDoom();
754    if (!new_eviction_) {
755      DecreaseNumEntries();
756    }
757    stats_.OnEvent(Stats::DOOM_ENTRY);
758  }
759
760  if (parent_entry) {
761    parent_entry->SetNextAddress(Addr(child));
762    parent_entry->Release();
763  } else if (!error) {
764    data_->table[hash & mask_] = child;
765  }
766
767  FlushIndex();
768}
769
770#if defined(NET_BUILD_STRESS_CACHE)
771
772CacheAddr BackendImpl::GetNextAddr(Addr address) {
773  EntriesMap::iterator it = open_entries_.find(address.value());
774  if (it != open_entries_.end()) {
775    EntryImpl* this_entry = it->second;
776    return this_entry->GetNextAddress();
777  }
778  DCHECK(block_files_.IsValid(address));
779  DCHECK(!address.is_separate_file() && address.file_type() == BLOCK_256);
780
781  CacheEntryBlock entry(File(address), address);
782  CHECK(entry.Load());
783  return entry.Data()->next;
784}
785
786void BackendImpl::NotLinked(EntryImpl* entry) {
787  Addr entry_addr = entry->entry()->address();
788  uint32 i = entry->GetHash() & mask_;
789  Addr address(data_->table[i]);
790  if (!address.is_initialized())
791    return;
792
793  for (;;) {
794    DCHECK(entry_addr.value() != address.value());
795    address.set_value(GetNextAddr(address));
796    if (!address.is_initialized())
797      break;
798  }
799}
800#endif  // NET_BUILD_STRESS_CACHE
801
802// An entry may be linked on the DELETED list for a while after being doomed.
803// This function is called when we want to remove it.
804void BackendImpl::RemoveEntry(EntryImpl* entry) {
805#if defined(NET_BUILD_STRESS_CACHE)
806  NotLinked(entry);
807#endif
808  if (!new_eviction_)
809    return;
810
811  DCHECK_NE(ENTRY_NORMAL, entry->entry()->Data()->state);
812
813  Trace("Remove entry 0x%p", entry);
814  eviction_.OnDestroyEntry(entry);
815  DecreaseNumEntries();
816}
817
818void BackendImpl::OnEntryDestroyBegin(Addr address) {
819  EntriesMap::iterator it = open_entries_.find(address.value());
820  if (it != open_entries_.end())
821    open_entries_.erase(it);
822}
823
824void BackendImpl::OnEntryDestroyEnd() {
825  DecreaseNumRefs();
826  if (data_->header.num_bytes > max_size_ && !read_only_ &&
827      (up_ticks_ > kTrimDelay || user_flags_ & kNoRandom))
828    eviction_.TrimCache(false);
829}
830
831EntryImpl* BackendImpl::GetOpenEntry(CacheRankingsBlock* rankings) const {
832  DCHECK(rankings->HasData());
833  EntriesMap::const_iterator it =
834      open_entries_.find(rankings->Data()->contents);
835  if (it != open_entries_.end()) {
836    // We have this entry in memory.
837    return it->second;
838  }
839
840  return NULL;
841}
842
843int32 BackendImpl::GetCurrentEntryId() const {
844  return data_->header.this_id;
845}
846
847int BackendImpl::MaxFileSize() const {
848  return cache_type() == net::PNACL_CACHE ? max_size_ : max_size_ / 8;
849}
850
851void BackendImpl::ModifyStorageSize(int32 old_size, int32 new_size) {
852  if (disabled_ || old_size == new_size)
853    return;
854  if (old_size > new_size)
855    SubstractStorageSize(old_size - new_size);
856  else
857    AddStorageSize(new_size - old_size);
858
859  FlushIndex();
860
861  // Update the usage statistics.
862  stats_.ModifyStorageStats(old_size, new_size);
863}
864
865void BackendImpl::TooMuchStorageRequested(int32 size) {
866  stats_.ModifyStorageStats(0, size);
867}
868
869bool BackendImpl::IsAllocAllowed(int current_size, int new_size) {
870  DCHECK_GT(new_size, current_size);
871  if (user_flags_ & kNoBuffering)
872    return false;
873
874  int to_add = new_size - current_size;
875  if (buffer_bytes_ + to_add > MaxBuffersSize())
876    return false;
877
878  buffer_bytes_ += to_add;
879  CACHE_UMA(COUNTS_50000, "BufferBytes", 0, buffer_bytes_ / 1024);
880  return true;
881}
882
883void BackendImpl::BufferDeleted(int size) {
884  buffer_bytes_ -= size;
885  DCHECK_GE(size, 0);
886}
887
888bool BackendImpl::IsLoaded() const {
889  CACHE_UMA(COUNTS, "PendingIO", 0, num_pending_io_);
890  if (user_flags_ & kNoLoadProtection)
891    return false;
892
893  return (num_pending_io_ > 5 || user_load_);
894}
895
896std::string BackendImpl::HistogramName(const char* name, int experiment) const {
897  if (!experiment)
898    return base::StringPrintf("DiskCache.%d.%s", cache_type_, name);
899  return base::StringPrintf("DiskCache.%d.%s_%d", cache_type_,
900                            name, experiment);
901}
902
903base::WeakPtr<BackendImpl> BackendImpl::GetWeakPtr() {
904  return ptr_factory_.GetWeakPtr();
905}
906
907// We want to remove biases from some histograms so we only send data once per
908// week.
909bool BackendImpl::ShouldReportAgain() {
910  if (uma_report_)
911    return uma_report_ == 2;
912
913  uma_report_++;
914  int64 last_report = stats_.GetCounter(Stats::LAST_REPORT);
915  Time last_time = Time::FromInternalValue(last_report);
916  if (!last_report || (Time::Now() - last_time).InDays() >= 7) {
917    stats_.SetCounter(Stats::LAST_REPORT, Time::Now().ToInternalValue());
918    uma_report_++;
919    return true;
920  }
921  return false;
922}
923
924void BackendImpl::FirstEviction() {
925  DCHECK(data_->header.create_time);
926  if (!GetEntryCount())
927    return;  // This is just for unit tests.
