Refactor PipelineImpl to use CompositeFilter to manage Filter state transitions.

media/base/composite_filter.cc

Index: media/base/composite_filter.cc
diff --git a/media/base/composite_filter.cc b/media/base/composite_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c29d74a5710eaa0a7f9fd4fd8a829ce6894f953c
--- /dev/null
+++ b/media/base/composite_filter.cc
@@ -0,0 +1,567 @@
+// Copyright (c) 2010 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 "base/stl_util-inl.h"
+#include "media/base/callback.h"
+#include "media/base/composite_filter.h"

[scherkus (not reviewing), 2010/12/15 16:44:02]

include corresponding .h first followed by blank line, then rest of includes

[acolwell GONE FROM CHROMIUM, 2010/12/15 18:20:11]

Done.

+
+namespace media {
+
+CompositeFilter::CompositeFilter(MessageLoop* message_loop)
+{

[scherkus (not reviewing), 2010/12/15 16:44:02]

style: { on previous line

[acolwell GONE FROM CHROMIUM, 2010/12/15 18:20:11]

Done.

+  Init(message_loop, NULL);
+}
+
+CompositeFilter::CompositeFilter(MessageLoop* message_loop,
+                                 ThreadFactoryFunction thread_factory)
+{

[scherkus (not reviewing), 2010/12/15 16:44:02]

style: { on previous line

[acolwell GONE FROM CHROMIUM, 2010/12/15 18:20:11]

Done.

