src/media/blink/buffered_data_source.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 "media/blink/buffered_data_source.h"
   6
   7 #include "base/bind.h"
   8 #include "base/callback_helpers.h"
   9 #include "base/location.h"
  10 #include "base/single_thread_task_runner.h"
  11 #include "media/base/media_log.h"
  12 #include "net/base/net_errors.h"
  13
  14 using blink::WebFrame;
  15
  16 namespace {
  17
  18 // BufferedDataSource has an intermediate buffer, this value governs the initial
  19 // size of that buffer. It is set to 32KB because this is a typical read size
  20 // of FFmpeg.
  21 const int kInitialReadBufferSize = 32768;
  22
  23 // Number of cache misses we allow for a single Read() before signaling an
  24 // error.
  25 const int kNumCacheMissRetries = 3;
  26
  27 }  // namespace
  28
  29 namespace media {
  30
  31 class BufferedDataSource::ReadOperation {
  32  public:
  33   ReadOperation(int64 position, int size, uint8* data,
  34                 const DataSource::ReadCB& callback);
  35   ~ReadOperation();
  36
  37   // Runs |callback_| with the given |result|, deleting the operation
  38   // afterwards.
  39   static void Run(scoped_ptr<ReadOperation> read_op, int result);
  40
  41   // State for the number of times this read operation has been retried.
  42   int retries() { return retries_; }
  43   void IncrementRetries() { ++retries_; }
  44
  45   int64 position() { return position_; }
  46   int size() { return size_; }
  47   uint8* data() { return data_; }
  48
  49  private:
  50   int retries_;
  51
  52   const int64 position_;
  53   const int size_;
  54   uint8* data_;
  55   DataSource::ReadCB callback_;
  56
  57   DISALLOW_IMPLICIT_CONSTRUCTORS(ReadOperation);
  58 };
  59
  60 BufferedDataSource::ReadOperation::ReadOperation(
  61     int64 position, int size, uint8* data,
  62     const DataSource::ReadCB& callback)
  63     : retries_(0),
  64       position_(position),
  65       size_(size),
  66       data_(data),
  67       callback_(callback) {
  68   DCHECK(!callback_.is_null());
  69 }
  70
  71 BufferedDataSource::ReadOperation::~ReadOperation() {
  72   DCHECK(callback_.is_null());
  73 }
  74
  75 // static
  76 void BufferedDataSource::ReadOperation::Run(
  77     scoped_ptr<ReadOperation> read_op, int result) {
  78   base::ResetAndReturn(&read_op->callback_).Run(result);
  79 }
  80
  81 BufferedDataSource::BufferedDataSource(
  82     const GURL& url,
  83     BufferedResourceLoader::CORSMode cors_mode,
  84     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
  85     WebFrame* frame,
  86     MediaLog* media_log,
  87     BufferedDataSourceHost* host,
  88     const DownloadingCB& downloading_cb)
  89     : url_(url),
  90       cors_mode_(cors_mode),
  91       total_bytes_(kPositionNotSpecified),
  92       streaming_(false),
  93       frame_(frame),
  94       intermediate_read_buffer_(kInitialReadBufferSize),
  95       render_task_runner_(task_runner),
  96       stop_signal_received_(false),
  97       media_has_played_(false),
  98       preload_(AUTO),
  99       bitrate_(0),
 100       playback_rate_(0.0),
 101       media_log_(media_log),
 102       host_(host),
 103       downloading_cb_(downloading_cb),
 104       weak_factory_(this) {
 105   DCHECK(host_);
 106   DCHECK(!downloading_cb_.is_null());
 107 }
 108
 109 BufferedDataSource::~BufferedDataSource() {}
 110
 111 // A factory method to create BufferedResourceLoader using the read parameters.
 112 // This method can be overridden to inject mock BufferedResourceLoader object
 113 // for testing purpose.
