bufferhubd: Add DetachedBufferChannel

1/ Introduces four new BufferHub RPC operations.
2/ Implements the ProducerBufferDetach with test case.
3/ Also fixes a bug that Hangup signal wasn't propogated to the client
   when bufferhubd closes a producer channel.

Bug: 38137191
Bug: 70046255
Bug: 70912269
Test: buffer_hub-test
Change-Id: Ia2ba0e95abd3c1b960670c505c6fdb9c9de3a6dd
diff --git a/libs/vr/libbufferhub/buffer_hub-test.cpp b/libs/vr/libbufferhub/buffer_hub-test.cpp
index b7a6099..3ce5c9f 100644
--- a/libs/vr/libbufferhub/buffer_hub-test.cpp
+++ b/libs/vr/libbufferhub/buffer_hub-test.cpp
@@ -25,7 +25,9 @@
 using android::dvr::BufferHubDefs::IsBufferAcquired;
 using android::dvr::BufferHubDefs::IsBufferReleased;
 using android::dvr::BufferProducer;
+using android::pdx::LocalChannelHandle;
 using android::pdx::LocalHandle;
+using android::pdx::Status;
 
 const int kWidth = 640;
 const int kHeight = 480;
@@ -717,3 +719,59 @@
   // Producer should be able to gain no matter what.
   EXPECT_EQ(0, p->GainAsync(&meta, &fence));
 }
+
+TEST_F(LibBufferHubTest, TestDetachBufferFromProducer) {
+  std::unique_ptr<BufferProducer> p = BufferProducer::Create(
+      kWidth, kHeight, kFormat, kUsage, sizeof(uint64_t));
+  std::unique_ptr<BufferConsumer> c =
+      BufferConsumer::Import(p->CreateConsumer());
+  ASSERT_TRUE(p.get() != nullptr);
+  ASSERT_TRUE(c.get() != nullptr);
+
+  DvrNativeBufferMetadata metadata;
+  LocalHandle invalid_fence;
+
+  // Detach in posted state should fail.
+  EXPECT_EQ(0, p->PostAsync(&metadata, invalid_fence));
+  EXPECT_GT(RETRY_EINTR(c->Poll(kPollTimeoutMs)), 0);
+  auto s1 = p->Detach();
+  EXPECT_FALSE(s1);
+
+  // Detach in acquired state should fail.
+  EXPECT_EQ(0, c->AcquireAsync(&metadata, &invalid_fence));
+  s1 = p->Detach();
+  EXPECT_FALSE(s1);
+
+  // Detach in released state should fail.
+  EXPECT_EQ(0, c->ReleaseAsync(&metadata, invalid_fence));
+  EXPECT_GT(RETRY_EINTR(p->Poll(kPollTimeoutMs)), 0);
+  s1 = p->Detach();
+  EXPECT_FALSE(s1);
+
+  // Detach in gained state should succeed.
+  EXPECT_EQ(0, p->GainAsync(&metadata, &invalid_fence));
+  s1 = p->Detach();
+  EXPECT_TRUE(s1);
+
+  LocalChannelHandle detached_buffer = s1.take();
+  EXPECT_TRUE(detached_buffer.valid());
+
+  // Both producer and consumer should have hangup.
+  EXPECT_GT(RETRY_EINTR(p->Poll(kPollTimeoutMs)), 0);
+  auto s2 = p->GetEventMask(POLLHUP);
+  EXPECT_TRUE(s2);
+  EXPECT_EQ(s2.get(), POLLHUP);
+
+  EXPECT_GT(RETRY_EINTR(c->Poll(kPollTimeoutMs)), 0);
+  s2 = p->GetEventMask(POLLHUP);
+  EXPECT_TRUE(s2);
+  EXPECT_EQ(s2.get(), POLLHUP);
+
+  auto s3 = p->CreateConsumer();
+  EXPECT_FALSE(s3);
+  EXPECT_EQ(s3.error(), EOPNOTSUPP);
+
+  s3 = c->CreateConsumer();
+  EXPECT_FALSE(s3);
+  EXPECT_EQ(s3.error(), EOPNOTSUPP);
+}
diff --git a/libs/vr/libbufferhub/buffer_hub_client.cpp b/libs/vr/libbufferhub/buffer_hub_client.cpp
index 6db09a9..13971eb 100644
--- a/libs/vr/libbufferhub/buffer_hub_client.cpp
+++ b/libs/vr/libbufferhub/buffer_hub_client.cpp
@@ -608,5 +608,23 @@
                        : LocalChannelHandle{nullptr, -status.error()});
 }
 
