content/child/fileapi/webfilesystem_impl.cc

   1 // Copyright 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 "content/child/fileapi/webfilesystem_impl.h"
   6
   7 #include "base/bind.h"
   8 #include "base/lazy_instance.h"
   9 #include "base/logging.h"
  10 #include "base/message_loop/message_loop_proxy.h"
  11 #include "base/strings/utf_string_conversions.h"
  12 #include "base/synchronization/waitable_event.h"
  13 #include "base/threading/thread_local.h"
  14 #include "content/child/child_thread.h"
  15 #include "content/child/file_info_util.h"
  16 #include "content/child/fileapi/file_system_dispatcher.h"
  17 #include "content/child/fileapi/webfilewriter_impl.h"
  18 #include "content/child/worker_task_runner.h"
  19 #include "content/common/fileapi/file_system_messages.h"
  20 #include "storage/common/fileapi/directory_entry.h"
  21 #include "storage/common/fileapi/file_system_util.h"
  22 #include "third_party/WebKit/public/platform/WebFileInfo.h"
  23 #include "third_party/WebKit/public/platform/WebFileSystemCallbacks.h"
  24 #include "third_party/WebKit/public/platform/WebString.h"
  25 #include "third_party/WebKit/public/platform/WebURL.h"
  26 #include "third_party/WebKit/public/web/WebHeap.h"
  27 #include "url/gurl.h"
  28
  29 using blink::WebFileInfo;
  30 using blink::WebFileSystemCallbacks;
  31 using blink::WebFileSystemEntry;
  32 using blink::WebString;
  33 using blink::WebURL;
  34 using blink::WebVector;
  35
  36 namespace content {
  37
  38 class WebFileSystemImpl::WaitableCallbackResults
  39     : public base::RefCountedThreadSafe<WaitableCallbackResults> {
  40  public:
  41   WaitableCallbackResults()
  42       : results_available_event_(true /* manual_reset */,
  43                                  false /* initially_signaled */) {}
  44
  45   void AddResultsAndSignal(const base::Closure& results_closure) {
  46     base::AutoLock lock(lock_);
  47     results_closures_.push_back(results_closure);
  48     results_available_event_.Signal();
  49   }
  50
  51   void WaitAndRun() {
  52     {
  53       blink::WebHeap::SafePointScope safe_point;
  54       results_available_event_.Wait();
  55     }
  56     Run();
  57   }
  58
  59   void Run() {
  60     std::vector<base::Closure> closures;
  61     {
  62       base::AutoLock lock(lock_);
  63       results_closures_.swap(closures);
  64       results_available_event_.Reset();
  65     }
  66     for (size_t i = 0; i < closures.size(); ++i)
  67       closures[i].Run();
  68   }
  69
  70  private:
  71   friend class base::RefCountedThreadSafe<WaitableCallbackResults>;
  72
  73   ~WaitableCallbackResults() {}
  74
  75   base::Lock lock_;
  76   base::WaitableEvent results_available_event_;
  77   std::vector<base::Closure> results_closures_;
  78   DISALLOW_COPY_AND_ASSIGN(WaitableCallbackResults);
  79 };
  80
  81 namespace {
  82
  83 typedef WebFileSystemImpl::WaitableCallbackResults WaitableCallbackResults;
  84
  85 base::LazyInstance<base::ThreadLocalPointer<WebFileSystemImpl> >::Leaky
  86     g_webfilesystem_tls = LAZY_INSTANCE_INITIALIZER;
  87
  88 void DidReceiveSnapshotFile(int request_id) {
  89   if (ChildThread::current())
  90     ChildThread::current()->Send(
  91         new FileSystemHostMsg_DidReceiveSnapshotFile(request_id));
  92 }
  93
  94 int CurrentWorkerId() {
  95   return WorkerTaskRunner::Instance()->CurrentWorkerId();
  96 }
  97
  98 template <typename Method, typename Params>
  99 void CallDispatcherOnMainThread(
 100     base::MessageLoopProxy* loop,
 101     Method method, const Params& params,
 102     WaitableCallbackResults* waitable_results) {
 103   if (!loop->RunsTasksOnCurrentThread()) {
 104     loop->PostTask(FROM_HERE,
 105                    base::Bind(&CallDispatcherOnMainThread<Method, Params>,
 106                               make_scoped_refptr(loop), method, params,
 107                               scoped_refptr<WaitableCallbackResults>()));
 108     if (!waitable_results)
 109       return;
 110     waitable_results->WaitAndRun();
 111   }
 112   if (!ChildThread::current() ||
 113       !ChildThread::current()->file_system_dispatcher())
 114     return;
 115
 116   DCHECK(!waitable_results);
 117   DispatchToMethod(ChildThread::current()->file_system_dispatcher(),
 118                    method, params);
 119 }
 120
 121 enum CallbacksUnregisterMode {
 122   UNREGISTER_CALLBACKS,
 123   DO_NOT_UNREGISTER_CALLBACKS,
 124 };
 125
 126 // Bridging functions that convert the arguments into Blink objects
 127 // (e.g. WebFileInfo, WebString, WebVector<WebFileSystemEntry>)
 128 // and call WebFileSystemCallbacks's methods.
