Remove reference counting from media::VideoDecoder and friends.

media/filters/gpu_video_decoder.cc

 // Copyright (c) 2012 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 "media/filters/gpu_video_decoder.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/cpu.h"
 #include "base/message_loop.h"
 #include "base/stl_util.h"
+#include "base/task_runner_util.h"
 #include "media/base/bind_to_loop.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/demuxer_stream.h"
 #include "media/base/pipeline.h"
 #include "media/base/pipeline_status.h"
 #include "media/base/video_decoder_config.h"
 
 namespace media {
 
 // Maximum number of concurrent VDA::Decode() operations GVD will maintain.
@@ skipping 25 matching lines @@
     : bitstream_buffer_id(bbid), timestamp(ts), visible_rect(vr),
       natural_size(ns) {
 }
 
 GpuVideoDecoder::BufferData::~BufferData() {}
 
 GpuVideoDecoder::GpuVideoDecoder(
     const scoped_refptr<base::MessageLoopProxy>& message_loop,
     const scoped_refptr<Factories>& factories)
     : gvd_loop_proxy_(message_loop),
+      weak_factory_(this),
       vda_loop_proxy_(factories->GetMessageLoop()),
       factories_(factories),
       state_(kNormal),
       demuxer_read_in_progress_(false),
       decoder_texture_target_(0),
       next_picture_buffer_id_(0),
       next_bitstream_buffer_id_(0),
       error_occured_(false),
       available_pictures_(-1) {
   DCHECK(factories_);
 }
 
 void GpuVideoDecoder::Reset(const base::Closure& closure)  {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
 
   if (state_ == kDrainingDecoder) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::Reset, this, closure));
+        &GpuVideoDecoder::Reset, weak_this_, closure));
     // NOTE: if we're deferring Reset() until a Flush() completes, return
     // queued pictures to the VDA so they can be used to finish that Flush().
     if (pending_read_cb_.is_null())
       ready_video_frames_.clear();
     return;
   }
 
   // Throw away any already-decoded, not-yet-delivered frames.
   ready_video_frames_.clear();
 
@@ skipping 18 matching lines @@
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   if (vda_.get())
     DestroyVDA();
   BindToCurrentLoop(closure).Run();
 }
 
 void GpuVideoDecoder::Initialize(const scoped_refptr<DemuxerStream>& stream,
                                  const PipelineStatusCB& orig_status_cb,
                                  const StatisticsCB& statistics_cb) {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
+  weak_this_ = weak_factory_.GetWeakPtr();
+
   PipelineStatusCB status_cb = CreateUMAReportingPipelineCB(
       "Media.GpuVideoDecoderInitializeStatus",
       BindToCurrentLoop(orig_status_cb));
   DCHECK(!demuxer_stream_);
 
   if (!stream) {
     status_cb.Run(PIPELINE_ERROR_DECODE);
     return;
   }
 
@@ skipping 31 matching lines @@
     return;
   }
 
   if (config.codec() == kCodecH264)
     stream->EnableBitstreamConverter();
 
   demuxer_stream_ = stream;
   statistics_cb_ = statistics_cb;
 
   DVLOG(1) << "GpuVideoDecoder::Initialize() succeeded.";
-  vda_loop_proxy_->PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&GpuVideoDecoder::SetVDA, this, vda),
-      base::Bind(status_cb, PIPELINE_OK));
+  PostTaskAndReplyWithResult(
+      vda_loop_proxy_, FROM_HERE,
+      base::Bind(&VideoDecodeAccelerator::AsWeakPtr, base::Unretained(vda)),
+      base::Bind(&GpuVideoDecoder::SetVDA, weak_this_, status_cb, vda));
 }
 
