net/disk_cache/simple/simple_index_file.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_file.h"
   6
   7 #include <vector>
   8
   9 #include "base/files/file.h"
  10 #include "base/files/file_util.h"
  11 #include "base/files/memory_mapped_file.h"
  12 #include "base/hash.h"
  13 #include "base/logging.h"
  14 #include "base/pickle.h"
  15 #include "base/single_thread_task_runner.h"
  16 #include "base/task_runner_util.h"
  17 #include "base/threading/thread_restrictions.h"
  18 #include "net/disk_cache/simple/simple_backend_version.h"
  19 #include "net/disk_cache/simple/simple_entry_format.h"
  20 #include "net/disk_cache/simple/simple_histogram_macros.h"
  21 #include "net/disk_cache/simple/simple_index.h"
  22 #include "net/disk_cache/simple/simple_synchronous_entry.h"
  23 #include "net/disk_cache/simple/simple_util.h"
  24 #include "third_party/zlib/zlib.h"
  25
  26 using base::File;
  27
  28 namespace disk_cache {
  29 namespace {
  30
  31 const int kEntryFilesHashLength = 16;
  32 const int kEntryFilesSuffixLength = 2;
  33
  34 const uint64 kMaxEntiresInIndex = 100000000;
  35
  36 uint32 CalculatePickleCRC(const base::Pickle& pickle) {
  37   return crc32(crc32(0, Z_NULL, 0),
  38                reinterpret_cast<const Bytef*>(pickle.payload()),
  39                pickle.payload_size());
  40 }
  41
  42 // Used in histograms. Please only add new values at the end.
  43 enum IndexFileState {
  44   INDEX_STATE_CORRUPT = 0,
  45   INDEX_STATE_STALE = 1,
  46   INDEX_STATE_FRESH = 2,
  47   INDEX_STATE_FRESH_CONCURRENT_UPDATES = 3,
  48   INDEX_STATE_MAX = 4,
  49 };
  50
  51 void UmaRecordIndexFileState(IndexFileState state, net::CacheType cache_type) {
  52   SIMPLE_CACHE_UMA(ENUMERATION,
  53                    "IndexFileStateOnLoad", cache_type, state, INDEX_STATE_MAX);
  54 }
  55
  56 // Used in histograms. Please only add new values at the end.
  57 enum IndexInitMethod {
  58   INITIALIZE_METHOD_RECOVERED = 0,
  59   INITIALIZE_METHOD_LOADED = 1,
  60   INITIALIZE_METHOD_NEWCACHE = 2,
  61   INITIALIZE_METHOD_MAX = 3,
  62 };
  63
  64 void UmaRecordIndexInitMethod(IndexInitMethod method,
  65                               net::CacheType cache_type) {
  66   SIMPLE_CACHE_UMA(ENUMERATION,
  67                    "IndexInitializeMethod", cache_type,
  68                    method, INITIALIZE_METHOD_MAX);
  69 }
  70
  71 bool WritePickleFile(base::Pickle* pickle, const base::FilePath& file_name) {
  72   File file(
  73       file_name,
  74       File::FLAG_CREATE | File::FLAG_WRITE | File::FLAG_SHARE_DELETE);
  75   if (!file.IsValid())
  76     return false;
  77
  78   int bytes_written =
  79       file.Write(0, static_cast<const char*>(pickle->data()), pickle->size());
  80   if (bytes_written != implicit_cast<int>(pickle->size())) {
  81     simple_util::SimpleCacheDeleteFile(file_name);
  82     return false;
  83   }
  84   return true;
  85 }
  86
  87 // Called for each cache directory traversal iteration.
  88 void ProcessEntryFile(SimpleIndex::EntrySet* entries,
  89                       const base::FilePath& file_path) {
  90   static const size_t kEntryFilesLength =
  91       kEntryFilesHashLength + kEntryFilesSuffixLength;
  92   // Converting to std::string is OK since we never use UTF8 wide chars in our
  93   // file names.
