src/content/renderer/media/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 "content/renderer/media/buffered_data_source.h"
   6
   7 #include "base/bind.h"
   8 #include "base/callback_helpers.h"
   9 #include "base/message_loop/message_loop_proxy.h"
  10 #include "content/public/common/url_constants.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 content {
  30
  31 class BufferedDataSource::ReadOperation {
  32  public:
  33   ReadOperation(int64 position, int size, uint8* data,
  34                 const media::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   media::DataSource::ReadCB callback_;
  56
  57   DISALLOW_IMPLICIT_CONSTRUCTORS(ReadOperation);
  58 };
  59
  60 BufferedDataSource::ReadOperation::ReadOperation(
  61     int64 position, int size, uint8* data,
  62     const media::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::MessageLoopProxy>& render_loop,
  85     WebFrame* frame,
  86     media::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_(new uint8[kInitialReadBufferSize]),
  95       intermediate_read_buffer_size_(kInitialReadBufferSize),
  96       render_loop_(render_loop),
  97       stop_signal_received_(false),
  98       media_has_played_(false),
  99       preload_(AUTO),
 100       bitrate_(0),
 101       playback_rate_(0.0),
 102       media_log_(media_log),
 103       host_(host),
 104       downloading_cb_(downloading_cb),
 105       weak_factory_(this) {
 106   DCHECK(host_);
 107   DCHECK(!downloading_cb_.is_null());
 108 }
 109
 110 BufferedDataSource::~BufferedDataSource() {}
 111
 112 // A factory method to create BufferedResourceLoader using the read parameters.
 113 // This method can be overridden to inject mock BufferedResourceLoader object
 114 // for testing purpose.
 115 BufferedResourceLoader* BufferedDataSource::CreateResourceLoader(
 116     int64 first_byte_position, int64 last_byte_position) {
 117   DCHECK(render_loop_->BelongsToCurrentThread());
 118
 119   BufferedResourceLoader::DeferStrategy strategy = preload_ == METADATA ?
 120       BufferedResourceLoader::kReadThenDefer :
 121       BufferedResourceLoader::kCapacityDefer;
 122
 123   return new BufferedResourceLoader(url_,
 124                                     cors_mode_,
 125                                     first_byte_position,
 126                                     last_byte_position,
 127                                     strategy,
 128                                     bitrate_,
 129                                     playback_rate_,
 130                                     media_log_.get());
 131 }
 132
 133 void BufferedDataSource::Initialize(const InitializeCB& init_cb) {
 134   DCHECK(render_loop_->BelongsToCurrentThread());
 135   DCHECK(!init_cb.is_null());
 136   DCHECK(!loader_.get());
 137
 138   init_cb_ = init_cb;
 139
 140   if (url_.SchemeIsHTTPOrHTTPS()) {
 141     // Do an unbounded range request starting at the beginning.  If the server
 142     // responds with 200 instead of 206 we'll fall back into a streaming mode.
 143     loader_.reset(CreateResourceLoader(0, kPositionNotSpecified));
 144   } else {
 145     // For all other protocols, assume they support range request. We fetch
 146     // the full range of the resource to obtain the instance size because
 147     // we won't be served HTTP headers.
 148     loader_.reset(CreateResourceLoader(kPositionNotSpecified,
 149                                        kPositionNotSpecified));
 150   }
 151
 152   base::WeakPtr<BufferedDataSource> weak_this = weak_factory_.GetWeakPtr();
 153   loader_->Start(
 154       base::Bind(&BufferedDataSource::StartCallback, weak_this),
 155       base::Bind(&BufferedDataSource::LoadingStateChangedCallback, weak_this),
 156       base::Bind(&BufferedDataSource::ProgressCallback, weak_this),
 157       frame_);
 158 }
 159
 160 void BufferedDataSource::SetPreload(Preload preload) {
 161   DCHECK(render_loop_->BelongsToCurrentThread());
 162   preload_ = preload;
 163 }
 164
 165 bool BufferedDataSource::HasSingleOrigin() {
 166   DCHECK(render_loop_->BelongsToCurrentThread());
 167   DCHECK(init_cb_.is_null() && loader_.get())
 168       << "Initialize() must complete before calling HasSingleOrigin()";
 169   return loader_->HasSingleOrigin();
 170 }
 171
 172 bool BufferedDataSource::DidPassCORSAccessCheck() const {
 173   return loader_.get() && loader_->DidPassCORSAccessCheck();
 174 }
 175
 176 void BufferedDataSource::Abort() {
 177   DCHECK(render_loop_->BelongsToCurrentThread());
 178   {
 179     base::AutoLock auto_lock(lock_);
 180     StopInternal_Locked();
 181   }
 182   StopLoader();
 183   frame_ = NULL;
 184 }
 185
 186 void BufferedDataSource::MediaPlaybackRateChanged(float playback_rate) {
 187   DCHECK(render_loop_->BelongsToCurrentThread());
 188   DCHECK(loader_.get());
 189
 190   if (playback_rate < 0.0f)
 191     return;
 192
 193   playback_rate_ = playback_rate;
 194   loader_->SetPlaybackRate(playback_rate);
 195 }
 196
 197 void BufferedDataSource::MediaIsPlaying() {
 198   DCHECK(render_loop_->BelongsToCurrentThread());
 199   media_has_played_ = true;
 200   UpdateDeferStrategy(false);
 201 }
 202
 203 void BufferedDataSource::MediaIsPaused() {
 204   DCHECK(render_loop_->BelongsToCurrentThread());
 205   UpdateDeferStrategy(true);
 206 }
 207
 208 /////////////////////////////////////////////////////////////////////////////
 209 // media::DataSource implementation.