-void GpuVideoDecoder::SetVDA(VideoDecodeAccelerator* vda) {
-  DCHECK(vda_loop_proxy_->BelongsToCurrentThread());
+void GpuVideoDecoder::SetVDA(
+    const PipelineStatusCB& status_cb,
+    VideoDecodeAccelerator* vda,
+    base::WeakPtr<VideoDecodeAccelerator> weak_vda) {
+  DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   DCHECK(!vda_.get());
   vda_.reset(vda);
-  weak_vda_ = vda->AsWeakPtr();
+  weak_vda_ = weak_vda;
+  status_cb.Run(PIPELINE_OK);
 }
 
 void GpuVideoDecoder::DestroyTextures() {
   for (std::map<int32, PictureBuffer>::iterator it =
           picture_buffers_in_decoder_.begin();
           it != picture_buffers_in_decoder_.end(); ++it) {
     factories_->DeleteTexture(it->second.texture_id());
   }
   picture_buffers_in_decoder_.clear();
 }
 
 void GpuVideoDecoder::DestroyVDA() {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   VideoDecodeAccelerator* vda ALLOW_UNUSED = vda_.release();
-  // Tricky: |this| needs to stay alive until after VDA::Destroy is actually
-  // called, not just posted, so we take an artificial ref to |this| and release
-  // it as |reply| after VDA::Destroy() returns.
-  AddRef();
-  vda_loop_proxy_->PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&VideoDecodeAccelerator::Destroy, weak_vda_),
-      base::Bind(&GpuVideoDecoder::Release, this));
+
+  // Note: I don't think it's possible to guarantee that VDA *won't* call us

[scherkus (not reviewing), 2013/03/28 02:00:01]

FYI

It's a bit late in the day, but I'm not sure if there's a way to solve this w/o
involving refcounting somehow.

If that's the case, we could introduce a ref-counted proxy class (sigh...) that
implements VDA::Client + target message loop.

We could then remove trampolining code inside GVD and null out the pointer to
GVD during Stop().


I wonder if we can get WMPI to help out here, perhaps via
GpuVideoDecoder::Factories. It would be nice to not rely on a ref-counted proxy
and figure out a proper shutdown + deletion sequence.

Hm.....

[Ami GONE FROM CHROMIUM, 2013/03/29 23:55:19]

Yes, this is the key point of this CL :)
Today GVD _relies_ on being refcounted as a means for staying alive until the
VDA::Destroy() is actually called (and pending callbacks in the VDA loop's queue
being handled), b/c that's the guarantee of no-more-callbacks.

I think you can still get what you want by replacing the current sequence of:

AddRef()
PostTaskAndReply(Destroy, Release)

with:
GVD* self = VRB::decoder_.release();
PostTaskAndReply(Destroy, Bind(Delete, self));

WDYT?

[scherkus (not reviewing), 2013/04/05 01:18:30]

I'd prefer to not mess around w/ transferring ownership from VRB to GVD :\

FWIW I think it'd have to be a scoped_ptr<T> instead of T* otherwise we can risk
leaking when the reply thread has been stopped:
  * VDA runs on render thread
  * WMPI is blocking render thread on Stop()
  * GVD receives Stop() on media thread
  * GVD posts VDA::Destroy() to render thread w/ reply to media thread
  * WMPI + GVD are destroyed
  **** Media thread is stopped ****
  * WMPI returns control to render thread
  * VDA::Destroy() is run
  * PostTaskAndReply() posts task to stopped media thread to destroy GVD
  * MessageLoopProxy drops task


I wrote up a client proxy. It's not too bad ... but I can't say I'm super happy.

+  // after GVD has been destroyed.
+  //
+  // Example:
+  //   * VDA runs on render thread
+  //   * WMPI is blocking render thread on Stop()
+  //   * GVD receives Stop() on media thread
+  //   * GVD posts VDA::Destroy() to render thread
+  //   * GVD completes Stop() and WMPI becomes unblocked
+  //   * WMPI + GVD are destroyed
+  //   * VDA executes pending work on GVD on render thread
+  //   * -- boom --
+  vda_loop_proxy_->PostTask(FROM_HERE, base::Bind(
+      &VideoDecodeAccelerator::Destroy, weak_vda_));
 
   DestroyTextures();
 }
 
 void GpuVideoDecoder::Read(const ReadCB& read_cb) {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   DCHECK(pending_reset_cb_.is_null());
   DCHECK(pending_read_cb_.is_null());
   pending_read_cb_ = BindToCurrentLoop(read_cb);
 
@@ skipping 31 matching lines @@
   return bitstream_buffers_in_decoder_.size() < kMaxInFlightDecodes;
 }
 
 void GpuVideoDecoder::RequestBufferDecode(
     DemuxerStream::Status status,
     const scoped_refptr<DecoderBuffer>& buffer) {
   DCHECK_EQ(status != DemuxerStream::kOk, !buffer) << status;
 