928
929  Time create_time = Time::FromInternalValue(data_->header.create_time);
930  CACHE_UMA(AGE, "FillupAge", 0, create_time);
931
932  int64 use_time = stats_.GetCounter(Stats::TIMER);
933  CACHE_UMA(HOURS, "FillupTime", 0, static_cast<int>(use_time / 120));
934  CACHE_UMA(PERCENTAGE, "FirstHitRatio", 0, stats_.GetHitRatio());
935
936  if (!use_time)
937    use_time = 1;
938  CACHE_UMA(COUNTS_10000, "FirstEntryAccessRate", 0,
939            static_cast<int>(data_->header.num_entries / use_time));
940  CACHE_UMA(COUNTS, "FirstByteIORate", 0,
941            static_cast<int>((data_->header.num_bytes / 1024) / use_time));
942
943  int avg_size = data_->header.num_bytes / GetEntryCount();
944  CACHE_UMA(COUNTS, "FirstEntrySize", 0, avg_size);
945
946  int large_entries_bytes = stats_.GetLargeEntriesSize();
947  int large_ratio = large_entries_bytes * 100 / data_->header.num_bytes;
948  CACHE_UMA(PERCENTAGE, "FirstLargeEntriesRatio", 0, large_ratio);
949
950  if (new_eviction_) {
951    CACHE_UMA(PERCENTAGE, "FirstResurrectRatio", 0, stats_.GetResurrectRatio());
952    CACHE_UMA(PERCENTAGE, "FirstNoUseRatio", 0,
953              data_->header.lru.sizes[0] * 100 / data_->header.num_entries);
954    CACHE_UMA(PERCENTAGE, "FirstLowUseRatio", 0,
955              data_->header.lru.sizes[1] * 100 / data_->header.num_entries);
956    CACHE_UMA(PERCENTAGE, "FirstHighUseRatio", 0,
957              data_->header.lru.sizes[2] * 100 / data_->header.num_entries);
958  }
959
960  stats_.ResetRatios();
961}
962
963void BackendImpl::CriticalError(int error) {
964  STRESS_NOTREACHED();
965  LOG(ERROR) << "Critical error found " << error;
966  if (disabled_)
967    return;
968
969  stats_.OnEvent(Stats::FATAL_ERROR);
970  LogStats();
971  ReportError(error);
972
973  // Setting the index table length to an invalid value will force re-creation
974  // of the cache files.
975  data_->header.table_len = 1;
976  disabled_ = true;
977
978  if (!num_refs_)
979    base::MessageLoop::current()->PostTask(
980        FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
981}
982
983void BackendImpl::ReportError(int error) {
984  STRESS_DCHECK(!error || error == ERR_PREVIOUS_CRASH ||
985                error == ERR_CACHE_CREATED);
986
987  // We transmit positive numbers, instead of direct error codes.
988  DCHECK_LE(error, 0);
989  CACHE_UMA(CACHE_ERROR, "Error", 0, error * -1);
990}
991
992void BackendImpl::OnEvent(Stats::Counters an_event) {
993  stats_.OnEvent(an_event);
994}
995
996void BackendImpl::OnRead(int32 bytes) {
997  DCHECK_GE(bytes, 0);
998  byte_count_ += bytes;
999  if (byte_count_ < 0)
1000    byte_count_ = kint32max;
1001}
1002
1003void BackendImpl::OnWrite(int32 bytes) {
1004  // We use the same implementation as OnRead... just log the number of bytes.
1005  OnRead(bytes);
1006}
1007
1008void BackendImpl::OnStatsTimer() {
1009  if (disabled_)
1010    return;
1011
1012  stats_.OnEvent(Stats::TIMER);
1013  int64 time = stats_.GetCounter(Stats::TIMER);
1014  int64 current = stats_.GetCounter(Stats::OPEN_ENTRIES);
1015
1016  // OPEN_ENTRIES is a sampled average of the number of open entries, avoiding
1017  // the bias towards 0.
1018  if (num_refs_ && (current != num_refs_)) {
1019    int64 diff = (num_refs_ - current) / 50;
1020    if (!diff)
1021      diff = num_refs_ > current ? 1 : -1;
1022    current = current + diff;
1023    stats_.SetCounter(Stats::OPEN_ENTRIES, current);
1024    stats_.SetCounter(Stats::MAX_ENTRIES, max_refs_);
1025  }
1026
1027  CACHE_UMA(COUNTS, "NumberOfReferences", 0, num_refs_);
1028
1029  CACHE_UMA(COUNTS_10000, "EntryAccessRate", 0, entry_count_);
1030  CACHE_UMA(COUNTS, "ByteIORate", 0, byte_count_ / 1024);
1031
1032  // These values cover about 99.5% of the population (Oct 2011).
1033  user_load_ = (entry_count_ > 300 || byte_count_ > 7 * 1024 * 1024);
1034  entry_count_ = 0;
1035  byte_count_ = 0;
1036  up_ticks_++;
1037
1038  if (!data_)
1039    first_timer_ = false;
1040  if (first_timer_) {
1041    first_timer_ = false;
1042    if (ShouldReportAgain())
1043      ReportStats();
1044  }
1045
1046  // Save stats to disk at 5 min intervals.
1047  if (time % 10 == 0)
1048    StoreStats();
1049}
1050
1051void BackendImpl::IncrementIoCount() {
1052  num_pending_io_++;
1053}
1054
1055void BackendImpl::DecrementIoCount() {
1056  num_pending_io_--;
1057}
1058
1059void BackendImpl::SetUnitTestMode() {
1060  user_flags_ |= kUnitTestMode;
1061  unit_test_ = true;
1062}
1063
1064void BackendImpl::SetUpgradeMode() {
1065  user_flags_ |= kUpgradeMode;
1066  read_only_ = true;
1067}
1068
1069void BackendImpl::SetNewEviction() {
1070  user_flags_ |= kNewEviction;
1071  new_eviction_ = true;
1072}
1073
1074void BackendImpl::SetFlags(uint32 flags) {
1075  user_flags_ |= flags;
1076}
1077
1078void BackendImpl::ClearRefCountForTest() {
1079  num_refs_ = 0;
1080}
1081
1082int BackendImpl::FlushQueueForTest(const CompletionCallback& callback) {
1083  background_queue_.FlushQueue(callback);
1084  return net::ERR_IO_PENDING;
1085}
1086
1087int BackendImpl::RunTaskForTest(const base::Closure& task,
1088                                const CompletionCallback& callback) {
1089  background_queue_.RunTask(task, callback);
1090  return net::ERR_IO_PENDING;
1091}
1092
1093void BackendImpl::TrimForTest(bool empty) {
1094  eviction_.SetTestMode();
1095  eviction_.TrimCache(empty);
1096}
1097
1098void BackendImpl::TrimDeletedListForTest(bool empty) {
1099  eviction_.SetTestMode();
1100  eviction_.TrimDeletedList(empty);
1101}
1102
1103base::RepeatingTimer<BackendImpl>* BackendImpl::GetTimerForTest() {
1104  return timer_.get();
1105}
1106
1107int BackendImpl::SelfCheck() {
1108  if (!init_) {
1109    LOG(ERROR) << "Init failed";
1110    return ERR_INIT_FAILED;
1111  }
1112
1113  int num_entries = rankings_.SelfCheck();
1114  if (num_entries < 0) {
1115    LOG(ERROR) << "Invalid rankings list, error " << num_entries;
1116#if !defined(NET_BUILD_STRESS_CACHE)
1117    return num_entries;
1118#endif
1119  }
1120
1121  if (num_entries != data_->header.num_entries) {
1122    LOG(ERROR) << "Number of entries mismatch";
1123#if !defined(NET_BUILD_STRESS_CACHE)
1124    return ERR_NUM_ENTRIES_MISMATCH;
1125#endif
1126  }
1127
1128  return CheckAllEntries();
1129}
1130
1131void BackendImpl::FlushIndex() {
1132  if (index_.get() && !disabled_)
1133    index_->Flush();
1134}
1135
1136// ------------------------------------------------------------------------
1137
1138net::CacheType BackendImpl::GetCacheType() const {
1139  return cache_type_;
1140}
1141
1142int32 BackendImpl::GetEntryCount() const {
1143  if (!index_.get() || disabled_)
1144    return 0;
1145  // num_entries includes entries already evicted.