 114 BufferedResourceLoader* BufferedDataSource::CreateResourceLoader(
 115     int64 first_byte_position, int64 last_byte_position) {
 116   DCHECK(render_task_runner_->BelongsToCurrentThread());
 117
 118   BufferedResourceLoader::DeferStrategy strategy = preload_ == METADATA ?
 119       BufferedResourceLoader::kReadThenDefer :
 120       BufferedResourceLoader::kCapacityDefer;
 121
 122   return new BufferedResourceLoader(url_,
 123                                     cors_mode_,
 124                                     first_byte_position,
 125                                     last_byte_position,
 126                                     strategy,
 127                                     bitrate_,
 128                                     playback_rate_,
 129                                     media_log_.get());
 130 }
 131
 132 void BufferedDataSource::Initialize(const InitializeCB& init_cb) {
 133   DCHECK(render_task_runner_->BelongsToCurrentThread());
 134   DCHECK(!init_cb.is_null());
 135   DCHECK(!loader_.get());
 136
 137   init_cb_ = init_cb;
 138
 139   if (url_.SchemeIsHTTPOrHTTPS()) {
 140     // Do an unbounded range request starting at the beginning.  If the server
 141     // responds with 200 instead of 206 we'll fall back into a streaming mode.
 142     loader_.reset(CreateResourceLoader(0, kPositionNotSpecified));
 143   } else {
 144     // For all other protocols, assume they support range request. We fetch
 145     // the full range of the resource to obtain the instance size because
 146     // we won't be served HTTP headers.
 147     loader_.reset(CreateResourceLoader(kPositionNotSpecified,
 148                                        kPositionNotSpecified));
 149   }
 150
 151   base::WeakPtr<BufferedDataSource> weak_this = weak_factory_.GetWeakPtr();
 152   loader_->Start(
 153       base::Bind(&BufferedDataSource::StartCallback, weak_this),
 154       base::Bind(&BufferedDataSource::LoadingStateChangedCallback, weak_this),
 155       base::Bind(&BufferedDataSource::ProgressCallback, weak_this),
 156       frame_);
 157 }
 158
 159 void BufferedDataSource::SetPreload(Preload preload) {
 160   DCHECK(render_task_runner_->BelongsToCurrentThread());
 161   preload_ = preload;
 162 }
 163
 164 bool BufferedDataSource::HasSingleOrigin() {
 165   DCHECK(render_task_runner_->BelongsToCurrentThread());
 166   DCHECK(init_cb_.is_null() && loader_.get())
 167       << "Initialize() must complete before calling HasSingleOrigin()";
 168   return loader_->HasSingleOrigin();
 169 }
 170
 171 bool BufferedDataSource::DidPassCORSAccessCheck() const {
 172   return loader_.get() && loader_->DidPassCORSAccessCheck();
 173 }
 174
 175 void BufferedDataSource::Abort() {
 176   DCHECK(render_task_runner_->BelongsToCurrentThread());
 177   {
 178     base::AutoLock auto_lock(lock_);
 179     StopInternal_Locked();
 180   }
 181   StopLoader();
 182   frame_ = NULL;
 183 }
 184
 185 void BufferedDataSource::MediaPlaybackRateChanged(float playback_rate) {
 186   DCHECK(render_task_runner_->BelongsToCurrentThread());
 187   DCHECK(loader_.get());
 188
 189   if (playback_rate < 0.0f)
 190     return;
 191
 192   playback_rate_ = playback_rate;
 193   loader_->SetPlaybackRate(playback_rate);
 194 }
 195
 196 void BufferedDataSource::MediaIsPlaying() {
 197   DCHECK(render_task_runner_->BelongsToCurrentThread());
 198   media_has_played_ = true;
 199   UpdateDeferStrategy(false);
 200 }
 201
 202 void BufferedDataSource::MediaIsPaused() {
 203   DCHECK(render_task_runner_->BelongsToCurrentThread());
 204   UpdateDeferStrategy(true);
 205 }
 206
 207 /////////////////////////////////////////////////////////////////////////////
 208 // DataSource implementation.
