src/net/disk_cache/simple/simple_index.cc

   1 // Copyright (c) 2013 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/simple/simple_index.h"
   6
   7 #include <algorithm>
   8 #include <limits>
   9 #include <string>
  10 #include <utility>
  11
  12 #include "base/bind.h"
  13 #include "base/bind_helpers.h"
  14 #include "base/files/file_enumerator.h"
  15 #include "base/files/file_util.h"
  16 #include "base/logging.h"
  17 #include "base/message_loop/message_loop.h"
  18 #include "base/metrics/field_trial.h"
  19 #include "base/numerics/safe_conversions.h"
  20 #include "base/pickle.h"
  21 #include "base/strings/string_number_conversions.h"
  22 #include "base/strings/string_tokenizer.h"
  23 #include "base/task_runner.h"
  24 #include "base/threading/worker_pool.h"
  25 #include "base/time/time.h"
  26 #include "net/base/net_errors.h"
  27 #include "net/disk_cache/simple/simple_entry_format.h"
  28 #include "net/disk_cache/simple/simple_histogram_macros.h"
  29 #include "net/disk_cache/simple/simple_index_delegate.h"
  30 #include "net/disk_cache/simple/simple_index_file.h"
  31 #include "net/disk_cache/simple/simple_synchronous_entry.h"
  32 #include "net/disk_cache/simple/simple_util.h"
  33
  34 #if defined(OS_POSIX)
  35 #include <sys/stat.h>
  36 #include <sys/time.h>
  37 #endif
  38
  39 namespace {
  40
  41 // How many milliseconds we delay writing the index to disk since the last cache
  42 // operation has happened.
  43 const int kWriteToDiskDelayMSecs = 20000;
  44 const int kWriteToDiskOnBackgroundDelayMSecs = 100;
  45
  46 // Divides the cache space into this amount of parts to evict when only one part
  47 // is left.
  48 const uint32 kEvictionMarginDivisor = 20;
  49
  50 const uint32 kBytesInKb = 1024;
  51
  52 // Utility class used for timestamp comparisons in entry metadata while sorting.
  53 class CompareHashesForTimestamp {
  54   typedef disk_cache::SimpleIndex SimpleIndex;
  55   typedef disk_cache::SimpleIndex::EntrySet EntrySet;
  56  public:
  57   explicit CompareHashesForTimestamp(const EntrySet& set);
  58
  59   bool operator()(uint64 hash1, uint64 hash2);
  60  private:
  61   const EntrySet& entry_set_;
  62 };
  63
  64 CompareHashesForTimestamp::CompareHashesForTimestamp(const EntrySet& set)
  65   : entry_set_(set) {
  66 }
  67
  68 bool CompareHashesForTimestamp::operator()(uint64 hash1, uint64 hash2) {
  69   EntrySet::const_iterator it1 = entry_set_.find(hash1);
  70   DCHECK(it1 != entry_set_.end());
  71   EntrySet::const_iterator it2 = entry_set_.find(hash2);
  72   DCHECK(it2 != entry_set_.end());
  73   return it1->second.GetLastUsedTime() < it2->second.GetLastUsedTime();
  74 }
  75
  76 }  // namespace
  77
  78 namespace disk_cache {
  79
  80 EntryMetadata::EntryMetadata()
  81   : last_used_time_seconds_since_epoch_(0),
  82     entry_size_(0) {
  83 }
  84
  85 EntryMetadata::EntryMetadata(base::Time last_used_time, int entry_size)
  86     : last_used_time_seconds_since_epoch_(0),
  87       entry_size_(entry_size) {
  88   SetLastUsedTime(last_used_time);
  89 }
  90
  91 base::Time EntryMetadata::GetLastUsedTime() const {
  92   // Preserve nullity.
  93   if (last_used_time_seconds_since_epoch_ == 0)
  94     return base::Time();
  95
  96   return base::Time::UnixEpoch() +
  97       base::TimeDelta::FromSeconds(last_used_time_seconds_since_epoch_);
  98 }
  99
 100 void EntryMetadata::SetLastUsedTime(const base::Time& last_used_time) {
 101   // Preserve nullity.
 102   if (last_used_time.is_null()) {
 103     last_used_time_seconds_since_epoch_ = 0;
 104     return;
 105   }
 106
 107   last_used_time_seconds_since_epoch_ = base::checked_cast<uint32>(
 108       (last_used_time - base::Time::UnixEpoch()).InSeconds());
 109   // Avoid accidental nullity.