1146  int32 not_deleted = data_->header.num_entries -
1147                      data_->header.lru.sizes[Rankings::DELETED];
1148
1149  if (not_deleted < 0) {
1150    NOTREACHED();
1151    not_deleted = 0;
1152  }
1153
1154  return not_deleted;
1155}
1156
1157int BackendImpl::OpenEntry(const std::string& key, Entry** entry,
1158                           const CompletionCallback& callback) {
1159  DCHECK(!callback.is_null());
1160  background_queue_.OpenEntry(key, entry, callback);
1161  return net::ERR_IO_PENDING;
1162}
1163
1164int BackendImpl::CreateEntry(const std::string& key, Entry** entry,
1165                             const CompletionCallback& callback) {
1166  DCHECK(!callback.is_null());
1167  background_queue_.CreateEntry(key, entry, callback);
1168  return net::ERR_IO_PENDING;
1169}
1170
1171int BackendImpl::DoomEntry(const std::string& key,
1172                           const CompletionCallback& callback) {
1173  DCHECK(!callback.is_null());
1174  background_queue_.DoomEntry(key, callback);
1175  return net::ERR_IO_PENDING;
1176}
1177
1178int BackendImpl::DoomAllEntries(const CompletionCallback& callback) {
1179  DCHECK(!callback.is_null());
1180  background_queue_.DoomAllEntries(callback);
1181  return net::ERR_IO_PENDING;
1182}
1183
1184int BackendImpl::DoomEntriesBetween(const base::Time initial_time,
1185                                    const base::Time end_time,
1186                                    const CompletionCallback& callback) {
1187  DCHECK(!callback.is_null());
1188  background_queue_.DoomEntriesBetween(initial_time, end_time, callback);
1189  return net::ERR_IO_PENDING;
1190}
1191
1192int BackendImpl::DoomEntriesSince(const base::Time initial_time,
1193                                  const CompletionCallback& callback) {
1194  DCHECK(!callback.is_null());
1195  background_queue_.DoomEntriesSince(initial_time, callback);
1196  return net::ERR_IO_PENDING;
1197}
1198
1199int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
1200                               const CompletionCallback& callback) {
1201  DCHECK(!callback.is_null());
1202  background_queue_.OpenNextEntry(iter, next_entry, callback);
1203  return net::ERR_IO_PENDING;
1204}
1205
1206void BackendImpl::EndEnumeration(void** iter) {
1207  background_queue_.EndEnumeration(*iter);
1208  *iter = NULL;
1209}
1210
1211void BackendImpl::GetStats(StatsItems* stats) {
1212  if (disabled_)
1213    return;
1214
1215  std::pair<std::string, std::string> item;
1216
1217  item.first = "Entries";
1218  item.second = base::StringPrintf("%d", data_->header.num_entries);
1219  stats->push_back(item);
1220
1221  item.first = "Pending IO";
1222  item.second = base::StringPrintf("%d", num_pending_io_);
1223  stats->push_back(item);
1224
1225  item.first = "Max size";
1226  item.second = base::StringPrintf("%d", max_size_);
1227  stats->push_back(item);
1228
1229  item.first = "Current size";
1230  item.second = base::StringPrintf("%d", data_->header.num_bytes);
1231  stats->push_back(item);
1232
1233  item.first = "Cache type";
1234  item.second = "Blockfile Cache";
1235  stats->push_back(item);
1236
1237  stats_.GetItems(stats);
1238}
1239
1240void BackendImpl::OnExternalCacheHit(const std::string& key) {
1241  background_queue_.OnExternalCacheHit(key);
1242}
1243
1244// ------------------------------------------------------------------------
1245
1246// We just created a new file so we're going to write the header and set the
1247// file length to include the hash table (zero filled).
1248bool BackendImpl::CreateBackingStore(disk_cache::File* file) {
1249  AdjustMaxCacheSize(0);
1250
1251  IndexHeader header;
1252  header.table_len = DesiredIndexTableLen(max_size_);
1253
1254  // We need file version 2.1 for the new eviction algorithm.
1255  if (new_eviction_)
1256    header.version = 0x20001;
1257
1258  header.create_time = Time::Now().ToInternalValue();
1259
1260  if (!file->Write(&header, sizeof(header), 0))
1261    return false;
1262
1263  return file->SetLength(GetIndexSize(header.table_len));
1264}
1265
1266bool BackendImpl::InitBackingStore(bool* file_created) {
1267  if (!base::CreateDirectory(path_))
1268    return false;
1269
1270  base::FilePath index_name = path_.AppendASCII(kIndexName);
1271
1272  int flags = base::File::FLAG_READ | base::File::FLAG_WRITE |
1273              base::File::FLAG_OPEN_ALWAYS | base::File::FLAG_EXCLUSIVE_WRITE;
1274  base::File base_file(index_name, flags);
1275  if (!base_file.IsValid())
1276    return false;
1277
1278  bool ret = true;
1279  *file_created = base_file.created();
1280
1281  scoped_refptr<disk_cache::File> file(new disk_cache::File(base_file.Pass()));
1282  if (*file_created)
1283    ret = CreateBackingStore(file.get());
1284
1285  file = NULL;
1286  if (!ret)
1287    return false;
1288
1289  index_ = new MappedFile();
1290  data_ = static_cast<Index*>(index_->Init(index_name, 0));
1291  if (!data_) {
1292    LOG(ERROR) << "Unable to map Index file";
1293    return false;
1294  }
1295
1296  if (index_->GetLength() < sizeof(Index)) {
1297    // We verify this again on CheckIndex() but it's easier to make sure now
1298    // that the header is there.
