Implement DetachedBuffer::Promote

1/ This enables a BufferHub-backed DetachedBuffer to be promoted into
   the ProducerBuffer.
2/ Add DetachedBuffer::IsConnected in addition to
   DetachedBuffer::IsValid.
3/ Cleaned up some using pdx:: namespace statements.

Bug: 69982239
Bug: 69981968
Bug: 70046255
Test: buffer_hub-test
Change-Id: I6ee99507b190d142647455532cdce0c2c780b2b0

9 files changed, 251 insertions, 35 deletions

diff --git a/libs/vr/libbufferhub/buffer_hub-test.cpp b/libs/vr/libbufferhub/buffer_hub-test.cpp
index 230282887f..e24739845d 100644
--- a/libs/vr/libbufferhub/buffer_hub-test.cpp
+++ b/libs/vr/libbufferhub/buffer_hub-test.cpp
@@ -19,18 +19,18 @@
     return result;                            \
   })()
 
-using android::sp;
 using android::GraphicBuffer;
+using android::sp;
 using android::dvr::BufferConsumer;
-using android::dvr::BufferHubDefs::kConsumerStateMask;
-using android::dvr::BufferHubDefs::kMetadataHeaderSize;
-using android::dvr::BufferHubDefs::kProducerStateBit;
+using android::dvr::BufferProducer;
+using android::dvr::DetachedBuffer;
+using android::dvr::BufferHubDefs::IsBufferAcquired;
 using android::dvr::BufferHubDefs::IsBufferGained;
 using android::dvr::BufferHubDefs::IsBufferPosted;
-using android::dvr::BufferHubDefs::IsBufferAcquired;
 using android::dvr::BufferHubDefs::IsBufferReleased;
-using android::dvr::BufferProducer;
-using android::dvr::DetachedBuffer;
+using android::dvr::BufferHubDefs::kConsumerStateMask;
+using android::dvr::BufferHubDefs::kMetadataHeaderSize;
+using android::dvr::BufferHubDefs::kProducerStateBit;
 using android::pdx::LocalChannelHandle;
 using android::pdx::LocalHandle;
 using android::pdx::Status;
@@ -376,8 +376,8 @@ TEST_F(LibBufferHubTest, TestMaxConsumers) {
   EXPECT_EQ(0, p->PostAsync(&metadata, invalid_fence));
   EXPECT_TRUE(IsBufferPosted(p->buffer_state()));
   for (size_t i = 0; i < kMaxConsumerCount; i++) {
-    EXPECT_TRUE(IsBufferPosted(cs[i]->buffer_state(),
-                               cs[i]->buffer_state_bit()));
+    EXPECT_TRUE(
+        IsBufferPosted(cs[i]->buffer_state(), cs[i]->buffer_state_bit()));
     EXPECT_LT(0, RETRY_EINTR(cs[i]->Poll(kPollTimeoutMs)));
     EXPECT_EQ(0, cs[i]->AcquireAsync(&metadata, &invalid_fence));
     EXPECT_TRUE(IsBufferAcquired(p->buffer_state()));
@@ -792,6 +792,7 @@ TEST_F(LibBufferHubTest, TestDetachBufferFromProducer) {
   // Detached buffer handle can be use to construct a new DetachedBuffer object.
   auto d = DetachedBuffer::Import(std::move(handle));
   EXPECT_FALSE(handle.valid());
+  EXPECT_TRUE(d->IsConnected());
   EXPECT_TRUE(d->IsValid());
 
   ASSERT_TRUE(d->buffer() != nullptr);
@@ -801,10 +802,11 @@ TEST_F(LibBufferHubTest, TestDetachBufferFromProducer) {
 
 TEST_F(LibBufferHubTest, TestCreateDetachedBufferFails) {
   // Buffer Creation will fail: BLOB format requires height to be 1.
-  auto b1 = DetachedBuffer::Create(kWidth, /*height=2*/2, kLayerCount,
+  auto b1 = DetachedBuffer::Create(kWidth, /*height=2*/ 2, kLayerCount,
                                    /*format=*/HAL_PIXEL_FORMAT_BLOB, kUsage,
                                    kUserMetadataSize);
 