+  DCHECK(thread_factory);
+  Init(message_loop, thread_factory);
+}
+
+void CompositeFilter::Init(MessageLoop* message_loop,
+                           ThreadFactoryFunction thread_factory) {
+  DCHECK(message_loop);
+  message_loop_ = message_loop;
+  thread_factory_ = thread_factory;
+
+  if (!thread_factory_) {
+    thread_factory_ = &CompositeFilter::DefaultThreadFactory;
+  }
+
+  state_ = kCreated;
+  sequence_index_ = -1;
+  host_ = NULL;
+  error_ = PIPELINE_OK;
+}
+
+CompositeFilter::~CompositeFilter() {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  DCHECK(state_ == kCreated || state_ == kStopped);
+
+  // Stop every running filter thread.
+  for (FilterThreadVector::iterator iter = filter_threads_.begin();
+       iter != filter_threads_.end();
+       ++iter) {
+    (*iter)->Stop();
+  }
+
+  // Reset the pipeline, which will decrement a reference to this object.
+  // We will get destroyed as soon as the remaining tasks finish executing.
+  // To be safe, we'll set our pipeline reference to NULL.
+  filters_.clear();
+  STLDeleteElements(&filter_threads_);
+}
+
+bool CompositeFilter::AddFilter(scoped_refptr<Filter> filter) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  if (!filter.get() || state_ != kCreated || !host_)
+    return false;
+
+  // Create a dedicated thread for this filter if applicable.
+  if (filter->requires_message_loop()) {
+    scoped_ptr<base::Thread> thread(
+        thread_factory_(filter->message_loop_name()));
+
+    if (!thread.get() || !thread->Start()) {
+      return false;
+    }
+
+    filter->set_message_loop(thread->message_loop());
+    filter_threads_.push_back(thread.release());
+  }
+
+  // Register ourselves as the filter's host.
+  filter->set_host(this);
+  filters_.push_back(make_scoped_refptr(filter.get()));
+  return true;
+}
+
+const char* CompositeFilter::major_mime_type() const {
+  return "";
+}
+
+void CompositeFilter::set_host(FilterHost* host) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  DCHECK(host);
+  DCHECK(!host_);
+  host_ = host;
+}
+
+FilterHost* CompositeFilter::host() {
+  return host_;
+}
+
+bool CompositeFilter::requires_message_loop() const {
+  return false;
+}
+
+const char* CompositeFilter::message_loop_name() const {
+  return "CompositeFilter";
+}
+
+void CompositeFilter::set_message_loop(MessageLoop* message_loop) {
+  NOTREACHED() << "Message loop should not be set.";
+}
+
+MessageLoop* CompositeFilter::message_loop() {
+  return NULL;
+}
+
+void CompositeFilter::Play(FilterCallback* play_callback) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  scoped_ptr<FilterCallback> callback(play_callback);
+  if (callback_.get()) {
+    SendErrorToHost(PIPELINE_ERROR_OPERATION_PENDING);
+    callback->Run();
+    return;
+  } else if (state_ == kPlaying) {
+    callback->Run();
+    return;
+  } else if (!host_ || (state_ != kPaused && state_ != kCreated)) {
+    SendErrorToHost(PIPELINE_ERROR_INVALID_STATE);
+    callback->Run();
+    return;
+  }
+
+  ChangeState(kPlayPending);
+  callback_.reset(callback.release());
+  StartSerialCallSequence();
+}
+
+void CompositeFilter::Pause(FilterCallback* pause_callback) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  scoped_ptr<FilterCallback> callback(pause_callback);
+  if (callback_.get()) {
+    SendErrorToHost(PIPELINE_ERROR_OPERATION_PENDING);
+    callback->Run();
+    return;
+  } else if (state_ == kPaused) {
+    callback->Run();
+    return;
+  } else if (!host_ || state_ != kPlaying) {
+    SendErrorToHost(PIPELINE_ERROR_INVALID_STATE);
+    callback->Run();
+    return;
+  }
+
+  ChangeState(kPausePending);
+  callback_.reset(callback.release());
+  StartSerialCallSequence();
+}
+
+void CompositeFilter::Flush(FilterCallback* flush_callback) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  scoped_ptr<FilterCallback> callback(flush_callback);
+  if (callback_.get()) {
+    SendErrorToHost(PIPELINE_ERROR_OPERATION_PENDING);
+    callback->Run();
+    return;
+  } else if (!host_ || (state_ != kCreated && state_ != kPaused)) {
+    SendErrorToHost(PIPELINE_ERROR_INVALID_STATE);
+    callback->Run();
+    return;
+  }
+
+  ChangeState(kFlushPending);
+  callback_.reset(callback.release());
+  StartParallelCallSequence();
+}
+
+void CompositeFilter::Stop(FilterCallback* stop_callback) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  scoped_ptr<FilterCallback> callback(stop_callback);
+  if (!host_) {
+    SendErrorToHost(PIPELINE_ERROR_INVALID_STATE);
+    callback->Run();
+    return;
+  } else if (state_ == kStopped) {
+    callback->Run();
+    return;
+  }
+
+  switch(state_) {
+    case kError:
+    case kCreated:
+    case kPaused:
+    case kPlaying:
+      ChangeState(kStopPending);
+      break;
+    case kPlayPending:
+      ChangeState(kStopWhilePlayPending);
+      break;
+    case kPausePending:
+      ChangeState(kStopWhilePausePending);
+      break;
+    case kFlushPending:
+      ChangeState(kStopWhileFlushPending);
+      break;
+    case kSeekPending:
+      ChangeState(kStopWhileSeekPending);
+      break;
+    default:
+      SendErrorToHost(PIPELINE_ERROR_INVALID_STATE);
+      callback->Run();
+      return;
+  }
+
+  callback_.reset(callback.release());
+  if (state_ == kStopPending) {
+    StartSerialCallSequence();
+  }
+}
+
+void CompositeFilter::SetPlaybackRate(float playback_rate) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  for (FilterVector::iterator iter = filters_.begin();
+       iter != filters_.end();
+       ++iter) {
+    (*iter)->SetPlaybackRate(playback_rate);
+  }
+}
+
+void CompositeFilter::Seek(base::TimeDelta time,
+                           FilterCallback* seek_callback) {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  scoped_ptr<FilterCallback> callback(seek_callback);
+  if (callback_.get()) {
+    SendErrorToHost(PIPELINE_ERROR_OPERATION_PENDING);
+    callback->Run();
+    return;
+  } else if (!host_ || (state_ != kPaused && state_ != kCreated)) {
+    SendErrorToHost(PIPELINE_ERROR_INVALID_STATE);
+    callback->Run();
+    return;
+  }
+
+  ChangeState(kSeekPending);
+  callback_.reset(callback.release());
+  pending_seek_time_ = time;
+  StartSerialCallSequence();
+}
+
+void CompositeFilter::OnAudioRendererDisabled() {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  for (FilterVector::iterator iter = filters_.begin();
+       iter != filters_.end();
+       ++iter) {
+    (*iter)->OnAudioRendererDisabled();
+  }
+}
+
+base::Thread* CompositeFilter::DefaultThreadFactory(
+    const char* thread_name) {
+  return new base::Thread(thread_name);
+}
+
+void CompositeFilter::ChangeState(State new_state) {
+  state_ = new_state;
+}
+
+void CompositeFilter::StartSerialCallSequence() {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  error_ = PIPELINE_OK;
+
+  if (filters_.size() > 0) {
+    sequence_index_ = 0;
+    CallFilter(filters_[sequence_index_],
+               NewThreadSafeCallback(&CompositeFilter::SerialCallback));
+  } else {
+    sequence_index_ = -1;
+    SerialCallback();
+  }
+}
+
+void CompositeFilter::StartParallelCallSequence() {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  error_ = PIPELINE_OK;
+
+  if (filters_.size() > 0) {
+    sequence_index_ = 0;
+    for (size_t i = 0; i < filters_.size(); i++)
+      CallFilter(filters_[i],

[scherkus (not reviewing), 2010/12/15 16:44:02]

I get freaked out when I see multi-line for/while bodies without {} -- mind
adding them?