1299    LOG(ERROR) << "Corrupt Index file";
1300    return false;
1301  }
1302
1303  return true;
1304}
1305
1306// The maximum cache size will be either set explicitly by the caller, or
1307// calculated by this code.
1308void BackendImpl::AdjustMaxCacheSize(int table_len) {
1309  if (max_size_)
1310    return;
1311
1312  // If table_len is provided, the index file exists.
1313  DCHECK(!table_len || data_->header.magic);
1314
1315  // The user is not setting the size, let's figure it out.
1316  int64 available = base::SysInfo::AmountOfFreeDiskSpace(path_);
1317  if (available < 0) {
1318    max_size_ = kDefaultCacheSize;
1319    return;
1320  }
1321
1322  if (table_len)
1323    available += data_->header.num_bytes;
1324
1325  max_size_ = PreferredCacheSize(available);
1326
1327  if (!table_len)
1328    return;
1329
1330  // If we already have a table, adjust the size to it.
1331  int current_max_size = MaxStorageSizeForTable(table_len);
1332  if (max_size_ > current_max_size)
1333    max_size_= current_max_size;
1334}
1335
1336bool BackendImpl::InitStats() {
1337  Addr address(data_->header.stats);
1338  int size = stats_.StorageSize();
1339
1340  if (!address.is_initialized()) {
1341    FileType file_type = Addr::RequiredFileType(size);
1342    DCHECK_NE(file_type, EXTERNAL);
1343    int num_blocks = Addr::RequiredBlocks(size, file_type);
1344
1345    if (!CreateBlock(file_type, num_blocks, &address))
1346      return false;
1347
1348    data_->header.stats = address.value();
1349    return stats_.Init(NULL, 0, address);
1350  }
1351
1352  if (!address.is_block_file()) {
1353    NOTREACHED();
1354    return false;
1355  }
1356
1357  // Load the required data.
1358  size = address.num_blocks() * address.BlockSize();
1359  MappedFile* file = File(address);
1360  if (!file)
1361    return false;
1362
1363  scoped_ptr<char[]> data(new char[size]);
1364  size_t offset = address.start_block() * address.BlockSize() +
1365                  kBlockHeaderSize;
1366  if (!file->Read(data.get(), size, offset))
1367    return false;
1368
1369  if (!stats_.Init(data.get(), size, address))
1370    return false;
1371  if (cache_type_ == net::DISK_CACHE && ShouldReportAgain())
1372    stats_.InitSizeHistogram();
1373  return true;
1374}
1375
1376void BackendImpl::StoreStats() {
1377  int size = stats_.StorageSize();
1378  scoped_ptr<char[]> data(new char[size]);
1379  Addr address;
1380  size = stats_.SerializeStats(data.get(), size, &address);
1381  DCHECK(size);
1382  if (!address.is_initialized())
1383    return;
1384
1385  MappedFile* file = File(address);
1386  if (!file)
1387    return;
1388
1389  size_t offset = address.start_block() * address.BlockSize() +
1390                  kBlockHeaderSize;
1391  file->Write(data.get(), size, offset);  // ignore result.
1392}
1393
1394void BackendImpl::RestartCache(bool failure) {
1395  int64 errors = stats_.GetCounter(Stats::FATAL_ERROR);
1396  int64 full_dooms = stats_.GetCounter(Stats::DOOM_CACHE);
1397  int64 partial_dooms = stats_.GetCounter(Stats::DOOM_RECENT);
1398  int64 last_report = stats_.GetCounter(Stats::LAST_REPORT);
1399
1400  PrepareForRestart();
1401  if (failure) {
1402    DCHECK(!num_refs_);
1403    DCHECK(!open_entries_.size());
1404    DelayedCacheCleanup(path_);
1405  } else {
1406    DeleteCache(path_, false);
1407  }
1408
1409  // Don't call Init() if directed by the unit test: we are simulating a failure
1410  // trying to re-enable the cache.
1411  if (unit_test_)
1412    init_ = true;  // Let the destructor do proper cleanup.
1413  else if (SyncInit() == net::OK) {
1414    stats_.SetCounter(Stats::FATAL_ERROR, errors);
1415    stats_.SetCounter(Stats::DOOM_CACHE, full_dooms);
1416    stats_.SetCounter(Stats::DOOM_RECENT, partial_dooms);
1417    stats_.SetCounter(Stats::LAST_REPORT, last_report);
1418  }
1419}
1420
1421void BackendImpl::PrepareForRestart() {
1422  // Reset the mask_ if it was not given by the user.
1423  if (!(user_flags_ & kMask))
1424    mask_ = 0;
1425
1426  if (!(user_flags_ & kNewEviction))
1427    new_eviction_ = false;
1428
1429  disabled_ = true;
1430  data_->header.crash = 0;
1431  index_->Flush();
1432  index_ = NULL;
1433  data_ = NULL;
1434  block_files_.CloseFiles();
1435  rankings_.Reset();
1436  init_ = false;
1437  restarted_ = true;
1438}
1439
1440int BackendImpl::NewEntry(Addr address, EntryImpl** entry) {
1441  EntriesMap::iterator it = open_entries_.find(address.value());
1442  if (it != open_entries_.end()) {
1443    // Easy job. This entry is already in memory.