+Status<LocalChannelHandle> BufferProducer::Detach() {
+  uint64_t buffer_state = buffer_state_->load();
+  if (!BufferHubDefs::IsBufferGained(buffer_state)) {
+    // Can only detach a BufferProducer when it's in gained state.
+    ALOGW("BufferProducer::Detach: The buffer (id=%d, state=0x%" PRIx64
+          ") is not in gained state.",
+          id(), buffer_state);
+    return {};
+  }
+
+  Status<LocalChannelHandle> status =
+      InvokeRemoteMethod<BufferHubRPC::ProducerBufferDetach>();
+  ALOGE_IF(!status,
+           "BufferProducer::Detach: Failed to detach buffer (id=%d): %s.", id(),
+           status.GetErrorMessage().c_str());
+  return status;
+}
+
 }  // namespace dvr
 }  // namespace android
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 c791250..32448a1 100644
--- a/libs/vr/libbufferhub/include/private/dvr/buffer_hub_client.h
+++ b/libs/vr/libbufferhub/include/private/dvr/buffer_hub_client.h
@@ -217,6 +217,14 @@
   // succeeded, or a negative errno code if local error check fails.
   int GainAsync(DvrNativeBufferMetadata* out_meta, LocalHandle* out_fence);
 
+  // Detaches a ProducerBuffer from an existing producer/consumer set. Can only
+  // be called when a producer buffer has exclusive access to the buffer (i.e.
+  // in the gain'ed state). On the successful return of the IPC call, a new
+  // LocalChannelHandle representing a detached buffer will be returned and all
+  // existing producer and consumer channels will be closed. Further IPCs
+  // towards those channels will return error.
+  Status<LocalChannelHandle> Detach();
+
  private:
   friend BASE;
 
diff --git a/libs/vr/libbufferhub/include/private/dvr/bufferhub_rpc.h b/libs/vr/libbufferhub/include/private/dvr/bufferhub_rpc.h
index c70fffc..fabefd5 100644
--- a/libs/vr/libbufferhub/include/private/dvr/bufferhub_rpc.h
+++ b/libs/vr/libbufferhub/include/private/dvr/bufferhub_rpc.h
@@ -373,6 +373,10 @@
     kOpConsumerAcquire,
     kOpConsumerRelease,
     kOpConsumerSetIgnore,
+    kOpProducerBufferDetach,
+    kOpConsumerBufferDetach,
+    kOpCreateDetachedBuffer,
+    kOpDetachedBufferPromote,
     kOpCreateProducerQueue,
     kOpCreateConsumerQueue,
     kOpGetQueueInfo,
@@ -400,6 +404,28 @@
   PDX_REMOTE_METHOD(ConsumerRelease, kOpConsumerRelease,
                     void(LocalFence release_fence));
   PDX_REMOTE_METHOD(ConsumerSetIgnore, kOpConsumerSetIgnore, void(bool ignore));
+  PDX_REMOTE_METHOD(ProducerBufferDetach, kOpProducerBufferDetach,
+                    LocalChannelHandle(Void));
+
+  // Detaches a ConsumerBuffer from an existing producer/consumer set. Can only
+  // be called when the consumer is the only consumer and it has exclusive
+  // access to the buffer (i.e. in the acquired'ed state). On the successful
+  // return of the IPC call, a new DetachedBufferChannel handle will be returned
+  // and all existing producer and consumer channels will be closed. Further
+  // IPCs towards those channels will return error.
+  PDX_REMOTE_METHOD(ConsumerBufferDetach, kOpConsumerBufferDetach,
+                    LocalChannelHandle(Void));
+
+  // Creates a standalone DetachedBuffer not associated with any
+  // producer/consumer set.
+  PDX_REMOTE_METHOD(CreateDetachedBuffer, kOpCreateDetachedBuffer,
+                    LocalChannelHandle(Void));
+
+  // 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.
+  PDX_REMOTE_METHOD(DetachedBufferPromote, kOpDetachedBufferPromote,
+                    LocalChannelHandle(Void));
 