+  EXPECT_FALSE(b1->IsConnected());
   EXPECT_FALSE(b1->IsValid());
   EXPECT_TRUE(b1->buffer() == nullptr);
 
@@ -813,6 +815,7 @@ TEST_F(LibBufferHubTest, TestCreateDetachedBufferFails) {
       kWidth, kHeight, kLayerCount, kFormat, kUsage,
       /*user_metadata_size=*/std::numeric_limits<size_t>::max());
 
+  EXPECT_FALSE(b2->IsConnected());
   EXPECT_FALSE(b2->IsValid());
   EXPECT_TRUE(b2->buffer() == nullptr);
 
@@ -822,6 +825,7 @@ TEST_F(LibBufferHubTest, TestCreateDetachedBufferFails) {
       /*user_metadata_size=*/std::numeric_limits<size_t>::max() -
           kMetadataHeaderSize);
 
+  EXPECT_FALSE(b3->IsConnected());
   EXPECT_FALSE(b3->IsValid());
   EXPECT_TRUE(b3->buffer() == nullptr);
 }
@@ -831,6 +835,7 @@ TEST_F(LibBufferHubTest, TestCreateDetachedBuffer) {
                                    kUsage, kUserMetadataSize);
   int b1_id = b1->id();
 
+  EXPECT_TRUE(b1->IsConnected());
   EXPECT_TRUE(b1->IsValid());
   ASSERT_TRUE(b1->buffer() != nullptr);
   EXPECT_NE(b1->id(), 0);
@@ -843,6 +848,7 @@ TEST_F(LibBufferHubTest, TestCreateDetachedBuffer) {
   ASSERT_TRUE(g1 != nullptr);
   EXPECT_TRUE(g1->isDetachedBuffer());
 
+  EXPECT_FALSE(b1->IsConnected());
   EXPECT_FALSE(b1->IsValid());
   EXPECT_TRUE(b1->buffer() == nullptr);
 
@@ -856,6 +862,7 @@ TEST_F(LibBufferHubTest, TestCreateDetachedBuffer) {
 
   auto b2 = DetachedBuffer::Import(std::move(h1->handle()));
   ASSERT_FALSE(h1->isValid());
+  EXPECT_TRUE(b2->IsConnected());
   EXPECT_TRUE(b2->IsValid());
 