  94   const base::FilePath::StringType base_name = file_path.BaseName().value();
  95   const std::string file_name(base_name.begin(), base_name.end());
  96   if (file_name.size() != kEntryFilesLength)
  97     return;
  98   const base::StringPiece hash_string(
  99       file_name.begin(), file_name.begin() + kEntryFilesHashLength);
 100   uint64 hash_key = 0;
 101   if (!simple_util::GetEntryHashKeyFromHexString(hash_string, &hash_key)) {
 102     LOG(WARNING) << "Invalid entry hash key filename while restoring index from"
 103                  << " disk: " << file_name;
 104     return;
 105   }
 106
 107   File::Info file_info;
 108   if (!base::GetFileInfo(file_path, &file_info)) {
 109     LOG(ERROR) << "Could not get file info for " << file_path.value();
 110     return;
 111   }
 112   base::Time last_used_time;
 113 #if defined(OS_POSIX)
 114   // For POSIX systems, a last access time is available. However, it's not
 115   // guaranteed to be more accurate than mtime. It is no worse though.
 116   last_used_time = file_info.last_accessed;
 117 #endif
 118   if (last_used_time.is_null())
 119     last_used_time = file_info.last_modified;
 120
 121   int64 file_size = file_info.size;
 122   SimpleIndex::EntrySet::iterator it = entries->find(hash_key);
 123   if (it == entries->end()) {
 124     SimpleIndex::InsertInEntrySet(
 125         hash_key,
 126         EntryMetadata(last_used_time, file_size),
 127         entries);
 128   } else {
 129     // Summing up the total size of the entry through all the *_[0-1] files
 130     it->second.SetEntrySize(it->second.GetEntrySize() + file_size);
 131   }
 132 }
 133
 134 }  // namespace
 135
 136 SimpleIndexLoadResult::SimpleIndexLoadResult() : did_load(false),
 137                                                  flush_required(false) {
 138 }
 139
 140 SimpleIndexLoadResult::~SimpleIndexLoadResult() {
 141 }
 142
 143 void SimpleIndexLoadResult::Reset() {
 144   did_load = false;
 145   flush_required = false;
 146   entries.clear();
 147 }
 148
 149 // static
 150 const char SimpleIndexFile::kIndexFileName[] = "the-real-index";
 151 // static
 152 const char SimpleIndexFile::kIndexDirectory[] = "index-dir";
 153 // static
 154 const char SimpleIndexFile::kTempIndexFileName[] = "temp-index";
 155
 156 SimpleIndexFile::IndexMetadata::IndexMetadata()
 157     : magic_number_(kSimpleIndexMagicNumber),
 158       version_(kSimpleVersion),
 159       number_of_entries_(0),
 160       cache_size_(0) {}
 161
 162 SimpleIndexFile::IndexMetadata::IndexMetadata(
 163     uint64 number_of_entries, uint64 cache_size)
 164     : magic_number_(kSimpleIndexMagicNumber),
 165       version_(kSimpleVersion),
 166       number_of_entries_(number_of_entries),
 167       cache_size_(cache_size) {}
 168
 169 void SimpleIndexFile::IndexMetadata::Serialize(base::Pickle* pickle) const {
 170   DCHECK(pickle);
 171   pickle->WriteUInt64(magic_number_);
 172   pickle->WriteUInt32(version_);
 173   pickle->WriteUInt64(number_of_entries_);
 174   pickle->WriteUInt64(cache_size_);
 175 }
 176
 177 // static
 178 bool SimpleIndexFile::SerializeFinalData(base::Time cache_modified,
 179                                          base::Pickle* pickle) {
 180   if (!pickle->WriteInt64(cache_modified.ToInternalValue()))
 181     return false;
 182   SimpleIndexFile::PickleHeader* header_p = pickle->headerT<PickleHeader>();
 183   header_p->crc = CalculatePickleCRC(*pickle);
 184   return true;
 185 }
 186
 187 bool SimpleIndexFile::IndexMetadata::Deserialize(base::PickleIterator* it) {
 188   DCHECK(it);
 189   return it->ReadUInt64(&magic_number_) &&
 190       it->ReadUInt32(&version_) &&
 191       it->ReadUInt64(&number_of_entries_)&&
 192       it->ReadUInt64(&cache_size_);
 193 }
 194
 195 void SimpleIndexFile::SyncWriteToDisk(net::CacheType cache_type,
 196                                       const base::FilePath& cache_directory,
 197                                       const base::FilePath& index_filename,
 198                                       const base::FilePath& temp_index_filename,
 199                                       scoped_ptr<base::Pickle> pickle,
 200                                       const base::TimeTicks& start_time,
 201                                       bool app_on_background) {
 202   DCHECK_EQ(index_filename.DirName().value(),
 203             temp_index_filename.DirName().value());
 204   base::FilePath index_file_directory = temp_index_filename.DirName();
 205   if (!base::DirectoryExists(index_file_directory) &&
 206       !base::CreateDirectory(index_file_directory)) {
 207     LOG(ERROR) << "Could not create a directory to hold the index file";
 208     return;
 209   }
 210
 211   // There is a chance that the index containing all the necessary data about
 212   // newly created entries will appear to be stale. This can happen if on-disk
 213   // part of a Create operation does not fit into the time budget for the index
 214   // flush delay. This simple approach will be reconsidered if it does not allow
 215   // for maintaining freshness.