   // Buffer Queue Methods.
   PDX_REMOTE_METHOD(CreateProducerQueue, kOpCreateProducerQueue,
diff --git a/services/vr/bufferhubd/Android.bp b/services/vr/bufferhubd/Android.bp
index 6009a95..6122846 100644
--- a/services/vr/bufferhubd/Android.bp
+++ b/services/vr/bufferhubd/Android.bp
@@ -17,6 +17,7 @@
     "bufferhubd.cpp",
     "consumer_channel.cpp",
     "producer_channel.cpp",
+    "detached_buffer_channel.cpp",
     "consumer_queue_channel.cpp",
     "producer_queue_channel.cpp",
 ]
diff --git a/services/vr/bufferhubd/buffer_hub.cpp b/services/vr/bufferhubd/buffer_hub.cpp
index 1eb4ef9..e4e19c7 100644
--- a/services/vr/bufferhubd/buffer_hub.cpp
+++ b/services/vr/bufferhubd/buffer_hub.cpp
@@ -100,6 +100,41 @@
       stream << std::setw(8) << info.index;
       stream << std::endl;
     }
+
+    if (channel->channel_type() == BufferHubChannel::kDetachedBufferType) {
+      BufferHubChannel::BufferInfo info = channel->GetBufferInfo();
+
+      stream << std::right;
+      stream << std::setw(6) << info.id;
+      stream << " ";
+      stream << std::setw(9) << "N/A";
+      stream << " ";
+      if (info.format == HAL_PIXEL_FORMAT_BLOB) {
+        std::string size = std::to_string(info.width) + " B";
+        stream << std::setw(14) << size;
+      } else {
+        std::string dimensions = std::to_string(info.width) + "x" +
+                                 std::to_string(info.height) + "x" +
+                                 std::to_string(info.layer_count);
+        stream << std::setw(14) << dimensions;
+      }
+      stream << " ";
+      stream << std::setw(6) << info.format;
+      stream << " ";
+      stream << "0x" << std::hex << std::setfill('0');
+      stream << std::setw(8) << info.usage;
+      stream << std::dec << std::setfill(' ');
+      stream << " ";
+      stream << std::setw(9) << "N/A";
+      stream << " ";
+      stream << std::hex << std::setfill(' ');
+      stream << std::setw(18) << "Detached";
+      stream << " ";
+      stream << std::setw(18) << "N/A";
+      stream << " ";
+      stream << std::setw(10) << "N/A";
+      stream << std::endl;
+    }
   }
 
   stream << std::endl;
@@ -215,6 +250,15 @@
           *this, &BufferHubService::OnCreateProducerQueue, message);
       return {};
 
