net/disk_cache/simple/simple_entry_impl.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_entry_impl.h"
   6
   7 #include <algorithm>
   8 #include <cstring>
   9 #include <vector>
  10
  11 #include "base/bind.h"
  12 #include "base/bind_helpers.h"
  13 #include "base/callback.h"
  14 #include "base/location.h"
  15 #include "base/logging.h"
  16 #include "base/single_thread_task_runner.h"
  17 #include "base/task_runner.h"
  18 #include "base/task_runner_util.h"
  19 #include "base/thread_task_runner_handle.h"
  20 #include "base/time/time.h"
  21 #include "net/base/io_buffer.h"
  22 #include "net/base/net_errors.h"
  23 #include "net/disk_cache/net_log_parameters.h"
  24 #include "net/disk_cache/simple/simple_backend_impl.h"
  25 #include "net/disk_cache/simple/simple_histogram_macros.h"
  26 #include "net/disk_cache/simple/simple_index.h"
  27 #include "net/disk_cache/simple/simple_net_log_parameters.h"
  28 #include "net/disk_cache/simple/simple_synchronous_entry.h"
  29 #include "net/disk_cache/simple/simple_util.h"
  30 #include "third_party/zlib/zlib.h"
  31
  32 namespace disk_cache {
  33 namespace {
  34
  35 // An entry can store sparse data taking up to 1 / kMaxSparseDataSizeDivisor of
  36 // the cache.
  37 const int64 kMaxSparseDataSizeDivisor = 10;
  38
  39 // Used in histograms, please only add entries at the end.
  40 enum ReadResult {
  41   READ_RESULT_SUCCESS = 0,
  42   READ_RESULT_INVALID_ARGUMENT = 1,
  43   READ_RESULT_NONBLOCK_EMPTY_RETURN = 2,
  44   READ_RESULT_BAD_STATE = 3,
  45   READ_RESULT_FAST_EMPTY_RETURN = 4,
  46   READ_RESULT_SYNC_READ_FAILURE = 5,
  47   READ_RESULT_SYNC_CHECKSUM_FAILURE = 6,
  48   READ_RESULT_MAX = 7,
  49 };
  50
  51 // Used in histograms, please only add entries at the end.
  52 enum WriteResult {
  53   WRITE_RESULT_SUCCESS = 0,
  54   WRITE_RESULT_INVALID_ARGUMENT = 1,
  55   WRITE_RESULT_OVER_MAX_SIZE = 2,
  56   WRITE_RESULT_BAD_STATE = 3,
  57   WRITE_RESULT_SYNC_WRITE_FAILURE = 4,
  58   WRITE_RESULT_FAST_EMPTY_RETURN = 5,
  59   WRITE_RESULT_MAX = 6,
  60 };
  61
  62 // Used in histograms, please only add entries at the end.
  63 enum HeaderSizeChange {
  64   HEADER_SIZE_CHANGE_INITIAL,
  65   HEADER_SIZE_CHANGE_SAME,
  66   HEADER_SIZE_CHANGE_INCREASE,
  67   HEADER_SIZE_CHANGE_DECREASE,
  68   HEADER_SIZE_CHANGE_UNEXPECTED_WRITE,
  69   HEADER_SIZE_CHANGE_MAX
  70 };
  71
  72 void RecordReadResult(net::CacheType cache_type, ReadResult result) {
  73   SIMPLE_CACHE_UMA(ENUMERATION,
  74                    "ReadResult", cache_type, result, READ_RESULT_MAX);
  75 }
  76
  77 void RecordWriteResult(net::CacheType cache_type, WriteResult result) {
  78   SIMPLE_CACHE_UMA(ENUMERATION,
  79                    "WriteResult2", cache_type, result, WRITE_RESULT_MAX);
  80 }
  81
  82 // TODO(ttuttle): Consider removing this once we have a good handle on header
  83 // size changes.
  84 void RecordHeaderSizeChange(net::CacheType cache_type,
  85                             int old_size, int new_size) {
  86   HeaderSizeChange size_change;
  87
  88   SIMPLE_CACHE_UMA(COUNTS_10000, "HeaderSize", cache_type, new_size);
  89
  90   if (old_size == 0) {
  91     size_change = HEADER_SIZE_CHANGE_INITIAL;
  92   } else if (new_size == old_size) {
  93     size_change = HEADER_SIZE_CHANGE_SAME;
  94   } else if (new_size > old_size) {
  95     int delta = new_size - old_size;
  96     SIMPLE_CACHE_UMA(COUNTS_10000,
  97                      "HeaderSizeIncreaseAbsolute", cache_type, delta);
  98     SIMPLE_CACHE_UMA(PERCENTAGE,
  99                      "HeaderSizeIncreasePercentage", cache_type,
 100                      delta * 100 / old_size);
 101     size_change = HEADER_SIZE_CHANGE_INCREASE;
 102   } else {  // new_size < old_size
 103     int delta = old_size - new_size;
 104     SIMPLE_CACHE_UMA(COUNTS_10000,
 105                      "HeaderSizeDecreaseAbsolute", cache_type, delta);
 106     SIMPLE_CACHE_UMA(PERCENTAGE,
 107                      "HeaderSizeDecreasePercentage", cache_type,
 108                      delta * 100 / old_size);
 109     size_change = HEADER_SIZE_CHANGE_DECREASE;
 110   }
 111
 112   SIMPLE_CACHE_UMA(ENUMERATION,
 113                    "HeaderSizeChange", cache_type,
 114                    size_change, HEADER_SIZE_CHANGE_MAX);
 115 }
 116
 117 void RecordUnexpectedStream0Write(net::CacheType cache_type) {
 118   SIMPLE_CACHE_UMA(ENUMERATION,
 119                    "HeaderSizeChange", cache_type,
 120                    HEADER_SIZE_CHANGE_UNEXPECTED_WRITE, HEADER_SIZE_CHANGE_MAX);
 121 }
 122
 123 int g_open_entry_count = 0;
 124
 125 void AdjustOpenEntryCountBy(net::CacheType cache_type, int offset) {
 126   g_open_entry_count += offset;
 127   SIMPLE_CACHE_UMA(COUNTS_10000,
 128                    "GlobalOpenEntryCount", cache_type, g_open_entry_count);
 129 }
 130
 131 void InvokeCallbackIfBackendIsAlive(
 132     const base::WeakPtr<SimpleBackendImpl>& backend,
 133     const net::CompletionCallback& completion_callback,
 134     int result) {
 135   DCHECK(!completion_callback.is_null());
 136   if (!backend.get())
 137     return;
 138   completion_callback.Run(result);
 139 }
 140
 141 }  // namespace
 142
 143 using base::Closure;
 144 using base::FilePath;
 145 using base::Time;
 146 using base::TaskRunner;
 147
 148 // A helper class to insure that RunNextOperationIfNeeded() is called when
 149 // exiting the current stack frame.
 150 class SimpleEntryImpl::ScopedOperationRunner {
 151  public:
 152   explicit ScopedOperationRunner(SimpleEntryImpl* entry) : entry_(entry) {
 153   }
 154
 155   ~ScopedOperationRunner() {
 156     entry_->RunNextOperationIfNeeded();
 157   }
 158
 159  private:
 160   SimpleEntryImpl* const entry_;
 161 };
 162
 163 SimpleEntryImpl::ActiveEntryProxy::~ActiveEntryProxy() {}
 164
 165 SimpleEntryImpl::SimpleEntryImpl(net::CacheType cache_type,
 166                                  const FilePath& path,
 167                                  const uint64 entry_hash,
 168                                  OperationsMode operations_mode,
 169                                  SimpleBackendImpl* backend,
 170                                  net::NetLog* net_log)
 171     : backend_(backend->AsWeakPtr()),
 172       cache_type_(cache_type),
 173       worker_pool_(backend->worker_pool()),
 174       path_(path),
 175       entry_hash_(entry_hash),
 176       use_optimistic_operations_(operations_mode == OPTIMISTIC_OPERATIONS),
 177       last_used_(Time::Now()),
 178       last_modified_(last_used_),
 179       sparse_data_size_(0),
 180       open_count_(0),
 181       doomed_(false),
 182       state_(STATE_UNINITIALIZED),
 183       synchronous_entry_(NULL),
 184       net_log_(net::BoundNetLog::Make(
 185           net_log, net::NetLog::SOURCE_DISK_CACHE_ENTRY)),
 186       stream_0_data_(new net::GrowableIOBuffer()) {
 187   static_assert(arraysize(data_size_) == arraysize(crc32s_end_offset_),
 188                 "arrays should be the same size");
 189   static_assert(arraysize(data_size_) == arraysize(crc32s_),
 190                 "arrays should be the same size");
 191   static_assert(arraysize(data_size_) == arraysize(have_written_),
 192                 "arrays should be the same size");
 193   static_assert(arraysize(data_size_) == arraysize(crc_check_state_),
 194                 "arrays should be the same size");
 195   MakeUninitialized();
 196   net_log_.BeginEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY,
 197       CreateNetLogSimpleEntryConstructionCallback(this));
 198 }
 199
 200 void SimpleEntryImpl::SetActiveEntryProxy(
 201     scoped_ptr<ActiveEntryProxy> active_entry_proxy) {
 202   DCHECK(!active_entry_proxy_);
 203   active_entry_proxy_.reset(active_entry_proxy.release());
 204 }
 205
 206 int SimpleEntryImpl::OpenEntry(Entry** out_entry,
 207                                const CompletionCallback& callback) {
 208   DCHECK(backend_.get());
 209
 210   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_CALL);
 211
 212   bool have_index = backend_->index()->initialized();
 213   // This enumeration is used in histograms, add entries only at end.