 209 void BufferedDataSource::Stop() {
 210   {
 211     base::AutoLock auto_lock(lock_);
 212     StopInternal_Locked();
 213   }
 214
 215   render_task_runner_->PostTask(
 216       FROM_HERE,
 217       base::Bind(&BufferedDataSource::StopLoader, weak_factory_.GetWeakPtr()));
 218 }
 219
 220 void BufferedDataSource::SetBitrate(int bitrate) {
 221   render_task_runner_->PostTask(FROM_HERE,
 222                          base::Bind(&BufferedDataSource::SetBitrateTask,
 223                                     weak_factory_.GetWeakPtr(),
 224                                     bitrate));
 225 }
 226
 227 void BufferedDataSource::Read(
 228     int64 position, int size, uint8* data,
 229     const DataSource::ReadCB& read_cb) {
 230   DVLOG(1) << "Read: " << position << " offset, " << size << " bytes";
 231   DCHECK(!read_cb.is_null());
 232
 233   {
 234     base::AutoLock auto_lock(lock_);
 235     DCHECK(!read_op_);
 236
 237     if (stop_signal_received_) {
 238       read_cb.Run(kReadError);
 239       return;
 240     }
 241
 242     read_op_.reset(new ReadOperation(position, size, data, read_cb));
 243   }
 244
 245   render_task_runner_->PostTask(
 246       FROM_HERE,
 247       base::Bind(&BufferedDataSource::ReadTask, weak_factory_.GetWeakPtr()));
 248 }
 249
 250 bool BufferedDataSource::GetSize(int64* size_out) {
 251   if (total_bytes_ != kPositionNotSpecified) {
 252     *size_out = total_bytes_;
 253     return true;
 254   }
 255   *size_out = 0;
 256   return false;
 257 }
 258
 259 bool BufferedDataSource::IsStreaming() {
 260   return streaming_;
 261 }
 262
 263 /////////////////////////////////////////////////////////////////////////////
 264 // Render thread tasks.
 265 void BufferedDataSource::ReadTask() {
 266   DCHECK(render_task_runner_->BelongsToCurrentThread());
 267   ReadInternal();
 268 }
 269
 270 void BufferedDataSource::StopInternal_Locked() {
 271   lock_.AssertAcquired();
 272   if (stop_signal_received_)
 273     return;
 274
 275   stop_signal_received_ = true;
 276
 277   // Initialize() isn't part of the DataSource interface so don't call it in
 278   // response to Stop().
 279   init_cb_.Reset();
 280
 281   if (read_op_)
 282     ReadOperation::Run(read_op_.Pass(), kReadError);
 283 }
 284
 285 void BufferedDataSource::StopLoader() {
 286   DCHECK(render_task_runner_->BelongsToCurrentThread());
 287
 288   if (loader_)
 289     loader_->Stop();
 290 }
 291
 292 void BufferedDataSource::SetBitrateTask(int bitrate) {
 293   DCHECK(render_task_runner_->BelongsToCurrentThread());
 294   DCHECK(loader_.get());
 295
 296   bitrate_ = bitrate;
 297   loader_->SetBitrate(bitrate);
 298 }
 299
 300 // This method is the place where actual read happens, |loader_| must be valid
 301 // prior to make this method call.
 302 void BufferedDataSource::ReadInternal() {
 303   DCHECK(render_task_runner_->BelongsToCurrentThread());
 304   int64 position = 0;
 305   int size = 0;
 306   {
 307     base::AutoLock auto_lock(lock_);
 308     if (stop_signal_received_)
 309       return;
 310
 311     position = read_op_->position();
 312     size = read_op_->size();
 313   }
 314
 315   // First we prepare the intermediate read buffer for BufferedResourceLoader
 316   // to write to.
 317   if (static_cast<int>(intermediate_read_buffer_.size()) < size)
 318     intermediate_read_buffer_.resize(size);
 319
 320   // Perform the actual read with BufferedResourceLoader.
 321   DCHECK(!intermediate_read_buffer_.empty());
 322   loader_->Read(position,
 323                 size,
 324                 &intermediate_read_buffer_[0],
 325                 base::Bind(&BufferedDataSource::ReadCallback,
 326                            weak_factory_.GetWeakPtr()));
 327 }
 328
 329
 330 /////////////////////////////////////////////////////////////////////////////
 331 // BufferedResourceLoader callback methods.