 110   if (last_used_time_seconds_since_epoch_ == 0)
 111     last_used_time_seconds_since_epoch_ = 1;
 112 }
 113
 114 void EntryMetadata::Serialize(Pickle* pickle) const {
 115   DCHECK(pickle);
 116   int64 internal_last_used_time = GetLastUsedTime().ToInternalValue();
 117   pickle->WriteInt64(internal_last_used_time);
 118   pickle->WriteUInt64(entry_size_);
 119 }
 120
 121 bool EntryMetadata::Deserialize(PickleIterator* it) {
 122   DCHECK(it);
 123   int64 tmp_last_used_time;
 124   uint64 tmp_entry_size;
 125   if (!it->ReadInt64(&tmp_last_used_time) || !it->ReadUInt64(&tmp_entry_size))
 126     return false;
 127   SetLastUsedTime(base::Time::FromInternalValue(tmp_last_used_time));
 128   entry_size_ = tmp_entry_size;
 129   return true;
 130 }
 131
 132 SimpleIndex::SimpleIndex(
 133     const scoped_refptr<base::SingleThreadTaskRunner>& io_thread,
 134     SimpleIndexDelegate* delegate,
 135     net::CacheType cache_type,
 136     scoped_ptr<SimpleIndexFile> index_file)
 137     : delegate_(delegate),
 138       cache_type_(cache_type),
 139       cache_size_(0),
 140       max_size_(0),
 141       high_watermark_(0),
 142       low_watermark_(0),
 143       eviction_in_progress_(false),
 144       initialized_(false),
 145       index_file_(index_file.Pass()),
 146       io_thread_(io_thread),
 147       // Creating the callback once so it is reused every time
 148       // write_to_disk_timer_.Start() is called.
 149       write_to_disk_cb_(base::Bind(&SimpleIndex::WriteToDisk, AsWeakPtr())),
 150       app_on_background_(false) {
 151 }
 152
 153 SimpleIndex::~SimpleIndex() {
 154   DCHECK(io_thread_checker_.CalledOnValidThread());
 155
 156   // Fail all callbacks waiting for the index to come up.
 157   for (CallbackList::iterator it = to_run_when_initialized_.begin(),
 158        end = to_run_when_initialized_.end(); it != end; ++it) {
 159     it->Run(net::ERR_ABORTED);
 160   }
 161 }
 162
 163 void SimpleIndex::Initialize(base::Time cache_mtime) {
 164   DCHECK(io_thread_checker_.CalledOnValidThread());
 165
 166 #if defined(OS_ANDROID)
 167   if (base::android::IsVMInitialized()) {
 168     app_status_listener_.reset(new base::android::ApplicationStatusListener(
 169         base::Bind(&SimpleIndex::OnApplicationStateChange, AsWeakPtr())));
 170   }
 171 #endif
 172
 173   SimpleIndexLoadResult* load_result = new SimpleIndexLoadResult();
 174   scoped_ptr<SimpleIndexLoadResult> load_result_scoped(load_result);
 175   base::Closure reply = base::Bind(
 176       &SimpleIndex::MergeInitializingSet,
 177       AsWeakPtr(),
 178       base::Passed(&load_result_scoped));
 179   index_file_->LoadIndexEntries(cache_mtime, reply, load_result);
 180 }
 181
 182 bool SimpleIndex::SetMaxSize(int max_bytes) {
 183   if (max_bytes < 0)
 184     return false;
 185
 186   // Zero size means use the default.