 129 // These are called by RunCallbacks after crossing threads to ensure
 130 // thread safety, because the Blink objects cannot be passed across
 131 // threads by base::Bind().
 132 void DidSucceed(WebFileSystemCallbacks* callbacks) {
 133   callbacks->didSucceed();
 134 }
 135
 136 void DidReadMetadata(const base::File::Info& file_info,
 137                      WebFileSystemCallbacks* callbacks) {
 138   WebFileInfo web_file_info;
 139   FileInfoToWebFileInfo(file_info, &web_file_info);
 140   callbacks->didReadMetadata(web_file_info);
 141 }
 142
 143 void DidReadDirectory(const std::vector<storage::DirectoryEntry>& entries,
 144                       bool has_more,
 145                       WebFileSystemCallbacks* callbacks) {
 146   WebVector<WebFileSystemEntry> file_system_entries(entries.size());
 147   for (size_t i = 0; i < entries.size(); ++i) {
 148     file_system_entries[i].name =
 149         base::FilePath(entries[i].name).AsUTF16Unsafe();
 150     file_system_entries[i].isDirectory = entries[i].is_directory;
 151   }
 152   callbacks->didReadDirectory(file_system_entries, has_more);
 153 }
 154
 155 void DidOpenFileSystem(const base::string16& name, const GURL& root,
 156                        WebFileSystemCallbacks* callbacks) {
 157   callbacks->didOpenFileSystem(name, root);
 158 }
 159
 160 void DidResolveURL(const base::string16& name,
 161                    const GURL& root_url,
 162                    storage::FileSystemType mount_type,
 163                    const base::string16& file_path,
 164                    bool is_directory,
 165                    WebFileSystemCallbacks* callbacks) {
 166   callbacks->didResolveURL(
 167       name,
 168       root_url,
 169       static_cast<blink::WebFileSystemType>(mount_type),
 170       file_path,
 171       is_directory);
 172 }
 173
 174 void DidFail(base::File::Error error, WebFileSystemCallbacks* callbacks) {
 175   callbacks->didFail(storage::FileErrorToWebFileError(error));
 176 }
 177
 178 // Run WebFileSystemCallbacks's |method| with |params|.
 179 void RunCallbacks(
 180     int callbacks_id,
 181     const base::Callback<void(WebFileSystemCallbacks*)>& callback,
 182     CallbacksUnregisterMode callbacks_unregister_mode) {
 183   WebFileSystemImpl* filesystem =
 184       WebFileSystemImpl::ThreadSpecificInstance(NULL);
 185   if (!filesystem)
 186     return;
 187   WebFileSystemCallbacks callbacks = filesystem->GetCallbacks(callbacks_id);
 188   if (callbacks_unregister_mode == UNREGISTER_CALLBACKS)
 189     filesystem->UnregisterCallbacks(callbacks_id);
 190   callback.Run(&callbacks);
 191 }
 192
 193 void DispatchResultsClosure(int thread_id, int callbacks_id,
 194                             WaitableCallbackResults* waitable_results,
 195                             const base::Closure& results_closure) {
 196   if (thread_id != CurrentWorkerId()) {
 197     if (waitable_results) {
 198       // If someone is waiting, this should result in running the closure.