 332 void BufferedDataSource::StartCallback(
 333     BufferedResourceLoader::Status status) {
 334   DCHECK(render_task_runner_->BelongsToCurrentThread());
 335   DCHECK(loader_.get());
 336
 337   bool init_cb_is_null = false;
 338   {
 339     base::AutoLock auto_lock(lock_);
 340     init_cb_is_null = init_cb_.is_null();
 341   }
 342   if (init_cb_is_null) {
 343     loader_->Stop();
 344     return;
 345   }
 346
 347   // All responses must be successful. Resources that are assumed to be fully
 348   // buffered must have a known content length.
 349   bool success = status == BufferedResourceLoader::kOk &&
 350                  (!assume_fully_buffered() ||
 351                   loader_->instance_size() != kPositionNotSpecified);
 352
 353   if (success) {
 354     total_bytes_ = loader_->instance_size();
 355     streaming_ =
 356         !assume_fully_buffered() &&
 357         (total_bytes_ == kPositionNotSpecified || !loader_->range_supported());
 358
 359     media_log_->SetDoubleProperty("total_bytes",
 360                                   static_cast<double>(total_bytes_));
 361     media_log_->SetBooleanProperty("streaming", streaming_);
 362   } else {
 363     loader_->Stop();
 364   }
 365
 366   // TODO(scherkus): we shouldn't have to lock to signal host(), see
 367   // http://crbug.com/113712 for details.
 368   base::AutoLock auto_lock(lock_);
 369   if (stop_signal_received_)
 370     return;
 371
 372   if (success) {
 373     if (total_bytes_ != kPositionNotSpecified) {
 374       host_->SetTotalBytes(total_bytes_);
 375       if (assume_fully_buffered())
 376         host_->AddBufferedByteRange(0, total_bytes_);
 377     }
 378
 379     media_log_->SetBooleanProperty("single_origin", loader_->HasSingleOrigin());
 380     media_log_->SetBooleanProperty("passed_cors_access_check",
 381                                    loader_->DidPassCORSAccessCheck());
 382     media_log_->SetBooleanProperty("range_header_supported",
 383                                    loader_->range_supported());
 384   }
 385
 386   base::ResetAndReturn(&init_cb_).Run(success);
 387 }
 388
 389 void BufferedDataSource::PartialReadStartCallback(
 390     BufferedResourceLoader::Status status) {
 391   DCHECK(render_task_runner_->BelongsToCurrentThread());
 392   DCHECK(loader_.get());
 393
 394   if (status == BufferedResourceLoader::kOk) {
 395     // Once the request has started successfully, we can proceed with
 396     // reading from it.
 397     ReadInternal();
 398     return;
 399   }
 400
 401   // Stop the resource loader since we have received an error.
 402   loader_->Stop();
 403
 404   // TODO(scherkus): we shouldn't have to lock to signal host(), see
 405   // http://crbug.com/113712 for details.
 406   base::AutoLock auto_lock(lock_);
 407   if (stop_signal_received_)
 408     return;
 409   ReadOperation::Run(read_op_.Pass(), kReadError);
 410 }
 411
 412 void BufferedDataSource::ReadCallback(
 413     BufferedResourceLoader::Status status,
 414     int bytes_read) {
 415   DCHECK(render_task_runner_->BelongsToCurrentThread());
 416
 417   // TODO(scherkus): we shouldn't have to lock to signal host(), see
 418   // http://crbug.com/113712 for details.
 419   base::AutoLock auto_lock(lock_);
 420   if (stop_signal_received_)
 421     return;
 422
 423   if (status != BufferedResourceLoader::kOk) {
 424     // Stop the resource load if it failed.
 425     loader_->Stop();
 426
 427     if (status == BufferedResourceLoader::kCacheMiss &&
 428         read_op_->retries() < kNumCacheMissRetries) {
 429       read_op_->IncrementRetries();
 430
 431       // Recreate a loader starting from where we last left off until the
 432       // end of the resource.
