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 "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 ResumedCB& resumed_cb,
    const PipelineStatusCB& error_cb)
    : pipeline_(pipeline),
      renderer_factory_cb_(renderer_factory_cb),
      seeked_cb_(seeked_cb),
      suspended_cb_(suspended_cb),
      resumed_cb_(resumed_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(!resumed_cb_.is_null());
  DCHECK(!error_cb_.is_null());
}

PipelineController::~PipelineController() {
  DCHECK(thread_checker_.CalledOnValidThread());
}

// 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(thread_checker_.CalledOnValidThread());
  DCHECK(state_ == State::CREATED);

  if (chunk_demuxer)
    DCHECK_EQ(demuxer, chunk_demuxer);

  // Once the pipeline is started, we want to call the seeked callback but
  // without a time update.
  pending_seeked_cb_ = true;
  state_ = State::STARTING;

  chunk_demuxer_ = chunk_demuxer;
  is_streaming_ = is_streaming;
  pipeline_->Start(
      demuxer, renderer_factory_cb_.Run(), ended_cb,
      BindToCurrentLoop(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) {
  DCHECK(thread_checker_.CalledOnValidThread());

  // 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_updated_ = true;
  pending_seeked_cb_ = 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() {
  DCHECK(thread_checker_.CalledOnValidThread());
  pending_resume_ = false;
  if (state_ != State::SUSPENDING && state_ != State::SUSPENDED) {
    pending_suspend_ = true;
    Dispatch();
  }
}

void PipelineController::Resume() {
  DCHECK(thread_checker_.CalledOnValidThread());
  pending_suspend_ = false;
  if (state_ == State::SUSPENDING || state_ == State::SUSPENDED) {
    pending_resume_ = true;
    Dispatch();
  }
}

bool PipelineController::IsStable() {
  DCHECK(thread_checker_.CalledOnValidThread());
  return (state_ == State::PLAYING);
}

bool PipelineController::IsSuspended() {
  DCHECK(thread_checker_.CalledOnValidThread());
  return (state_ == State::SUSPENDED);
}

void PipelineController::OnPipelineStatus(State state,
                                          PipelineStatus pipeline_status) {
  DCHECK(thread_checker_.CalledOnValidThread());

  if (pipeline_status != PIPELINE_OK) {
    error_cb_.Run(pipeline_status);
    return;
  }

  state_ = state;

  if (state == State::PLAYING) {
    // Start(), Seek(), or Resume() completed; we can be sure that
    // |chunk_demuxer_| got the seek it was waiting for.
    waiting_for_seek_ = false;
    if (pending_resumed_cb_) {
      pending_resumed_cb_ = false;

      // Warning: possibly reentrant. The state may change inside this callback.
      // It must be safe to call Dispatch() twice in a row here.
      resumed_cb_.Run();
    }
  } else if (state == State::SUSPENDED) {
    pending_resumed_cb_ = true;

    // Warning: possibly reentrant. The state may change inside this callback.
    // It must be safe to call Dispatch() twice in a row here.
    suspended_cb_.Run();
  }

  Dispatch();
}

// Note: Dispatch() may be called re-entrantly (by callbacks internally) or
// twice in a row (by OnPipelineStatus()).
void PipelineController::Dispatch() {
  DCHECK(thread_checker_.CalledOnValidThread());

  // 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_updated_ = 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_cb_) {
      // |seeked_cb_| may be reentrant, so update state first and return
      // immediately.
      pending_seeked_cb_ = false;
      bool was_pending_time_updated = pending_time_updated_;
      pending_time_updated_ = false;
      seeked_cb_.Run(was_pending_time_updated);
      return;
    }
  }
}

}  // namespace media