Chromecast: mitigate threading issue between AvPipeline/MediaKeys.

chromecast/media/cma/pipeline/av_pipeline_impl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromecast/media/cma/pipeline/av_pipeline_impl.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 27 matching lines @@
       media_component_device_(media_component_device),
       state_(kUninitialized),
       buffered_time_(::media::kNoTimestamp()),
       playable_buffered_time_(::media::kNoTimestamp()),
       enable_feeding_(false),
       pending_read_(false),
       pending_push_(false),
       enable_time_update_(false),
       pending_time_update_task_(false),
       media_keys_(NULL),
-      media_keys_callback_id_(kNoCallbackId),
-      weak_factory_(this) {
+      media_keys_callback_id_(kNoCallbackId) {
   DCHECK(media_component_device);
-  weak_this_ = weak_factory_.GetWeakPtr();
   thread_checker_.DetachFromThread();
 }
 
 AvPipelineImpl::~AvPipelineImpl() {
   // If there are weak pointers in the wild, they must be invalidated
   // on the right thread.
   DCHECK(thread_checker_.CalledOnValidThread());
   media_component_device_->SetClient(MediaComponentDevice::Client());
 
-  if (media_keys_ && media_keys_callback_id_ != kNoCallbackId)
-    media_keys_->UnregisterPlayer(media_keys_callback_id_);
+  {
+    base::AutoLock lock(media_keys_lock_);
+    if (media_keys_ && media_keys_callback_id_ != kNoCallbackId)
+      media_keys_->UnregisterPlayer(media_keys_callback_id_);
+  }
 }
 
 void AvPipelineImpl::TransitionToState(State state) {
   DCHECK(thread_checker_.CalledOnValidThread());
   state_ = state;
 }
 
 void AvPipelineImpl::SetCodedFrameProvider(
     scoped_ptr<CodedFrameProvider> frame_provider,
     size_t max_buffer_size,
     size_t max_frame_size) {
   DCHECK_EQ(state_, kUninitialized);
   DCHECK(frame_provider);
 
   // Wrap the incoming frame provider to add some buffering capabilities.
   frame_provider_.reset(
       new BufferingFrameProvider(
           frame_provider.Pass(),
           max_buffer_size,
           max_frame_size,
-          base::Bind(&AvPipelineImpl::OnFrameBuffered, weak_this_)));
+          base::Bind(&AvPipelineImpl::OnFrameBuffered, this)));
 }
 
 void AvPipelineImpl::SetClient(const AvPipelineClient& client) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_EQ(state_, kUninitialized);
   client_ = client;
 }
 
 bool AvPipelineImpl::Initialize() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_EQ(state_, kUninitialized);
 
   MediaComponentDevice::Client client;
-  client.eos_cb = base::Bind(&AvPipelineImpl::OnEos, weak_this_);
+  client.eos_cb = base::Bind(&AvPipelineImpl::OnEos, this);
   media_component_device_->SetClient(client);
   if (!media_component_device_->SetState(MediaComponentDevice::kStateIdle))
     return false;
 
   return true;
 }
 
 bool AvPipelineImpl::StartPlayingFrom(
     base::TimeDelta time,
     const scoped_refptr<BufferingState>& buffering_state) {
@@ skipping 13 matching lines @@
   if (buffering_state_.get())
     buffering_state_->SetMediaTime(time);
 
   if (!media_component_device_->SetState(MediaComponentDevice::kStateRunning))
     return false;
 
   // Start feeding the pipeline.
   enable_feeding_ = true;
   base::MessageLoopProxy::current()->PostTask(
       FROM_HERE,
-      base::Bind(&AvPipelineImpl::FetchBufferIfNeeded, weak_this_));
+      base::Bind(&AvPipelineImpl::FetchBufferIfNeeded, this));
 
   return true;
 }
 
 void AvPipelineImpl::Flush(const base::Closure& done_cb) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_EQ(state_, kFlushing);
   DCHECK_EQ(
       media_component_device_->GetState(), MediaComponentDevice::kStateRunning);
   // Note: returning to idle state aborts any pending frame push.
@@ skipping 34 matching lines @@
   if (media_component_device_->GetState() == MediaComponentDevice::kStateIdle) {
     media_component_device_->SetState(
         MediaComponentDevice::kStateUninitialized);
   }
 }
 
 void AvPipelineImpl::SetCdm(BrowserCdmCast* media_keys) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(media_keys);
 