 199       waitable_results->AddResultsAndSignal(results_closure);
 200       // In case no one is waiting, post a task to run the closure.
 201       WorkerTaskRunner::Instance()->PostTask(
 202           thread_id,
 203           base::Bind(&WaitableCallbackResults::Run,
 204                      make_scoped_refptr(waitable_results)));
 205       return;
 206     }
 207     WorkerTaskRunner::Instance()->PostTask(thread_id, results_closure);
 208     return;
 209   }
 210   results_closure.Run();
 211 }
 212
 213 void CallbackFileSystemCallbacks(
 214     int thread_id, int callbacks_id,
 215     WaitableCallbackResults* waitable_results,
 216     const base::Callback<void(WebFileSystemCallbacks*)>& callback,
 217     CallbacksUnregisterMode callbacksunregister_mode) {
 218   DispatchResultsClosure(
 219       thread_id, callbacks_id, waitable_results,
 220       base::Bind(&RunCallbacks, callbacks_id, callback,
 221                  callbacksunregister_mode));
 222 }
 223
 224 //-----------------------------------------------------------------------------
 225 // Callback adapters. Callbacks must be called on the original calling thread,
 226 // so these callback adapters relay back the results to the calling thread
 227 // if necessary.
 228
 229 void OpenFileSystemCallbackAdapter(
 230     int thread_id, int callbacks_id,
 231     WaitableCallbackResults* waitable_results,
 232     const std::string& name, const GURL& root) {
 233   CallbackFileSystemCallbacks(
 234       thread_id, callbacks_id, waitable_results,
 235       base::Bind(&DidOpenFileSystem, base::UTF8ToUTF16(name), root),
 236       UNREGISTER_CALLBACKS);
 237 }
 238
 239 void ResolveURLCallbackAdapter(int thread_id,
 240                                int callbacks_id,
 241                                WaitableCallbackResults* waitable_results,
 242                                const storage::FileSystemInfo& info,
 243                                const base::FilePath& file_path,
 244                                bool is_directory) {
 245   base::FilePath normalized_path(
 246       storage::VirtualPath::GetNormalizedFilePath(file_path));
 247   CallbackFileSystemCallbacks(
 248       thread_id, callbacks_id, waitable_results,
 249       base::Bind(&DidResolveURL, base::UTF8ToUTF16(info.name), info.root_url,
 250                  info.mount_type,
 251                  normalized_path.AsUTF16Unsafe(), is_directory),
 252       UNREGISTER_CALLBACKS);
 253 }
 254
 255 void StatusCallbackAdapter(int thread_id, int callbacks_id,
 256                            WaitableCallbackResults* waitable_results,
 257                            base::File::Error error) {
 258   if (error == base::File::FILE_OK) {
 259     CallbackFileSystemCallbacks(
 260         thread_id, callbacks_id, waitable_results,
 261         base::Bind(&DidSucceed),
 262         UNREGISTER_CALLBACKS);
 263   } else {
 264     CallbackFileSystemCallbacks(
 265         thread_id, callbacks_id, waitable_results,
 266         base::Bind(&DidFail, error),
 267         UNREGISTER_CALLBACKS);
 268   }
 269 }
 270
 271 void ReadMetadataCallbackAdapter(int thread_id, int callbacks_id,