[acolwell GONE FROM CHROMIUM, 2010/12/15 18:20:11]

Done.

+                 NewThreadSafeCallback(&CompositeFilter::ParallelCallback));
+  } else {
+    sequence_index_ = -1;
+    ParallelCallback();
+  }
+}
+
+void CompositeFilter::CallFilter(scoped_refptr<Filter>& filter,
+                                 FilterCallback* callback) {
+  switch(state_) {
+    case kPlayPending:
+      filter->Play(callback);
+      break;
+    case kPausePending:
+      filter->Pause(callback);
+      break;
+    case kFlushPending:
+      filter->Flush(callback);
+      break;
+    case kStopPending:
+      filter->Stop(callback);
+      break;
+    case kSeekPending:
+      filter->Seek(pending_seek_time_, callback);
+      break;
+    default:
+      delete callback;
+      ChangeState(kError);
+      HandleError(PIPELINE_ERROR_INVALID_STATE);
+  }
+}
+
+void CompositeFilter::DispatchPendingCallback() {
+  if (callback_.get()) {
+    scoped_ptr<FilterCallback> callback(callback_.release());
+    callback->Run();
+  }
+}
+
+CompositeFilter::State CompositeFilter::GetNextState(State state) const {
+  State ret = kInvalid;
+  switch (state) {
+    case kPlayPending:
+      ret = kPlaying;
+      break;
+    case kPausePending:
+      ret = kPaused;
+    case kFlushPending:
+      ret = kPaused;
+      break;
+    case kStopPending:
+      ret = kStopped;
+      break;
+    case kSeekPending:
+      ret = kPaused;
+      break;
+    case kStopWhilePlayPending:
+    case kStopWhilePausePending:
+    case kStopWhileFlushPending:
+    case kStopWhileSeekPending:
+      ret = kStopPending;
+      break;
+
+    case kInvalid:
+    case kCreated:
+    case kPlaying:
+    case kPaused:
+    case kStopped:
+    case kError:
+      ret = kInvalid;
+      break;
+
+    // default: intentionally left out to catch missing states.
+  }
+
+  return ret;
+}
+
+void CompositeFilter::SerialCallback() {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  if (error_ != PIPELINE_OK) {
+    // We encountered an error. Terminate the sequence now.
+    ChangeState(kError);
+    HandleError(error_);
+    return;
+  }
+
+  sequence_index_++;
+  if (sequence_index_ == filters_.size()) {
+    // All filters have been successfully called without error.
+    OnCallSequenceDone();
+  } else if (GetNextState(state_) == kStopPending) {
+    // Abort sequence early and start issuing Stop() calls.
+    ChangeState(kStopPending);
+    StartSerialCallSequence();
+  } else {
+    // We aren't done with the sequence. Call the next filter.
+    CallFilter(filters_[sequence_index_],
+               NewThreadSafeCallback(&CompositeFilter::SerialCallback));
+  }
+}
+
+void CompositeFilter::ParallelCallback() {
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  sequence_index_++;
+  if (sequence_index_ == filters_.size()) {
+    if (error_ != PIPELINE_OK) {
+      // We encountered an error.
+      ChangeState(kError);
+      HandleError(error_);
+      return;
+    }
+
+    OnCallSequenceDone();
+  }
+}
+
+void CompositeFilter::OnCallSequenceDone() {
+  State next_state = GetNextState(state_);
+
+  if (next_state == kInvalid) {
+    // We somehow got into an unexpected state.
+    ChangeState(kError);
+    HandleError(PIPELINE_ERROR_INVALID_STATE);
+  }
+
+  ChangeState(next_state);
+
+  if (state_ == kStopPending) {
+    // Handle a deferred Stop().
+    StartSerialCallSequence();
+  } else {
+    // Call the callback to indicate that the operation has completed.
+    DispatchPendingCallback();
+  }
+}
+
+void CompositeFilter::SendErrorToHost(PipelineError error) {
+  if (host_)
+    host_->SetError(error);
+}
+
+void CompositeFilter::HandleError(PipelineError error) {
+  if (error != PIPELINE_OK) {
+    SendErrorToHost(error);
+  }
+
+  DispatchPendingCallback();
+}
+
+FilterCallback* CompositeFilter::NewThreadSafeCallback(
+      void (CompositeFilter::*method)()) {

[scherkus (not reviewing), 2010/12/15 16:44:02]

de-indent by 2

[acolwell GONE FROM CHROMIUM, 2010/12/15 18:20:11]

Done.