 210 void BufferedDataSource::Stop() {
 211   {
 212     base::AutoLock auto_lock(lock_);
 213     StopInternal_Locked();
 214   }
 215
 216   render_loop_->PostTask(
 217       FROM_HERE,
 218       base::Bind(&BufferedDataSource::StopLoader, weak_factory_.GetWeakPtr()));
 219 }
 220
 221 void BufferedDataSource::SetBitrate(int bitrate) {
 222   render_loop_->PostTask(FROM_HERE,
 223                          base::Bind(&BufferedDataSource::SetBitrateTask,
 224                                     weak_factory_.GetWeakPtr(),
 225                                     bitrate));
 226 }
 227
 228 void BufferedDataSource::Read(
 229     int64 position, int size, uint8* data,
 230     const media::DataSource::ReadCB& read_cb) {
 231   DVLOG(1) << "Read: " << position << " offset, " << size << " bytes";
 232   DCHECK(!read_cb.is_null());
 233
 234   {
 235     base::AutoLock auto_lock(lock_);
 236     DCHECK(!read_op_);
 237
 238     if (stop_signal_received_) {
 239       read_cb.Run(kReadError);
 240       return;
 241     }
 242
 243     read_op_.reset(new ReadOperation(position, size, data, read_cb));
 244   }
 245
 246   render_loop_->PostTask(
 247       FROM_HERE,
 248       base::Bind(&BufferedDataSource::ReadTask, weak_factory_.GetWeakPtr()));
 249 }
 250
 251 bool BufferedDataSource::GetSize(int64* size_out) {
 252   if (total_bytes_ != kPositionNotSpecified) {
 253     *size_out = total_bytes_;
 254     return true;
 255   }
 256   *size_out = 0;
 257   return false;
 258 }
 259
 260 bool BufferedDataSource::IsStreaming() {
 261   return streaming_;
 262 }
 263
 264 /////////////////////////////////////////////////////////////////////////////
 265 // Render thread tasks.
 266 void BufferedDataSource::ReadTask() {
 267   DCHECK(render_loop_->BelongsToCurrentThread());
 268   ReadInternal();
 269 }
 270
 271 void BufferedDataSource::StopInternal_Locked() {
 272   lock_.AssertAcquired();
 273   if (stop_signal_received_)
 274     return;
 275
 276   stop_signal_received_ = true;
 277
 278   // Initialize() isn't part of the DataSource interface so don't call it in
 279   // response to Stop().
 280   init_cb_.Reset();
 281
 282   if (read_op_)
 283     ReadOperation::Run(read_op_.Pass(), kReadError);
 284 }
 285
 286 void BufferedDataSource::StopLoader() {
 287   DCHECK(render_loop_->BelongsToCurrentThread());
 288
 289   if (loader_)
 290     loader_->Stop();
 291 }
 292
 293 void BufferedDataSource::SetBitrateTask(int bitrate) {
 294   DCHECK(render_loop_->BelongsToCurrentThread());
 295   DCHECK(loader_.get());
 296
 297   bitrate_ = bitrate;
 298   loader_->SetBitrate(bitrate);
 299 }
 300
 301 // This method is the place where actual read happens, |loader_| must be valid
 302 // prior to make this method call.
 303 void BufferedDataSource::ReadInternal() {
 304   DCHECK(render_loop_->BelongsToCurrentThread());
 305   int64 position = 0;
 306   int size = 0;
 307   {
 308     base::AutoLock auto_lock(lock_);
 309     if (stop_signal_received_)
 310       return;
 311
 312     position = read_op_->position();
 313     size = read_op_->size();
 314   }
 315
 316   // First we prepare the intermediate read buffer for BufferedResourceLoader
 317   // to write to.
 318   if (size > intermediate_read_buffer_size_) {
 319     intermediate_read_buffer_.reset(new uint8[size]);
 320   }
 321
 322   // Perform the actual read with BufferedResourceLoader.
 323   loader_->Read(position,
 324                 size,
 325                 intermediate_read_buffer_.get(),
 326                 base::Bind(&BufferedDataSource::ReadCallback,
 327                            weak_factory_.GetWeakPtr()));
 328 }
 329
 330
 331 /////////////////////////////////////////////////////////////////////////////
 332 // BufferedResourceLoader callback methods.