 272                                  WaitableCallbackResults* waitable_results,
 273                                  const base::File::Info& file_info) {
 274   CallbackFileSystemCallbacks(
 275       thread_id, callbacks_id, waitable_results,
 276       base::Bind(&DidReadMetadata, file_info),
 277       UNREGISTER_CALLBACKS);
 278 }
 279
 280 void ReadDirectoryCallbackAdapter(
 281     int thread_id,
 282     int callbacks_id,
 283     WaitableCallbackResults* waitable_results,
 284     const std::vector<storage::DirectoryEntry>& entries,
 285     bool has_more) {
 286   CallbackFileSystemCallbacks(
 287       thread_id, callbacks_id, waitable_results,
 288       base::Bind(&DidReadDirectory, entries, has_more),
 289       has_more ? DO_NOT_UNREGISTER_CALLBACKS : UNREGISTER_CALLBACKS);
 290 }
 291
 292 void DidCreateFileWriter(
 293     int callbacks_id,
 294     const GURL& path,
 295     blink::WebFileWriterClient* client,
 296     base::MessageLoopProxy* main_thread_loop,
 297     const base::File::Info& file_info) {
 298   WebFileSystemImpl* filesystem =
 299       WebFileSystemImpl::ThreadSpecificInstance(NULL);
 300   if (!filesystem)
 301     return;
 302
 303   WebFileSystemCallbacks callbacks = filesystem->GetCallbacks(callbacks_id);
 304   filesystem->UnregisterCallbacks(callbacks_id);
 305
 306   if (file_info.is_directory || file_info.size < 0) {
 307     callbacks.didFail(blink::WebFileErrorInvalidState);
 308     return;
 309   }
 310   WebFileWriterImpl::Type type =
 311       callbacks.shouldBlockUntilCompletion() ?
 312           WebFileWriterImpl::TYPE_SYNC : WebFileWriterImpl::TYPE_ASYNC;
 313   callbacks.didCreateFileWriter(
 314       new WebFileWriterImpl(path, client, type, main_thread_loop),
 315       file_info.size);
 316 }
 317
 318 void CreateFileWriterCallbackAdapter(
 319     int thread_id, int callbacks_id,
 320     WaitableCallbackResults* waitable_results,
 321     base::MessageLoopProxy* main_thread_loop,
 322     const GURL& path,
 323     blink::WebFileWriterClient* client,
 324     const base::File::Info& file_info) {
 325   DispatchResultsClosure(
 326       thread_id, callbacks_id, waitable_results,
 327       base::Bind(&DidCreateFileWriter, callbacks_id, path, client,
 328                  make_scoped_refptr(main_thread_loop), file_info));
 329 }
 330
 331 void DidCreateSnapshotFile(
 332     int callbacks_id,
 333     base::MessageLoopProxy* main_thread_loop,
 334     const base::File::Info& file_info,
 335     const base::FilePath& platform_path,
 336     int request_id) {
 337   WebFileSystemImpl* filesystem =
 338       WebFileSystemImpl::ThreadSpecificInstance(NULL);
 339   if (!filesystem)
 340     return;
 341
 342   WebFileSystemCallbacks callbacks = filesystem->GetCallbacks(callbacks_id);
 343   filesystem->UnregisterCallbacks(callbacks_id);
 344
 345   WebFileInfo web_file_info;
 346   FileInfoToWebFileInfo(file_info, &web_file_info);
 347   web_file_info.platformPath = platform_path.AsUTF16Unsafe();
 348   callbacks.didCreateSnapshotFile(web_file_info);
 349
 350   // TODO(michaeln,kinuko): Use ThreadSafeSender when Blob becomes
 351   // non-bridge model.