+  return TaskToCallbackAdapter::NewCallback(
+      NewRunnableMethod(this,
+                        &CompositeFilter::OnCallback,
+                        message_loop_,
+                        method));
+}
+
+void CompositeFilter::OnCallback(MessageLoop* message_loop,
+                                 void (CompositeFilter::*method)()) {
+  if (MessageLoop::current() != message_loop) {
+    // Posting callback to the proper thread.
+    message_loop->PostTask(FROM_HERE, NewRunnableMethod(this, method));
+    return;
+  }
+
+  (this->*method)();
+}
+
+bool CompositeFilter::CanForwardError() {
+  return (state_ == kCreated) || (state_ == kPlaying) || (state_ == kPaused);
+}
+
+// media::FilterHost methods.
+void CompositeFilter::SetError(PipelineError error) {
+  if (message_loop_ != MessageLoop::current()) {
+    message_loop_->PostTask(FROM_HERE,
+        NewRunnableMethod(this, &CompositeFilter::SetError, error));
+    return;
+  }
+
+  DCHECK_EQ(message_loop_, MessageLoop::current());
+  DCHECK(host_);
+
+  // Drop errors recieved while stopping or stopped.
+  // This shields the owner of this object from having
+  // to deal with errors it can't do anything about.
+  if (state_ == kStopPending || state_ == kStopped)
+    return;
+
+  error_ = error;
+  if (host_ && CanForwardError())
+    host_->SetError(error);
+}
+
+base::TimeDelta CompositeFilter::GetTime() const {
+  DCHECK(host_);
+  return host_ ? host_->GetTime() : base::TimeDelta();
+}
+
+base::TimeDelta CompositeFilter::GetDuration() const {
+  DCHECK(host_);
+  return host_ ? host_->GetDuration() : base::TimeDelta();
+}
+
+void CompositeFilter::SetTime(base::TimeDelta time) {
+  DCHECK(host_);

[scherkus (not reviewing), 2010/12/15 16:44:02]

I'd enforce a guarantee that host_ must be present and remove all these DCHECKs
and if statements

if CompositeFilter doesn't implement Filter, then there's no need for set_host()
and host_ can be set via constructor

WDYT?

[acolwell GONE FROM CHROMIUM, 2010/12/15 18:20:11]

Once I move the FilterHost impl to an inner class I can remove all the checks
and replace it with one in the inner class constructor.
I'm still standing by that this code should implement Filter. I think eventually
set_host() should be removed in favor of constructor parameters, but that is a
different CL.

[scherkus (not reviewing), 2010/12/15 18:57:44]

Sounds good!

+  if (host_)
+    host_->SetTime(time);
+}
+
+void CompositeFilter::SetDuration(base::TimeDelta duration) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetDuration(duration);
+}
+
+void CompositeFilter::SetBufferedTime(base::TimeDelta buffered_time) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetBufferedTime(buffered_time);
+}
+
+void CompositeFilter::SetTotalBytes(int64 total_bytes) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetTotalBytes(total_bytes);
+}
+
+void CompositeFilter::SetBufferedBytes(int64 buffered_bytes) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetBufferedBytes(buffered_bytes);
+}
+
+void CompositeFilter::SetVideoSize(size_t width, size_t height) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetVideoSize(width, height);
+}
+
+void CompositeFilter::SetStreaming(bool streaming) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetStreaming(streaming);
+}
+
+void CompositeFilter::NotifyEnded() {
+  DCHECK(host_);
+  if (host_)
+    host_->NotifyEnded();
+}
+
+void CompositeFilter::SetLoaded(bool loaded) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetLoaded(loaded);
+}
+
+void CompositeFilter::SetNetworkActivity(bool network_activity) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetNetworkActivity(network_activity);
+}
+
+void CompositeFilter::DisableAudioRenderer() {
+  DCHECK(host_);
+  if (host_)
+    host_->DisableAudioRenderer();
+}
+
+void CompositeFilter::SetCurrentReadPosition(int64 offset) {
+  DCHECK(host_);
+  if (host_)
+    host_->SetCurrentReadPosition(offset);
+}
+
+int64 CompositeFilter::GetCurrentReadPosition() {
+  DCHECK(host_);
+  return host_ ? host_->GetCurrentReadPosition() : 0;
+}
+
+}  // namespace media