1444    EntryImpl* this_entry = it->second;
1445    this_entry->AddRef();
1446    *entry = this_entry;
1447    return 0;
1448  }
1449
1450  STRESS_DCHECK(block_files_.IsValid(address));
1451
1452  if (!address.SanityCheckForEntryV2()) {
1453    LOG(WARNING) << "Wrong entry address.";
1454    STRESS_NOTREACHED();
1455    return ERR_INVALID_ADDRESS;
1456  }
1457
1458  scoped_refptr<EntryImpl> cache_entry(
1459      new EntryImpl(this, address, read_only_));
1460  IncreaseNumRefs();
1461  *entry = NULL;
1462
1463  TimeTicks start = TimeTicks::Now();
1464  if (!cache_entry->entry()->Load())
1465    return ERR_READ_FAILURE;
1466
1467  if (IsLoaded()) {
1468    CACHE_UMA(AGE_MS, "LoadTime", 0, start);
1469  }
1470
1471  if (!cache_entry->SanityCheck()) {
1472    LOG(WARNING) << "Messed up entry found.";
1473    STRESS_NOTREACHED();
1474    return ERR_INVALID_ENTRY;
1475  }
1476
1477  STRESS_DCHECK(block_files_.IsValid(
1478                    Addr(cache_entry->entry()->Data()->rankings_node)));
1479
1480  if (!cache_entry->LoadNodeAddress())
1481    return ERR_READ_FAILURE;
1482
1483  if (!rankings_.SanityCheck(cache_entry->rankings(), false)) {
1484    STRESS_NOTREACHED();
1485    cache_entry->SetDirtyFlag(0);
1486    // Don't remove this from the list (it is not linked properly). Instead,
1487    // break the link back to the entry because it is going away, and leave the
1488    // rankings node to be deleted if we find it through a list.
1489    rankings_.SetContents(cache_entry->rankings(), 0);
1490  } else if (!rankings_.DataSanityCheck(cache_entry->rankings(), false)) {
1491    STRESS_NOTREACHED();
1492    cache_entry->SetDirtyFlag(0);
1493    rankings_.SetContents(cache_entry->rankings(), address.value());
1494  }
1495
1496  if (!cache_entry->DataSanityCheck()) {
1497    LOG(WARNING) << "Messed up entry found.";
1498    cache_entry->SetDirtyFlag(0);
1499    cache_entry->FixForDelete();
1500  }
1501
1502  // Prevent overwriting the dirty flag on the destructor.
1503  cache_entry->SetDirtyFlag(GetCurrentEntryId());
1504
1505  if (cache_entry->dirty()) {
1506    Trace("Dirty entry 0x%p 0x%x", reinterpret_cast<void*>(cache_entry.get()),
1507          address.value());
1508  }
1509
1510  open_entries_[address.value()] = cache_entry.get();
1511
1512  cache_entry->BeginLogging(net_log_, false);
1513  cache_entry.swap(entry);
1514  return 0;
1515}
1516
1517EntryImpl* BackendImpl::MatchEntry(const std::string& key, uint32 hash,
1518                                   bool find_parent, Addr entry_addr,
1519                                   bool* match_error) {
1520  Addr address(data_->table[hash & mask_]);
1521  scoped_refptr<EntryImpl> cache_entry, parent_entry;
1522  EntryImpl* tmp = NULL;
1523  bool found = false;
1524  std::set<CacheAddr> visited;
1525  *match_error = false;
1526
1527  for (;;) {
1528    if (disabled_)
1529      break;
1530
1531    if (visited.find(address.value()) != visited.end()) {
1532      // It's possible for a buggy version of the code to write a loop. Just
1533      // break it.
1534      Trace("Hash collision loop 0x%x", address.value());
1535      address.set_value(0);
1536      parent_entry->SetNextAddress(address);
1537    }
1538    visited.insert(address.value());
1539
1540    if (!address.is_initialized()) {
1541      if (find_parent)
1542        found = true;
1543      break;
1544    }
1545
1546    int error = NewEntry(address, &tmp);
1547    cache_entry.swap(&tmp);
1548
1549    if (error || cache_entry->dirty()) {
1550      // This entry is dirty on disk (it was not properly closed): we cannot
1551      // trust it.
1552      Addr child(0);
1553      if (!error)
1554        child.set_value(cache_entry->GetNextAddress());
1555
1556      if (parent_entry.get()) {
1557        parent_entry->SetNextAddress(child);
1558        parent_entry = NULL;
1559      } else {
1560        data_->table[hash & mask_] = child.value();
1561      }
1562
1563      Trace("MatchEntry dirty %d 0x%x 0x%x", find_parent, entry_addr.value(),
1564            address.value());
1565
1566      if (!error) {
1567        // It is important to call DestroyInvalidEntry after removing this
1568        // entry from the table.
1569        DestroyInvalidEntry(cache_entry.get());
1570        cache_entry = NULL;
1571      } else {
1572        Trace("NewEntry failed on MatchEntry 0x%x", address.value());
1573      }
1574
1575      // Restart the search.
1576      address.set_value(data_->table[hash & mask_]);
1577      visited.clear();
1578      continue;
1579    }
1580
1581    DCHECK_EQ(hash & mask_, cache_entry->entry()->Data()->hash & mask_);
1582    if (cache_entry->IsSameEntry(key, hash)) {
1583      if (!cache_entry->Update())
1584        cache_entry = NULL;
1585      found = true;
1586      if (find_parent && entry_addr.value() != address.value()) {
1587        Trace("Entry not on the index 0x%x", address.value());
1588        *match_error = true;
1589        parent_entry = NULL;
1590      }
1591      break;
1592    }
1593    if (!cache_entry->Update())
1594      cache_entry = NULL;
1595    parent_entry = cache_entry;
1596    cache_entry = NULL;
1597    if (!parent_entry.get())
1598      break;
1599
1600    address.set_value(parent_entry->GetNextAddress());
1601  }
1602
1603  if (parent_entry.get() && (!find_parent || !found))
1604    parent_entry = NULL;
1605
1606  if (find_parent && entry_addr.is_initialized() && !cache_entry.get()) {
1607    *match_error = true;
1608    parent_entry = NULL;
1609  }
1610
1611  if (cache_entry.get() && (find_parent || !found))
1612    cache_entry = NULL;
1613
1614  find_parent ? parent_entry.swap(&tmp) : cache_entry.swap(&tmp);
1615  FlushIndex();
1616  return tmp;
1617}
1618
1619// This is the actual implementation for OpenNextEntry and OpenPrevEntry.
1620EntryImpl* BackendImpl::OpenFollowingEntry(bool forward, void** iter) {
1621  if (disabled_)
1622    return NULL;
1623
1624  DCHECK(iter);
1625
1626  const int kListsToSearch = 3;
1627  scoped_refptr<EntryImpl> entries[kListsToSearch];
1628  scoped_ptr<Rankings::Iterator> iterator(
1629      reinterpret_cast<Rankings::Iterator*>(*iter));
1630  *iter = NULL;
1631
1632  if (!iterator.get()) {
1633    iterator.reset(new Rankings::Iterator(&rankings_));
1634    bool ret = false;
1635
1636    // Get an entry from each list.
1637    for (int i = 0; i < kListsToSearch; i++) {
1638      EntryImpl* temp = NULL;
1639      ret |= OpenFollowingEntryFromList(forward, static_cast<Rankings::List>(i),
1640                                        &iterator->nodes[i], &temp);
1641      entries[i].swap(&temp);  // The entry was already addref'd.
