Re-land extract state management from WebMediaPlayerImpl.

media/filters/pipeline_controller.cc

+// Copyright 2016 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/pipeline_controller.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "build/build_config.h"
+#include "media/base/bind_to_current_loop.h"
+#include "media/filters/chunk_demuxer.h"
+
+namespace media {
+
+PipelineController::PipelineController(
+    Pipeline* pipeline,
+    const RendererFactoryCB& renderer_factory_cb,
+    const SeekedCB& seeked_cb,
+    const SuspendedCB& suspended_cb,
+    const PipelineStatusCB& error_cb)
+    : pipeline_(pipeline),
+      renderer_factory_cb_(renderer_factory_cb),
+      seeked_cb_(seeked_cb),
+      suspended_cb_(suspended_cb),
+      error_cb_(error_cb),
+      weak_factory_(this) {
+  DCHECK(pipeline_);
+  DCHECK(!renderer_factory_cb_.is_null());
+  DCHECK(!seeked_cb_.is_null());
+  DCHECK(!suspended_cb_.is_null());
+  DCHECK(!error_cb_.is_null());
+}
+
+PipelineController::~PipelineController() {}
+
+// TODO(sandersd): Move ChunkDemuxer API to Demuxer so that Pipeline can
+// implement all of this.
+// TODO(sandersd): If there is a pending suspend, don't call pipeline_.Start()
+// until Resume().
+void PipelineController::Start(
+    ChunkDemuxer* chunk_demuxer,
+    Demuxer* demuxer,
+    bool is_streaming,
+    const base::Closure& ended_cb,
+    const PipelineMetadataCB& metadata_cb,
+    const BufferingStateCB& buffering_state_cb,
+    const base::Closure& duration_change_cb,
+    const AddTextTrackCB& add_text_track_cb,
+    const base::Closure& waiting_for_decryption_key_cb) {
+  DCHECK(state_ == State::CREATED);
+

[wolenetz, 2016/02/26 02:30:11]

Let's further enforce the contract that, if chunk_demuxer is set, then it must
be the same demuxer as demuxer... e.g. DCHECK(!chunk_demuxer || (chunk_demuxer
== demuxer)). This was previously done inside one method in WMPI, now it's split
across two classes, so let's keep it clean :)
Perhaps this can be further cleaned-up in that follow-up CL by just using a
boolean to indicate if we're using MSE, or use two injected methods or something
for those specific non-Demuxer methods that ChunkDemuxer needs to be signalled
with by PipelineController in MSE case.

[sandersd (OOO until July 31), 2016/02/26 22:10:48]

Done.