 433       loader_.reset(CreateResourceLoader(
 434           read_op_->position(), kPositionNotSpecified));
 435
 436       base::WeakPtr<BufferedDataSource> weak_this = weak_factory_.GetWeakPtr();
 437       loader_->Start(
 438           base::Bind(&BufferedDataSource::PartialReadStartCallback, weak_this),
 439           base::Bind(&BufferedDataSource::LoadingStateChangedCallback,
 440                      weak_this),
 441           base::Bind(&BufferedDataSource::ProgressCallback, weak_this),
 442           frame_);
 443       return;
 444     }
 445
 446     ReadOperation::Run(read_op_.Pass(), kReadError);
 447     return;
 448   }
 449
 450   if (bytes_read > 0) {
 451     DCHECK(!intermediate_read_buffer_.empty());
 452     memcpy(read_op_->data(), &intermediate_read_buffer_[0], bytes_read);
 453   } else if (bytes_read == 0 && total_bytes_ == kPositionNotSpecified) {
 454     // We've reached the end of the file and we didn't know the total size
 455     // before. Update the total size so Read()s past the end of the file will
 456     // fail like they would if we had known the file size at the beginning.
 457     total_bytes_ = loader_->instance_size();
 458
 459     if (total_bytes_ != kPositionNotSpecified) {
 460       host_->SetTotalBytes(total_bytes_);
 461       host_->AddBufferedByteRange(loader_->first_byte_position(),
 462                                   total_bytes_);
 463     }
 464   }
 465   ReadOperation::Run(read_op_.Pass(), bytes_read);
 466 }
 467
 468 void BufferedDataSource::LoadingStateChangedCallback(
 469     BufferedResourceLoader::LoadingState state) {
 470   DCHECK(render_task_runner_->BelongsToCurrentThread());
 471
 472   if (assume_fully_buffered())
 473     return;
 474
 475   bool is_downloading_data;
 476   switch (state) {
 477     case BufferedResourceLoader::kLoading:
 478       is_downloading_data = true;
 479       break;
 480     case BufferedResourceLoader::kLoadingDeferred:
 481     case BufferedResourceLoader::kLoadingFinished:
 482       is_downloading_data = false;
 483       break;
 484
 485     // TODO(scherkus): we don't signal network activity changes when loads
 486     // fail to preserve existing behaviour when deferring is toggled, however
 487     // we should consider changing DownloadingCB to also propagate loading
 488     // state. For example there isn't any signal today to notify the client that
 489     // loading has failed (we only get errors on subsequent reads).
 490     case BufferedResourceLoader::kLoadingFailed:
 491       return;
 492   }
 493
 494   downloading_cb_.Run(is_downloading_data);
 495 }
 496
 497 void BufferedDataSource::ProgressCallback(int64 position) {
 498   DCHECK(render_task_runner_->BelongsToCurrentThread());
 499
 500   if (assume_fully_buffered())
 501     return;
 502
 503   // TODO(scherkus): we shouldn't have to lock to signal host(), see
 504   // http://crbug.com/113712 for details.
 505   base::AutoLock auto_lock(lock_);
 506   if (stop_signal_received_)
 507     return;
 508
 509   host_->AddBufferedByteRange(loader_->first_byte_position(), position);
 510 }
 511
 512 void BufferedDataSource::UpdateDeferStrategy(bool paused) {
 513   // No need to aggressively buffer when we are assuming the resource is fully
 514   // buffered.
 515   if (assume_fully_buffered()) {
 516     loader_->UpdateDeferStrategy(BufferedResourceLoader::kCapacityDefer);
 517     return;
 518   }
 519
 520   // If the playback has started (at which point the preload value is ignored)
 521   // and we're paused, then try to load as much as possible (the loader will
 522   // fall back to kCapacityDefer if it knows the current response won't be
 523   // useful from the cache in the future).
 524   if (media_has_played_ && paused && loader_->range_supported()) {
 525     loader_->UpdateDeferStrategy(BufferedResourceLoader::kNeverDefer);
 526     return;
 527   }
 528
 529   // If media is currently playing or the page indicated preload=auto or the
 530   // the server does not support the byte range request or we do not want to go
 531   // too far ahead of the read head, use threshold strategy to enable/disable
 532   // deferring when the buffer is full/depleted.
 533   loader_->UpdateDeferStrategy(BufferedResourceLoader::kCapacityDefer);
 534 }
 535
 536 }  // namespace media