-  if (media_keys_ && media_keys_callback_id_ != kNoCallbackId)
-    media_keys_->UnregisterPlayer(media_keys_callback_id_);
+  {
+    base::AutoLock lock(media_keys_lock_);
+    if (media_keys_ && media_keys_callback_id_ != kNoCallbackId)
+      media_keys_->UnregisterPlayer(media_keys_callback_id_);
 
-  media_keys_ = media_keys;
-  media_keys_callback_id_ = media_keys_->RegisterPlayer(
-      ::media::BindToCurrentLoop(
-          base::Bind(&AvPipelineImpl::OnCdmStateChanged, weak_this_)),
-      ::media::BindToCurrentLoop(
-          base::Bind(&AvPipelineImpl::OnCdmDestroyed, weak_this_)));
+    media_keys_ = media_keys;
+    media_keys_callback_id_ = media_keys_->RegisterPlayer(
+        ::media::BindToCurrentLoop(
+            base::Bind(&AvPipelineImpl::OnCdmStateChanged, this)),
+        // Note: this callback gets invoked in ~BrowserCdmCast. Posting
+        // OnCdmDestroyed to the media thread results in a race condition
+        // with media_keys_ accesses. This callback must run synchronously,
+        // otherwise media_keys_ access might occur after it is deleted.
+        base::Bind(&AvPipelineImpl::OnCdmDestroyed, this));
+  }
 }
 
 void AvPipelineImpl::OnEos() {
   DCHECK(thread_checker_.CalledOnValidThread());
   CMALOG(kLogControl) << __FUNCTION__;
   if (state_ != kPlaying)
     return;
 
   if (!client_.eos_cb.is_null())
     client_.eos_cb.Run();
 }
 
 void AvPipelineImpl::FetchBufferIfNeeded() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!enable_feeding_)
     return;
 
   if (pending_read_ || pending_buffer_.get())
     return;
 
   pending_read_ = true;
   frame_provider_->Read(
-      base::Bind(&AvPipelineImpl::OnNewFrame, weak_this_));
+      base::Bind(&AvPipelineImpl::OnNewFrame, this));
 }
 
 void AvPipelineImpl::OnNewFrame(
     const scoped_refptr<DecoderBufferBase>& buffer,
     const ::media::AudioDecoderConfig& audio_config,
     const ::media::VideoDecoderConfig& video_config) {
   DCHECK(thread_checker_.CalledOnValidThread());
   pending_read_ = false;
 
   if (audio_config.IsValidConfig() || video_config.IsValidConfig())
     update_config_cb_.Run(audio_config, video_config);
 
   pending_buffer_ = buffer;
   ProcessPendingBuffer();
 
   base::MessageLoopProxy::current()->PostTask(
       FROM_HERE,
-      base::Bind(&AvPipelineImpl::FetchBufferIfNeeded, weak_this_));
+      base::Bind(&AvPipelineImpl::FetchBufferIfNeeded, this));
 }
 
 void AvPipelineImpl::ProcessPendingBuffer() {
   if (!enable_feeding_)
     return;
 
   // Initiate a read if there isn't already one.
   if (!pending_buffer_.get() && !pending_read_) {
     base::MessageLoopProxy::current()->PostTask(
         FROM_HERE,
-        base::Bind(&AvPipelineImpl::FetchBufferIfNeeded, weak_this_));
+        base::Bind(&AvPipelineImpl::FetchBufferIfNeeded, this));
     return;
   }
 
   if (!pending_buffer_.get() || pending_push_)
     return;
 