 216   base::Time cache_dir_mtime;
 217   if (!simple_util::GetMTime(cache_directory, &cache_dir_mtime)) {
 218     LOG(ERROR) << "Could obtain information about cache age";
 219     return;
 220   }
 221   SerializeFinalData(cache_dir_mtime, pickle.get());
 222   if (!WritePickleFile(pickle.get(), temp_index_filename)) {
 223     LOG(ERROR) << "Failed to write the temporary index file";
 224     return;
 225   }
 226
 227   // Atomically rename the temporary index file to become the real one.
 228   // TODO(gavinp): DCHECK when not shutting down, since that is very strange.
 229   // The rename failing during shutdown is legal because it's legal to begin
 230   // erasing a cache as soon as the destructor has been called.
 231   if (!base::ReplaceFile(temp_index_filename, index_filename, NULL))
 232     return;
 233
 234   if (app_on_background) {
 235     SIMPLE_CACHE_UMA(TIMES,
 236                      "IndexWriteToDiskTime.Background", cache_type,
 237                      (base::TimeTicks::Now() - start_time));
 238   } else {
 239     SIMPLE_CACHE_UMA(TIMES,
 240                      "IndexWriteToDiskTime.Foreground", cache_type,
 241                      (base::TimeTicks::Now() - start_time));
 242   }
 243 }
 244
 245 bool SimpleIndexFile::IndexMetadata::CheckIndexMetadata() {
 246   return number_of_entries_ <= kMaxEntiresInIndex &&
 247       magic_number_ == kSimpleIndexMagicNumber &&
 248       version_ == kSimpleVersion;
 249 }
 250
 251 SimpleIndexFile::SimpleIndexFile(
 252     const scoped_refptr<base::SingleThreadTaskRunner>& cache_thread,
 253     const scoped_refptr<base::TaskRunner>& worker_pool,
 254     net::CacheType cache_type,
 255     const base::FilePath& cache_directory)
 256     : cache_thread_(cache_thread),
 257       worker_pool_(worker_pool),
 258       cache_type_(cache_type),
 259       cache_directory_(cache_directory),
 260       index_file_(cache_directory_.AppendASCII(kIndexDirectory)
 261                       .AppendASCII(kIndexFileName)),
 262       temp_index_file_(cache_directory_.AppendASCII(kIndexDirectory)
 263                            .AppendASCII(kTempIndexFileName)) {
 264 }
 265
 266 SimpleIndexFile::~SimpleIndexFile() {}
 267
 268 void SimpleIndexFile::LoadIndexEntries(base::Time cache_last_modified,
 269                                        const base::Closure& callback,
 270                                        SimpleIndexLoadResult* out_result) {
 271   base::Closure task = base::Bind(&SimpleIndexFile::SyncLoadIndexEntries,
 272                                   cache_type_,
 273                                   cache_last_modified, cache_directory_,
 274                                   index_file_, out_result);
 275   worker_pool_->PostTaskAndReply(FROM_HERE, task, callback);
 276 }
 277
 278 void SimpleIndexFile::WriteToDisk(const SimpleIndex::EntrySet& entry_set,
 279                                   uint64 cache_size,
 280                                   const base::TimeTicks& start,
 281                                   bool app_on_background,
 282                                   const base::Closure& callback) {
 283   IndexMetadata index_metadata(entry_set.size(), cache_size);
 284   scoped_ptr<base::Pickle> pickle = Serialize(index_metadata, entry_set);
 285   base::Closure task =
 286       base::Bind(&SimpleIndexFile::SyncWriteToDisk,
 287                  cache_type_, cache_directory_, index_file_, temp_index_file_,
 288                  base::Passed(&pickle), start, app_on_background);
 289   if (callback.is_null())
 290     cache_thread_->PostTask(FROM_HERE, task);
 291   else
 292     cache_thread_->PostTaskAndReply(FROM_HERE, task, callback);
 293 }
 294
 295 // static
 296 void SimpleIndexFile::SyncLoadIndexEntries(
 297     net::CacheType cache_type,
 298     base::Time cache_last_modified,
 299     const base::FilePath& cache_directory,
 300     const base::FilePath& index_file_path,
 301     SimpleIndexLoadResult* out_result) {
 302   // Load the index and find its age.