 187   if (!max_bytes)
 188     return true;
 189
 190   max_size_ = max_bytes;
 191   high_watermark_ = max_size_ - max_size_ / kEvictionMarginDivisor;
 192   low_watermark_ = max_size_ - 2 * (max_size_ / kEvictionMarginDivisor);
 193   return true;
 194 }
 195
 196 int SimpleIndex::ExecuteWhenReady(const net::CompletionCallback& task) {
 197   DCHECK(io_thread_checker_.CalledOnValidThread());
 198   if (initialized_)
 199     io_thread_->PostTask(FROM_HERE, base::Bind(task, net::OK));
 200   else
 201     to_run_when_initialized_.push_back(task);
 202   return net::ERR_IO_PENDING;
 203 }
 204
 205 scoped_ptr<SimpleIndex::HashList> SimpleIndex::GetEntriesBetween(
 206     base::Time initial_time, base::Time end_time) {
 207   DCHECK_EQ(true, initialized_);
 208
 209   if (!initial_time.is_null())
 210     initial_time -= EntryMetadata::GetLowerEpsilonForTimeComparisons();
 211   if (end_time.is_null())
 212     end_time = base::Time::Max();
 213   else
 214     end_time += EntryMetadata::GetUpperEpsilonForTimeComparisons();
 215   const base::Time extended_end_time =
 216       end_time.is_null() ? base::Time::Max() : end_time;
 217   DCHECK(extended_end_time >= initial_time);
 218   scoped_ptr<HashList> ret_hashes(new HashList());
 219   for (EntrySet::iterator it = entries_set_.begin(), end = entries_set_.end();
 220        it != end; ++it) {
 221     EntryMetadata& metadata = it->second;
 222     base::Time entry_time = metadata.GetLastUsedTime();
 223     if (initial_time <= entry_time && entry_time < extended_end_time)
 224       ret_hashes->push_back(it->first);
 225   }
 226   return ret_hashes.Pass();
 227 }
 228
 229 scoped_ptr<SimpleIndex::HashList> SimpleIndex::GetAllHashes() {
 230   return GetEntriesBetween(base::Time(), base::Time());
 231 }
 232
 233 int32 SimpleIndex::GetEntryCount() const {
 234   // TODO(pasko): return a meaningful initial estimate before initialized.
 235   return entries_set_.size();
 236 }
 237
 238 void SimpleIndex::Insert(uint64 entry_hash) {
 239   DCHECK(io_thread_checker_.CalledOnValidThread());
 240   // Upon insert we don't know yet the size of the entry.
 241   // It will be updated later when the SimpleEntryImpl finishes opening or
 242   // creating the new entry, and then UpdateEntrySize will be called.
 243   InsertInEntrySet(
 244       entry_hash, EntryMetadata(base::Time::Now(), 0), &entries_set_);
 245   if (!initialized_)
 246     removed_entries_.erase(entry_hash);
 247   PostponeWritingToDisk();
 248 }
 249
 250 void SimpleIndex::Remove(uint64 entry_hash) {
 251   DCHECK(io_thread_checker_.CalledOnValidThread());
 252   EntrySet::iterator it = entries_set_.find(entry_hash);
 253   if (it != entries_set_.end()) {
 254     UpdateEntryIteratorSize(&it, 0);
 255     entries_set_.erase(it);
 256   }
 257
 258   if (!initialized_)
 259     removed_entries_.insert(entry_hash);
 260   PostponeWritingToDisk();
 261 }
 262
 263 bool SimpleIndex::Has(uint64 hash) const {
 264   DCHECK(io_thread_checker_.CalledOnValidThread());
 265   // If not initialized, always return true, forcing it to go to the disk.
 266   return !initialized_ || entries_set_.count(hash) > 0;
 267 }
 268
 269 bool SimpleIndex::UseIfExists(uint64 entry_hash) {
 270   DCHECK(io_thread_checker_.CalledOnValidThread());
 271   // Always update the last used time, even if it is during initialization.
 272   // It will be merged later.
 273   EntrySet::iterator it = entries_set_.find(entry_hash);
 274   if (it == entries_set_.end())
 275     // If not initialized, always return true, forcing it to go to the disk.
 276     return !initialized_;
 277   it->second.SetLastUsedTime(base::Time::Now());
 278   PostponeWritingToDisk();
 279   return true;
 280 }
 281
 282 void SimpleIndex::StartEvictionIfNeeded() {
 283   DCHECK(io_thread_checker_.CalledOnValidThread());
 284   if (eviction_in_progress_ || cache_size_ <= high_watermark_)
 285     return;
 286   // Take all live key hashes from the index and sort them by time.