1642    }
1643    if (!ret)
1644      return NULL;
1645  } else {
1646    // Get the next entry from the last list, and the actual entries for the
1647    // elements on the other lists.
1648    for (int i = 0; i < kListsToSearch; i++) {
1649      EntryImpl* temp = NULL;
1650      if (iterator->list == i) {
1651          OpenFollowingEntryFromList(forward, iterator->list,
1652                                     &iterator->nodes[i], &temp);
1653      } else {
1654        temp = GetEnumeratedEntry(iterator->nodes[i],
1655                                  static_cast<Rankings::List>(i));
1656      }
1657
1658      entries[i].swap(&temp);  // The entry was already addref'd.
1659    }
1660  }
1661
1662  int newest = -1;
1663  int oldest = -1;
1664  Time access_times[kListsToSearch];
1665  for (int i = 0; i < kListsToSearch; i++) {
1666    if (entries[i].get()) {
1667      access_times[i] = entries[i]->GetLastUsed();
1668      if (newest < 0) {
1669        DCHECK_LT(oldest, 0);
1670        newest = oldest = i;
1671        continue;
1672      }
1673      if (access_times[i] > access_times[newest])
1674        newest = i;
1675      if (access_times[i] < access_times[oldest])
1676        oldest = i;
1677    }
1678  }
1679
1680  if (newest < 0 || oldest < 0)
1681    return NULL;
1682
1683  EntryImpl* next_entry;
1684  if (forward) {
1685    next_entry = entries[newest].get();
1686    iterator->list = static_cast<Rankings::List>(newest);
1687  } else {
1688    next_entry = entries[oldest].get();
1689    iterator->list = static_cast<Rankings::List>(oldest);
1690  }
1691
1692  *iter = iterator.release();
1693  next_entry->AddRef();
1694  return next_entry;
1695}
1696
1697bool BackendImpl::OpenFollowingEntryFromList(bool forward, Rankings::List list,
1698                                             CacheRankingsBlock** from_entry,
1699                                             EntryImpl** next_entry) {
1700  if (disabled_)
1701    return false;
1702
1703  if (!new_eviction_ && Rankings::NO_USE != list)
1704    return false;
1705
1706  Rankings::ScopedRankingsBlock rankings(&rankings_, *from_entry);
1707  CacheRankingsBlock* next_block = forward ?
1708      rankings_.GetNext(rankings.get(), list) :
1709      rankings_.GetPrev(rankings.get(), list);
1710  Rankings::ScopedRankingsBlock next(&rankings_, next_block);
1711  *from_entry = NULL;
1712
1713  *next_entry = GetEnumeratedEntry(next.get(), list);
1714  if (!*next_entry)
1715    return false;
1716
1717  *from_entry = next.release();
1718  return true;
1719}
1720
1721EntryImpl* BackendImpl::GetEnumeratedEntry(CacheRankingsBlock* next,
1722                                           Rankings::List list) {
1723  if (!next || disabled_)
1724    return NULL;
1725
1726  EntryImpl* entry;
1727  int rv = NewEntry(Addr(next->Data()->contents), &entry);
1728  if (rv) {
1729    STRESS_NOTREACHED();
1730    rankings_.Remove(next, list, false);
1731    if (rv == ERR_INVALID_ADDRESS) {
1732      // There is nothing linked from the index. Delete the rankings node.
1733      DeleteBlock(next->address(), true);
1734    }
1735    return NULL;
1736  }
1737
1738  if (entry->dirty()) {
1739    // We cannot trust this entry.
1740    InternalDoomEntry(entry);
1741    entry->Release();
1742    return NULL;
1743  }
1744
1745  if (!entry->Update()) {
1746    STRESS_NOTREACHED();
1747    entry->Release();
1748    return NULL;
1749  }
1750
1751  // Note that it is unfortunate (but possible) for this entry to be clean, but
1752  // not actually the real entry. In other words, we could have lost this entry
1753  // from the index, and it could have been replaced with a newer one. It's not
1754  // worth checking that this entry is "the real one", so we just return it and
1755  // let the enumeration continue; this entry will be evicted at some point, and
1756  // the regular path will work with the real entry. With time, this problem
1757  // will disasappear because this scenario is just a bug.
1758
1759  // Make sure that we save the key for later.
1760  entry->GetKey();
1761
1762  return entry;
1763}
1764
1765EntryImpl* BackendImpl::ResurrectEntry(EntryImpl* deleted_entry) {
1766  if (ENTRY_NORMAL == deleted_entry->entry()->Data()->state) {
1767    deleted_entry->Release();
1768    stats_.OnEvent(Stats::CREATE_MISS);
1769    Trace("create entry miss ");
1770    return NULL;
1771  }
1772
1773  // We are attempting to create an entry and found out that the entry was
1774  // previously deleted.
1775
1776  eviction_.OnCreateEntry(deleted_entry);
1777  entry_count_++;
1778
1779  stats_.OnEvent(Stats::RESURRECT_HIT);
1780  Trace("Resurrect entry hit ");
1781  return deleted_entry;
1782}
1783
1784void BackendImpl::DestroyInvalidEntry(EntryImpl* entry) {
1785  LOG(WARNING) << "Destroying invalid entry.";
1786  Trace("Destroying invalid entry 0x%p", entry);
1787
1788  entry->SetPointerForInvalidEntry(GetCurrentEntryId());
1789
1790  eviction_.OnDoomEntry(entry);
1791  entry->InternalDoom();
1792
1793  if (!new_eviction_)
1794    DecreaseNumEntries();
1795  stats_.OnEvent(Stats::INVALID_ENTRY);
1796}
1797
1798void BackendImpl::AddStorageSize(int32 bytes) {
1799  data_->header.num_bytes += bytes;
1800  DCHECK_GE(data_->header.num_bytes, 0);
1801}
1802
1803void BackendImpl::SubstractStorageSize(int32 bytes) {
1804  data_->header.num_bytes -= bytes;
1805  DCHECK_GE(data_->header.num_bytes, 0);
1806}
1807
1808void BackendImpl::IncreaseNumRefs() {
1809  num_refs_++;
1810  if (max_refs_ < num_refs_)
1811    max_refs_ = num_refs_;
1812}
1813
1814void BackendImpl::DecreaseNumRefs() {
1815  DCHECK(num_refs_);
1816  num_refs_--;
1817
1818  if (!num_refs_ && disabled_)
1819    base::MessageLoop::current()->PostTask(
1820        FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
1821}
1822
1823void BackendImpl::IncreaseNumEntries() {
1824  data_->header.num_entries++;
1825  DCHECK_GT(data_->header.num_entries, 0);
1826}
1827
1828void BackendImpl::DecreaseNumEntries() {
1829  data_->header.num_entries--;
1830  if (data_->header.num_entries < 0) {
1831    NOTREACHED();
1832    data_->header.num_entries = 0;
1833  }
1834}
1835
1836void BackendImpl::LogStats() {
1837  StatsItems stats;
1838  GetStats(&stats);
1839
1840  for (size_t index = 0; index < stats.size(); index++)
1841    VLOG(1) << stats[index].first << ": " << stats[index].second;
1842}
1843
1844void BackendImpl::ReportStats() {
1845  CACHE_UMA(COUNTS, "Entries", 0, data_->header.num_entries);
1846
1847  int current_size = data_->header.num_bytes / (1024 * 1024);
1848  int max_size = max_size_ / (1024 * 1024);
1849  int hit_ratio_as_percentage = stats_.GetHitRatio();
1850
1851  CACHE_UMA(COUNTS_10000, "Size2", 0, current_size);
1852  // For any bin in HitRatioBySize2, the hit ratio of caches of that size is the
1853  // ratio of that bin's total count to the count in the same bin in the Size2
1854  // histogram.