 303   base::Time last_cache_seen_by_index;
 304   SyncLoadFromDisk(index_file_path, &last_cache_seen_by_index, out_result);
 305
 306   // Consider the index loaded if it is fresh.
 307   const bool index_file_existed = base::PathExists(index_file_path);
 308   if (!out_result->did_load) {
 309     if (index_file_existed)
 310       UmaRecordIndexFileState(INDEX_STATE_CORRUPT, cache_type);
 311   } else {
 312     if (cache_last_modified <= last_cache_seen_by_index) {
 313       base::Time latest_dir_mtime;
 314       simple_util::GetMTime(cache_directory, &latest_dir_mtime);
 315       if (LegacyIsIndexFileStale(latest_dir_mtime, index_file_path)) {
 316         UmaRecordIndexFileState(INDEX_STATE_FRESH_CONCURRENT_UPDATES,
 317                                 cache_type);
 318       } else {
 319         UmaRecordIndexFileState(INDEX_STATE_FRESH, cache_type);
 320       }
 321       UmaRecordIndexInitMethod(INITIALIZE_METHOD_LOADED, cache_type);
 322       return;
 323     }
 324     UmaRecordIndexFileState(INDEX_STATE_STALE, cache_type);
 325   }
 326
 327   // Reconstruct the index by scanning the disk for entries.
 328   const base::TimeTicks start = base::TimeTicks::Now();
 329   SyncRestoreFromDisk(cache_directory, index_file_path, out_result);
 330   SIMPLE_CACHE_UMA(MEDIUM_TIMES, "IndexRestoreTime", cache_type,
 331                    base::TimeTicks::Now() - start);
 332   SIMPLE_CACHE_UMA(COUNTS, "IndexEntriesRestored", cache_type,
 333                    out_result->entries.size());
 334   if (index_file_existed) {
 335     UmaRecordIndexInitMethod(INITIALIZE_METHOD_RECOVERED, cache_type);
 336   } else {
 337     UmaRecordIndexInitMethod(INITIALIZE_METHOD_NEWCACHE, cache_type);
 338     SIMPLE_CACHE_UMA(COUNTS,
 339                      "IndexCreatedEntryCount", cache_type,
 340                      out_result->entries.size());
 341   }
 342 }
 343
 344 // static
 345 void SimpleIndexFile::SyncLoadFromDisk(const base::FilePath& index_filename,
 346                                        base::Time* out_last_cache_seen_by_index,
 347                                        SimpleIndexLoadResult* out_result) {
 348   out_result->Reset();
 349
 350   File file(index_filename,
 351             File::FLAG_OPEN | File::FLAG_READ | File::FLAG_SHARE_DELETE);
 352   if (!file.IsValid())
 353     return;
 354
 355   base::MemoryMappedFile index_file_map;
 356   if (!index_file_map.Initialize(file.Pass())) {
 357     simple_util::SimpleCacheDeleteFile(index_filename);
 358     return;
 359   }
 360
 361   SimpleIndexFile::Deserialize(
 362       reinterpret_cast<const char*>(index_file_map.data()),
 363       index_file_map.length(),
 364       out_last_cache_seen_by_index,
 365       out_result);
 366
 367   if (!out_result->did_load)
 368     simple_util::SimpleCacheDeleteFile(index_filename);
 369 }
 370
 371 // static
 372 scoped_ptr<base::Pickle> SimpleIndexFile::Serialize(
 373     const SimpleIndexFile::IndexMetadata& index_metadata,
 374     const SimpleIndex::EntrySet& entries) {
 375   scoped_ptr<base::Pickle> pickle(
 376       new base::Pickle(sizeof(SimpleIndexFile::PickleHeader)));
 377
 378   index_metadata.Serialize(pickle.get());
 379   for (SimpleIndex::EntrySet::const_iterator it = entries.begin();
 380        it != entries.end(); ++it) {
 381     pickle->WriteUInt64(it->first);
 382     it->second.Serialize(pickle.get());
 383   }
 384   return pickle.Pass();
 385 }
 386
 387 // static