   ASSERT_TRUE(b2->buffer() != nullptr);
@@ -865,3 +872,76 @@ TEST_F(LibBufferHubTest, TestCreateDetachedBuffer) {
   EXPECT_EQ(b2->id(), b1_id);
   EXPECT_FALSE(b2->buffer()->isDetachedBuffer());
 }
+
+TEST_F(LibBufferHubTest, TestPromoteDetachedBuffer) {
+  auto b1 = DetachedBuffer::Create(kWidth, kHeight, kLayerCount, kFormat,
+                                   kUsage, kUserMetadataSize);
+  int b1_id = b1->id();
+  EXPECT_TRUE(b1->IsValid());
+
+  auto status_or_handle = b1->Promote();
+  EXPECT_TRUE(status_or_handle);
+
+  // The detached buffer should have hangup.
+  EXPECT_GT(RETRY_EINTR(b1->Poll(kPollTimeoutMs)), 0);
+  auto status_or_int = b1->GetEventMask(POLLHUP);
+  EXPECT_TRUE(status_or_int.ok());
+  EXPECT_EQ(status_or_int.get(), POLLHUP);
+
+  // The buffer client is still considered as connected but invalid.
+  EXPECT_TRUE(b1->IsConnected());
+  EXPECT_FALSE(b1->IsValid());
+
+  // Gets the channel handle for the producer.
+  LocalChannelHandle h1 = status_or_handle.take();
+  EXPECT_TRUE(h1.valid());
+
+  std::unique_ptr<BufferProducer> p1 = BufferProducer::Import(std::move(h1));
+  EXPECT_FALSE(h1.valid());
+  ASSERT_TRUE(p1 != nullptr);
+  int p1_id = p1->id();
+
+  // A newly promoted ProducerBuffer should inherit the same buffer id.
+  EXPECT_EQ(b1_id, p1_id);
+  EXPECT_TRUE(IsBufferGained(p1->buffer_state()));
+}
+
+TEST_F(LibBufferHubTest, TestDetachThenPromote) {
+  std::unique_ptr<BufferProducer> p1 = BufferProducer::Create(
+      kWidth, kHeight, kFormat, kUsage, sizeof(uint64_t));
+  ASSERT_TRUE(p1.get() != nullptr);
+  int p1_id = p1->id();
+
+  // Detached the producer.
+  auto status_or_handle = p1->Detach();
+  EXPECT_TRUE(status_or_handle.ok());
+  LocalChannelHandle h1 = status_or_handle.take();
+  EXPECT_TRUE(h1.valid());
+
+  // Detached buffer handle can be use to construct a new DetachedBuffer object.
+  auto b1 = DetachedBuffer::Import(std::move(h1));
+  EXPECT_FALSE(h1.valid());
+  EXPECT_TRUE(b1->IsValid());
+  int b1_id = b1->id();
+  EXPECT_EQ(b1_id, p1_id);
+
+  // Promote the detached buffer.
+  status_or_handle = b1->Promote();
+  // The buffer client is still considered as connected but invalid.
+  EXPECT_TRUE(b1->IsConnected());
+  EXPECT_FALSE(b1->IsValid());
+  EXPECT_TRUE(status_or_handle.ok());
+
+  // Gets the channel handle for the producer.
+  LocalChannelHandle h2 = status_or_handle.take();
+  EXPECT_TRUE(h2.valid());
+
+  std::unique_ptr<BufferProducer> p2 = BufferProducer::Import(std::move(h2));
+  EXPECT_FALSE(h2.valid());
+  ASSERT_TRUE(p2 != nullptr);
+  int p2_id = p2->id();
+
+  // A newly promoted ProducerBuffer should inherit the same buffer id.
+  EXPECT_EQ(b1_id, p2_id);
+  EXPECT_TRUE(IsBufferGained(p2->buffer_state()));
+}
diff --git a/libs/vr/libbufferhub/detached_buffer.cpp b/libs/vr/libbufferhub/detached_buffer.cpp
index 1d59cf374c..6fae16d265 100644
--- a/libs/vr/libbufferhub/detached_buffer.cpp
+++ b/libs/vr/libbufferhub/detached_buffer.cpp
@@ -3,7 +3,11 @@
 #include <pdx/file_handle.h>
 #include <ui/DetachedBufferHandle.h>
 
+#include <poll.h>
+
+using android::pdx::LocalChannelHandle;
 using android::pdx::LocalHandle;
+using android::pdx::Status;
 
 namespace android {
 namespace dvr {
@@ -78,9 +82,26 @@ int DetachedBuffer::ImportGraphicBuffer() {
   return 0;
 }
 
-std::unique_ptr<BufferProducer> DetachedBuffer::Promote() {
-  ALOGE("DetachedBuffer::Promote: Not implemented.");
-  return nullptr;
+int DetachedBuffer::Poll(int timeout_ms) {
+  ATRACE_NAME("DetachedBuffer::Poll");
+  pollfd p = {client_.event_fd(), POLLIN, 0};
+  return poll(&p, 1, timeout_ms);
+}
+
+Status<LocalChannelHandle> DetachedBuffer::Promote() {
+  ATRACE_NAME("DetachedBuffer::Promote");
+  ALOGD_IF(TRACE, "DetachedBuffer::Promote: id=%d.", id_);
+
+  auto status_or_handle =
+      client_.InvokeRemoteMethod<DetachedBufferRPC::Promote>();
+  if (status_or_handle.ok()) {
+    // Invalidate the buffer.
+    buffer_ = {};
+  } else {
+    ALOGE("DetachedBuffer::Promote: Failed to promote buffer (id=%d): %s.", id_,
+          status_or_handle.GetErrorMessage().c_str());
+  }
+  return status_or_handle;
 }
 