+    case BufferHubRPC::ProducerBufferDetach::Opcode:
+      // In addition to the message handler in the ProducerChannel's
+      // HandleMessage method, we also need to invalid the producer channel (and
+      // all associated consumer channels). 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/buffer_hub.h b/services/vr/bufferhubd/buffer_hub.h
index b487b0b..e04967a 100644
--- a/services/vr/bufferhubd/buffer_hub.h
+++ b/services/vr/bufferhubd/buffer_hub.h
@@ -23,6 +23,7 @@
   enum ChannelType {
     kProducerType,
     kConsumerType,
+    kDetachedBufferType,
     kProducerQueueType,
     kConsumerQueueType,
   };
diff --git a/services/vr/bufferhubd/detached_buffer_channel.cpp b/services/vr/bufferhubd/detached_buffer_channel.cpp
new file mode 100644
index 0000000..edb2111
--- /dev/null
+++ b/services/vr/bufferhubd/detached_buffer_channel.cpp
@@ -0,0 +1,57 @@
+#include "detached_buffer_channel.h"
+
+using android::pdx::ErrorStatus;
+using android::pdx::Message;
+using android::pdx::RemoteChannelHandle;
+using android::pdx::Status;
+using android::pdx::rpc::DispatchRemoteMethod;
+
+namespace android {
+namespace dvr {
+
+DetachedBufferChannel::DetachedBufferChannel(BufferHubService* service,
+                                             int buffer_id, int channel_id,
+                                             IonBuffer buffer,
+                                             IonBuffer metadata_buffer,
+                                             size_t user_metadata_size)
+    : BufferHubChannel(service, buffer_id, channel_id, kDetachedBufferType),
+      buffer_(std::move(buffer)),
+      metadata_buffer_(std::move(metadata_buffer)),
+      user_metadata_size_(user_metadata_size) {}
+
+BufferHubChannel::BufferInfo DetachedBufferChannel::GetBufferInfo() const {
+  return BufferInfo(buffer_id(), /*consumer_count=*/0, buffer_.width(),
+                    buffer_.height(), buffer_.layer_count(), buffer_.format(),
+                    buffer_.usage(), /*pending_count=*/0, /*state=*/0,
+                    /*signaled_mask=*/0, /*index=*/0);
+}
+
+void DetachedBufferChannel::HandleImpulse(Message& /*message*/) {
+  ATRACE_NAME("DetachedBufferChannel::HandleImpulse");
+}
+
+bool DetachedBufferChannel::HandleMessage(Message& message) {
+  ATRACE_NAME("DetachedBufferChannel::HandleMessage");
+  switch (message.GetOp()) {
+    case BufferHubRPC::DetachedBufferPromote::Opcode:
+      DispatchRemoteMethod<BufferHubRPC::DetachedBufferPromote>(
+          *this, &DetachedBufferChannel::OnPromote, message);
+      return true;
+
+    default:
+      return false;
+  }
+}
+
+Status<RemoteChannelHandle> DetachedBufferChannel::OnPromote(
+    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);
+}
+
+}  // namespace dvr
+}  // namespace android
diff --git a/services/vr/bufferhubd/detached_buffer_channel.h b/services/vr/bufferhubd/detached_buffer_channel.h
new file mode 100644
index 0000000..7ce4aed
--- /dev/null
+++ b/services/vr/bufferhubd/detached_buffer_channel.h
@@ -0,0 +1,43 @@
+#ifndef ANDROID_DVR_BUFFERHUBD_DETACHED_BUFFER_CHANNEL_H_
+#define ANDROID_DVR_BUFFERHUBD_DETACHED_BUFFER_CHANNEL_H_
+
+#include "buffer_hub.h"
+
+// #include <pdx/channel_handle.h>
+// #include <pdx/file_handle.h>
+// #include <pdx/rpc/buffer_wrapper.h>
+// #include <private/dvr/ion_buffer.h>
+
+namespace android {
+namespace dvr {
+
+class DetachedBufferChannel : public BufferHubChannel {
+ public:
+  // Creates a detached buffer.
+  DetachedBufferChannel(BufferHubService* service, int buffer_id,
+                        int channel_id, IonBuffer buffer,
+                        IonBuffer metadata_buffer, size_t user_metadata_size);
+
+  size_t user_metadata_size() const { return user_metadata_size_; }
+
+  // Captures buffer info for use by BufferHubService::DumpState().
+  BufferInfo GetBufferInfo() const override;
+
+  bool HandleMessage(pdx::Message& message) override;
+  void HandleImpulse(pdx::Message& message) override;
+
+ private:
+  pdx::Status<pdx::RemoteChannelHandle> OnPromote(pdx::Message& message);
+
+  // Gralloc buffer handles.
+  IonBuffer buffer_;
+  IonBuffer metadata_buffer_;
+
+  // Size of user requested metadata.
+  const size_t user_metadata_size_;
+};
+
+}  // namespace dvr
+}  // namespace android
+
+#endif  // ANDROID_DVR_BUFFERHUBD_DETACHED_BUFFER_CHANNEL_H_
diff --git a/services/vr/bufferhubd/producer_channel.cpp b/services/vr/bufferhubd/producer_channel.cpp
index 8160193..e141b91 100644
--- a/services/vr/bufferhubd/producer_channel.cpp
+++ b/services/vr/bufferhubd/producer_channel.cpp
@@ -13,6 +13,7 @@
 