 352   main_thread_loop->PostTask(
 353       FROM_HERE, base::Bind(&DidReceiveSnapshotFile, request_id));
 354 }
 355
 356 void CreateSnapshotFileCallbackAdapter(
 357     int thread_id, int callbacks_id,
 358     WaitableCallbackResults* waitable_results,
 359     base::MessageLoopProxy* main_thread_loop,
 360     const base::File::Info& file_info,
 361     const base::FilePath& platform_path,
 362     int request_id) {
 363   DispatchResultsClosure(
 364       thread_id, callbacks_id, waitable_results,
 365       base::Bind(&DidCreateSnapshotFile, callbacks_id,
 366                  make_scoped_refptr(main_thread_loop),
 367                  file_info, platform_path, request_id));
 368 }
 369
 370 }  // namespace
 371
 372 //-----------------------------------------------------------------------------
 373 // WebFileSystemImpl
 374
 375 WebFileSystemImpl* WebFileSystemImpl::ThreadSpecificInstance(
 376     base::MessageLoopProxy* main_thread_loop) {
 377   if (g_webfilesystem_tls.Pointer()->Get() || !main_thread_loop)
 378     return g_webfilesystem_tls.Pointer()->Get();
 379   WebFileSystemImpl* filesystem = new WebFileSystemImpl(main_thread_loop);
 380   if (WorkerTaskRunner::Instance()->CurrentWorkerId())
 381     WorkerTaskRunner::Instance()->AddStopObserver(filesystem);
 382   return filesystem;
 383 }
 384
 385 void WebFileSystemImpl::DeleteThreadSpecificInstance() {
 386   DCHECK(!WorkerTaskRunner::Instance()->CurrentWorkerId());
 387   if (g_webfilesystem_tls.Pointer()->Get())
 388     delete g_webfilesystem_tls.Pointer()->Get();
 389 }
 390
 391 WebFileSystemImpl::WebFileSystemImpl(base::MessageLoopProxy* main_thread_loop)
 392     : main_thread_loop_(main_thread_loop),
 393       next_callbacks_id_(1) {
 394   g_webfilesystem_tls.Pointer()->Set(this);
 395 }
 396
 397 WebFileSystemImpl::~WebFileSystemImpl() {
 398   g_webfilesystem_tls.Pointer()->Set(NULL);
 399 }
 400
 401 void WebFileSystemImpl::OnWorkerRunLoopStopped() {
 402   delete this;
 403 }
 404
 405 void WebFileSystemImpl::openFileSystem(
 406     const blink::WebURL& storage_partition,
 407     blink::WebFileSystemType type,
 408     WebFileSystemCallbacks callbacks) {
 409   int callbacks_id = RegisterCallbacks(callbacks);
 410   scoped_refptr<WaitableCallbackResults> waitable_results =
 411       MaybeCreateWaitableResults(callbacks, callbacks_id);
 412   CallDispatcherOnMainThread(
 413       main_thread_loop_.get(),
 414       &FileSystemDispatcher::OpenFileSystem,
 415       MakeTuple(GURL(storage_partition),
 416                 static_cast<storage::FileSystemType>(type),
 417                 base::Bind(&OpenFileSystemCallbackAdapter,
 418                            CurrentWorkerId(),
 419                            callbacks_id,
 420                            waitable_results),
 421                 base::Bind(&StatusCallbackAdapter,
 422                            CurrentWorkerId(),
 423                            callbacks_id,
 424                            waitable_results)),
 425       waitable_results.get());
 426 }
 427
 428 void WebFileSystemImpl::resolveURL(
 429     const blink::WebURL& filesystem_url,
 430     WebFileSystemCallbacks callbacks) {
 431   int callbacks_id = RegisterCallbacks(callbacks);
 432   scoped_refptr<WaitableCallbackResults> waitable_results =
 433       MaybeCreateWaitableResults(callbacks, callbacks_id);
 434   CallDispatcherOnMainThread(
 435       main_thread_loop_.get(),
 436       &FileSystemDispatcher::ResolveURL,
 437       MakeTuple(GURL(filesystem_url),
 438                 base::Bind(&ResolveURLCallbackAdapter,
 439                            CurrentWorkerId(), callbacks_id, waitable_results),
 440                 base::Bind(&StatusCallbackAdapter,
 441                            CurrentWorkerId(), callbacks_id, waitable_results)),