1855  if (base::RandInt(0, 99) < hit_ratio_as_percentage)
1856    CACHE_UMA(COUNTS_10000, "HitRatioBySize2", 0, current_size);
1857  CACHE_UMA(COUNTS_10000, "MaxSize2", 0, max_size);
1858  if (!max_size)
1859    max_size++;
1860  CACHE_UMA(PERCENTAGE, "UsedSpace", 0, current_size * 100 / max_size);
1861
1862  CACHE_UMA(COUNTS_10000, "AverageOpenEntries2", 0,
1863            static_cast<int>(stats_.GetCounter(Stats::OPEN_ENTRIES)));
1864  CACHE_UMA(COUNTS_10000, "MaxOpenEntries2", 0,
1865            static_cast<int>(stats_.GetCounter(Stats::MAX_ENTRIES)));
1866  stats_.SetCounter(Stats::MAX_ENTRIES, 0);
1867
1868  CACHE_UMA(COUNTS_10000, "TotalFatalErrors", 0,
1869            static_cast<int>(stats_.GetCounter(Stats::FATAL_ERROR)));
1870  CACHE_UMA(COUNTS_10000, "TotalDoomCache", 0,
1871            static_cast<int>(stats_.GetCounter(Stats::DOOM_CACHE)));
1872  CACHE_UMA(COUNTS_10000, "TotalDoomRecentEntries", 0,
1873            static_cast<int>(stats_.GetCounter(Stats::DOOM_RECENT)));
1874  stats_.SetCounter(Stats::FATAL_ERROR, 0);
1875  stats_.SetCounter(Stats::DOOM_CACHE, 0);
1876  stats_.SetCounter(Stats::DOOM_RECENT, 0);
1877
1878  int age = (Time::Now() -
1879             Time::FromInternalValue(data_->header.create_time)).InHours();
1880  if (age)
1881    CACHE_UMA(HOURS, "FilesAge", 0, age);
1882
1883  int64 total_hours = stats_.GetCounter(Stats::TIMER) / 120;
1884  if (!data_->header.create_time || !data_->header.lru.filled) {
1885    int cause = data_->header.create_time ? 0 : 1;
1886    if (!data_->header.lru.filled)
1887      cause |= 2;
1888    CACHE_UMA(CACHE_ERROR, "ShortReport", 0, cause);
1889    CACHE_UMA(HOURS, "TotalTimeNotFull", 0, static_cast<int>(total_hours));
1890    return;
1891  }
1892
1893  // This is an up to date client that will report FirstEviction() data. After
1894  // that event, start reporting this:
1895
1896  CACHE_UMA(HOURS, "TotalTime", 0, static_cast<int>(total_hours));
1897  // For any bin in HitRatioByTotalTime, the hit ratio of caches of that total
1898  // time is the ratio of that bin's total count to the count in the same bin in
1899  // the TotalTime histogram.
1900  if (base::RandInt(0, 99) < hit_ratio_as_percentage)
1901    CACHE_UMA(HOURS, "HitRatioByTotalTime", 0, implicit_cast<int>(total_hours));
1902
1903  int64 use_hours = stats_.GetCounter(Stats::LAST_REPORT_TIMER) / 120;
1904  stats_.SetCounter(Stats::LAST_REPORT_TIMER, stats_.GetCounter(Stats::TIMER));
1905
1906  // We may see users with no use_hours at this point if this is the first time
1907  // we are running this code.
1908  if (use_hours)
1909    use_hours = total_hours - use_hours;
1910
1911  if (!use_hours || !GetEntryCount() || !data_->header.num_bytes)
1912    return;
1913
1914  CACHE_UMA(HOURS, "UseTime", 0, static_cast<int>(use_hours));
1915  // For any bin in HitRatioByUseTime, the hit ratio of caches of that use time
1916  // is the ratio of that bin's total count to the count in the same bin in the
1917  // UseTime histogram.
1918  if (base::RandInt(0, 99) < hit_ratio_as_percentage)
1919    CACHE_UMA(HOURS, "HitRatioByUseTime", 0, implicit_cast<int>(use_hours));
1920  CACHE_UMA(PERCENTAGE, "HitRatio", 0, hit_ratio_as_percentage);
1921
1922  int64 trim_rate = stats_.GetCounter(Stats::TRIM_ENTRY) / use_hours;
1923  CACHE_UMA(COUNTS, "TrimRate", 0, static_cast<int>(trim_rate));
1924
1925  int avg_size = data_->header.num_bytes / GetEntryCount();
1926  CACHE_UMA(COUNTS, "EntrySize", 0, avg_size);
1927  CACHE_UMA(COUNTS, "EntriesFull", 0, data_->header.num_entries);
1928
1929  CACHE_UMA(PERCENTAGE, "IndexLoad", 0,
1930            data_->header.num_entries * 100 / (mask_ + 1));
1931
1932  int large_entries_bytes = stats_.GetLargeEntriesSize();
1933  int large_ratio = large_entries_bytes * 100 / data_->header.num_bytes;
1934  CACHE_UMA(PERCENTAGE, "LargeEntriesRatio", 0, large_ratio);
1935
1936  if (new_eviction_) {
1937    CACHE_UMA(PERCENTAGE, "ResurrectRatio", 0, stats_.GetResurrectRatio());
1938    CACHE_UMA(PERCENTAGE, "NoUseRatio", 0,
1939              data_->header.lru.sizes[0] * 100 / data_->header.num_entries);
1940    CACHE_UMA(PERCENTAGE, "LowUseRatio", 0,
1941              data_->header.lru.sizes[1] * 100 / data_->header.num_entries);
1942    CACHE_UMA(PERCENTAGE, "HighUseRatio", 0,
1943              data_->header.lru.sizes[2] * 100 / data_->header.num_entries);
1944    CACHE_UMA(PERCENTAGE, "DeletedRatio", 0,
1945              data_->header.lru.sizes[4] * 100 / data_->header.num_entries);
1946  }
1947
1948  stats_.ResetRatios();
1949  stats_.SetCounter(Stats::TRIM_ENTRY, 0);
1950
1951  if (cache_type_ == net::DISK_CACHE)
1952    block_files_.ReportStats();
1953}
1954
1955void BackendImpl::UpgradeTo2_1() {
1956  // 2.1 is basically the same as 2.0, except that new fields are actually
1957  // updated by the new eviction algorithm.