 214   enum OpenEntryIndexEnum {
 215     INDEX_NOEXIST = 0,
 216     INDEX_MISS = 1,
 217     INDEX_HIT = 2,
 218     INDEX_MAX = 3,
 219   };
 220   OpenEntryIndexEnum open_entry_index_enum = INDEX_NOEXIST;
 221   if (have_index) {
 222     if (backend_->index()->Has(entry_hash_))
 223       open_entry_index_enum = INDEX_HIT;
 224     else
 225       open_entry_index_enum = INDEX_MISS;
 226   }
 227   SIMPLE_CACHE_UMA(ENUMERATION,
 228                    "OpenEntryIndexState", cache_type_,
 229                    open_entry_index_enum, INDEX_MAX);
 230
 231   // If entry is not known to the index, initiate fast failover to the network.
 232   if (open_entry_index_enum == INDEX_MISS) {
 233     net_log_.AddEventWithNetErrorCode(
 234         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_END,
 235         net::ERR_FAILED);
 236     return net::ERR_FAILED;
 237   }
 238
 239   pending_operations_.push(SimpleEntryOperation::OpenOperation(
 240       this, have_index, callback, out_entry));
 241   RunNextOperationIfNeeded();
 242   return net::ERR_IO_PENDING;
 243 }
 244
 245 int SimpleEntryImpl::CreateEntry(Entry** out_entry,
 246                                  const CompletionCallback& callback) {
 247   DCHECK(backend_.get());
 248   DCHECK_EQ(entry_hash_, simple_util::GetEntryHashKey(key_));
 249
 250   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CREATE_CALL);
 251
 252   bool have_index = backend_->index()->initialized();
 253   int ret_value = net::ERR_FAILED;
 254   if (use_optimistic_operations_ &&
 255       state_ == STATE_UNINITIALIZED && pending_operations_.size() == 0) {
 256     net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CREATE_OPTIMISTIC);
 257
 258     ReturnEntryToCaller(out_entry);
 259     pending_operations_.push(SimpleEntryOperation::CreateOperation(
 260         this, have_index, CompletionCallback(), static_cast<Entry**>(NULL)));
 261     ret_value = net::OK;
 262   } else {
 263     pending_operations_.push(SimpleEntryOperation::CreateOperation(
 264         this, have_index, callback, out_entry));
 265     ret_value = net::ERR_IO_PENDING;
 266   }
 267
 268   // We insert the entry in the index before creating the entry files in the
 269   // SimpleSynchronousEntry, because this way the worst scenario is when we
 270   // have the entry in the index but we don't have the created files yet, this
 271   // way we never leak files. CreationOperationComplete will remove the entry
 272   // from the index if the creation fails.
 273   backend_->index()->Insert(entry_hash_);
 274
 275   RunNextOperationIfNeeded();
 276   return ret_value;
 277 }
 278
 279 int SimpleEntryImpl::DoomEntry(const CompletionCallback& callback) {
 280   if (doomed_)
 281     return net::OK;
 282   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_DOOM_CALL);
 283   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_DOOM_BEGIN);
 284
 285   MarkAsDoomed();
 286   if (backend_.get())
 287     backend_->OnDoomStart(entry_hash_);
 288   pending_operations_.push(SimpleEntryOperation::DoomOperation(this, callback));
 289   RunNextOperationIfNeeded();
 290   return net::ERR_IO_PENDING;
 291 }
 292
 293 void SimpleEntryImpl::SetKey(const std::string& key) {
 294   key_ = key;
 295   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_SET_KEY,
 296       net::NetLog::StringCallback("key", &key));
 297 }
 298
 299 void SimpleEntryImpl::Doom() {
 300   DoomEntry(CompletionCallback());
 301 }
 302
 303 void SimpleEntryImpl::Close() {
 304   DCHECK(io_thread_checker_.CalledOnValidThread());
 305   DCHECK_LT(0, open_count_);
 306
 307   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CLOSE_CALL);
 308
 309   if (--open_count_ > 0) {
 310     DCHECK(!HasOneRef());
 311     Release();  // Balanced in ReturnEntryToCaller().
 312     return;
 313   }
 314
 315   pending_operations_.push(SimpleEntryOperation::CloseOperation(this));
 316   DCHECK(!HasOneRef());
 317   Release();  // Balanced in ReturnEntryToCaller().
 318   RunNextOperationIfNeeded();
 319 }
 320
 321 std::string SimpleEntryImpl::GetKey() const {
 322   DCHECK(io_thread_checker_.CalledOnValidThread());
 323   return key_;
 324 }
 325
 326 Time SimpleEntryImpl::GetLastUsed() const {
 327   DCHECK(io_thread_checker_.CalledOnValidThread());
 328   return last_used_;
 329 }
 330
 331 Time SimpleEntryImpl::GetLastModified() const {
 332   DCHECK(io_thread_checker_.CalledOnValidThread());
 333   return last_modified_;
 334 }
 335
 336 int32 SimpleEntryImpl::GetDataSize(int stream_index) const {
 337   DCHECK(io_thread_checker_.CalledOnValidThread());
 338   DCHECK_LE(0, data_size_[stream_index]);
 339   return data_size_[stream_index];
 340 }
 341
 342 int SimpleEntryImpl::ReadData(int stream_index,
 343                               int offset,
 344                               net::IOBuffer* buf,
 345                               int buf_len,
 346                               const CompletionCallback& callback) {
 347   DCHECK(io_thread_checker_.CalledOnValidThread());
 348
 349   if (net_log_.IsCapturing()) {
 350     net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_READ_CALL,
 351         CreateNetLogReadWriteDataCallback(stream_index, offset, buf_len,
 352                                           false));
 353   }
 354
 355   if (stream_index < 0 || stream_index >= kSimpleEntryStreamCount ||
 356       buf_len < 0) {
 357     if (net_log_.IsCapturing()) {
 358       net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_READ_END,
 359           CreateNetLogReadWriteCompleteCallback(net::ERR_INVALID_ARGUMENT));
 360     }
 361
 362     RecordReadResult(cache_type_, READ_RESULT_INVALID_ARGUMENT);
 363     return net::ERR_INVALID_ARGUMENT;
 364   }
 365   if (pending_operations_.empty() && (offset >= GetDataSize(stream_index) ||
 366                                       offset < 0 || !buf_len)) {
 367     if (net_log_.IsCapturing()) {
 368       net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_READ_END,
 369           CreateNetLogReadWriteCompleteCallback(0));
 370     }
 371
 372     RecordReadResult(cache_type_, READ_RESULT_NONBLOCK_EMPTY_RETURN);
 373     return 0;
 374   }
 375
 376   // TODO(clamy): return immediatly when reading from stream 0.
 377
 378   // TODO(felipeg): Optimization: Add support for truly parallel read
 379   // operations.