 442       waitable_results.get());
 443 }
 444
 445 void WebFileSystemImpl::deleteFileSystem(
 446     const blink::WebURL& storage_partition,
 447     blink::WebFileSystemType type,
 448     WebFileSystemCallbacks callbacks) {
 449   int callbacks_id = RegisterCallbacks(callbacks);
 450   scoped_refptr<WaitableCallbackResults> waitable_results =
 451       MaybeCreateWaitableResults(callbacks, callbacks_id);
 452   CallDispatcherOnMainThread(
 453       main_thread_loop_.get(),
 454       &FileSystemDispatcher::DeleteFileSystem,
 455       MakeTuple(GURL(storage_partition),
 456                 static_cast<storage::FileSystemType>(type),
 457                 base::Bind(&StatusCallbackAdapter,
 458                            CurrentWorkerId(),
 459                            callbacks_id,
 460                            waitable_results)),
 461       waitable_results.get());
 462 }
 463
 464 void WebFileSystemImpl::move(
 465     const blink::WebURL& src_path,
 466     const blink::WebURL& dest_path,
 467     WebFileSystemCallbacks callbacks) {
 468   int callbacks_id = RegisterCallbacks(callbacks);
 469   scoped_refptr<WaitableCallbackResults> waitable_results =
 470       MaybeCreateWaitableResults(callbacks, callbacks_id);
 471   CallDispatcherOnMainThread(
 472       main_thread_loop_.get(),
 473       &FileSystemDispatcher::Move,
 474       MakeTuple(GURL(src_path), GURL(dest_path),
 475                 base::Bind(&StatusCallbackAdapter,
 476                            CurrentWorkerId(), callbacks_id, waitable_results)),
 477       waitable_results.get());
 478 }
 479
 480 void WebFileSystemImpl::copy(
 481     const blink::WebURL& src_path,
 482     const blink::WebURL& dest_path,
 483     WebFileSystemCallbacks callbacks) {
 484   int callbacks_id = RegisterCallbacks(callbacks);
 485   scoped_refptr<WaitableCallbackResults> waitable_results =
 486       MaybeCreateWaitableResults(callbacks, callbacks_id);
 487   CallDispatcherOnMainThread(
 488       main_thread_loop_.get(),
 489       &FileSystemDispatcher::Copy,
 490       MakeTuple(GURL(src_path), GURL(dest_path),
 491                 base::Bind(&StatusCallbackAdapter,
 492                            CurrentWorkerId(), callbacks_id, waitable_results)),
 493       waitable_results.get());
 494 }
 495
 496 void WebFileSystemImpl::remove(
 497     const blink::WebURL& path,
 498     WebFileSystemCallbacks callbacks) {
 499   int callbacks_id = RegisterCallbacks(callbacks);
 500   scoped_refptr<WaitableCallbackResults> waitable_results =
 501       MaybeCreateWaitableResults(callbacks, callbacks_id);
 502   CallDispatcherOnMainThread(
 503       main_thread_loop_.get(),
 504       &FileSystemDispatcher::Remove,
 505       MakeTuple(GURL(path), false /* recursive */,
 506                 base::Bind(&StatusCallbackAdapter,
 507                            CurrentWorkerId(), callbacks_id, waitable_results)),
 508       waitable_results.get());
 509 }
 510
 511 void WebFileSystemImpl::removeRecursively(
 512     const blink::WebURL& path,
 513     WebFileSystemCallbacks callbacks) {
 514   int callbacks_id = RegisterCallbacks(callbacks);
 515   scoped_refptr<WaitableCallbackResults> waitable_results =
 516       MaybeCreateWaitableResults(callbacks, callbacks_id);
 517   CallDispatcherOnMainThread(
 518       main_thread_loop_.get(),
 519       &FileSystemDispatcher::Remove,
 520       MakeTuple(GURL(path), true /* recursive */,
 521                 base::Bind(&StatusCallbackAdapter,
 522                            CurrentWorkerId(), callbacks_id, waitable_results)),
 523       waitable_results.get());
 524 }
 525
 526 void WebFileSystemImpl::readMetadata(
 527     const blink::WebURL& path,
 528     WebFileSystemCallbacks callbacks) {
