从流中读取时，Grpc服务器中未处理异常

Question

我制作了一个简单的应用程序，其中文件块从客户端流式传输到服务器。服务器端我已经处理了异常，这样我自己的响应就会返回到客户端。然而，当我在从流读取完成之前抛出异常时，即使它被捕获并返回自定义响应，客户端我仍然会得到一个未处理的RpcException，状态为Cancelled。

public override async Task<UploadFileResponse> UploadFile(
IAsyncStreamReader<UploadFileRequest> requestStream,
ServerCallContext context)
{
try
{
bool moveNext = await requestStream.MoveNext();
using (var stream = System.IO.File.Create($"foo.txt"))
{
while (moveNext)
{
// If something goes wrong here, before the stream has been fully read, an RpcException
// of status Cancelled is caught in the client instead of receiving an UploadFileResponse of
// type 'Failed'. Despite the fact that we catch it in the server and return a Failed response.
await stream.WriteAsync(requestStream.Current.Data.ToByteArray());
moveNext = await requestStream.MoveNext();
throw new Exception();
}
// If something goes wrong here, when the stream has been fully read, we catch it and successfully return
// a response of our own instead of an RpcException.
// throw new Exception();
}
return new UploadFileResponse()
{
StatusCode = UploadStatusCode.Ok
};
}
catch (Exception ex)
{
return new UploadFileResponse()
{
Message = ex.Message,
StatusCode = UploadStatusCode.Failed
};
}
}

也许我实施这项行动的方式是错误的。我可以理解为什么服务器会返回CancelledRPC异常，因为我们确实在流被完全读取之前取消了调用，但我不明白为什么它会覆盖自定义响应。这两种情况的处理可能都必须在客户端完成——一个失败的响应和一个潜在的RPC异常。

Answer 1

我找到了一些关于"服务器和客户端"主题的材料。

显然，每当出现无效响应时，抛出RpcException是很常见的，正如这里的官方gRPC Github存储库中所示。