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/file_util.h"
  15 #include "base/files/file_enumerator.h"
  16 #include "base/logging.h"
  17 #include "base/message_loop/message_loop.h"
  18 #include "base/metrics/field_trial.h"
  19 #include "base/pickle.h"
  20 #include "base/strings/string_number_conversions.h"
  21 #include "base/strings/string_tokenizer.h"
  22 #include "base/task_runner.h"
  23 #include "base/threading/worker_pool.h"
  24 #include "base/time/time.h"
  25 #include "net/base/net_errors.h"
  26 #include "net/disk_cache/simple/simple_entry_format.h"
  27 #include "net/disk_cache/simple/simple_histogram_macros.h"
  28 #include "net/disk_cache/simple/simple_index_delegate.h"
  29 #include "net/disk_cache/simple/simple_index_file.h"
  30 #include "net/disk_cache/simple/simple_synchronous_entry.h"
  31 #include "net/disk_cache/simple/simple_util.h"
  32
  33 #if defined(OS_POSIX)
  34 #include <sys/stat.h>
  35 #include <sys/time.h>
  36 #endif
  37
  38 namespace {
  39
  40 // How many milliseconds we delay writing the index to disk since the last cache
  41 // operation has happened.
  42 const int kWriteToDiskDelayMSecs = 20000;
  43 const int kWriteToDiskOnBackgroundDelayMSecs = 100;
  44
  45 // Divides the cache space into this amount of parts to evict when only one part
  46 // is left.
  47 const uint32 kEvictionMarginDivisor = 20;
  48
  49 const uint32 kBytesInKb = 1024;
  50
  51 // Utility class used for timestamp comparisons in entry metadata while sorting.
  52 class CompareHashesForTimestamp {
  53   typedef disk_cache::SimpleIndex SimpleIndex;
  54   typedef disk_cache::SimpleIndex::EntrySet EntrySet;
  55  public:
  56   explicit CompareHashesForTimestamp(const EntrySet& set);
  57
  58   bool operator()(uint64 hash1, uint64 hash2);
  59  private:
  60   const EntrySet& entry_set_;
  61 };
  62
  63 CompareHashesForTimestamp::CompareHashesForTimestamp(const EntrySet& set)
  64   : entry_set_(set) {
  65 }
  66
  67 bool CompareHashesForTimestamp::operator()(uint64 hash1, uint64 hash2) {
  68   EntrySet::const_iterator it1 = entry_set_.find(hash1);
  69   DCHECK(it1 != entry_set_.end());
  70   EntrySet::const_iterator it2 = entry_set_.find(hash2);
  71   DCHECK(it2 != entry_set_.end());
  72   return it1->second.GetLastUsedTime() < it2->second.GetLastUsedTime();
  73 }
  74
  75 }  // namespace
  76
  77 namespace disk_cache {
  78
  79 EntryMetadata::EntryMetadata()
  80   : last_used_time_seconds_since_epoch_(0),
  81     entry_size_(0) {
  82 }
  83
  84 EntryMetadata::EntryMetadata(base::Time last_used_time, int entry_size)
  85     : last_used_time_seconds_since_epoch_(0),
  86       entry_size_(entry_size) {
  87   SetLastUsedTime(last_used_time);
  88 }
  89
  90 base::Time EntryMetadata::GetLastUsedTime() const {
  91   // Preserve nullity.
  92   if (last_used_time_seconds_since_epoch_ == 0)
  93     return base::Time();
  94
  95   return base::Time::UnixEpoch() +
  96       base::TimeDelta::FromSeconds(last_used_time_seconds_since_epoch_);
  97 }
  98
  99 void EntryMetadata::SetLastUsedTime(const base::Time& last_used_time) {
 100   // Preserve nullity.
 101   if (last_used_time.is_null()) {
 102     last_used_time_seconds_since_epoch_ = 0;
 103     return;
 104   }
 105
 106   const base::TimeDelta since_unix_epoch =
 107       last_used_time - base::Time::UnixEpoch();
 108   const int64 seconds_since_unix_epoch = since_unix_epoch.InSeconds();
 109   DCHECK_LE(implicit_cast<int64>(std::numeric_limits<uint32>::min()),
 110             seconds_since_unix_epoch);
 111   DCHECK_GE(implicit_cast<int64>(std::numeric_limits<uint32>::max()),
 112             seconds_since_unix_epoch);
 113
 114   last_used_time_seconds_since_epoch_ = seconds_since_unix_epoch;
 115   // Avoid accidental nullity.