 380   bool alone_in_queue =
 381       pending_operations_.size() == 0 && state_ == STATE_READY;
 382   pending_operations_.push(SimpleEntryOperation::ReadOperation(
 383       this, stream_index, offset, buf_len, buf, callback, alone_in_queue));
 384   RunNextOperationIfNeeded();
 385   return net::ERR_IO_PENDING;
 386 }
 387
 388 int SimpleEntryImpl::WriteData(int stream_index,
 389                                int offset,
 390                                net::IOBuffer* buf,
 391                                int buf_len,
 392                                const CompletionCallback& callback,
 393                                bool truncate) {
 394   DCHECK(io_thread_checker_.CalledOnValidThread());
 395
 396   if (net_log_.IsCapturing()) {
 397     net_log_.AddEvent(
 398         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_WRITE_CALL,
 399         CreateNetLogReadWriteDataCallback(stream_index, offset, buf_len,
 400                                           truncate));
 401   }
 402
 403   if (stream_index < 0 || stream_index >= kSimpleEntryStreamCount ||
 404       offset < 0 || buf_len < 0) {
 405     if (net_log_.IsCapturing()) {
 406       net_log_.AddEvent(
 407           net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_WRITE_END,
 408           CreateNetLogReadWriteCompleteCallback(net::ERR_INVALID_ARGUMENT));
 409     }
 410     RecordWriteResult(cache_type_, WRITE_RESULT_INVALID_ARGUMENT);
 411     return net::ERR_INVALID_ARGUMENT;
 412   }
 413   if (backend_.get() && offset + buf_len > backend_->GetMaxFileSize()) {
 414     if (net_log_.IsCapturing()) {
 415       net_log_.AddEvent(
 416           net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_WRITE_END,
 417           CreateNetLogReadWriteCompleteCallback(net::ERR_FAILED));
 418     }
 419     RecordWriteResult(cache_type_, WRITE_RESULT_OVER_MAX_SIZE);
 420     return net::ERR_FAILED;
 421   }
 422   ScopedOperationRunner operation_runner(this);
 423
 424   // Stream 0 data is kept in memory, so can be written immediatly if there are
 425   // no IO operations pending.
 426   if (stream_index == 0 && state_ == STATE_READY &&
 427       pending_operations_.size() == 0)
 428     return SetStream0Data(buf, offset, buf_len, truncate);
 429
 430   // We can only do optimistic Write if there is no pending operations, so
 431   // that we are sure that the next call to RunNextOperationIfNeeded will
 432   // actually run the write operation that sets the stream size. It also
 433   // prevents from previous possibly-conflicting writes that could be stacked
 434   // in the |pending_operations_|. We could optimize this for when we have
 435   // only read operations enqueued.
 436   const bool optimistic =
 437       (use_optimistic_operations_ && state_ == STATE_READY &&
 438        pending_operations_.size() == 0);
 439   CompletionCallback op_callback;
 440   scoped_refptr<net::IOBuffer> op_buf;
 441   int ret_value = net::ERR_FAILED;
 442   if (!optimistic) {
 443     op_buf = buf;
 444     op_callback = callback;
 445     ret_value = net::ERR_IO_PENDING;
 446   } else {
 447     // TODO(gavinp,pasko): For performance, don't use a copy of an IOBuffer
 448     // here to avoid paying the price of the RefCountedThreadSafe atomic
 449     // operations.
 450     if (buf) {
 451       op_buf = new IOBuffer(buf_len);
 452       memcpy(op_buf->data(), buf->data(), buf_len);
 453     }
 454     op_callback = CompletionCallback();
 455     ret_value = buf_len;
 456     if (net_log_.IsCapturing()) {
 457       net_log_.AddEvent(
 458           net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_WRITE_OPTIMISTIC,
 459           CreateNetLogReadWriteCompleteCallback(buf_len));
 460     }
 461   }
 462
 463   pending_operations_.push(SimpleEntryOperation::WriteOperation(this,
 464                                                                 stream_index,
 465                                                                 offset,
 466                                                                 buf_len,
 467                                                                 op_buf.get(),
 468                                                                 truncate,
 469                                                                 optimistic,
 470                                                                 op_callback));
 471   return ret_value;
 472 }
 473
 474 int SimpleEntryImpl::ReadSparseData(int64 offset,
 475                                     net::IOBuffer* buf,
 476                                     int buf_len,
 477                                     const CompletionCallback& callback) {
 478   DCHECK(io_thread_checker_.CalledOnValidThread());
 479
 480   ScopedOperationRunner operation_runner(this);
 481   pending_operations_.push(SimpleEntryOperation::ReadSparseOperation(
 482       this, offset, buf_len, buf, callback));
 483   return net::ERR_IO_PENDING;
 484 }
 485
 486 int SimpleEntryImpl::WriteSparseData(int64 offset,
 487                                      net::IOBuffer* buf,
 488                                      int buf_len,
 489                                      const CompletionCallback& callback) {
 490   DCHECK(io_thread_checker_.CalledOnValidThread());
 491
 492   ScopedOperationRunner operation_runner(this);
 493   pending_operations_.push(SimpleEntryOperation::WriteSparseOperation(
 494       this, offset, buf_len, buf, callback));
 495   return net::ERR_IO_PENDING;
 496 }
 497
 498 int SimpleEntryImpl::GetAvailableRange(int64 offset,
 499                                        int len,
 500                                        int64* start,
 501                                        const CompletionCallback& callback) {
 502   DCHECK(io_thread_checker_.CalledOnValidThread());
 503
 504   ScopedOperationRunner operation_runner(this);
 505   pending_operations_.push(SimpleEntryOperation::GetAvailableRangeOperation(
 506       this, offset, len, start, callback));
 507   return net::ERR_IO_PENDING;
 508 }
 509
 510 bool SimpleEntryImpl::CouldBeSparse() const {
 511   DCHECK(io_thread_checker_.CalledOnValidThread());
 512   // TODO(ttuttle): Actually check.
 513   return true;
 514 }
 515
 516 void SimpleEntryImpl::CancelSparseIO() {
 517   DCHECK(io_thread_checker_.CalledOnValidThread());
 518   // The Simple Cache does not return distinct objects for the same non-doomed
 519   // entry, so there's no need to coordinate which object is performing sparse
 520   // I/O.  Therefore, CancelSparseIO and ReadyForSparseIO succeed instantly.
 521 }
 522
 523 int SimpleEntryImpl::ReadyForSparseIO(const CompletionCallback& callback) {
 524   DCHECK(io_thread_checker_.CalledOnValidThread());
 525   // The simple Cache does not return distinct objects for the same non-doomed
 526   // entry, so there's no need to coordinate which object is performing sparse
 527   // I/O.  Therefore, CancelSparseIO and ReadyForSparseIO succeed instantly.
 528   return net::OK;
 529 }
 530
 531 SimpleEntryImpl::~SimpleEntryImpl() {
 532   DCHECK(io_thread_checker_.CalledOnValidThread());
 533   DCHECK_EQ(0U, pending_operations_.size());
 534   DCHECK(state_ == STATE_UNINITIALIZED || state_ == STATE_FAILURE);
 535   DCHECK(!synchronous_entry_);
 536   net_log_.EndEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY);
 537 }
 538
 539 void SimpleEntryImpl::PostClientCallback(const CompletionCallback& callback,
 540                                          int result) {
 541   if (callback.is_null())
 542     return;
 543   // Note that the callback is posted rather than directly invoked to avoid
 544   // reentrancy issues.
 545   base::ThreadTaskRunnerHandle::Get()->PostTask(
 546       FROM_HERE,
 547       base::Bind(&InvokeCallbackIfBackendIsAlive, backend_, callback, result));
 548 }
 549
 550 void SimpleEntryImpl::MakeUninitialized() {
 551   state_ = STATE_UNINITIALIZED;
 552   std::memset(crc32s_end_offset_, 0, sizeof(crc32s_end_offset_));
 553   std::memset(crc32s_, 0, sizeof(crc32s_));
 554   std::memset(have_written_, 0, sizeof(have_written_));
 555   std::memset(data_size_, 0, sizeof(data_size_));
 556   for (size_t i = 0; i < arraysize(crc_check_state_); ++i) {
 557     crc_check_state_[i] = CRC_CHECK_NEVER_READ_AT_ALL;
 558   }
 559 }
 560
 561 void SimpleEntryImpl::ReturnEntryToCaller(Entry** out_entry) {
 562   DCHECK(out_entry);
 563   ++open_count_;
 564   AddRef();  // Balanced in Close()
 565   if (!backend_.get()) {
 566     // This method can be called when an asynchronous operation completed.
 567     // If the backend no longer exists, the callback won't be invoked, and so we
 568     // must close ourselves to avoid leaking. As well, there's no guarantee the
 569     // client-provided pointer (|out_entry|) hasn't been freed, and no point
 570     // dereferencing it, either.