   // Break the feeding loop when the end of stream is reached.
   if (pending_buffer_->end_of_stream()) {
     CMALOG(kLogControl) << __FUNCTION__ << ": EOS reached, stopped feeding";
     enable_feeding_ = false;
   }
 
   scoped_refptr<DecryptContext> decrypt_context;
   if (!pending_buffer_->end_of_stream() &&
       pending_buffer_->decrypt_config()) {
     // Verify that CDM has the key ID.
     // Should not send the frame if the key ID is not available yet.
     std::string key_id(pending_buffer_->decrypt_config()->key_id());
-    if (!media_keys_) {
-      CMALOG(kLogControl) << "No CDM for frame: pts="
-                          << pending_buffer_->timestamp().InMilliseconds();
-      return;
+    {
+      base::AutoLock lock(media_keys_lock_);
+      if (!media_keys_) {
+        CMALOG(kLogControl) << "No CDM for frame: pts="
+                            << pending_buffer_->timestamp().InMilliseconds();
+        return;
+      }
+      decrypt_context = media_keys_->GetDecryptContext(key_id);
     }
-    decrypt_context = media_keys_->GetDecryptContext(key_id);
     if (!decrypt_context.get()) {
       CMALOG(kLogControl) << "frame(pts="
                           << pending_buffer_->timestamp().InMilliseconds()
                           << "): waiting for key id "
                           << base::HexEncode(&key_id[0], key_id.size());
       return;
     }
 
     // If we do have the clear key, decrypt the pending buffer
     // and reset the decryption context (not needed anymore).
     crypto::SymmetricKey* key = decrypt_context->GetKey();
     if (key != NULL) {
       pending_buffer_ = DecryptDecoderBuffer(pending_buffer_, key);
       decrypt_context = scoped_refptr<DecryptContext>();
     }
   }
 
   if (!pending_buffer_->end_of_stream() && buffering_state_.get()) {
     base::TimeDelta timestamp = pending_buffer_->timestamp();
     if (timestamp != ::media::kNoTimestamp())
       buffering_state_->SetMaxRenderingTime(timestamp);
   }
 
   MediaComponentDevice::FrameStatus status = media_component_device_->PushFrame(
       decrypt_context,
       pending_buffer_,
-      base::Bind(&AvPipelineImpl::OnFramePushed, weak_this_));
+      base::Bind(&AvPipelineImpl::OnFramePushed, this));
   pending_buffer_ = scoped_refptr<DecoderBufferBase>();
 
   pending_push_ = (status == MediaComponentDevice::kFramePending);
   if (!pending_push_)
     OnFramePushed(status);
 }
 
 void AvPipelineImpl::OnFramePushed(MediaComponentDevice::FrameStatus status) {
   DCHECK(thread_checker_.CalledOnValidThread());
   pending_push_ = false;
   if (status == MediaComponentDevice::kFrameFailed) {
     LOG(WARNING) << "AvPipelineImpl: PushFrame failed";
     enable_feeding_ = false;
     state_ = kError;
     return;
   }
   base::MessageLoopProxy::current()->PostTask(
       FROM_HERE,
-      base::Bind(&AvPipelineImpl::ProcessPendingBuffer, weak_this_));
+      base::Bind(&AvPipelineImpl::ProcessPendingBuffer, this));
 }
 
 void AvPipelineImpl::OnCdmStateChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // Update the buffering state if needed.
   if (buffering_state_.get())
     UpdatePlayableFrames();
 
   // Process the pending buffer in case the CDM now has the frame key id.
   ProcessPendingBuffer();
 }
 
 void AvPipelineImpl::OnCdmDestroyed() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  base::AutoLock lock(media_keys_lock_);
   media_keys_ = NULL;
 }
 
 void AvPipelineImpl::OnFrameBuffered(
     const scoped_refptr<DecoderBufferBase>& buffer,
     bool is_at_max_capacity) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (!buffering_state_.get())
     return;
@@ skipping 40 matching lines @@
       }
     }
 
     // The frame is playable: remove it from the list of non playable frames.
     non_playable_frames_.pop_front();
   }
 }
 
 }  // namespace media
 }  // namespace chromecast