 116   if (last_used_time_seconds_since_epoch_ == 0)
 117     last_used_time_seconds_since_epoch_ = 1;
 118 }
 119
 120 void EntryMetadata::Serialize(Pickle* pickle) const {
 121   DCHECK(pickle);
 122   int64 internal_last_used_time = GetLastUsedTime().ToInternalValue();
 123   pickle->WriteInt64(internal_last_used_time);
 124   pickle->WriteUInt64(entry_size_);
 125 }
 126
 127 bool EntryMetadata::Deserialize(PickleIterator* it) {
 128   DCHECK(it);
 129   int64 tmp_last_used_time;
 130   uint64 tmp_entry_size;
 131   if (!it->ReadInt64(&tmp_last_used_time) || !it->ReadUInt64(&tmp_entry_size))
 132     return false;
 133   SetLastUsedTime(base::Time::FromInternalValue(tmp_last_used_time));
 134   entry_size_ = tmp_entry_size;
 135   return true;
 136 }
 137
 138 SimpleIndex::SimpleIndex(base::SingleThreadTaskRunner* io_thread,
 139                          SimpleIndexDelegate* delegate,
 140                          net::CacheType cache_type,
 141                          scoped_ptr<SimpleIndexFile> index_file)
 142     : delegate_(delegate),
 143       cache_type_(cache_type),
 144       cache_size_(0),
 145       max_size_(0),
 146       high_watermark_(0),
 147       low_watermark_(0),
 148       eviction_in_progress_(false),
 149       initialized_(false),
 150       index_file_(index_file.Pass()),
 151       io_thread_(io_thread),
 152       // Creating the callback once so it is reused every time
 153       // write_to_disk_timer_.Start() is called.
 154       write_to_disk_cb_(base::Bind(&SimpleIndex::WriteToDisk, AsWeakPtr())),
 155       app_on_background_(false) {}
 156
 157 SimpleIndex::~SimpleIndex() {
 158   DCHECK(io_thread_checker_.CalledOnValidThread());
 159
 160   // Fail all callbacks waiting for the index to come up.
 161   for (CallbackList::iterator it = to_run_when_initialized_.begin(),
 162        end = to_run_when_initialized_.end(); it != end; ++it) {
 163     it->Run(net::ERR_ABORTED);
 164   }
 165 }
 166
 167 void SimpleIndex::Initialize(base::Time cache_mtime) {
 168   DCHECK(io_thread_checker_.CalledOnValidThread());
 169
 170 #if defined(OS_ANDROID)
 171   if (base::android::IsVMInitialized()) {
 172     app_status_listener_.reset(new base::android::ApplicationStatusListener(
 173         base::Bind(&SimpleIndex::OnApplicationStateChange, AsWeakPtr())));
 174   }
 175 #endif
 176
 177   SimpleIndexLoadResult* load_result = new SimpleIndexLoadResult();
 178   scoped_ptr<SimpleIndexLoadResult> load_result_scoped(load_result);
 179   base::Closure reply = base::Bind(
 180       &SimpleIndex::MergeInitializingSet,
 181       AsWeakPtr(),
 182       base::Passed(&load_result_scoped));
 183   index_file_->LoadIndexEntries(cache_mtime, reply, load_result);
 184 }
 185
 186 bool SimpleIndex::SetMaxSize(int max_bytes) {
 187   if (max_bytes < 0)
 188     return false;
 189
 190   // Zero size means use the default.