 287   eviction_in_progress_ = true;
 288   eviction_start_time_ = base::TimeTicks::Now();
 289   SIMPLE_CACHE_UMA(MEMORY_KB,
 290                    "Eviction.CacheSizeOnStart2", cache_type_,
 291                    cache_size_ / kBytesInKb);
 292   SIMPLE_CACHE_UMA(MEMORY_KB,
 293                    "Eviction.MaxCacheSizeOnStart2", cache_type_,
 294                    max_size_ / kBytesInKb);
 295   std::vector<uint64> entry_hashes;
 296   entry_hashes.reserve(entries_set_.size());
 297   for (EntrySet::const_iterator it = entries_set_.begin(),
 298        end = entries_set_.end(); it != end; ++it) {
 299     entry_hashes.push_back(it->first);
 300   }
 301   std::sort(entry_hashes.begin(), entry_hashes.end(),
 302             CompareHashesForTimestamp(entries_set_));
 303
 304   // Remove as many entries from the index to get below |low_watermark_|.
 305   std::vector<uint64>::iterator it = entry_hashes.begin();
 306   uint64 evicted_so_far_size = 0;
 307   while (evicted_so_far_size < cache_size_ - low_watermark_) {
 308     DCHECK(it != entry_hashes.end());
 309     EntrySet::iterator found_meta = entries_set_.find(*it);
 310     DCHECK(found_meta != entries_set_.end());
 311     uint64 to_evict_size = found_meta->second.GetEntrySize();
 312     evicted_so_far_size += to_evict_size;
 313     ++it;
 314   }
 315
 316   // Take out the rest of hashes from the eviction list.
 317   entry_hashes.erase(it, entry_hashes.end());
 318   SIMPLE_CACHE_UMA(COUNTS,
 319                    "Eviction.EntryCount", cache_type_, entry_hashes.size());
 320   SIMPLE_CACHE_UMA(TIMES,
 321                    "Eviction.TimeToSelectEntries", cache_type_,
 322                    base::TimeTicks::Now() - eviction_start_time_);
 323   SIMPLE_CACHE_UMA(MEMORY_KB,
 324                    "Eviction.SizeOfEvicted2", cache_type_,
 325                    evicted_so_far_size / kBytesInKb);
 326
 327   delegate_->DoomEntries(&entry_hashes, base::Bind(&SimpleIndex::EvictionDone,
 328                                                    AsWeakPtr()));
 329 }
 330
 331 bool SimpleIndex::UpdateEntrySize(uint64 entry_hash, int entry_size) {
 332   DCHECK(io_thread_checker_.CalledOnValidThread());
 333   EntrySet::iterator it = entries_set_.find(entry_hash);
 334   if (it == entries_set_.end())
 335     return false;
 336
 337   UpdateEntryIteratorSize(&it, entry_size);
 338   PostponeWritingToDisk();
 339   StartEvictionIfNeeded();
 340   return true;
 341 }
 342
 343 void SimpleIndex::EvictionDone(int result) {
 344   DCHECK(io_thread_checker_.CalledOnValidThread());
 345
 346   // Ignore the result of eviction. We did our best.
 347   eviction_in_progress_ = false;
 348   SIMPLE_CACHE_UMA(BOOLEAN, "Eviction.Result", cache_type_, result == net::OK);
 349   SIMPLE_CACHE_UMA(TIMES,
 350                    "Eviction.TimeToDone", cache_type_,
 351                    base::TimeTicks::Now() - eviction_start_time_);
 352   SIMPLE_CACHE_UMA(MEMORY_KB,
 353                    "Eviction.SizeWhenDone2", cache_type_,
 354                    cache_size_ / kBytesInKb);
 355 }
 356
 357 // static
 358 void SimpleIndex::InsertInEntrySet(
 359     uint64 entry_hash,
 360     const disk_cache::EntryMetadata& entry_metadata,
 361     EntrySet* entry_set) {
 362   DCHECK(entry_set);
 363   entry_set->insert(std::make_pair(entry_hash, entry_metadata));
 364 }
 365
 366 void SimpleIndex::PostponeWritingToDisk() {
 367   if (!initialized_)
 368     return;
 369   const int delay = app_on_background_ ? kWriteToDiskOnBackgroundDelayMSecs
 370                                        : kWriteToDiskDelayMSecs;
 371   // If the timer is already active, Start() will just Reset it, postponing it.
 372   write_to_disk_timer_.Start(
 373       FROM_HERE, base::TimeDelta::FromMilliseconds(delay), write_to_disk_cb_);
 374 }
 375
 376 void SimpleIndex::UpdateEntryIteratorSize(EntrySet::iterator* it,
 377                                           int entry_size) {
 378   // Update the total cache size with the new entry size.