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::RequestBufferDecode, this, status, buffer));
+        &GpuVideoDecoder::RequestBufferDecode, weak_this_, status, buffer));
     return;
   }
   demuxer_read_in_progress_ = false;
 
   if (status != DemuxerStream::kOk) {
     if (pending_read_cb_.is_null())
       return;
 
     // TODO(acolwell): Add support for reinitializing the decoder when
     // |status| == kConfigChanged. For now we just trigger a decode error.
@@ skipping 85 matching lines @@
 
 void GpuVideoDecoder::NotifyInitializeDone() {
   NOTREACHED() << "GpuVideoDecodeAcceleratorHost::Initialize is synchronous!";
 }
 
 void GpuVideoDecoder::ProvidePictureBuffers(uint32 count,
                                             const gfx::Size& size,
                                             uint32 texture_target) {
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::ProvidePictureBuffers, this, count, size,
+        &GpuVideoDecoder::ProvidePictureBuffers, weak_this_, count, size,
         texture_target));
     return;
   }
 
   std::vector<uint32> texture_ids;
   decoder_texture_target_ = texture_target;
   if (!factories_->CreateTextures(
       count, size, &texture_ids, decoder_texture_target_)) {
     NotifyError(VideoDecodeAccelerator::PLATFORM_FAILURE);
     return;
@@ skipping 14 matching lines @@
     DCHECK(inserted);
   }
   vda_loop_proxy_->PostTask(FROM_HERE, base::Bind(
       &VideoDecodeAccelerator::AssignPictureBuffers, weak_vda_,
       picture_buffers));
 }
 
 void GpuVideoDecoder::DismissPictureBuffer(int32 id) {
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::DismissPictureBuffer, this, id));
+        &GpuVideoDecoder::DismissPictureBuffer, weak_this_, id));
     return;
   }
   std::map<int32, PictureBuffer>::iterator it =
       picture_buffers_in_decoder_.find(id);
   if (it == picture_buffers_in_decoder_.end()) {
     NOTREACHED() << "Missing picture buffer: " << id;
     return;
   }
   factories_->DeleteTexture(it->second.texture_id());
   picture_buffers_in_decoder_.erase(it);
 }
 
 void GpuVideoDecoder::PictureReady(const media::Picture& picture) {
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::PictureReady, this, picture));
+        &GpuVideoDecoder::PictureReady, weak_this_, picture));
     return;
   }
   std::map<int32, PictureBuffer>::iterator it =
       picture_buffers_in_decoder_.find(picture.picture_buffer_id());
   if (it == picture_buffers_in_decoder_.end()) {
     NOTREACHED() << "Missing picture buffer: " << picture.picture_buffer_id();
     NotifyError(VideoDecodeAccelerator::PLATFORM_FAILURE);
     return;
   }
   const PictureBuffer& pb = it->second;
 
   // Update frame's timestamp.
   base::TimeDelta timestamp;
   gfx::Rect visible_rect;
   gfx::Size natural_size;
   GetBufferData(picture.bitstream_buffer_id(), &timestamp, &visible_rect,
                 &natural_size);
   DCHECK(decoder_texture_target_);
   scoped_refptr<VideoFrame> frame(
       VideoFrame::WrapNativeTexture(
           pb.texture_id(), decoder_texture_target_, pb.size(), visible_rect,
           natural_size, timestamp,
           base::Bind(&Factories::ReadPixels, factories_, pb.texture_id(),
                      decoder_texture_target_,
                      gfx::Size(visible_rect.width(), visible_rect.height())),
-          base::Bind(&GpuVideoDecoder::ReusePictureBuffer, this,
-                     picture.picture_buffer_id())));
+          BindToCurrentLoop(base::Bind(
+              &GpuVideoDecoder::ReusePictureBuffer, weak_this_,
+              picture.picture_buffer_id()))));
   CHECK_GT(available_pictures_, 0);
   available_pictures_--;
 
   EnqueueFrameAndTriggerFrameDelivery(frame);
 }
 
 void GpuVideoDecoder::EnqueueFrameAndTriggerFrameDelivery(
     const scoped_refptr<VideoFrame>& frame) {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
 