 571     Close();
 572     return;
 573   }
 574   *out_entry = this;
 575 }
 576
 577 void SimpleEntryImpl::MarkAsDoomed() {
 578   doomed_ = true;
 579   if (!backend_.get())
 580     return;
 581   backend_->index()->Remove(entry_hash_);
 582   active_entry_proxy_.reset();
 583 }
 584
 585 void SimpleEntryImpl::RunNextOperationIfNeeded() {
 586   DCHECK(io_thread_checker_.CalledOnValidThread());
 587   SIMPLE_CACHE_UMA(CUSTOM_COUNTS,
 588                    "EntryOperationsPending", cache_type_,
 589                    pending_operations_.size(), 0, 100, 20);
 590   if (!pending_operations_.empty() && state_ != STATE_IO_PENDING) {
 591     scoped_ptr<SimpleEntryOperation> operation(
 592         new SimpleEntryOperation(pending_operations_.front()));
 593     pending_operations_.pop();
 594     switch (operation->type()) {
 595       case SimpleEntryOperation::TYPE_OPEN:
 596         OpenEntryInternal(operation->have_index(),
 597                           operation->callback(),
 598                           operation->out_entry());
 599         break;
 600       case SimpleEntryOperation::TYPE_CREATE:
 601         CreateEntryInternal(operation->have_index(),
 602                             operation->callback(),
 603                             operation->out_entry());
 604         break;
 605       case SimpleEntryOperation::TYPE_CLOSE:
 606         CloseInternal();
 607         break;
 608       case SimpleEntryOperation::TYPE_READ:
 609         RecordReadIsParallelizable(*operation);
 610         ReadDataInternal(operation->index(),
 611                          operation->offset(),
 612                          operation->buf(),
 613                          operation->length(),
 614                          operation->callback());
 615         break;
 616       case SimpleEntryOperation::TYPE_WRITE:
 617         RecordWriteDependencyType(*operation);
 618         WriteDataInternal(operation->index(),
 619                           operation->offset(),
 620                           operation->buf(),
 621                           operation->length(),
 622                           operation->callback(),
 623                           operation->truncate());
 624         break;
 625       case SimpleEntryOperation::TYPE_READ_SPARSE:
 626         ReadSparseDataInternal(operation->sparse_offset(),
 627                                operation->buf(),
 628                                operation->length(),
 629                                operation->callback());
 630         break;
 631       case SimpleEntryOperation::TYPE_WRITE_SPARSE:
 632         WriteSparseDataInternal(operation->sparse_offset(),
 633                                 operation->buf(),
 634                                 operation->length(),
 635                                 operation->callback());
 636         break;
 637       case SimpleEntryOperation::TYPE_GET_AVAILABLE_RANGE:
 638         GetAvailableRangeInternal(operation->sparse_offset(),
 639                                   operation->length(),
 640                                   operation->out_start(),
 641                                   operation->callback());
 642         break;
 643       case SimpleEntryOperation::TYPE_DOOM:
 644         DoomEntryInternal(operation->callback());
 645         break;
 646       default:
 647         NOTREACHED();
 648     }
 649     // The operation is kept for histograms. Makes sure it does not leak
 650     // resources.
 651     executing_operation_.swap(operation);
 652     executing_operation_->ReleaseReferences();
 653     // |this| may have been deleted.
 654   }
 655 }
 656
 657 void SimpleEntryImpl::OpenEntryInternal(bool have_index,
 658                                         const CompletionCallback& callback,
 659                                         Entry** out_entry) {
 660   ScopedOperationRunner operation_runner(this);
 661
 662   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_BEGIN);
 663
 664   if (state_ == STATE_READY) {
 665     ReturnEntryToCaller(out_entry);
 666     PostClientCallback(callback, net::OK);
 667     net_log_.AddEvent(
 668         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_END,
 669         CreateNetLogSimpleEntryCreationCallback(this, net::OK));
 670     return;
 671   }
 672   if (state_ == STATE_FAILURE) {
 673     PostClientCallback(callback, net::ERR_FAILED);
 674     net_log_.AddEvent(
 675         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_END,
 676         CreateNetLogSimpleEntryCreationCallback(this, net::ERR_FAILED));
 677     return;
 678   }
 679
 680   DCHECK_EQ(STATE_UNINITIALIZED, state_);
 681   DCHECK(!synchronous_entry_);
 682   state_ = STATE_IO_PENDING;
 683   const base::TimeTicks start_time = base::TimeTicks::Now();
 684   scoped_ptr<SimpleEntryCreationResults> results(
 685       new SimpleEntryCreationResults(
 686           SimpleEntryStat(last_used_, last_modified_, data_size_,
 687                           sparse_data_size_)));
 688   Closure task = base::Bind(&SimpleSynchronousEntry::OpenEntry,
 689                             cache_type_,
 690                             path_,
 691                             entry_hash_,
 692                             have_index,
 693                             results.get());
 694   Closure reply = base::Bind(&SimpleEntryImpl::CreationOperationComplete,
 695                              this,
 696                              callback,
 697                              start_time,
 698                              base::Passed(&results),
 699                              out_entry,
 700                              net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_END);
 701   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
 702 }
 703
 704 void SimpleEntryImpl::CreateEntryInternal(bool have_index,
 705                                           const CompletionCallback& callback,
 706                                           Entry** out_entry) {
 707   ScopedOperationRunner operation_runner(this);
 708
 709   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CREATE_BEGIN);
 710
 711   if (state_ != STATE_UNINITIALIZED) {
 712     // There is already an active normal entry.
 713     net_log_.AddEvent(
 714         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CREATE_END,
 715         CreateNetLogSimpleEntryCreationCallback(this, net::ERR_FAILED));
 716     PostClientCallback(callback, net::ERR_FAILED);
 717     return;
 718   }
 719   DCHECK_EQ(STATE_UNINITIALIZED, state_);
 720   DCHECK(!synchronous_entry_);
 721
 722   state_ = STATE_IO_PENDING;
 723
 724   // Since we don't know the correct values for |last_used_| and
 725   // |last_modified_| yet, we make this approximation.
 726   last_used_ = last_modified_ = base::Time::Now();
 727
 728   // If creation succeeds, we should mark all streams to be saved on close.
 729   for (int i = 0; i < kSimpleEntryStreamCount; ++i)
 730     have_written_[i] = true;
 731
 732   const base::TimeTicks start_time = base::TimeTicks::Now();
 733   scoped_ptr<SimpleEntryCreationResults> results(
 734       new SimpleEntryCreationResults(
 735           SimpleEntryStat(last_used_, last_modified_, data_size_,
 736                           sparse_data_size_)));
 737   Closure task = base::Bind(&SimpleSynchronousEntry::CreateEntry,
 738                             cache_type_,
 739                             path_,
 740                             key_,
 741                             entry_hash_,
 742                             have_index,
 743                             results.get());
 744   Closure reply = base::Bind(&SimpleEntryImpl::CreationOperationComplete,
 745                              this,
 746                              callback,
 747                              start_time,
 748                              base::Passed(&results),
 749                              out_entry,
 750                              net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CREATE_END);
 751   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
 752 }
 753
 754 void SimpleEntryImpl::CloseInternal() {
 755   DCHECK(io_thread_checker_.CalledOnValidThread());
 756   typedef SimpleSynchronousEntry::CRCRecord CRCRecord;
 757   scoped_ptr<std::vector<CRCRecord> >
 758       crc32s_to_write(new std::vector<CRCRecord>());
 759
 760   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CLOSE_BEGIN);
 761
 762   if (state_ == STATE_READY) {
 763     DCHECK(synchronous_entry_);
 764     state_ = STATE_IO_PENDING;
 765     for (int i = 0; i < kSimpleEntryStreamCount; ++i) {
 766       if (have_written_[i]) {
 767         if (GetDataSize(i) == crc32s_end_offset_[i]) {
 768           int32 crc = GetDataSize(i) == 0 ? crc32(0, Z_NULL, 0) : crc32s_[i];
 769           crc32s_to_write->push_back(CRCRecord(i, true, crc));
 770         } else {
 771           crc32s_to_write->push_back(CRCRecord(i, false, 0));
 772         }
 773       }
 774     }
 775   } else {
 776     DCHECK(STATE_UNINITIALIZED == state_ || STATE_FAILURE == state_);
 777   }
 778
 779   if (synchronous_entry_) {
 780     Closure task =
 781         base::Bind(&SimpleSynchronousEntry::Close,
 782                    base::Unretained(synchronous_entry_),
 783                    SimpleEntryStat(last_used_, last_modified_, data_size_,
 784                                    sparse_data_size_),
 785                    base::Passed(&crc32s_to_write),
 786                    stream_0_data_);
 787     Closure reply = base::Bind(&SimpleEntryImpl::CloseOperationComplete, this);
 788     synchronous_entry_ = NULL;
 789     worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
 790
 791     for (int i = 0; i < kSimpleEntryStreamCount; ++i) {
 792       if (!have_written_[i]) {
 793         SIMPLE_CACHE_UMA(ENUMERATION,
 794                          "CheckCRCResult", cache_type_,
 795                          crc_check_state_[i], CRC_CHECK_MAX);
 796       }
 797     }
 798   } else {
 799     CloseOperationComplete();
 800   }
 801 }
 802
 803 void SimpleEntryImpl::ReadDataInternal(int stream_index,
 804                                        int offset,
 805                                        net::IOBuffer* buf,
 806                                        int buf_len,
 807                                        const CompletionCallback& callback) {
 808   DCHECK(io_thread_checker_.CalledOnValidThread());
 809   ScopedOperationRunner operation_runner(this);
 810
 811   if (net_log_.IsCapturing()) {
 812     net_log_.AddEvent(
 813         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_READ_BEGIN,
 814         CreateNetLogReadWriteDataCallback(stream_index, offset, buf_len,
 815                                           false));
 816   }
 817
 818   if (state_ == STATE_FAILURE || state_ == STATE_UNINITIALIZED) {
 819     if (!callback.is_null()) {
 820       RecordReadResult(cache_type_, READ_RESULT_BAD_STATE);
 821       // Note that the API states that client-provided callbacks for entry-level
 822       // (i.e. non-backend) operations (e.g. read, write) are invoked even if
 823       // the backend was already destroyed.