 191   if (!max_bytes)
 192     return true;
 193
 194   max_size_ = max_bytes;
 195   high_watermark_ = max_size_ - max_size_ / kEvictionMarginDivisor;
 196   low_watermark_ = max_size_ - 2 * (max_size_ / kEvictionMarginDivisor);
 197   return true;
 198 }
 199
 200 int SimpleIndex::ExecuteWhenReady(const net::CompletionCallback& task) {
 201   DCHECK(io_thread_checker_.CalledOnValidThread());
 202   if (initialized_)
 203     io_thread_->PostTask(FROM_HERE, base::Bind(task, net::OK));
 204   else
 205     to_run_when_initialized_.push_back(task);
 206   return net::ERR_IO_PENDING;
 207 }
 208
 209 scoped_ptr<SimpleIndex::HashList> SimpleIndex::GetEntriesBetween(
 210     base::Time initial_time, base::Time end_time) {
 211   DCHECK_EQ(true, initialized_);
 212
 213   if (!initial_time.is_null())
 214     initial_time -= EntryMetadata::GetLowerEpsilonForTimeComparisons();
 215   if (end_time.is_null())
 216     end_time = base::Time::Max();
 217   else
 218     end_time += EntryMetadata::GetUpperEpsilonForTimeComparisons();
 219   const base::Time extended_end_time =
 220       end_time.is_null() ? base::Time::Max() : end_time;
 221   DCHECK(extended_end_time >= initial_time);
 222   scoped_ptr<HashList> ret_hashes(new HashList());
 223   for (EntrySet::iterator it = entries_set_.begin(), end = entries_set_.end();
 224        it != end; ++it) {
 225     EntryMetadata& metadata = it->second;
 226     base::Time entry_time = metadata.GetLastUsedTime();
 227     if (initial_time <= entry_time && entry_time < extended_end_time)
 228       ret_hashes->push_back(it->first);
 229   }
 230   return ret_hashes.Pass();
 231 }
 232
 233 scoped_ptr<SimpleIndex::HashList> SimpleIndex::GetAllHashes() {
 234   return GetEntriesBetween(base::Time(), base::Time());
 235 }
 236
 237 int32 SimpleIndex::GetEntryCount() const {
 238   // TODO(pasko): return a meaningful initial estimate before initialized.
 239   return entries_set_.size();
 240 }
 241
 242 void SimpleIndex::Insert(uint64 entry_hash) {
 243   DCHECK(io_thread_checker_.CalledOnValidThread());
 244   // Upon insert we don't know yet the size of the entry.
 245   // It will be updated later when the SimpleEntryImpl finishes opening or
 246   // creating the new entry, and then UpdateEntrySize will be called.
 247   InsertInEntrySet(
 248       entry_hash, EntryMetadata(base::Time::Now(), 0), &entries_set_);
 249   if (!initialized_)
 250     removed_entries_.erase(entry_hash);
 251   PostponeWritingToDisk();
 252 }
 253
 254 void SimpleIndex::Remove(uint64 entry_hash) {
 255   DCHECK(io_thread_checker_.CalledOnValidThread());
 256   EntrySet::iterator it = entries_set_.find(entry_hash);
 257   if (it != entries_set_.end()) {
 258     UpdateEntryIteratorSize(&it, 0);
 259     entries_set_.erase(it);
 260   }
 261
 262   if (!initialized_)
 263     removed_entries_.insert(entry_hash);
 264   PostponeWritingToDisk();
 265 }
 266
 267 bool SimpleIndex::Has(uint64 hash) const {
 268   DCHECK(io_thread_checker_.CalledOnValidThread());
 269   // If not initialized, always return true, forcing it to go to the disk.
 270   return !initialized_ || entries_set_.count(hash) > 0;
 271 }
 272
 273 bool SimpleIndex::UseIfExists(uint64 entry_hash) {
 274   DCHECK(io_thread_checker_.CalledOnValidThread());
 275   // Always update the last used time, even if it is during initialization.
 276   // It will be merged later.
 277   EntrySet::iterator it = entries_set_.find(entry_hash);
 278   if (it == entries_set_.end())
 279     // If not initialized, always return true, forcing it to go to the disk.
 280     return !initialized_;
 281   it->second.SetLastUsedTime(base::Time::Now());
 282   PostponeWritingToDisk();
 283   return true;
 284 }
 285
 286 void SimpleIndex::StartEvictionIfNeeded() {
 287   DCHECK(io_thread_checker_.CalledOnValidThread());
 288   if (eviction_in_progress_ || cache_size_ <= high_watermark_)
 289     return;
 290   // Take all live key hashes from the index and sort them by time.
