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Question about TcpSocket::Peek() / Get() [message #57123]

Thu, 27 May 2021 15:06

Xemuth
Messages: 387
Registered: August 2018
Location: France

Senior Member

Hello,

I'm digging the TcpSocket class mostly to learn how it has been done. Something have pinged my attention :

Inet.h

        enum { BUFFERSIZE = 512 };
	enum { NONE, CONNECT, ACCEPT, SSL_CONNECTED };
	SOCKET                  socket;
	int                     mode;
	char                    buffer[BUFFERSIZE];
	char                   *ptr;
	char                   *end;
...
        int                     Get_();
	int                     Peek_();
	int                     Peek_(int end_time);
	int                     Peek(int end_time)          { return ptr < end ? (byte)*ptr : Peek_(end_time); }

Socket.c

int TcpSocket::Get_()
{
	if(!IsOpen() || IsError() || IsEof() || IsAbort())
		return -1;
	ReadBuffer(GetEndTime());
	return ptr < end ? (byte)*ptr++ : -1;
}
...
void TcpSocket::ReadBuffer(int end_time)
{
	ptr = end = buffer;
	if(Wait(WAIT_READ, end_time))
		end = buffer + Recv(buffer, BUFFERSIZE);
}

Maybe the question is stupid, or maybe I missed something. But, Technicaly, what's the point of having a tiny buffer to receive data when this one is used only in Get() and Peek() and other function to retrieve data (except GetLine()) directly receive from socket ? (ie the function below)

Maybe to perform a software timeout instead of a low level timeout ?

Thanks in advance.

int TcpSocket::Get(void *buffer, int count)
{
	LLOG("Get " << count);

	if(!IsOpen() || IsError() || IsEof() || IsAbort())
		return 0;
	
	int l = (int)(end - ptr);
	done = 0;
	if(l > 0) {
		if(l < count) {
			memcpy(buffer, ptr, l);
			done += l;
			ptr = end;
		}
		else {
			memcpy(buffer, ptr, count);
			ptr += count;
			return count;
		}
	}
	int end_time = GetEndTime();
	while(done < count && !IsError() && !IsEof()) {
		if(!Wait(WAIT_READ, end_time))
			break;
		int part = Recv((char *)buffer + done, count - done);
		if(part > 0)
			done += part;
		if(timeout == 0)
			break;
	}
	return done;
}

[Updated on: Thu, 27 May 2021 15:13]

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