What is a valid handle to an open stream object?

[AvatarGanymede]

I'm trying to implement a quic server with 4 connections to it. When sending data, I maintain a ref_count variable, before sending, ref_count++, when getting SEND_COMPLETE event, ref_count--. When ref_count == 0 I free the send buffer.
So I try to pass a struct as the context of StreamSend:

typedef struct MANAGER {
	uint32_t ref_count;
	uint32_t Length;
	_Field_size_bytes_(Length)
	uint8_t* Buffer;
} MANAGER;

MsQuic->StreamSend(Stream, SendBuffer, 1, QUIC_SEND_FLAG_NONE | QUIC_SEND_FLAG_ALLOW_0_RTT, Manager))

In StreamCallBack funciton:

    MANAGER* ClientContext = (MANAGER*)(Event->SEND_COMPLETE.ClientContext);
    switch (Event->Type) {
    ...
    case QUIC_STREAM_EVENT_SEND_COMPLETE:
        ClientContext->ref_count --;
        if (ClientContext->ref_count == 0) {
            free(ClientContext);
        }
        break;
    default:
        break;
    }

The program failed, without any feedbacks.
In the doc, it says

ClientSendContext

The valid handle to an open stream object.

What is a "valid handle to an open stream object"?
I've read all the examples in this repo and found that the context of StreamSend is either SendBuffer or nullptr. Does this means that the "valid" SendContext should be SendBuffer?

[nibanks]

First off, it's a doc bug that it says ClientSendContext should be "The valid handle to an open stream object." It can be any data the application wants; and is simply a pass through, eventually being delivered to the app in the QUIC_STREAM_EVENT_SEND_COMPLETE events. So that wouldn't be the cause of your failure. It's likely some other variable you are passing into the function is bad. What exactly is failing? And with what error?

[AvatarGanymede]

OK, now it's confirmed that any data can be passed as SendContext, which is important for me. Next I will concentrate on debugging ( have tried for 3 hours though -_-). Thanks for your reply !