feat: implement Packet.GetProtoList (#1080)

* feat: implement Packet.GetProtoList

* perf: avoid allocation

Packages/com.github.homuler.mediapipe/Runtime/Scripts/External/SerializedProtoVector.cs

@@ -27,6 +27,19 @@ public void Dispose()
     {
       var protos = new List<T>(_size);
 
+      Deserialize(parser, protos);
+
+      return protos;
+    }
+
+    /// <summary>
+    ///   Deserializes the data as a list of <typeparamref name="T" />.
+    /// </summary>
+    /// <param name="protos">A list of <typeparamref name="T" /> to populate</param>
+    public void Deserialize<T>(pb::MessageParser<T> parser, List<T> protos) where T : pb::IMessage<T>
+    {
+      protos.Clear();
+
       unsafe
       {
         var protoPtr = (SerializedProto*)_data;
@@ -37,8 +50,6 @@ public void Dispose()
           protos.Add(serializedProto.Deserialize(parser));
         }
       }
-
-      return protos;
     }
   }
 }

Packages/com.github.homuler.mediapipe/Runtime/Scripts/Framework/Packet.cs

@@ -478,7 +478,7 @@ public ImageFrame GetImageFrame()
     ///   On some platforms (e.g. Windows), it will abort the process when <see cref="MediaPipeException"/> should be thrown.
     /// </remarks>
     /// <exception cref="MediaPipeException">
-    ///   If the <see cref="Packet"/> doesn't contain <see langword="int"/>  data.
+    ///   If the <see cref="Packet"/> doesn't contain <see langword="int"/> data.
     /// </exception>
     public int GetInt()
     {
@@ -499,7 +499,7 @@ public int GetInt()
     /// </exception>
     public T GetProto<T>(MessageParser<T> parser) where T : IMessage<T>
     {
-      UnsafeNativeMethods.mp_Packet__GetProto(mpPtr, out var value).Assert();
+      UnsafeNativeMethods.mp_Packet__GetProtoMessageLite(mpPtr, out var value).Assert();
 
       GC.KeepAlive(this);
 
@@ -509,6 +509,45 @@ public int GetInt()
       return proto;
     }
 
+    /// <summary>
+    ///   Get the content of the <see cref="Packet"/> as a proto message list.
+    /// </summary>
+    /// <remarks>
+    ///   On some platforms (e.g. Windows), it will abort the process when <see cref="MediaPipeException"/> should be thrown.
+    /// </remarks>
+    /// <exception cref="MediaPipeException">
+    ///   If the <see cref="Packet"/> doesn't contain a proto message list.
+    /// </exception>
+    public List<T> GetProtoList<T>(MessageParser<T> parser) where T : IMessage<T>
+    {
+      var value = new List<T>();
+      GetProtoList(parser, value);
+
+      return value;
+    }
+
+    /// <summary>
+    ///   Get the content of the <see cref="Packet"/> as a proto message list.
+    /// </summary>
+    /// <remarks>
+    ///   On some platforms (e.g. Windows), it will abort the process when <see cref="MediaPipeException"/> should be thrown.
+    /// </remarks>
+    /// <param name="value">
+    ///   The <see cref="List{T}"/> to be filled with the content of the <see cref="Packet"/>.
+    /// </param>
+    /// <exception cref="MediaPipeException">
+    ///   If the <see cref="Packet"/> doesn't contain a proto message list.
+    /// </exception>
+    public void GetProtoList<T>(MessageParser<T> parser, List<T> value) where T : IMessage<T>
+    {
+      UnsafeNativeMethods.mp_Packet__GetVectorOfProtoMessageLite(mpPtr, out var serializedProtoVector).Assert();
+
+      GC.KeepAlive(this);
+
+      serializedProtoVector.Deserialize(parser, value);
+      serializedProtoVector.Dispose();
+    }
+
     /// <summary>
     ///   Validate if the content of the <see cref="Packet"/> is a boolean.
     /// </summary>

Packages/com.github.homuler.mediapipe/Runtime/Scripts/PInvoke/NativeMethods/Framework/Packet_Unsafe.cs

@@ -186,7 +186,10 @@ internal static partial class UnsafeNativeMethods
         out IntPtr status, out IntPtr packet);
 