+  // Once the pipeline is started, we want to call the seeked callback but
+  // without a time update.
+  pending_seeked_ = true;
+  state_ = State::STARTING;
+
+  chunk_demuxer_ = chunk_demuxer;
+  is_streaming_ = is_streaming;
+  pipeline_->Start(
+      demuxer, renderer_factory_cb_.Run(), ended_cb, error_cb_,
+      BindToCurrentLoop(base::Bind(&PipelineController::OnPipelineStatus,
+                                   weak_factory_.GetWeakPtr(), State::PLAYING)),
+      metadata_cb, buffering_state_cb, duration_change_cb, add_text_track_cb,
+      waiting_for_decryption_key_cb);
+}
+
+void PipelineController::Seek(base::TimeDelta time, bool time_updated) {
+  // It would be slightly more clear to set this in Dispatch(), but we want to
+  // be sure it gets updated even if the seek is elided.
+  if (time_updated)
+    pending_time_update_ = true;
+  pending_seeked_ = true;
+
+  // If we are already seeking to |time|, just clear any pending seek. This does
+  // not apply to MSE because the underlying buffer could have been changed
+  // between the seek calls.
+  // TODO(sandersd): The underlying buffer could also have changed for
+  // File objects, but WMPI is also broken in that case (because it caches).
+  if ((state_ == State::SEEKING || state_ == State::RESUMING) &&
+      seek_time_ == time && !chunk_demuxer_) {
+    pending_seek_ = false;
+    return;
+  }
+
+  pending_seek_time_ = time;
+  pending_seek_ = true;
+  Dispatch();
+}
+
+// TODO(sandersd): It may be easier to use this interface if |suspended_cb_| is
+// executed when Suspend() is called while already suspended.
+void PipelineController::Suspend() {
+  pending_resume_ = false;
+  if (state_ != State::SUSPENDING && state_ != State::SUSPENDED) {
+    pending_suspend_ = true;
+    Dispatch();
+  }
+}
+
+void PipelineController::Resume() {
+  pending_suspend_ = false;
+  if (state_ == State::SUSPENDING || state_ == State::SUSPENDED) {
+    pending_resume_ = true;
+    Dispatch();
+  }
+}
+
+bool PipelineController::IsStable() {
+  return (state_ == State::PLAYING);
+}
+
+bool PipelineController::IsSuspended() {
+  return (state_ == State::SUSPENDED);
+}
+
+void PipelineController::OnPipelineStatus(State state,
+                                          PipelineStatus pipeline_status) {
+  if (pipeline_status != PIPELINE_OK) {
+    error_cb_.Run(pipeline_status);
+    return;
+  }
+
+  state_ = state;
+
+  // Start(), Seek(), or Resume() completed; we can be sure that
+  // |chunk_demuxer_| got the seek it was waiting for.
+  if (state == State::PLAYING)
+    waiting_for_seek_ = false;
+
+  // Sadly we need to signal this state change via a possibly reentrant
+  // callback. Keep in mind that the state may change inside the callback!
+  // (In particular, it must be safe to call Dispatch() twice in a row here.)
+  if (state == State::SUSPENDED)
+    suspended_cb_.Run();
+
+  Dispatch();
+}
+
+// Note: Dispatch() may be called re-entrantly (by callbacks internally) or
+// twice in a row (by OnPipelineStatus()).
+void PipelineController::Dispatch() {
+  // Suspend/resume transitions take priority because seeks before a suspend
+  // are wasted, and seeks after can be merged into the resume operation.
+  if (pending_suspend_ && state_ == State::PLAYING) {
+    pending_suspend_ = false;
+    state_ = State::SUSPENDING;
+    pipeline_->Suspend(BindToCurrentLoop(
+        base::Bind(&PipelineController::OnPipelineStatus,
+                   weak_factory_.GetWeakPtr(), State::SUSPENDED)));
+    return;
+  }
+
+  if (pending_resume_ && state_ == State::SUSPENDED) {
+    // If there is a pending seek, resume to that time instead.
+    if (pending_seek_) {
+      seek_time_ = pending_seek_time_;
+      pending_seek_ = false;
+    } else {
+      seek_time_ = pipeline_->GetMediaTime();
+    }
+
+    // Unless the media is streaming, in which case we resume at the start
+    // because seeking doesn't work well.
+    if (is_streaming_ && !seek_time_.is_zero()) {
+      seek_time_ = base::TimeDelta();
+
+      // In this case we want to make sure that the controls get updated
+      // immediately, so we don't try to hide the seek.
+      pending_time_update_ = true;
+    }
+
+    // Tell |chunk_demuxer_| to expect our resume.
+    if (chunk_demuxer_) {
+      DCHECK(!waiting_for_seek_);
+      chunk_demuxer_->StartWaitingForSeek(seek_time_);
+      waiting_for_seek_ = true;
+    }
+
+    pending_resume_ = false;
+    state_ = State::RESUMING;
+    pipeline_->Resume(renderer_factory_cb_.Run(), seek_time_,
+                      BindToCurrentLoop(base::Bind(
+                          &PipelineController::OnPipelineStatus,
+                          weak_factory_.GetWeakPtr(), State::PLAYING)));
+    return;
+  }
+
+  // |chunk_demuxer_| supports aborting seeks. Make use of that when we have
+  // other pending operations.
+  if ((pending_seek_ || pending_suspend_) && waiting_for_seek_) {
+    CHECK(chunk_demuxer_);
+
+    // If there is no pending seek, return the current seek to pending status.
+    if (!pending_seek_) {
+      pending_seek_time_ = seek_time_;
+      pending_seek_ = true;
+    }
+
+    // CancelPendingSeek() may be reentrant, so update state first and return
+    // immediately.
+    waiting_for_seek_ = false;
+    chunk_demuxer_->CancelPendingSeek(pending_seek_time_);
+    return;
+  }
+
+  // Ordinary seeking.
+  if (pending_seek_ && state_ == State::PLAYING) {
+    seek_time_ = pending_seek_time_;
+
+    // Tell |chunk_demuxer_| to expect our seek.
+    if (chunk_demuxer_) {
+      DCHECK(!waiting_for_seek_);
+      waiting_for_seek_ = true;
+      chunk_demuxer_->StartWaitingForSeek(seek_time_);
+    }
+
+    pending_seek_ = false;
+    state_ = State::SEEKING;
+    pipeline_->Seek(seek_time_,
+                    BindToCurrentLoop(base::Bind(
+                        &PipelineController::OnPipelineStatus,
+                        weak_factory_.GetWeakPtr(), State::PLAYING)));
+    return;
+  }
+
+  // If |state_| is PLAYING and we didn't trigger an operation above then we
+  // are in a stable state. If there is a seeked callback pending, emit it.
+  if (state_ == State::PLAYING) {
+    if (pending_seeked_) {
+      // |seeked_cb_| may be reentrant, so update state first and return
+      // immediately.
+      pending_seeked_ = false;
+      bool was_pending_time_update = pending_time_update_;
+      pending_time_update_ = false;
+      seeked_cb_.Run(was_pending_time_update);
+      return;
+    }
+  }
+}
+
+}  // namespace media