 379   DCHECK(io_thread_checker_.CalledOnValidThread());
 380   DCHECK_GE(cache_size_, implicit_cast<uint64>((*it)->second.GetEntrySize()));
 381   cache_size_ -= (*it)->second.GetEntrySize();
 382   cache_size_ += entry_size;
 383   (*it)->second.SetEntrySize(entry_size);
 384 }
 385
 386 void SimpleIndex::MergeInitializingSet(
 387     scoped_ptr<SimpleIndexLoadResult> load_result) {
 388   DCHECK(io_thread_checker_.CalledOnValidThread());
 389   DCHECK(load_result->did_load);
 390
 391   EntrySet* index_file_entries = &load_result->entries;
 392
 393   for (base::hash_set<uint64>::const_iterator it = removed_entries_.begin();
 394        it != removed_entries_.end(); ++it) {
 395     index_file_entries->erase(*it);
 396   }
 397   removed_entries_.clear();
 398
 399   for (EntrySet::const_iterator it = entries_set_.begin();
 400        it != entries_set_.end(); ++it) {
 401     const uint64 entry_hash = it->first;
 402     std::pair<EntrySet::iterator, bool> insert_result =
 403         index_file_entries->insert(EntrySet::value_type(entry_hash,
 404                                                         EntryMetadata()));
 405     EntrySet::iterator& possibly_inserted_entry = insert_result.first;
 406     possibly_inserted_entry->second = it->second;
 407   }
 408
 409   uint64 merged_cache_size = 0;
 410   for (EntrySet::iterator it = index_file_entries->begin();
 411        it != index_file_entries->end(); ++it) {
 412     merged_cache_size += it->second.GetEntrySize();
 413   }
 414
 415   entries_set_.swap(*index_file_entries);
 416   cache_size_ = merged_cache_size;
 417   initialized_ = true;
 418
 419   // The actual IO is asynchronous, so calling WriteToDisk() shouldn't slow the
 420   // merge down much.
 421   if (load_result->flush_required)
 422     WriteToDisk();
 423
 424   SIMPLE_CACHE_UMA(CUSTOM_COUNTS,
 425                    "IndexInitializationWaiters", cache_type_,
 426                    to_run_when_initialized_.size(), 0, 100, 20);
 427   // Run all callbacks waiting for the index to come up.
 428   for (CallbackList::iterator it = to_run_when_initialized_.begin(),
 429        end = to_run_when_initialized_.end(); it != end; ++it) {
 430     io_thread_->PostTask(FROM_HERE, base::Bind((*it), net::OK));
 431   }
 432   to_run_when_initialized_.clear();
 433 }
 434
 435 #if defined(OS_ANDROID)
 436 void SimpleIndex::OnApplicationStateChange(
 437     base::android::ApplicationState state) {
 438   DCHECK(io_thread_checker_.CalledOnValidThread());
 439   // For more info about android activities, see:
 440   // developer.android.com/training/basics/activity-lifecycle/pausing.html
 441   if (state == base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES) {
 442     app_on_background_ = false;
 443   } else if (state ==
 444       base::android::APPLICATION_STATE_HAS_STOPPED_ACTIVITIES) {
 445     app_on_background_ = true;
 446     WriteToDisk();
 447   }
 448 }
 449 #endif
 450
 451 void SimpleIndex::WriteToDisk() {
 452   DCHECK(io_thread_checker_.CalledOnValidThread());
 453   if (!initialized_)
 454     return;
 455   SIMPLE_CACHE_UMA(CUSTOM_COUNTS,
 456                    "IndexNumEntriesOnWrite", cache_type_,
 457                    entries_set_.size(), 0, 100000, 50);
 458   const base::TimeTicks start = base::TimeTicks::Now();
 459   if (!last_write_to_disk_.is_null()) {
 460     if (app_on_background_) {
 461       SIMPLE_CACHE_UMA(MEDIUM_TIMES,
 462                        "IndexWriteInterval.Background", cache_type_,
 463                        start - last_write_to_disk_);
 464     } else {
 465       SIMPLE_CACHE_UMA(MEDIUM_TIMES,
 466                        "IndexWriteInterval.Foreground", cache_type_,
 467                        start - last_write_to_disk_);
 468     }
 469   }
 470   last_write_to_disk_ = start;
 471
 472   index_file_->WriteToDisk(entries_set_, cache_size_,
 473                            start, app_on_background_, base::Closure());
 474 }
 475
 476 }  // namespace disk_cache