 291   eviction_in_progress_ = true;
 292   eviction_start_time_ = base::TimeTicks::Now();
 293   SIMPLE_CACHE_UMA(MEMORY_KB,
 294                    "Eviction.CacheSizeOnStart2", cache_type_,
 295                    cache_size_ / kBytesInKb);
 296   SIMPLE_CACHE_UMA(MEMORY_KB,
 297                    "Eviction.MaxCacheSizeOnStart2", cache_type_,
 298                    max_size_ / kBytesInKb);
 299   std::vector<uint64> entry_hashes;
 300   entry_hashes.reserve(entries_set_.size());
 301   for (EntrySet::const_iterator it = entries_set_.begin(),
 302        end = entries_set_.end(); it != end; ++it) {
 303     entry_hashes.push_back(it->first);
 304   }
 305   std::sort(entry_hashes.begin(), entry_hashes.end(),
 306             CompareHashesForTimestamp(entries_set_));
 307
 308   // Remove as many entries from the index to get below |low_watermark_|.
 309   std::vector<uint64>::iterator it = entry_hashes.begin();
 310   uint64 evicted_so_far_size = 0;
 311   while (evicted_so_far_size < cache_size_ - low_watermark_) {
 312     DCHECK(it != entry_hashes.end());
 313     EntrySet::iterator found_meta = entries_set_.find(*it);
 314     DCHECK(found_meta != entries_set_.end());
 315     uint64 to_evict_size = found_meta->second.GetEntrySize();
 316     evicted_so_far_size += to_evict_size;
 317     ++it;
 318   }
 319
 320   // Take out the rest of hashes from the eviction list.
 321   entry_hashes.erase(it, entry_hashes.end());
 322   SIMPLE_CACHE_UMA(COUNTS,
 323                    "Eviction.EntryCount", cache_type_, entry_hashes.size());
 324   SIMPLE_CACHE_UMA(TIMES,
 325                    "Eviction.TimeToSelectEntries", cache_type_,
 326                    base::TimeTicks::Now() - eviction_start_time_);
 327   SIMPLE_CACHE_UMA(MEMORY_KB,
 328                    "Eviction.SizeOfEvicted2", cache_type_,
 329                    evicted_so_far_size / kBytesInKb);
 330
 331   delegate_->DoomEntries(&entry_hashes, base::Bind(&SimpleIndex::EvictionDone,
 332                                                    AsWeakPtr()));
 333 }
 334
 335 bool SimpleIndex::UpdateEntrySize(uint64 entry_hash, int entry_size) {
 336   DCHECK(io_thread_checker_.CalledOnValidThread());
 337   EntrySet::iterator it = entries_set_.find(entry_hash);
 338   if (it == entries_set_.end())
 339     return false;
 340
 341   UpdateEntryIteratorSize(&it, entry_size);
 342   PostponeWritingToDisk();
 343   StartEvictionIfNeeded();
 344   return true;
 345 }
 346
 347 void SimpleIndex::EvictionDone(int result) {
 348   DCHECK(io_thread_checker_.CalledOnValidThread());
 349
 350   // Ignore the result of eviction. We did our best.
 351   eviction_in_progress_ = false;
 352   SIMPLE_CACHE_UMA(BOOLEAN, "Eviction.Result", cache_type_, result == net::OK);
 353   SIMPLE_CACHE_UMA(TIMES,
 354                    "Eviction.TimeToDone", cache_type_,
 355                    base::TimeTicks::Now() - eviction_start_time_);
 356   SIMPLE_CACHE_UMA(MEMORY_KB,
 357                    "Eviction.SizeWhenDone2", cache_type_,
 358                    cache_size_ / kBytesInKb);
 359 }
 360
 361 // static
 362 void SimpleIndex::InsertInEntrySet(
 363     uint64 entry_hash,
 364     const disk_cache::EntryMetadata& entry_metadata,
 365     EntrySet* entry_set) {
 366   DCHECK(entry_set);
 367   entry_set->insert(std::make_pair(entry_hash, entry_metadata));
 368 }
 369
 370 void SimpleIndex::PostponeWritingToDisk() {
 371   if (!initialized_)
 372     return;
 373   const int delay = app_on_background_ ? kWriteToDiskOnBackgroundDelayMSecs
 374                                        : kWriteToDiskDelayMSecs;
 375   // If the timer is already active, Start() will just Reset it, postponing it.
 376   write_to_disk_timer_.Start(
 377       FROM_HERE, base::TimeDelta::FromMilliseconds(delay), write_to_disk_cb_);
 378 }
 379
 380 void SimpleIndex::UpdateEntryIteratorSize(EntrySet::iterator* it,
 381                                           int entry_size) {
 382   // Update the total cache size with the new entry size.