   // During a pending vda->Reset(), we don't accumulate frames.  Drop it on the
   // floor and return.
   if (!pending_reset_cb_.is_null())
     return;
 
   if (frame)
     ready_video_frames_.push_back(frame);
   else
     DCHECK(!ready_video_frames_.empty());
 
   if (pending_read_cb_.is_null())
     return;
 
   base::ResetAndReturn(&pending_read_cb_).Run(kOk, ready_video_frames_.front());
   ready_video_frames_.pop_front();
 }
 
 void GpuVideoDecoder::ReusePictureBuffer(int64 picture_buffer_id) {
-  if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
-    gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::ReusePictureBuffer, this, picture_buffer_id));
-    return;
-  }
+  DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   CHECK_GE(available_pictures_, 0);
   available_pictures_++;
 
   if (!vda_.get())
     return;
   vda_loop_proxy_->PostTask(FROM_HERE, base::Bind(
       &VideoDecodeAccelerator::ReusePictureBuffer, weak_vda_,
       picture_buffer_id));
 }
 
@@ skipping 12 matching lines @@
 }
 
 void GpuVideoDecoder::PutSHM(SHMBuffer* shm_buffer) {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   available_shm_segments_.push_back(shm_buffer);
 }
 
 void GpuVideoDecoder::NotifyEndOfBitstreamBuffer(int32 id) {
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::NotifyEndOfBitstreamBuffer, this, id));
+        &GpuVideoDecoder::NotifyEndOfBitstreamBuffer, weak_this_, id));
     return;
   }
 
   std::map<int32, BufferPair>::iterator it =
       bitstream_buffers_in_decoder_.find(id);
   if (it == bitstream_buffers_in_decoder_.end()) {
     NotifyError(VideoDecodeAccelerator::PLATFORM_FAILURE);
     NOTREACHED() << "Missing bitstream buffer: " << id;
     return;
   }
@@ skipping 31 matching lines @@
   DestroyTextures();
 }
 
 void GpuVideoDecoder::EnsureDemuxOrDecode() {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   if (demuxer_read_in_progress_)
     return;
   demuxer_read_in_progress_ = true;
   gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
       &DemuxerStream::Read, demuxer_stream_.get(),
-      base::Bind(&GpuVideoDecoder::RequestBufferDecode, this)));
+      base::Bind(&GpuVideoDecoder::RequestBufferDecode, weak_this_)));
 }
 
 void GpuVideoDecoder::NotifyFlushDone() {
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::NotifyFlushDone, this));
+        &GpuVideoDecoder::NotifyFlushDone, weak_this_));
     return;
   }
   DCHECK_EQ(state_, kDrainingDecoder);
   state_ = kDecoderDrained;
   EnqueueFrameAndTriggerFrameDelivery(VideoFrame::CreateEmptyFrame());
 }
 
 void GpuVideoDecoder::NotifyResetDone() {
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::NotifyResetDone, this));
+        &GpuVideoDecoder::NotifyResetDone, weak_this_));
     return;
   }
 
   if (!vda_.get())
     return;
 
   DCHECK(ready_video_frames_.empty());
 
   // This needs to happen after the Reset() on vda_ is done to ensure pictures
   // delivered during the reset can find their time data.
   input_buffer_data_.clear();
 
   if (!pending_reset_cb_.is_null())
     base::ResetAndReturn(&pending_reset_cb_).Run();
 
   if (!pending_read_cb_.is_null())
     EnqueueFrameAndTriggerFrameDelivery(VideoFrame::CreateEmptyFrame());
 }
 
 void GpuVideoDecoder::NotifyError(media::VideoDecodeAccelerator::Error error) {
   if (!gvd_loop_proxy_->BelongsToCurrentThread()) {
     gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-        &GpuVideoDecoder::NotifyError, this, error));
+        &GpuVideoDecoder::NotifyError, weak_this_, error));
     return;
   }
   if (!vda_.get())
     return;
 
   DLOG(ERROR) << "VDA Error: " << error;
   DestroyVDA();
 
   error_occured_ = true;
 
   if (!pending_read_cb_.is_null()) {
     base::ResetAndReturn(&pending_read_cb_).Run(kDecodeError, NULL);
     return;
   }
 }
 
 }  // namespace media