 sp<GraphicBuffer> DetachedBuffer::TakeGraphicBuffer() {
diff --git a/libs/vr/libbufferhub/include/private/dvr/buffer_hub_client.h b/libs/vr/libbufferhub/include/private/dvr/buffer_hub_client.h
index c1cc7f34f8..0ea77c85fb 100644
--- a/libs/vr/libbufferhub/include/private/dvr/buffer_hub_client.h
+++ b/libs/vr/libbufferhub/include/private/dvr/buffer_hub_client.h
@@ -18,17 +18,17 @@ namespace dvr {
 
 class BufferHubClient : public pdx::Client {
  public:
-  using LocalChannelHandle = pdx::LocalChannelHandle;
-
   BufferHubClient();
-  explicit BufferHubClient(LocalChannelHandle channel_handle);
+  explicit BufferHubClient(pdx::LocalChannelHandle channel_handle);
 
   bool IsValid() const;
-  LocalChannelHandle TakeChannelHandle();
+  pdx::LocalChannelHandle TakeChannelHandle();
 
   using pdx::Client::Close;
+  using pdx::Client::GetChannel;
   using pdx::Client::InvokeRemoteMethod;
   using pdx::Client::IsConnected;
+  using pdx::Client::event_fd;
 };
 
 class BufferHubBuffer : public pdx::Client {
diff --git a/libs/vr/libbufferhub/include/private/dvr/detached_buffer.h b/libs/vr/libbufferhub/include/private/dvr/detached_buffer.h
index 73e895d7ef..6d0b502271 100644
--- a/libs/vr/libbufferhub/include/private/dvr/detached_buffer.h
+++ b/libs/vr/libbufferhub/include/private/dvr/detached_buffer.h
@@ -8,8 +8,6 @@ namespace dvr {
 
 class DetachedBuffer {
  public:
-  using LocalChannelHandle = pdx::LocalChannelHandle;
-
   // Allocates a standalone DetachedBuffer not associated with any producer
   // consumer set.
   static std::unique_ptr<DetachedBuffer> Create(uint32_t width, uint32_t height,
@@ -22,7 +20,7 @@ class DetachedBuffer {
 
   // Imports the given channel handle to a DetachedBuffer, taking ownership.
   static std::unique_ptr<DetachedBuffer> Import(
-      LocalChannelHandle channel_handle) {
+      pdx::LocalChannelHandle channel_handle) {
     return std::unique_ptr<DetachedBuffer>(
         new DetachedBuffer(std::move(channel_handle)));
   }
@@ -33,12 +31,31 @@ class DetachedBuffer {
   const sp<GraphicBuffer>& buffer() const { return buffer_.buffer(); }
 
   int id() const { return id_; }
-  bool IsValid() const { return client_.IsValid(); }
+
+  // Returns true if the buffer holds an open PDX channels towards bufferhubd.
+  bool IsConnected() const { return client_.IsValid(); }
+
+  // Returns true if the buffer holds an valid gralloc buffer handle that's
+  // availble for the client to read from and/or write into.
+  bool IsValid() const { return buffer_.IsValid(); }
+
+  // Returns the event mask for all the events that are pending on this buffer
+  // (see sys/poll.h for all possible bits).
+  pdx::Status<int> GetEventMask(int events) {
+    if (auto* channel = client_.GetChannel()) {
+      return channel->GetEventMask(events);
+    } else {
+      return pdx::ErrorStatus(EINVAL);
+    }
+  }
+
+  // Polls the fd for |timeout_ms| milliseconds (-1 for infinity).
+  int Poll(int timeout_ms);
 