1958  DCHECK(0x20000 == data_->header.version);
1959  data_->header.version = 0x20001;
1960  data_->header.lru.sizes[Rankings::NO_USE] = data_->header.num_entries;
1961}
1962
1963bool BackendImpl::CheckIndex() {
1964  DCHECK(data_);
1965
1966  size_t current_size = index_->GetLength();
1967  if (current_size < sizeof(Index)) {
1968    LOG(ERROR) << "Corrupt Index file";
1969    return false;
1970  }
1971
1972  if (new_eviction_) {
1973    // We support versions 2.0 and 2.1, upgrading 2.0 to 2.1.
1974    if (kIndexMagic != data_->header.magic ||
1975        kCurrentVersion >> 16 != data_->header.version >> 16) {
1976      LOG(ERROR) << "Invalid file version or magic";
1977      return false;
1978    }
1979    if (kCurrentVersion == data_->header.version) {
1980      // We need file version 2.1 for the new eviction algorithm.
1981      UpgradeTo2_1();
1982    }
1983  } else {
1984    if (kIndexMagic != data_->header.magic ||
1985        kCurrentVersion != data_->header.version) {
1986      LOG(ERROR) << "Invalid file version or magic";
1987      return false;
1988    }
1989  }
1990
1991  if (!data_->header.table_len) {
1992    LOG(ERROR) << "Invalid table size";
1993    return false;
1994  }
1995
1996  if (current_size < GetIndexSize(data_->header.table_len) ||
1997      data_->header.table_len & (kBaseTableLen - 1)) {
1998    LOG(ERROR) << "Corrupt Index file";
1999    return false;
2000  }
2001
2002  AdjustMaxCacheSize(data_->header.table_len);
2003
2004#if !defined(NET_BUILD_STRESS_CACHE)
2005  if (data_->header.num_bytes < 0 ||
2006      (max_size_ < kint32max - kDefaultCacheSize &&
2007       data_->header.num_bytes > max_size_ + kDefaultCacheSize)) {
2008    LOG(ERROR) << "Invalid cache (current) size";
2009    return false;
2010  }
2011#endif
2012
2013  if (data_->header.num_entries < 0) {
2014    LOG(ERROR) << "Invalid number of entries";
2015    return false;
2016  }
2017
2018  if (!mask_)
2019    mask_ = data_->header.table_len - 1;
2020
2021  // Load the table into memory.
2022  return index_->Preload();
2023}
2024
2025int BackendImpl::CheckAllEntries() {
2026  int num_dirty = 0;
2027  int num_entries = 0;
2028  DCHECK(mask_ < kuint32max);
2029  for (unsigned int i = 0; i <= mask_; i++) {
2030    Addr address(data_->table[i]);
2031    if (!address.is_initialized())
2032      continue;
2033    for (;;) {
2034      EntryImpl* tmp;
2035      int ret = NewEntry(address, &tmp);
2036      if (ret) {
2037        STRESS_NOTREACHED();
2038        return ret;
2039      }
2040      scoped_refptr<EntryImpl> cache_entry;
2041      cache_entry.swap(&tmp);
2042
2043      if (cache_entry->dirty())
2044        num_dirty++;
2045      else if (CheckEntry(cache_entry.get()))
2046        num_entries++;
2047      else
2048        return ERR_INVALID_ENTRY;
2049
2050      DCHECK_EQ(i, cache_entry->entry()->Data()->hash & mask_);
2051      address.set_value(cache_entry->GetNextAddress());
2052      if (!address.is_initialized())
2053        break;
2054    }
2055  }
2056
2057  Trace("CheckAllEntries End");
2058  if (num_entries + num_dirty != data_->header.num_entries) {
2059    LOG(ERROR) << "Number of entries " << num_entries << " " << num_dirty <<
2060                  " " << data_->header.num_entries;
2061    DCHECK_LT(num_entries, data_->header.num_entries);
2062    return ERR_NUM_ENTRIES_MISMATCH;
2063  }
2064
2065  return num_dirty;
2066}
2067
2068bool BackendImpl::CheckEntry(EntryImpl* cache_entry) {
2069  bool ok = block_files_.IsValid(cache_entry->entry()->address());
2070  ok = ok && block_files_.IsValid(cache_entry->rankings()->address());
2071  EntryStore* data = cache_entry->entry()->Data();
2072  for (size_t i = 0; i < arraysize(data->data_addr); i++) {
2073    if (data->data_addr[i]) {
2074      Addr address(data->data_addr[i]);
2075      if (address.is_block_file())
2076        ok = ok && block_files_.IsValid(address);
2077    }
2078  }
2079
2080  return ok && cache_entry->rankings()->VerifyHash();
2081}
2082
2083int BackendImpl::MaxBuffersSize() {
2084  static int64 total_memory = base::SysInfo::AmountOfPhysicalMemory();
2085  static bool done = false;
2086
2087  if (!done) {
2088    const int kMaxBuffersSize = 30 * 1024 * 1024;
2089
2090    // We want to use up to 2% of the computer's memory.
2091    total_memory = total_memory * 2 / 100;
2092    if (total_memory > kMaxBuffersSize || total_memory <= 0)
2093      total_memory = kMaxBuffersSize;
2094
2095    done = true;
2096  }
2097
2098  return static_cast<int>(total_memory);
2099}
2100
2101}  // namespace disk_cache
2102