 529   int callbacks_id = RegisterCallbacks(callbacks);
 530   scoped_refptr<WaitableCallbackResults> waitable_results =
 531       MaybeCreateWaitableResults(callbacks, callbacks_id);
 532   CallDispatcherOnMainThread(
 533       main_thread_loop_.get(),
 534       &FileSystemDispatcher::ReadMetadata,
 535       MakeTuple(GURL(path),
 536                 base::Bind(&ReadMetadataCallbackAdapter,
 537                            CurrentWorkerId(), callbacks_id, waitable_results),
 538                 base::Bind(&StatusCallbackAdapter,
 539                            CurrentWorkerId(), callbacks_id, waitable_results)),
 540       waitable_results.get());
 541 }
 542
 543 void WebFileSystemImpl::createFile(
 544     const blink::WebURL& path,
 545     bool exclusive,
 546     WebFileSystemCallbacks callbacks) {
 547   int callbacks_id = RegisterCallbacks(callbacks);
 548   scoped_refptr<WaitableCallbackResults> waitable_results =
 549       MaybeCreateWaitableResults(callbacks, callbacks_id);
 550   CallDispatcherOnMainThread(
 551       main_thread_loop_.get(),
 552       &FileSystemDispatcher::CreateFile,
 553       MakeTuple(GURL(path), exclusive,
 554                 base::Bind(&StatusCallbackAdapter,
 555                            CurrentWorkerId(), callbacks_id, waitable_results)),
 556       waitable_results.get());
 557 }
 558
 559 void WebFileSystemImpl::createDirectory(
 560     const blink::WebURL& path,
 561     bool exclusive,
 562     WebFileSystemCallbacks callbacks) {
 563   int callbacks_id = RegisterCallbacks(callbacks);
 564   scoped_refptr<WaitableCallbackResults> waitable_results =
 565       MaybeCreateWaitableResults(callbacks, callbacks_id);
 566   CallDispatcherOnMainThread(
 567       main_thread_loop_.get(),
 568       &FileSystemDispatcher::CreateDirectory,
 569       MakeTuple(GURL(path), exclusive, false /* recursive */,
 570                 base::Bind(&StatusCallbackAdapter,
 571                            CurrentWorkerId(), callbacks_id, waitable_results)),
 572       waitable_results.get());
 573 }
 574
 575 void WebFileSystemImpl::fileExists(
 576     const blink::WebURL& path,
 577     WebFileSystemCallbacks callbacks) {
 578   int callbacks_id = RegisterCallbacks(callbacks);
 579   scoped_refptr<WaitableCallbackResults> waitable_results =
 580       MaybeCreateWaitableResults(callbacks, callbacks_id);
 581   CallDispatcherOnMainThread(
 582       main_thread_loop_.get(),
 583       &FileSystemDispatcher::Exists,
 584       MakeTuple(GURL(path), false /* directory */,
 585                 base::Bind(&StatusCallbackAdapter,
 586                            CurrentWorkerId(), callbacks_id, waitable_results)),
 587       waitable_results.get());
 588 }
 589
 590 void WebFileSystemImpl::directoryExists(
 591     const blink::WebURL& path,
 592     WebFileSystemCallbacks callbacks) {
 593   int callbacks_id = RegisterCallbacks(callbacks);
 594   scoped_refptr<WaitableCallbackResults> waitable_results =
 595       MaybeCreateWaitableResults(callbacks, callbacks_id);
 596   CallDispatcherOnMainThread(
 597       main_thread_loop_.get(),
 598       &FileSystemDispatcher::Exists,
 599       MakeTuple(GURL(path), true /* directory */,
 600                 base::Bind(&StatusCallbackAdapter,
 601                            CurrentWorkerId(), callbacks_id, waitable_results)),
 602       waitable_results.get());
 603 }
 604
 605 int WebFileSystemImpl::readDirectory(
 606     const blink::WebURL& path,
 607     WebFileSystemCallbacks callbacks) {
 608   int callbacks_id = RegisterCallbacks(callbacks);
 609   scoped_refptr<WaitableCallbackResults> waitable_results =
 610       MaybeCreateWaitableResults(callbacks, callbacks_id);
 611   CallDispatcherOnMainThread(
 612       main_thread_loop_.get(),