 824       base::ThreadTaskRunnerHandle::Get()->PostTask(
 825           FROM_HERE, base::Bind(callback, net::ERR_FAILED));
 826     }
 827     if (net_log_.IsCapturing()) {
 828       net_log_.AddEvent(
 829           net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_READ_END,
 830           CreateNetLogReadWriteCompleteCallback(net::ERR_FAILED));
 831     }
 832     return;
 833   }
 834   DCHECK_EQ(STATE_READY, state_);
 835   if (offset >= GetDataSize(stream_index) || offset < 0 || !buf_len) {
 836     RecordReadResult(cache_type_, READ_RESULT_FAST_EMPTY_RETURN);
 837     // If there is nothing to read, we bail out before setting state_ to
 838     // STATE_IO_PENDING.
 839     if (!callback.is_null())
 840       base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 841                                                     base::Bind(callback, 0));
 842     return;
 843   }
 844
 845   buf_len = std::min(buf_len, GetDataSize(stream_index) - offset);
 846
 847   // Since stream 0 data is kept in memory, it is read immediately.
 848   if (stream_index == 0) {
 849     int ret_value = ReadStream0Data(buf, offset, buf_len);
 850     if (!callback.is_null()) {
 851       base::ThreadTaskRunnerHandle::Get()->PostTask(
 852           FROM_HERE, base::Bind(callback, ret_value));
 853     }
 854     return;
 855   }
 856
 857   state_ = STATE_IO_PENDING;
 858   if (!doomed_ && backend_.get())
 859     backend_->index()->UseIfExists(entry_hash_);
 860
 861   scoped_ptr<uint32> read_crc32(new uint32());
 862   scoped_ptr<int> result(new int());
 863   scoped_ptr<SimpleEntryStat> entry_stat(
 864       new SimpleEntryStat(last_used_, last_modified_, data_size_,
 865                           sparse_data_size_));
 866   Closure task = base::Bind(
 867       &SimpleSynchronousEntry::ReadData,
 868       base::Unretained(synchronous_entry_),
 869       SimpleSynchronousEntry::EntryOperationData(stream_index, offset, buf_len),
 870       make_scoped_refptr(buf),
 871       read_crc32.get(),
 872       entry_stat.get(),
 873       result.get());
 874   Closure reply = base::Bind(&SimpleEntryImpl::ReadOperationComplete,
 875                              this,
 876                              stream_index,
 877                              offset,
 878                              callback,
 879                              base::Passed(&read_crc32),
 880                              base::Passed(&entry_stat),
 881                              base::Passed(&result));
 882   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
 883 }
 884
 885 void SimpleEntryImpl::WriteDataInternal(int stream_index,
 886                                        int offset,
 887                                        net::IOBuffer* buf,
 888                                        int buf_len,
 889                                        const CompletionCallback& callback,
 890                                        bool truncate) {
 891   DCHECK(io_thread_checker_.CalledOnValidThread());
 892   ScopedOperationRunner operation_runner(this);
 893
 894   if (net_log_.IsCapturing()) {
 895     net_log_.AddEvent(
 896         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_WRITE_BEGIN,
 897         CreateNetLogReadWriteDataCallback(stream_index, offset, buf_len,
 898                                           truncate));
 899   }
 900
 901   if (state_ == STATE_FAILURE || state_ == STATE_UNINITIALIZED) {
 902     RecordWriteResult(cache_type_, WRITE_RESULT_BAD_STATE);
 903     if (net_log_.IsCapturing()) {
 904       net_log_.AddEvent(
 905           net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_WRITE_END,
 906           CreateNetLogReadWriteCompleteCallback(net::ERR_FAILED));
 907     }
 908     if (!callback.is_null()) {
 909       base::ThreadTaskRunnerHandle::Get()->PostTask(
 910           FROM_HERE, base::Bind(callback, net::ERR_FAILED));
 911     }
 912     // |this| may be destroyed after return here.
 913     return;
 914   }
 915
 916   DCHECK_EQ(STATE_READY, state_);
 917
 918   // Since stream 0 data is kept in memory, it will be written immediatly.
 919   if (stream_index == 0) {
 920     int ret_value = SetStream0Data(buf, offset, buf_len, truncate);
 921     if (!callback.is_null()) {
 922       base::ThreadTaskRunnerHandle::Get()->PostTask(
 923           FROM_HERE, base::Bind(callback, ret_value));
 924     }
 925     return;
 926   }
 927
 928   // Ignore zero-length writes that do not change the file size.
 929   if (buf_len == 0) {
 930     int32 data_size = data_size_[stream_index];
 931     if (truncate ? (offset == data_size) : (offset <= data_size)) {
 932       RecordWriteResult(cache_type_, WRITE_RESULT_FAST_EMPTY_RETURN);
 933       if (!callback.is_null()) {
 934         base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 935                                                       base::Bind(callback, 0));
 936       }
 937       return;
 938     }
 939   }
 940   state_ = STATE_IO_PENDING;
 941   if (!doomed_ && backend_.get())
 942     backend_->index()->UseIfExists(entry_hash_);
 943
 944   AdvanceCrc(buf, offset, buf_len, stream_index);
 945
 946   // |entry_stat| needs to be initialized before modifying |data_size_|.
 947   scoped_ptr<SimpleEntryStat> entry_stat(
 948       new SimpleEntryStat(last_used_, last_modified_, data_size_,
 949                           sparse_data_size_));
 950   if (truncate) {
 951     data_size_[stream_index] = offset + buf_len;
 952   } else {
 953     data_size_[stream_index] = std::max(offset + buf_len,
 954                                         GetDataSize(stream_index));
 955   }
 956
 957   // Since we don't know the correct values for |last_used_| and
 958   // |last_modified_| yet, we make this approximation.
 959   last_used_ = last_modified_ = base::Time::Now();
 960
 961   have_written_[stream_index] = true;
 962   // Writing on stream 1 affects the placement of stream 0 in the file, the EOF
 963   // record will have to be rewritten.