   // Promotes a DetachedBuffer to become a ProducerBuffer. Once promoted the
   // DetachedBuffer channel will be closed automatically on successful IPC
   // return. Further IPCs towards this channel will return error.
-  std::unique_ptr<BufferProducer> Promote();
+  pdx::Status<pdx::LocalChannelHandle> Promote();
 
   // Takes the underlying graphic buffer out of this DetachedBuffer. This call
   // immediately invalidates this DetachedBuffer object and transfers the
@@ -49,7 +66,7 @@ class DetachedBuffer {
   DetachedBuffer(uint32_t width, uint32_t height, uint32_t layer_count,
                  uint32_t format, uint64_t usage, size_t user_metadata_size);
 
-  DetachedBuffer(LocalChannelHandle channel_handle);
+  DetachedBuffer(pdx::LocalChannelHandle channel_handle);
 
   int ImportGraphicBuffer();
 
diff --git a/services/vr/bufferhubd/buffer_hub.cpp b/services/vr/bufferhubd/buffer_hub.cpp
index 72bf6f2eb7..e57c8edfe3 100644
--- a/services/vr/bufferhubd/buffer_hub.cpp
+++ b/services/vr/bufferhubd/buffer_hub.cpp
@@ -266,6 +266,14 @@ pdx::Status<void> BufferHubService::HandleMessage(Message& message) {
       SetChannel(channel->channel_id(), nullptr);
       return {};
 
+    case DetachedBufferRPC::Promote::Opcode:
+      // In addition to the message handler in the DetachedBufferChannel's
+      // HandleMessage method, we also need to invalid the channel. Note that
+      // this has to be done after HandleMessage returns to make sure the IPC
+      // request has went back to the client first.
+      SetChannel(channel->channel_id(), nullptr);
+      return {};
+
     default:
       return DefaultHandleMessage(message);
   }
diff --git a/services/vr/bufferhubd/detached_buffer_channel.cpp b/services/vr/bufferhubd/detached_buffer_channel.cpp
index 4f4160ab88..a5cf68dcfd 100644
--- a/services/vr/bufferhubd/detached_buffer_channel.cpp
+++ b/services/vr/bufferhubd/detached_buffer_channel.cpp
@@ -1,4 +1,5 @@
 #include "detached_buffer_channel.h"
+#include "producer_channel.h"
 
 using android::pdx::BorrowedHandle;
 using android::pdx::ErrorStatus;
@@ -62,6 +63,14 @@ DetachedBufferChannel::DetachedBufferChannel(BufferHubService* service,
   }
 }
 
+DetachedBufferChannel::~DetachedBufferChannel() {
+  ALOGD_IF(TRACE,
+           "DetachedBufferChannel::~DetachedBufferChannel: channel_id=%d "
+           "buffer_id=%d.",
+           channel_id(), buffer_id());
+  Hangup();
+}
+
 BufferHubChannel::BufferInfo DetachedBufferChannel::GetBufferInfo() const {
   return BufferInfo(buffer_id(), /*consumer_count=*/0, buffer_.width(),
                     buffer_.height(), buffer_.layer_count(), buffer_.format(),
@@ -106,13 +115,44 @@ Status<BufferDescription<BorrowedHandle>> DetachedBufferChannel::OnImport(
 }
 
 Status<RemoteChannelHandle> DetachedBufferChannel::OnPromote(
-    Message& /*message*/) {
+    Message& message) {
   ATRACE_NAME("DetachedBufferChannel::OnPromote");
   ALOGD_IF(TRACE, "DetachedBufferChannel::OnPromote: buffer_id=%d",
            buffer_id());
 