 388 void SimpleIndexFile::Deserialize(const char* data, int data_len,
 389                                   base::Time* out_cache_last_modified,
 390                                   SimpleIndexLoadResult* out_result) {
 391   DCHECK(data);
 392
 393   out_result->Reset();
 394   SimpleIndex::EntrySet* entries = &out_result->entries;
 395
 396   base::Pickle pickle(data, data_len);
 397   if (!pickle.data()) {
 398     LOG(WARNING) << "Corrupt Simple Index File.";
 399     return;
 400   }
 401
 402   base::PickleIterator pickle_it(pickle);
 403   SimpleIndexFile::PickleHeader* header_p =
 404       pickle.headerT<SimpleIndexFile::PickleHeader>();
 405   const uint32 crc_read = header_p->crc;
 406   const uint32 crc_calculated = CalculatePickleCRC(pickle);
 407
 408   if (crc_read != crc_calculated) {
 409     LOG(WARNING) << "Invalid CRC in Simple Index file.";
 410     return;
 411   }
 412
 413   SimpleIndexFile::IndexMetadata index_metadata;
 414   if (!index_metadata.Deserialize(&pickle_it)) {
 415     LOG(ERROR) << "Invalid index_metadata on Simple Cache Index.";
 416     return;
 417   }
 418
 419   if (!index_metadata.CheckIndexMetadata()) {
 420     LOG(ERROR) << "Invalid index_metadata on Simple Cache Index.";
 421     return;
 422   }
 423
 424 #if !defined(OS_WIN)
 425   // TODO(gavinp): Consider using std::unordered_map.
 426   entries->resize(index_metadata.GetNumberOfEntries() + kExtraSizeForMerge);
 427 #endif
 428   while (entries->size() < index_metadata.GetNumberOfEntries()) {
 429     uint64 hash_key;
 430     EntryMetadata entry_metadata;
 431     if (!pickle_it.ReadUInt64(&hash_key) ||
 432         !entry_metadata.Deserialize(&pickle_it)) {
 433       LOG(WARNING) << "Invalid EntryMetadata in Simple Index file.";
 434       entries->clear();
 435       return;
 436     }
 437     SimpleIndex::InsertInEntrySet(hash_key, entry_metadata, entries);
 438   }
 439
 440   int64 cache_last_modified;
 441   if (!pickle_it.ReadInt64(&cache_last_modified)) {
 442     entries->clear();
 443     return;
 444   }
 445   DCHECK(out_cache_last_modified);
 446   *out_cache_last_modified = base::Time::FromInternalValue(cache_last_modified);
 447
 448   out_result->did_load = true;
 449 }
 450
 451 // static
 452 void SimpleIndexFile::SyncRestoreFromDisk(
 453     const base::FilePath& cache_directory,
 454     const base::FilePath& index_file_path,
 455     SimpleIndexLoadResult* out_result) {
 456   VLOG(1) << "Simple Cache Index is being restored from disk.";
 457   simple_util::SimpleCacheDeleteFile(index_file_path);
 458   out_result->Reset();
 459   SimpleIndex::EntrySet* entries = &out_result->entries;
 460
 461   const bool did_succeed = TraverseCacheDirectory(
 462       cache_directory, base::Bind(&ProcessEntryFile, entries));
 463   if (!did_succeed) {
 464     LOG(ERROR) << "Could not reconstruct index from disk";
 465     return;
 466   }
 467   out_result->did_load = true;
 468   // When we restore from disk we write the merged index file to disk right
 469   // away, this might save us from having to restore again next time.
 470   out_result->flush_required = true;
 471 }
 472
 473 // static
 474 bool SimpleIndexFile::LegacyIsIndexFileStale(
 475     base::Time cache_last_modified,
 476     const base::FilePath& index_file_path) {
 477   base::Time index_mtime;
 478   if (!simple_util::GetMTime(index_file_path, &index_mtime))
 479     return true;
 480   return index_mtime < cache_last_modified;
 481 }
 482
 483 }  // namespace disk_cache