 964   if (stream_index == 1)
 965     have_written_[0] = true;
 966
 967   scoped_ptr<int> result(new int());
 968   Closure task = base::Bind(&SimpleSynchronousEntry::WriteData,
 969                             base::Unretained(synchronous_entry_),
 970                             SimpleSynchronousEntry::EntryOperationData(
 971                                 stream_index, offset, buf_len, truncate,
 972                                 doomed_),
 973                             make_scoped_refptr(buf),
 974                             entry_stat.get(),
 975                             result.get());
 976   Closure reply = base::Bind(&SimpleEntryImpl::WriteOperationComplete,
 977                              this,
 978                              stream_index,
 979                              callback,
 980                              base::Passed(&entry_stat),
 981                              base::Passed(&result));
 982   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
 983 }
 984
 985 void SimpleEntryImpl::ReadSparseDataInternal(
 986     int64 sparse_offset,
 987     net::IOBuffer* buf,
 988     int buf_len,
 989     const CompletionCallback& callback) {
 990   DCHECK(io_thread_checker_.CalledOnValidThread());
 991   ScopedOperationRunner operation_runner(this);
 992
 993   DCHECK_EQ(STATE_READY, state_);
 994   state_ = STATE_IO_PENDING;
 995
 996   scoped_ptr<int> result(new int());
 997   scoped_ptr<base::Time> last_used(new base::Time());
 998   Closure task = base::Bind(&SimpleSynchronousEntry::ReadSparseData,
 999                             base::Unretained(synchronous_entry_),
1000                             SimpleSynchronousEntry::EntryOperationData(
1001                                 sparse_offset, buf_len),
1002                             make_scoped_refptr(buf),
1003                             last_used.get(),
1004                             result.get());
1005   Closure reply = base::Bind(&SimpleEntryImpl::ReadSparseOperationComplete,
1006                              this,
1007                              callback,
1008                              base::Passed(&last_used),
1009                              base::Passed(&result));
1010   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
1011 }
1012
1013 void SimpleEntryImpl::WriteSparseDataInternal(
1014     int64 sparse_offset,
1015     net::IOBuffer* buf,
1016     int buf_len,
1017     const CompletionCallback& callback) {
1018   DCHECK(io_thread_checker_.CalledOnValidThread());
1019   ScopedOperationRunner operation_runner(this);
1020
1021   DCHECK_EQ(STATE_READY, state_);
1022   state_ = STATE_IO_PENDING;
1023
1024   uint64 max_sparse_data_size = kint64max;
1025   if (backend_.get()) {
1026     uint64 max_cache_size = backend_->index()->max_size();
1027     max_sparse_data_size = max_cache_size / kMaxSparseDataSizeDivisor;
1028   }
1029
1030   scoped_ptr<SimpleEntryStat> entry_stat(
1031       new SimpleEntryStat(last_used_, last_modified_, data_size_,
1032                           sparse_data_size_));
1033
1034   last_used_ = last_modified_ = base::Time::Now();
1035
1036   scoped_ptr<int> result(new int());
1037   Closure task = base::Bind(&SimpleSynchronousEntry::WriteSparseData,
1038                             base::Unretained(synchronous_entry_),
1039                             SimpleSynchronousEntry::EntryOperationData(
1040                                 sparse_offset, buf_len),
1041                             make_scoped_refptr(buf),
1042                             max_sparse_data_size,
1043                             entry_stat.get(),
1044                             result.get());
1045   Closure reply = base::Bind(&SimpleEntryImpl::WriteSparseOperationComplete,
1046                              this,
1047                              callback,
1048                              base::Passed(&entry_stat),
1049                              base::Passed(&result));
1050   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
1051 }
1052
1053 void SimpleEntryImpl::GetAvailableRangeInternal(
1054     int64 sparse_offset,
1055     int len,
1056     int64* out_start,
1057     const CompletionCallback& callback) {
1058   DCHECK(io_thread_checker_.CalledOnValidThread());
1059   ScopedOperationRunner operation_runner(this);
1060
1061   DCHECK_EQ(STATE_READY, state_);
1062   state_ = STATE_IO_PENDING;
1063
1064   scoped_ptr<int> result(new int());
1065   Closure task = base::Bind(&SimpleSynchronousEntry::GetAvailableRange,
1066                             base::Unretained(synchronous_entry_),
1067                             SimpleSynchronousEntry::EntryOperationData(
1068                                 sparse_offset, len),
1069                             out_start,
1070                             result.get());
1071   Closure reply = base::Bind(
1072       &SimpleEntryImpl::GetAvailableRangeOperationComplete,
1073       this,
1074       callback,
1075       base::Passed(&result));
1076   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
1077 }
1078
1079 void SimpleEntryImpl::DoomEntryInternal(const CompletionCallback& callback) {
1080   PostTaskAndReplyWithResult(
1081       worker_pool_.get(),
1082       FROM_HERE,
1083       base::Bind(&SimpleSynchronousEntry::DoomEntry, path_, entry_hash_),
1084       base::Bind(
1085           &SimpleEntryImpl::DoomOperationComplete, this, callback, state_));
1086   state_ = STATE_IO_PENDING;
1087 }
1088
1089 void SimpleEntryImpl::CreationOperationComplete(
1090     const CompletionCallback& completion_callback,
1091     const base::TimeTicks& start_time,
1092     scoped_ptr<SimpleEntryCreationResults> in_results,
1093     Entry** out_entry,
1094     net::NetLog::EventType end_event_type) {
1095   DCHECK(io_thread_checker_.CalledOnValidThread());
1096   DCHECK_EQ(state_, STATE_IO_PENDING);
1097   DCHECK(in_results);
1098   ScopedOperationRunner operation_runner(this);
1099   SIMPLE_CACHE_UMA(BOOLEAN,
1100                    "EntryCreationResult", cache_type_,
1101                    in_results->result == net::OK);
1102   if (in_results->result != net::OK) {
1103     if (in_results->result != net::ERR_FILE_EXISTS)
1104       MarkAsDoomed();
1105
1106     net_log_.AddEventWithNetErrorCode(end_event_type, net::ERR_FAILED);
1107     PostClientCallback(completion_callback, net::ERR_FAILED);
1108     MakeUninitialized();
1109     return;
1110   }
1111   // If out_entry is NULL, it means we already called ReturnEntryToCaller from
1112   // the optimistic Create case.
1113   if (out_entry)
1114     ReturnEntryToCaller(out_entry);
1115
1116   state_ = STATE_READY;
1117   synchronous_entry_ = in_results->sync_entry;
1118   if (in_results->stream_0_data.get()) {
1119     stream_0_data_ = in_results->stream_0_data;
1120     // The crc was read in SimpleSynchronousEntry.
1121     crc_check_state_[0] = CRC_CHECK_DONE;
1122     crc32s_[0] = in_results->stream_0_crc32;
1123     crc32s_end_offset_[0] = in_results->entry_stat.data_size(0);
1124   }
1125   if (key_.empty()) {
1126     SetKey(synchronous_entry_->key());
1127   } else {
1128     // This should only be triggered when creating an entry. The key check in
1129     // the open case is handled in SimpleBackendImpl.
1130     DCHECK_EQ(key_, synchronous_entry_->key());
1131   }
1132   UpdateDataFromEntryStat(in_results->entry_stat);
1133   SIMPLE_CACHE_UMA(TIMES,
1134                    "EntryCreationTime", cache_type_,
1135                    (base::TimeTicks::Now() - start_time));
1136   AdjustOpenEntryCountBy(cache_type_, 1);
1137
1138   net_log_.AddEvent(end_event_type);
1139   PostClientCallback(completion_callback, net::OK);
1140 }
1141
1142 void SimpleEntryImpl::EntryOperationComplete(
1143     const CompletionCallback& completion_callback,
1144     const SimpleEntryStat& entry_stat,
1145     scoped_ptr<int> result) {
1146   DCHECK(io_thread_checker_.CalledOnValidThread());
1147   DCHECK(synchronous_entry_);
1148   DCHECK_EQ(STATE_IO_PENDING, state_);
1149   DCHECK(result);
1150   if (*result < 0) {
1151     state_ = STATE_FAILURE;
1152     MarkAsDoomed();
1153   } else {
1154     state_ = STATE_READY;
1155     UpdateDataFromEntryStat(entry_stat);
1156   }
1157
1158   if (!completion_callback.is_null()) {
1159     base::ThreadTaskRunnerHandle::Get()->PostTask(
1160         FROM_HERE, base::Bind(completion_callback, *result));
1161   }
1162   RunNextOperationIfNeeded();
1163 }
1164
1165 void SimpleEntryImpl::ReadOperationComplete(
1166     int stream_index,
1167     int offset,
1168     const CompletionCallback& completion_callback,
1169     scoped_ptr<uint32> read_crc32,
1170     scoped_ptr<SimpleEntryStat> entry_stat,
1171     scoped_ptr<int> result) {
1172   DCHECK(io_thread_checker_.CalledOnValidThread());
1173   DCHECK(synchronous_entry_);
1174   DCHECK_EQ(STATE_IO_PENDING, state_);
1175   DCHECK(read_crc32);
1176   DCHECK(result);
1177
1178   if (*result > 0 &&
1179       crc_check_state_[stream_index] == CRC_CHECK_NEVER_READ_AT_ALL) {
1180     crc_check_state_[stream_index] = CRC_CHECK_NEVER_READ_TO_END;
1181   }
1182
1183   if (*result > 0 && crc32s_end_offset_[stream_index] == offset) {
1184     uint32 current_crc = offset == 0 ? crc32(0, Z_NULL, 0)
1185                                      : crc32s_[stream_index];
1186     crc32s_[stream_index] = crc32_combine(current_crc, *read_crc32, *result);
1187     crc32s_end_offset_[stream_index] += *result;
1188     if (!have_written_[stream_index] &&
1189         GetDataSize(stream_index) == crc32s_end_offset_[stream_index]) {
1190       // We have just read a file from start to finish, and so we have
1191       // computed a crc of the entire file. We can check it now. If a cache
1192       // entry has a single reader, the normal pattern is to read from start
1193       // to finish.