-  // TODO(b/69982239): Implement the logic to promote a detached buffer.
-  return ErrorStatus(ENOSYS);
+  // Note that the new ProducerChannel will have different channel_id, but
+  // inherits the buffer_id from the DetachedBuffer.
+  int channel_id;
+  auto status = message.PushChannel(0, nullptr, &channel_id);
+  if (!status) {
+    ALOGE(
+        "DetachedBufferChannel::OnPromote: Failed to push ProducerChannel: %s.",
+        status.GetErrorMessage().c_str());
+    return ErrorStatus(ENOMEM);
+  }
+
+  std::unique_ptr<ProducerChannel> channel = ProducerChannel::Create(
+      service(), buffer_id(), channel_id, std::move(buffer_),
+      std::move(metadata_buffer_), user_metadata_size_);
+  if (!channel) {
+    ALOGE(
+        "DetachedBufferChannel::OnPromote: Failed to create ProducerChannel "
+        "from a DetachedBufferChannel, buffer_id=%d.",
+        buffer_id());
+  }
+
+  const auto channel_status =
+      service()->SetChannel(channel_id, std::move(channel));
+  if (!channel_status) {
+    // Technically, this should never fail, as we just pushed the channel. Note
+    // that LOG_FATAL will be stripped out in non-debug build.
+    LOG_FATAL(
+        "DetachedBufferChannel::OnPromote: Failed to set new producer buffer "
+        "channel: %s.",
+        channel_status.GetErrorMessage().c_str());
+  }
+
+  return status;
 }
 
 }  // namespace dvr
diff --git a/services/vr/bufferhubd/detached_buffer_channel.h b/services/vr/bufferhubd/detached_buffer_channel.h
index 079ba72d88..8b6dab8538 100644
--- a/services/vr/bufferhubd/detached_buffer_channel.h
+++ b/services/vr/bufferhubd/detached_buffer_channel.h
@@ -11,6 +11,8 @@ namespace dvr {
 
 class DetachedBufferChannel : public BufferHubChannel {
  public:
+  ~DetachedBufferChannel() override;
+
   template <typename... Args>
   static std::unique_ptr<DetachedBufferChannel> Create(Args&&... args) {
     auto buffer = std::unique_ptr<DetachedBufferChannel>(
diff --git a/services/vr/bufferhubd/producer_channel.cpp b/services/vr/bufferhubd/producer_channel.cpp
index a753168750..b6977aaa63 100644
--- a/services/vr/bufferhubd/producer_channel.cpp
+++ b/services/vr/bufferhubd/producer_channel.cpp
@@ -35,6 +35,30 @@ static inline uint64_t FindNextClearedBit(uint64_t bits) {
 
 }  // namespace
 
+ProducerChannel::ProducerChannel(BufferHubService* service, int buffer_id,
+                                 int channel_id, IonBuffer buffer,
+                                 IonBuffer metadata_buffer,
+                                 size_t user_metadata_size, int* error)
+    : BufferHubChannel(service, buffer_id, channel_id, kProducerType),
+      buffer_(std::move(buffer)),
+      metadata_buffer_(std::move(metadata_buffer)),
+      user_metadata_size_(user_metadata_size),
+      metadata_buf_size_(BufferHubDefs::kMetadataHeaderSize +
+                         user_metadata_size) {
+  if (!buffer_.IsValid()) {
+    ALOGE("ProducerChannel::ProducerChannel: Invalid buffer.");
+    *error = -EINVAL;
+    return;
+  }
+  if (!metadata_buffer_.IsValid()) {
+    ALOGE("ProducerChannel::ProducerChannel: Invalid metadata buffer.");
+    *error = -EINVAL;
+    return;
+  }
+
+  *error = InitializeBuffer();
+}
+
 ProducerChannel::ProducerChannel(BufferHubService* service, int channel_id,
                                  uint32_t width, uint32_t height,
                                  uint32_t layer_count, uint32_t format,
@@ -63,13 +87,16 @@ ProducerChannel::ProducerChannel(BufferHubService* service, int channel_id,
     return;
   }
 