 383   DCHECK(io_thread_checker_.CalledOnValidThread());
 384   DCHECK_GE(cache_size_, implicit_cast<uint64>((*it)->second.GetEntrySize()));
 385   cache_size_ -= (*it)->second.GetEntrySize();
 386   cache_size_ += entry_size;
 387   (*it)->second.SetEntrySize(entry_size);
 388 }
 389
 390 void SimpleIndex::MergeInitializingSet(
 391     scoped_ptr<SimpleIndexLoadResult> load_result) {
 392   DCHECK(io_thread_checker_.CalledOnValidThread());
 393   DCHECK(load_result->did_load);
 394
 395   EntrySet* index_file_entries = &load_result->entries;
 396
 397   for (base::hash_set<uint64>::const_iterator it = removed_entries_.begin();
 398        it != removed_entries_.end(); ++it) {
 399     index_file_entries->erase(*it);
 400   }
 401   removed_entries_.clear();
 402
 403   for (EntrySet::const_iterator it = entries_set_.begin();
 404        it != entries_set_.end(); ++it) {
 405     const uint64 entry_hash = it->first;
 406     std::pair<EntrySet::iterator, bool> insert_result =
 407         index_file_entries->insert(EntrySet::value_type(entry_hash,
 408                                                         EntryMetadata()));
 409     EntrySet::iterator& possibly_inserted_entry = insert_result.first;
 410     possibly_inserted_entry->second = it->second;
 411   }
 412
 413   uint64 merged_cache_size = 0;
 414   for (EntrySet::iterator it = index_file_entries->begin();
 415        it != index_file_entries->end(); ++it) {
 416     merged_cache_size += it->second.GetEntrySize();
 417   }
 418
 419   entries_set_.swap(*index_file_entries);
 420   cache_size_ = merged_cache_size;
 421   initialized_ = true;
 422
 423   // The actual IO is asynchronous, so calling WriteToDisk() shouldn't slow the
 424   // merge down much.
 425   if (load_result->flush_required)
 426     WriteToDisk();
 427
 428   SIMPLE_CACHE_UMA(CUSTOM_COUNTS,
 429                    "IndexInitializationWaiters", cache_type_,
 430                    to_run_when_initialized_.size(), 0, 100, 20);
 431   // Run all callbacks waiting for the index to come up.
 432   for (CallbackList::iterator it = to_run_when_initialized_.begin(),
 433        end = to_run_when_initialized_.end(); it != end; ++it) {
 434     io_thread_->PostTask(FROM_HERE, base::Bind((*it), net::OK));
 435   }
 436   to_run_when_initialized_.clear();
 437 }
 438
 439 #if defined(OS_ANDROID)
 440 void SimpleIndex::OnApplicationStateChange(
 441     base::android::ApplicationState state) {
 442   DCHECK(io_thread_checker_.CalledOnValidThread());
 443   // For more info about android activities, see:
 444   // developer.android.com/training/basics/activity-lifecycle/pausing.html
 445   if (state == base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES) {
 446     app_on_background_ = false;
 447   } else if (state ==
 448       base::android::APPLICATION_STATE_HAS_STOPPED_ACTIVITIES) {
 449     app_on_background_ = true;
 450     WriteToDisk();
 451   }
 452 }
 453 #endif
 454
 455 void SimpleIndex::WriteToDisk() {
 456   DCHECK(io_thread_checker_.CalledOnValidThread());
 457   if (!initialized_)
 458     return;
 459   SIMPLE_CACHE_UMA(CUSTOM_COUNTS,
 460                    "IndexNumEntriesOnWrite", cache_type_,
 461                    entries_set_.size(), 0, 100000, 50);
 462   const base::TimeTicks start = base::TimeTicks::Now();
 463   if (!last_write_to_disk_.is_null()) {
 464     if (app_on_background_) {
 465       SIMPLE_CACHE_UMA(MEDIUM_TIMES,
 466                        "IndexWriteInterval.Background", cache_type_,
 467                        start - last_write_to_disk_);
 468     } else {
 469       SIMPLE_CACHE_UMA(MEDIUM_TIMES,
 470                        "IndexWriteInterval.Foreground", cache_type_,
 471                        start - last_write_to_disk_);
 472     }
 473   }
 474   last_write_to_disk_ = start;
 475
 476   index_file_->WriteToDisk(entries_set_, cache_size_,
 477                            start, app_on_background_);
 478 }
 479
 480 }  // namespace disk_cache