1194
1195       net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CHECKSUM_BEGIN);
1196
1197       scoped_ptr<int> new_result(new int());
1198       Closure task = base::Bind(&SimpleSynchronousEntry::CheckEOFRecord,
1199                                 base::Unretained(synchronous_entry_),
1200                                 stream_index,
1201                                 *entry_stat,
1202                                 crc32s_[stream_index],
1203                                 new_result.get());
1204       Closure reply = base::Bind(&SimpleEntryImpl::ChecksumOperationComplete,
1205                                  this, *result, stream_index,
1206                                  completion_callback,
1207                                  base::Passed(&new_result));
1208       worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
1209       crc_check_state_[stream_index] = CRC_CHECK_DONE;
1210       return;
1211     }
1212   }
1213
1214   if (*result < 0) {
1215     crc32s_end_offset_[stream_index] = 0;
1216   }
1217
1218   if (*result < 0) {
1219     RecordReadResult(cache_type_, READ_RESULT_SYNC_READ_FAILURE);
1220   } else {
1221     RecordReadResult(cache_type_, READ_RESULT_SUCCESS);
1222     if (crc_check_state_[stream_index] == CRC_CHECK_NEVER_READ_TO_END &&
1223         offset + *result == GetDataSize(stream_index)) {
1224       crc_check_state_[stream_index] = CRC_CHECK_NOT_DONE;
1225     }
1226   }
1227   if (net_log_.IsCapturing()) {
1228     net_log_.AddEvent(
1229         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_READ_END,
1230         CreateNetLogReadWriteCompleteCallback(*result));
1231   }
1232
1233   EntryOperationComplete(completion_callback, *entry_stat, result.Pass());
1234 }
1235
1236 void SimpleEntryImpl::WriteOperationComplete(
1237     int stream_index,
1238     const CompletionCallback& completion_callback,
1239     scoped_ptr<SimpleEntryStat> entry_stat,
1240     scoped_ptr<int> result) {
1241   if (*result >= 0)
1242     RecordWriteResult(cache_type_, WRITE_RESULT_SUCCESS);
1243   else
1244     RecordWriteResult(cache_type_, WRITE_RESULT_SYNC_WRITE_FAILURE);
1245   if (net_log_.IsCapturing()) {
1246     net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_WRITE_END,
1247         CreateNetLogReadWriteCompleteCallback(*result));
1248   }
1249
1250   if (*result < 0) {
1251     crc32s_end_offset_[stream_index] = 0;
1252   }
1253
1254   EntryOperationComplete(completion_callback, *entry_stat, result.Pass());
1255 }
1256
1257 void SimpleEntryImpl::ReadSparseOperationComplete(
1258     const CompletionCallback& completion_callback,
1259     scoped_ptr<base::Time> last_used,
1260     scoped_ptr<int> result) {
1261   DCHECK(io_thread_checker_.CalledOnValidThread());
1262   DCHECK(synchronous_entry_);
1263   DCHECK(result);
1264
1265   SimpleEntryStat entry_stat(*last_used, last_modified_, data_size_,
1266                              sparse_data_size_);
1267   EntryOperationComplete(completion_callback, entry_stat, result.Pass());
1268 }
1269
1270 void SimpleEntryImpl::WriteSparseOperationComplete(
1271     const CompletionCallback& completion_callback,
1272     scoped_ptr<SimpleEntryStat> entry_stat,
1273     scoped_ptr<int> result) {
1274   DCHECK(io_thread_checker_.CalledOnValidThread());
1275   DCHECK(synchronous_entry_);
1276   DCHECK(result);
1277
1278   EntryOperationComplete(completion_callback, *entry_stat, result.Pass());
1279 }
1280
1281 void SimpleEntryImpl::GetAvailableRangeOperationComplete(
1282     const CompletionCallback& completion_callback,
1283     scoped_ptr<int> result) {
1284   DCHECK(io_thread_checker_.CalledOnValidThread());
1285   DCHECK(synchronous_entry_);
1286   DCHECK(result);
1287
1288   SimpleEntryStat entry_stat(last_used_, last_modified_, data_size_,
1289                              sparse_data_size_);
1290   EntryOperationComplete(completion_callback, entry_stat, result.Pass());
1291 }
1292
1293 void SimpleEntryImpl::DoomOperationComplete(
1294     const CompletionCallback& callback,
1295     State state_to_restore,
1296     int result) {
1297   state_ = state_to_restore;
1298   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_DOOM_END);
1299   if (!callback.is_null())
1300     callback.Run(result);
1301   RunNextOperationIfNeeded();
1302   if (backend_)
1303     backend_->OnDoomComplete(entry_hash_);
1304 }
1305
1306 void SimpleEntryImpl::ChecksumOperationComplete(
1307     int orig_result,
1308     int stream_index,
1309     const CompletionCallback& completion_callback,
1310     scoped_ptr<int> result) {
1311   DCHECK(io_thread_checker_.CalledOnValidThread());
1312   DCHECK(synchronous_entry_);
1313   DCHECK_EQ(STATE_IO_PENDING, state_);
1314   DCHECK(result);
1315
1316   if (net_log_.IsCapturing()) {
1317     net_log_.AddEventWithNetErrorCode(
1318         net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CHECKSUM_END,
1319         *result);
1320   }
1321
1322   if (*result == net::OK) {
1323     *result = orig_result;
1324     if (orig_result >= 0)
1325       RecordReadResult(cache_type_, READ_RESULT_SUCCESS);
1326     else
1327       RecordReadResult(cache_type_, READ_RESULT_SYNC_READ_FAILURE);
1328   } else {
1329     RecordReadResult(cache_type_, READ_RESULT_SYNC_CHECKSUM_FAILURE);
1330   }
1331   if (net_log_.IsCapturing()) {
1332     net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_READ_END,
1333         CreateNetLogReadWriteCompleteCallback(*result));
1334   }
1335
1336   SimpleEntryStat entry_stat(last_used_, last_modified_, data_size_,
1337                              sparse_data_size_);
1338   EntryOperationComplete(completion_callback, entry_stat, result.Pass());
1339 }
1340
1341 void SimpleEntryImpl::CloseOperationComplete() {
1342   DCHECK(!synchronous_entry_);
1343   DCHECK_EQ(0, open_count_);
1344   DCHECK(STATE_IO_PENDING == state_ || STATE_FAILURE == state_ ||
1345          STATE_UNINITIALIZED == state_);
1346   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_CLOSE_END);
1347   AdjustOpenEntryCountBy(cache_type_, -1);
1348   MakeUninitialized();
1349   RunNextOperationIfNeeded();
1350 }
1351
1352 void SimpleEntryImpl::UpdateDataFromEntryStat(
1353     const SimpleEntryStat& entry_stat) {
1354   DCHECK(io_thread_checker_.CalledOnValidThread());
1355   DCHECK(synchronous_entry_);
1356   DCHECK_EQ(STATE_READY, state_);
1357
1358   last_used_ = entry_stat.last_used();
1359   last_modified_ = entry_stat.last_modified();
1360   for (int i = 0; i < kSimpleEntryStreamCount; ++i) {
1361     data_size_[i] = entry_stat.data_size(i);
1362   }
1363   sparse_data_size_ = entry_stat.sparse_data_size();
1364   if (!doomed_ && backend_.get())
1365     backend_->index()->UpdateEntrySize(entry_hash_, GetDiskUsage());
1366 }
1367
1368 int64 SimpleEntryImpl::GetDiskUsage() const {
1369   int64 file_size = 0;
1370   for (int i = 0; i < kSimpleEntryStreamCount; ++i) {
1371     file_size +=
1372         simple_util::GetFileSizeFromKeyAndDataSize(key_, data_size_[i]);
1373   }
1374   file_size += sparse_data_size_;
1375   return file_size;
1376 }
1377
1378 void SimpleEntryImpl::RecordReadIsParallelizable(
1379     const SimpleEntryOperation& operation) const {
1380   if (!executing_operation_)
1381     return;
1382   // Used in histograms, please only add entries at the end.