+  *error = InitializeBuffer();
+}
+
+int ProducerChannel::InitializeBuffer() {
   void* metadata_ptr = nullptr;
   if (int ret = metadata_buffer_.Lock(BufferHubDefs::kMetadataUsage, /*x=*/0,
                                       /*y=*/0, metadata_buf_size_,
                                       /*height=*/1, &metadata_ptr)) {
     ALOGE("ProducerChannel::ProducerChannel: Failed to lock metadata.");
-    *error = -ret;
-    return;
+    return ret;
   }
   metadata_header_ =
       reinterpret_cast<BufferHubDefs::MetadataHeader*>(metadata_ptr);
@@ -85,15 +112,13 @@ ProducerChannel::ProducerChannel(BufferHubService* service, int channel_id,
   release_fence_fd_.Reset(epoll_create1(EPOLL_CLOEXEC));
   if (!acquire_fence_fd_ || !release_fence_fd_) {
     ALOGE("ProducerChannel::ProducerChannel: Failed to create shared fences.");
-    *error = -EIO;
-    return;
+    return -EIO;
   }
 
   dummy_fence_fd_.Reset(eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK));
   if (!dummy_fence_fd_) {
     ALOGE("ProducerChannel::ProducerChannel: Failed to create dummy fences.");
-    *error = -EIO;
-    return;
+    return EIO;
   }
 
   epoll_event event;
@@ -105,12 +130,25 @@ ProducerChannel::ProducerChannel(BufferHubService* service, int channel_id,
         "ProducerChannel::ProducerChannel: Failed to modify the shared "
         "release fence to include the dummy fence: %s",
         strerror(errno));
-    *error = -EIO;
-    return;
+    return -EIO;
   }
 
   // Success.
-  *error = 0;
+  return 0;
+}
+
+std::unique_ptr<ProducerChannel> ProducerChannel::Create(
+    BufferHubService* service, int buffer_id, int channel_id, IonBuffer buffer,
+    IonBuffer metadata_buffer, size_t user_metadata_size) {
+  int error = 0;
+  std::unique_ptr<ProducerChannel> producer(new ProducerChannel(
+      service, buffer_id, channel_id, std::move(buffer),
+      std::move(metadata_buffer), user_metadata_size, &error));
+
+  if (error < 0)
+    return nullptr;
+  else
+    return producer;
 }
 
 Status<std::shared_ptr<ProducerChannel>> ProducerChannel::Create(
diff --git a/services/vr/bufferhubd/producer_channel.h b/services/vr/bufferhubd/producer_channel.h
index de9ff31749..67fdf150a0 100644
--- a/services/vr/bufferhubd/producer_channel.h
+++ b/services/vr/bufferhubd/producer_channel.h
@@ -30,6 +30,12 @@ class ProducerChannel : public BufferHubChannel {
   template <typename T>
   using BufferWrapper = pdx::rpc::BufferWrapper<T>;
 
+  static std::unique_ptr<ProducerChannel> Create(BufferHubService* service,
+                                                 int buffer_id, int channel_id,
+                                                 IonBuffer buffer,
+                                                 IonBuffer metadata_buffer,
+                                                 size_t user_metadata_size);
+
   static pdx::Status<std::shared_ptr<ProducerChannel>> Create(
       BufferHubService* service, int channel_id, uint32_t width,
       uint32_t height, uint32_t layer_count, uint32_t format, uint64_t usage,
@@ -92,10 +98,14 @@ class ProducerChannel : public BufferHubChannel {
   pdx::LocalHandle release_fence_fd_;
   pdx::LocalHandle dummy_fence_fd_;
 
+  ProducerChannel(BufferHubService* service, int buffer_id, int channel_id,
+                  IonBuffer buffer, IonBuffer metadata_buffer,
+                  size_t user_metadata_size, int* error);
   ProducerChannel(BufferHubService* service, int channel, uint32_t width,
                   uint32_t height, uint32_t layer_count, uint32_t format,
                   uint64_t usage, size_t user_metadata_size, int* error);
 
+  int InitializeBuffer();
   pdx::Status<BufferDescription<BorrowedHandle>> OnGetBuffer(Message& message);
   pdx::Status<void> OnProducerPost(Message& message, LocalFence acquire_fence);
   pdx::Status<LocalFence> OnProducerGain(Message& message);