 613       &FileSystemDispatcher::ReadDirectory,
 614       MakeTuple(GURL(path),
 615                 base::Bind(&ReadDirectoryCallbackAdapter,
 616                            CurrentWorkerId(), callbacks_id, waitable_results),
 617                 base::Bind(&StatusCallbackAdapter,
 618                            CurrentWorkerId(), callbacks_id, waitable_results)),
 619       waitable_results.get());
 620   return callbacks_id;
 621 }
 622
 623 void WebFileSystemImpl::createFileWriter(
 624     const WebURL& path,
 625     blink::WebFileWriterClient* client,
 626     WebFileSystemCallbacks callbacks) {
 627   int callbacks_id = RegisterCallbacks(callbacks);
 628   scoped_refptr<WaitableCallbackResults> waitable_results =
 629       MaybeCreateWaitableResults(callbacks, callbacks_id);
 630   CallDispatcherOnMainThread(
 631       main_thread_loop_.get(),
 632       &FileSystemDispatcher::ReadMetadata,
 633       MakeTuple(GURL(path),
 634                 base::Bind(&CreateFileWriterCallbackAdapter,
 635                            CurrentWorkerId(), callbacks_id, waitable_results,
 636                            main_thread_loop_, GURL(path), client),
 637                 base::Bind(&StatusCallbackAdapter,
 638                            CurrentWorkerId(), callbacks_id, waitable_results)),
 639       waitable_results.get());
 640 }
 641
 642 void WebFileSystemImpl::createSnapshotFileAndReadMetadata(
 643     const blink::WebURL& path,
 644     WebFileSystemCallbacks callbacks) {
 645   int callbacks_id = RegisterCallbacks(callbacks);
 646   scoped_refptr<WaitableCallbackResults> waitable_results =
 647       MaybeCreateWaitableResults(callbacks, callbacks_id);
 648   CallDispatcherOnMainThread(
 649       main_thread_loop_.get(),
 650       &FileSystemDispatcher::CreateSnapshotFile,
 651       MakeTuple(GURL(path),
 652                 base::Bind(&CreateSnapshotFileCallbackAdapter,
 653                            CurrentWorkerId(), callbacks_id, waitable_results,
 654                            main_thread_loop_),
 655                 base::Bind(&StatusCallbackAdapter,
 656                            CurrentWorkerId(), callbacks_id, waitable_results)),
 657       waitable_results.get());
 658 }
 659
 660 bool WebFileSystemImpl::waitForAdditionalResult(int callbacksId) {
 661   WaitableCallbackResultsMap::iterator found =
 662       waitable_results_.find(callbacksId);
 663   if (found == waitable_results_.end())
 664     return false;
 665
 666   found->second->WaitAndRun();
 667   return true;
 668 }
 669
 670 int WebFileSystemImpl::RegisterCallbacks(
 671     const WebFileSystemCallbacks& callbacks) {
 672   DCHECK(CalledOnValidThread());
 673   int id = next_callbacks_id_++;
 674   callbacks_[id] = callbacks;
 675   return id;
 676 }
 677
 678 WebFileSystemCallbacks WebFileSystemImpl::GetCallbacks(int callbacks_id) {
 679   DCHECK(CalledOnValidThread());
 680   CallbacksMap::iterator found = callbacks_.find(callbacks_id);
 681   DCHECK(found != callbacks_.end());
 682   return found->second;
 683 }
 684
 685 void WebFileSystemImpl::UnregisterCallbacks(int callbacks_id) {
 686   DCHECK(CalledOnValidThread());
 687   CallbacksMap::iterator found = callbacks_.find(callbacks_id);
 688   DCHECK(found != callbacks_.end());
 689   callbacks_.erase(found);
 690
 691   waitable_results_.erase(callbacks_id);
 692 }
 693
 694 WaitableCallbackResults* WebFileSystemImpl::MaybeCreateWaitableResults(
 695     const WebFileSystemCallbacks& callbacks, int callbacks_id) {
 696   if (!callbacks.shouldBlockUntilCompletion())
 697     return NULL;
 698   WaitableCallbackResults* results = new WaitableCallbackResults();
 699   waitable_results_[callbacks_id] = results;
 700   return results;
 701 }
 702
 703 }  // namespace content