1383   enum ReadDependencyType {
1384     // READ_STANDALONE = 0, Deprecated.
1385     READ_FOLLOWS_READ = 1,
1386     READ_FOLLOWS_CONFLICTING_WRITE = 2,
1387     READ_FOLLOWS_NON_CONFLICTING_WRITE = 3,
1388     READ_FOLLOWS_OTHER = 4,
1389     READ_ALONE_IN_QUEUE = 5,
1390     READ_DEPENDENCY_TYPE_MAX = 6,
1391   };
1392
1393   ReadDependencyType type = READ_FOLLOWS_OTHER;
1394   if (operation.alone_in_queue()) {
1395     type = READ_ALONE_IN_QUEUE;
1396   } else if (executing_operation_->type() == SimpleEntryOperation::TYPE_READ) {
1397     type = READ_FOLLOWS_READ;
1398   } else if (executing_operation_->type() == SimpleEntryOperation::TYPE_WRITE) {
1399     if (executing_operation_->ConflictsWith(operation))
1400       type = READ_FOLLOWS_CONFLICTING_WRITE;
1401     else
1402       type = READ_FOLLOWS_NON_CONFLICTING_WRITE;
1403   }
1404   SIMPLE_CACHE_UMA(ENUMERATION,
1405                    "ReadIsParallelizable", cache_type_,
1406                    type, READ_DEPENDENCY_TYPE_MAX);
1407 }
1408
1409 void SimpleEntryImpl::RecordWriteDependencyType(
1410     const SimpleEntryOperation& operation) const {
1411   if (!executing_operation_)
1412     return;
1413   // Used in histograms, please only add entries at the end.
1414   enum WriteDependencyType {
1415     WRITE_OPTIMISTIC = 0,
1416     WRITE_FOLLOWS_CONFLICTING_OPTIMISTIC = 1,
1417     WRITE_FOLLOWS_NON_CONFLICTING_OPTIMISTIC = 2,
1418     WRITE_FOLLOWS_CONFLICTING_WRITE = 3,
1419     WRITE_FOLLOWS_NON_CONFLICTING_WRITE = 4,
1420     WRITE_FOLLOWS_CONFLICTING_READ = 5,
1421     WRITE_FOLLOWS_NON_CONFLICTING_READ = 6,
1422     WRITE_FOLLOWS_OTHER = 7,
1423     WRITE_DEPENDENCY_TYPE_MAX = 8,
1424   };
1425
1426   WriteDependencyType type = WRITE_FOLLOWS_OTHER;
1427   if (operation.optimistic()) {
1428     type = WRITE_OPTIMISTIC;
1429   } else if (executing_operation_->type() == SimpleEntryOperation::TYPE_READ ||
1430              executing_operation_->type() == SimpleEntryOperation::TYPE_WRITE) {
1431     bool conflicting = executing_operation_->ConflictsWith(operation);
1432
1433     if (executing_operation_->type() == SimpleEntryOperation::TYPE_READ) {
1434       type = conflicting ? WRITE_FOLLOWS_CONFLICTING_READ
1435                          : WRITE_FOLLOWS_NON_CONFLICTING_READ;
1436     } else if (executing_operation_->optimistic()) {
1437       type = conflicting ? WRITE_FOLLOWS_CONFLICTING_OPTIMISTIC
1438                          : WRITE_FOLLOWS_NON_CONFLICTING_OPTIMISTIC;
1439     } else {
1440       type = conflicting ? WRITE_FOLLOWS_CONFLICTING_WRITE
1441                          : WRITE_FOLLOWS_NON_CONFLICTING_WRITE;
1442     }
1443   }
1444   SIMPLE_CACHE_UMA(ENUMERATION,
1445                    "WriteDependencyType", cache_type_,
1446                    type, WRITE_DEPENDENCY_TYPE_MAX);
1447 }
1448
1449 int SimpleEntryImpl::ReadStream0Data(net::IOBuffer* buf,
1450                                      int offset,
1451                                      int buf_len) {
1452   if (buf_len < 0) {
1453     RecordReadResult(cache_type_, READ_RESULT_SYNC_READ_FAILURE);
1454     return 0;
1455   }
1456   memcpy(buf->data(), stream_0_data_->data() + offset, buf_len);
1457   UpdateDataFromEntryStat(
1458       SimpleEntryStat(base::Time::Now(), last_modified_, data_size_,
1459                       sparse_data_size_));
1460   RecordReadResult(cache_type_, READ_RESULT_SUCCESS);
1461   return buf_len;
1462 }
1463
1464 int SimpleEntryImpl::SetStream0Data(net::IOBuffer* buf,
1465                                     int offset,
1466                                     int buf_len,
1467                                     bool truncate) {
1468   // Currently, stream 0 is only used for HTTP headers, and always writes them
1469   // with a single, truncating write. Detect these writes and record the size
1470   // changes of the headers. Also, support writes to stream 0 that have
1471   // different access patterns, as required by the API contract.
1472   // All other clients of the Simple Cache are encouraged to use stream 1.
1473   have_written_[0] = true;
1474   int data_size = GetDataSize(0);
1475   if (offset == 0 && truncate) {
1476     RecordHeaderSizeChange(cache_type_, data_size, buf_len);
1477     stream_0_data_->SetCapacity(buf_len);
1478     memcpy(stream_0_data_->data(), buf->data(), buf_len);
1479     data_size_[0] = buf_len;
1480   } else {
1481     RecordUnexpectedStream0Write(cache_type_);
1482     const int buffer_size =
1483         truncate ? offset + buf_len : std::max(offset + buf_len, data_size);
1484     stream_0_data_->SetCapacity(buffer_size);
1485     // If |stream_0_data_| was extended, the extension until offset needs to be
1486     // zero-filled.
1487     const int fill_size = offset <= data_size ? 0 : offset - data_size;
1488     if (fill_size > 0)
1489       memset(stream_0_data_->data() + data_size, 0, fill_size);
1490     if (buf)
1491       memcpy(stream_0_data_->data() + offset, buf->data(), buf_len);
1492     data_size_[0] = buffer_size;
1493   }
1494   base::Time modification_time = base::Time::Now();
1495   AdvanceCrc(buf, offset, buf_len, 0);
1496   UpdateDataFromEntryStat(
1497       SimpleEntryStat(modification_time, modification_time, data_size_,
1498                       sparse_data_size_));
1499   RecordWriteResult(cache_type_, WRITE_RESULT_SUCCESS);
1500   return buf_len;
1501 }
1502
1503 void SimpleEntryImpl::AdvanceCrc(net::IOBuffer* buffer,
1504                                  int offset,
1505                                  int length,
1506                                  int stream_index) {
1507   // It is easy to incrementally compute the CRC from [0 .. |offset + buf_len|)
1508   // if |offset == 0| or we have already computed the CRC for [0 .. offset).
1509   // We rely on most write operations being sequential, start to end to compute
1510   // the crc of the data. When we write to an entry and close without having
1511   // done a sequential write, we don't check the CRC on read.
1512   if (offset == 0 || crc32s_end_offset_[stream_index] == offset) {
1513     uint32 initial_crc =
1514         (offset != 0) ? crc32s_[stream_index] : crc32(0, Z_NULL, 0);
1515     if (length > 0) {
1516       crc32s_[stream_index] = crc32(
1517           initial_crc, reinterpret_cast<const Bytef*>(buffer->data()), length);
1518     }
1519     crc32s_end_offset_[stream_index] = offset + length;
1520   } else if (offset < crc32s_end_offset_[stream_index]) {
1521     // If a range for which the crc32 was already computed is rewritten, the
1522     // computation of the crc32 need to start from 0 again.
1523     crc32s_end_offset_[stream_index] = 0;
1524   }
1525 }
1526
1527 }  // namespace disk_cache