 #include <private/dvr/bufferhub_rpc.h>
 #include "consumer_channel.h"
+#include "detached_buffer_channel.h"
 
 using android::pdx::BorrowedHandle;
 using android::pdx::ErrorStatus;
@@ -131,8 +132,11 @@
            "ProducerChannel::~ProducerChannel: channel_id=%d buffer_id=%d "
            "state=%" PRIx64 ".",
            channel_id(), buffer_id(), buffer_state_->load());
-  for (auto consumer : consumer_channels_)
+  for (auto consumer : consumer_channels_) {
     consumer->OnProducerClosed();
+    service()->SetChannel(consumer->channel_id(), nullptr);
+  }
+  Hangup();
 }
 
 BufferHubChannel::BufferInfo ProducerChannel::GetBufferInfo() const {
@@ -183,6 +187,11 @@
           *this, &ProducerChannel::OnProducerGain, message);
       return true;
 
+    case BufferHubRPC::ProducerBufferDetach::Opcode:
+      DispatchRemoteMethod<BufferHubRPC::ProducerBufferDetach>(
+          *this, &ProducerChannel::OnProducerDetach, message);
+      return true;
+
     default:
       return false;
   }
@@ -337,6 +346,55 @@
   return {std::move(returned_fence_)};
 }
 
+Status<RemoteChannelHandle> ProducerChannel::OnProducerDetach(
+    Message& message) {
+  ATRACE_NAME("ProducerChannel::OnProducerDetach");
+  ALOGD_IF(TRACE, "ProducerChannel::OnProducerDetach: buffer_id=%d",
+           buffer_id());
+
+  uint64_t buffer_state = buffer_state_->load();
+  if (!BufferHubDefs::IsBufferGained(buffer_state)) {
+    // Can only detach a BufferProducer when it's in gained state.
+    ALOGW(
+        "ProducerChannel::OnProducerDetach: The buffer (id=%d, state=0x%" PRIx64
+        ") is not in gained state.",
+        buffer_id(), buffer_state);
+    return {};
+  }
+
+  int channel_id;
+  auto status = message.PushChannel(0, nullptr, &channel_id);
+  if (!status) {
+    ALOGE(
+        "ProducerChannel::OnProducerDetach: Failed to push detached buffer "
+        "channel: %s",
+        status.GetErrorMessage().c_str());
+    return ErrorStatus(ENOMEM);
+  }
+
+  // Make sure we unlock the buffer.
+  if (int ret = metadata_buffer_.Unlock()) {
+    ALOGE("ProducerChannel::OnProducerDetach: Failed to unlock metadata.");
+    return ErrorStatus(-ret);
+  };
+
+  auto channel = std::make_shared<DetachedBufferChannel>(
+      service(), buffer_id(), channel_id, std::move(buffer_),
+      std::move(metadata_buffer_), user_metadata_size_);
+
+  const auto channel_status = service()->SetChannel(channel_id, 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(
+        "ProducerChannel::OnProducerDetach: Failed to set new detached buffer "
+        "channel: %s.",
+        channel_status.GetErrorMessage().c_str());
+  }
+
+  return status;
+}
+
 Status<LocalFence> ProducerChannel::OnConsumerAcquire(Message& /*message*/) {
   ATRACE_NAME("ProducerChannel::OnConsumerAcquire");
   ALOGD_IF(TRACE, "ProducerChannel::OnConsumerAcquire: buffer_id=%d",
diff --git a/services/vr/bufferhubd/producer_channel.h b/services/vr/bufferhubd/producer_channel.h
index c5dbf0e..de9ff31 100644
--- a/services/vr/bufferhubd/producer_channel.h
+++ b/services/vr/bufferhubd/producer_channel.h
@@ -99,6 +99,7 @@
   pdx::Status<BufferDescription<BorrowedHandle>> OnGetBuffer(Message& message);
   pdx::Status<void> OnProducerPost(Message& message, LocalFence acquire_fence);
   pdx::Status<LocalFence> OnProducerGain(Message& message);
+  pdx::Status<RemoteChannelHandle> OnProducerDetach(Message& message);
 
   ProducerChannel(const ProducerChannel&) = delete;
   void operator=(const ProducerChannel&) = delete;