 333 void BufferedDataSource::StartCallback(
 334     BufferedResourceLoader::Status status) {
 335   DCHECK(render_loop_->BelongsToCurrentThread());
 336   DCHECK(loader_.get());
 337
 338   bool init_cb_is_null = false;
 339   {
 340     base::AutoLock auto_lock(lock_);
 341     init_cb_is_null = init_cb_.is_null();
 342   }
 343   if (init_cb_is_null) {
 344     loader_->Stop();
 345     return;
 346   }
 347
 348   // All responses must be successful. Resources that are assumed to be fully
 349   // buffered must have a known content length.
 350   bool success = status == BufferedResourceLoader::kOk &&
 351                  (!assume_fully_buffered() ||
 352                   loader_->instance_size() != kPositionNotSpecified);
 353
 354   if (success) {
 355     total_bytes_ = loader_->instance_size();
 356     streaming_ =
 357         !assume_fully_buffered() &&
 358         (total_bytes_ == kPositionNotSpecified || !loader_->range_supported());
 359
 360     media_log_->SetDoubleProperty("total_bytes",
 361                                   static_cast<double>(total_bytes_));
 362     media_log_->SetBooleanProperty("streaming", streaming_);
 363   } else {
 364     loader_->Stop();
 365   }
 366
 367   // TODO(scherkus): we shouldn't have to lock to signal host(), see
 368   // http://crbug.com/113712 for details.
 369   base::AutoLock auto_lock(lock_);
 370   if (stop_signal_received_)
 371     return;
 372
 373   if (success) {
 374     if (total_bytes_ != kPositionNotSpecified) {
 375       host_->SetTotalBytes(total_bytes_);
 376       if (assume_fully_buffered())
 377         host_->AddBufferedByteRange(0, total_bytes_);
 378     }
 379
 380     media_log_->SetBooleanProperty("single_origin", loader_->HasSingleOrigin());
 381     media_log_->SetBooleanProperty("passed_cors_access_check",
 382                                    loader_->DidPassCORSAccessCheck());
 383     media_log_->SetBooleanProperty("range_header_supported",
 384                                    loader_->range_supported());
 385   }
 386
 387   base::ResetAndReturn(&init_cb_).Run(success);
 388 }
 389
 390 void BufferedDataSource::PartialReadStartCallback(
 391     BufferedResourceLoader::Status status) {
 392   DCHECK(render_loop_->BelongsToCurrentThread());
 393   DCHECK(loader_.get());
 394
 395   if (status == BufferedResourceLoader::kOk) {
 396     // Once the request has started successfully, we can proceed with
 397     // reading from it.
 398     ReadInternal();
 399     return;
 400   }
 401
 402   // Stop the resource loader since we have received an error.
 403   loader_->Stop();
 404
 405   // TODO(scherkus): we shouldn't have to lock to signal host(), see
 406   // http://crbug.com/113712 for details.
 407   base::AutoLock auto_lock(lock_);
 408   if (stop_signal_received_)
 409     return;
 410   ReadOperation::Run(read_op_.Pass(), kReadError);
 411 }
 412
 413 void BufferedDataSource::ReadCallback(
 414     BufferedResourceLoader::Status status,
 415     int bytes_read) {
 416   DCHECK(render_loop_->BelongsToCurrentThread());
 417
 418   // TODO(scherkus): we shouldn't have to lock to signal host(), see
 419   // http://crbug.com/113712 for details.
 420   base::AutoLock auto_lock(lock_);
 421   if (stop_signal_received_)
 422     return;
 423
 424   if (status != BufferedResourceLoader::kOk) {
 425     // Stop the resource load if it failed.
 426     loader_->Stop();
 427
 428     if (status == BufferedResourceLoader::kCacheMiss &&
 429         read_op_->retries() < kNumCacheMissRetries) {
 430       read_op_->IncrementRetries();
 431
 432       // Recreate a loader starting from where we last left off until the
 433       // end of the resource.
 434       loader_.reset(CreateResourceLoader(
 435           read_op_->position(), kPositionNotSpecified));
 436
 437       base::WeakPtr<BufferedDataSource> weak_this = weak_factory_.GetWeakPtr();
 438       loader_->Start(
 439           base::Bind(&BufferedDataSource::PartialReadStartCallback, weak_this),
 440           base::Bind(&BufferedDataSource::LoadingStateChangedCallback,
 441                      weak_this),
 442           base::Bind(&BufferedDataSource::ProgressCallback, weak_this),
 443           frame_);
 444       return;
 445     }
 446
 447     ReadOperation::Run(read_op_.Pass(), kReadError);
 448     return;
 449   }
 450
 451   if (bytes_read > 0) {
 452     memcpy(read_op_->data(), intermediate_read_buffer_.get(), 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_loop_->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_loop_->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 content