     [DllImport(MediaPipeLibrary, ExactSpelling = true)]
-    public static extern MpReturnCode mp_Packet__GetProto(IntPtr packet, out SerializedProto value);
+    public static extern MpReturnCode mp_Packet__GetProtoMessageLite(IntPtr packet, out SerializedProto value);
+
+    [DllImport(MediaPipeLibrary, ExactSpelling = true)]
+    public static extern MpReturnCode mp_Packet__GetVectorOfProtoMessageLite(IntPtr packet, out SerializedProtoVector value);
 
     [DllImport(MediaPipeLibrary, ExactSpelling = true)]
     public static extern MpReturnCode mp_Packet__ValidateAsProtoMessageLite(IntPtr packet, out IntPtr status);

mediapipe_api/external/protobuf.h

@@ -46,6 +46,17 @@ inline void SerializeProtoVector(const std::vector<T>& proto_vec, mp_api::Struct
   serialized_proto_vector->size = static_cast<int>(vec_size);
 }
 
+inline void SerializeProtoVector(const std::vector<const google::protobuf::MessageLite*>& proto_vec, mp_api::StructArray<mp_api::SerializedProto>* serialized_proto_vector) {
+  auto vec_size = proto_vec.size();
+  auto data = new mp_api::SerializedProto[vec_size];
+
+  for (auto i = 0; i < vec_size; ++i) {
+    SerializeProto(*proto_vec[i], &data[i]);
+  }
+  serialized_proto_vector->data = data;
+  serialized_proto_vector->size = static_cast<int>(vec_size);
+}
+
 template <class T>
 inline T ParseFromStringAsProto(const char* serialized_data, int size) {
   T proto;

mediapipe_api/framework/packet.cc

@@ -400,14 +400,26 @@ MpReturnCode mp__PacketFromDynamicProto_At__PKc_PKc_i_ll(const char* type_name,
   CATCH_ALL
 }
 
-MpReturnCode mp_Packet__GetProto(mediapipe::Packet* packet, mp_api::SerializedProto* serialized_proto) {
+MpReturnCode mp_Packet__GetProtoMessageLite(mediapipe::Packet* packet, mp_api::SerializedProto* serialized_proto) {
   TRY_ALL
     const auto& proto = packet->GetProtoMessageLite();
     SerializeProto(proto, serialized_proto);
     RETURN_CODE(MpReturnCode::Success);
   CATCH_ALL
 }
 
+MpReturnCode mp_Packet__GetVectorOfProtoMessageLite(mediapipe::Packet* packet, mp_api::StructArray<mp_api::SerializedProto>* value_out) {
+  TRY_ALL
+    const auto status_or_vec = packet->GetVectorOfProtoMessageLitePtrs();
+    if (!status_or_vec.ok()) {
+      LOG(FATAL) << status_or_vec.status().message();
+    }
+
+    SerializeProtoVector(status_or_vec.value(), value_out);
+    RETURN_CODE(MpReturnCode::Success);
+  CATCH_ALL
+}
+
 MpReturnCode mp_Packet__ValidateAsProtoMessageLite(mediapipe::Packet* packet, absl::Status** status_out) {
   TRY
     *status_out = new absl::Status{packet->ValidateAsProtoMessageLite()};

mediapipe_api/framework/packet.h

@@ -108,7 +108,8 @@ MP_CAPI(MpReturnCode) mp__PacketFromDynamicProto__PKc_PKc_i(const char* type_nam
 MP_CAPI(MpReturnCode) mp__PacketFromDynamicProto_At__PKc_PKc_i_ll(const char* type_name, const char* serialized_proto, int size,
                                                                   int64 timestampMicrosec,
                                                                   absl::Status** status_out, mediapipe::Packet** packet_out);
-MP_CAPI(MpReturnCode) mp_Packet__GetProto(mediapipe::Packet* packet, mp_api::SerializedProto* serialized_proto);
+MP_CAPI(MpReturnCode) mp_Packet__GetProtoMessageLite(mediapipe::Packet* packet, mp_api::SerializedProto* value_out);
+MP_CAPI(MpReturnCode) mp_Packet__GetVectorOfProtoMessageLite(mediapipe::Packet* packet, mp_api::StructArray<mp_api::SerializedProto>* value_out);
 MP_CAPI(MpReturnCode) mp_Packet__ValidateAsProtoMessageLite(mediapipe::Packet* packet, absl::Status** status_out);
 
 /** PacketMap API */