Motown: Framework parts for mojo transport (producer/consumer/mediapipe) and control (audiotrack).

services/media/framework_mojo/mojo_pull_mode_producer.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 "base/logging.h"
+#include "services/media/framework_mojo/mojo_pull_mode_producer.h"
+
+namespace mojo {
+namespace media {
+
+MojoPullModeProducer::MojoPullModeProducer() :
+    state_(MediaState::UNPREPARED),
+    demand_(Demand::kNegative),
+    presentation_time_(0),
+    cached_packet_(nullptr) {}
+
+MojoPullModeProducer::~MojoPullModeProducer() {
+  base::AutoLock lock(lock_);
+}
+
+void MojoPullModeProducer::AddBinding(
+    InterfaceRequest<MediaPullModeProducer> producer) {
+  bindings_.AddBinding(this, producer.Pass());
+}
+
+void MojoPullModeProducer::GetBuffer(const GetBufferCallback& callback) {
+  if (!mojo_allocator_.initialized()) {
+    mojo_allocator_.InitNew(256 * 1024); // TODO(dalesat): Made up!
+  }
+
+  {
+    base::AutoLock lock(lock_);
+    if (state_ == MediaState::UNPREPARED) {
+      state_ = MediaState::PAUSED;
+    }
+  }
+
+  callback.Run(mojo_allocator_.GetDuplicateHandle());
+
+  DCHECK(!cached_packet_);
+  DCHECK(demand_callback_);
+  demand_callback_(Demand::kPositive);
+}
+
+void MojoPullModeProducer::PullPacket(
+    MediaPacketPtr to_release,
+    const PullPacketCallback& callback) {
+  if (to_release) {
+    // The client has piggy-backed a release on this pull request.
+    ReleasePacket(to_release.Pass());
+  }
+
+  {
+    base::AutoLock lock(lock_);
+
+    if (state_ == MediaState::UNPREPARED) {
+      // The consumer has yet to call GetBuffer. This request will have to wait.
+      pending_pulls_.push_back(callback);
+      return;
+    }
+
+    DCHECK(mojo_allocator_.initialized());
+
+    // If there are no pending requests, see if we can handle this now. If
+    // requests are pending, add the callback to the pending queue.
+    if (!pending_pulls_.empty() || !MaybeHandlePullUnsafe(callback)) {
+      pending_pulls_.push_back(callback);
+    }
+
+    DCHECK(!cached_packet_);
+  }
+
+  DCHECK(demand_callback_);
+  demand_callback_(Demand::kPositive);
+}
+
+void MojoPullModeProducer::ReleasePacket(MediaPacketPtr to_release) {
+  {
+    base::AutoLock lock(lock_);
+    uint64_t size = to_release->payload ? to_release->payload->length : 0;
+    void* payload = size == 0 ? nullptr :
+        mojo_allocator_.PtrFromOffset(to_release->payload->offset);
+
+    for (auto iterator = unreleased_packets_.begin(); true; ++iterator) {
+      if (iterator == unreleased_packets_.end()) {
+        DCHECK(false) << "released packet has bad offset and/or size";
+        break;
+      }
+
+      if ((*iterator)->payload() == payload && (*iterator)->size() == size) {
+        unreleased_packets_.erase(iterator);
+        break;
+      }
+    }
+
+    // TODO(dalesat): What if the allocator has starved?
+  }
+
+  DCHECK(demand_callback_);
+  demand_callback_(cached_packet_ ? Demand::kNegative : Demand::kPositive);
+}
+
+PayloadAllocator* MojoPullModeProducer::allocator() {
+  return mojo_allocator_.initialized() ? &mojo_allocator_ : nullptr;
+}
+
+void MojoPullModeProducer::SetDemandCallback(
+    const DemandCallback& demand_callback) {
+  demand_callback_ = demand_callback;
+}
+
+void MojoPullModeProducer::Prime() {
+  DCHECK(demand_callback_);
+  demand_callback_(Demand::kNeutral);
+}
+
+Demand MojoPullModeProducer::SupplyPacket(PacketPtr packet) {
+  base::AutoLock lock(lock_);
+  DCHECK(demand_ != Demand::kNegative) << "packet pushed with negative demand";
+  DCHECK(state_ != MediaState::ENDED) << "packet pushed after end-of-stream";
+
+  DCHECK(!cached_packet_);
+
+  // If there's no binding on the stream, throw the packet away. This can
+  // happen if a pull client disconnects unexpectedly.
+  if (bindings_.size() == 0) {
+    demand_ = Demand::kNegative;
+    state_ = MediaState::UNPREPARED;
+    // TODO(dalesat): More shutdown?
+    return demand_;
+  }
+
+  // Accept the packet and handle pending pulls with it.
+  cached_packet_ = std::move(packet);
+
+  HandlePendingPullsUnsafe();
+
+  demand_ = cached_packet_ ? Demand::kNegative : Demand::kPositive;
+  return demand_;
+}
+
+void MojoPullModeProducer::HandlePendingPullsUnsafe() {
+  lock_.AssertAcquired();
+
+  while (!pending_pulls_.empty()) {
+    DCHECK(mojo_allocator_.initialized());
+
+    if (MaybeHandlePullUnsafe(pending_pulls_.front())) {
+      pending_pulls_.pop_front();
+    } else {
+      break;
+    }
+  }
+}
+
+bool MojoPullModeProducer::MaybeHandlePullUnsafe(
+    const PullPacketCallback& callback) {
+  DCHECK(!callback.is_null());
+  lock_.AssertAcquired();
+
+  if (state_ == MediaState::ENDED) {
+    // At end-of-stream. Respond with empty end-of-stream packet.
+    HandlePullWithPacketUnsafe(
+        callback,
+        Packet::CreateEndOfStream(presentation_time_));
+    return true;
+  }
+
+  if (!cached_packet_) {
+    // Waiting for packet or end-of-stream indication.
+    return false;
+  }
+
+  HandlePullWithPacketUnsafe(callback, std::move(cached_packet_));
+  return true;
+}
+
+void MojoPullModeProducer::HandlePullWithPacketUnsafe(
+    const PullPacketCallback& callback,
+    PacketPtr packet) {
+  DCHECK(packet);
+  lock_.AssertAcquired();
+
+  // TODO(dalesat): Use TaskRunner for this callback.
+  callback.Run(CreateMediaPacket(packet));
+  unreleased_packets_.push_back(std::move(packet));
+}
+
+MediaPacketPtr MojoPullModeProducer::CreateMediaPacket(
+    const PacketPtr& packet) {
+  DCHECK(packet);
+
+  MediaPacketRegionPtr region = MediaPacketRegion::New();
+  region->offset = mojo_allocator_.OffsetFromPtr(packet->payload());
+  region->length = packet->size();
+
+  MediaPacketPtr media_packet = MediaPacket::New();
+  media_packet->pts = packet->presentation_time();
+  media_packet->duration = packet->duration();
+  media_packet->end_of_stream = packet->end_of_stream();
+  media_packet->payload = region.Pass();
+  presentation_time_ = packet->presentation_time() + packet->duration();
+
+  return media_packet.Pass();
+}
+
+} // namespace media
+} // namespace mojo