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using Google.Protobuf;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
using System.Runtime.ExceptionServices;
namespace Tango.PMR
{
/// <summary>
/// Represents a standard C++ protobuf method delegate.
/// </summary>
/// <param name="requestArray">The request array.</param>
/// <param name="requestArraySize">Size of the request array.</param>
/// <param name="resultArray">The result array.</param>
/// <returns>The size of the result array.</returns>
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate int NativeMethodDelegate(IntPtr requestArray, int requestArraySize, ref IntPtr resultArray);
/// <summary>
/// Represents a PMR wrapper for invoking native protobuf supported methods.
/// </summary>
/// <typeparam name="Request">The type of the Request.</typeparam>
/// <typeparam name="Response">The type of the Response.</typeparam>
public class NativePMR<Request, Response> where Request : IMessage<Request> where Response : class, IMessage<Response>
{
private NativeMethodDelegate _nativeMethod;
/// <summary>
/// Initializes a new instance of the <see cref="NativePMR{Request, Response}"/> class.
/// </summary>
/// <param name="nativeMethod">The native method.</param>
public NativePMR(NativeMethodDelegate nativeMethod)
{
_nativeMethod = nativeMethod;
}
/// <summary>
/// Invokes the native method with the specified request.
/// </summary>
/// <param name="request">The request.</param>
/// <param name="nativeMethod">The native method.</param>
/// <returns></returns>
[HandleProcessCorruptedStateExceptions]
public Response Invoke(Request request)
{
try
{
//Serialize the request to byte array.
byte[] messageData = request.ToByteArray();
//Allocate unmanaged array on memory.
IntPtr unmanagedArr = Marshal.AllocHGlobal(messageData.Length);
//Copy the request data to the unmanaged array.
Marshal.Copy(messageData, 0, unmanagedArr, messageData.Length);
//Initialize pointer for pointing to the result array.
IntPtr output = IntPtr.Zero;
//Invoke the native method.
int size = _nativeMethod(unmanagedArr, messageData.Length, ref output);
if (size == 0) return null;
//Initialize a new byte array for holding the native result.
byte[] responseData = new byte[size];
//Copy the unmanaged byte array result to the managed result array.
Marshal.Copy(output, responseData, 0, size);
//Generate response parser.
MessageParser<Response> parser = new MessageParser<Response>(() => Activator.CreateInstance<Response>());
//Parse the response
Response response = parser.ParseFrom(responseData);
//Free unmanaged memory.
Marshal.FreeHGlobal(unmanagedArr);
return response;
}
catch (Exception)
{
throw;
}
}
}
}
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