MessageStream Class Reference

Length-prefixed framing layer over a TCP stream socket. More...

#include <MessageStream.hpp>

Public Member Functions
	MessageStream ()=default
	PR-5b: default-construct so server Connection (which embeds a MessageStream) can be try_emplace'd into the clients map.
	MessageStream (NET_StreamSocket *sock)
bool	send (const void *data, Uint32 size)
	Send a framed message over the socket.
bool	poll (const std::function< void(const void *data, Uint32 size)> &callback)
	Read all available bytes from the socket and invoke the callback once per complete message frame.
bool	pumpReads ()
	Read-only half of poll(): drain the kernel into recvBuf.
void	drainComplete (const std::function< void(const void *data, Uint32 size)> &callback)
	Decode-only half of poll(): invoke the callback for each complete message currently buffered.

Public Attributes
NET_StreamSocket *	socket = nullptr
	Underlying SDL_net stream socket.

Private Member Functions
Uint32	recvAvailable () const noexcept
	Bytes available for parsing in recvBuf, starting at recvHead.
const Uint8 *	recvFront () const noexcept
	Pointer to the first unconsumed byte.
void	recvCompact ()
	Compact recvBuf: shift unconsumed bytes to the front, reset head.

Private Attributes
std::vector< Uint8 >	recvBuf
	Accumulates partial data between poll() calls.
Uint32	recvHead = 0
	Offset of next unconsumed byte in recvBuf (avoids O(N) erase).

Detailed Description

Length-prefixed framing layer over a TCP stream socket.

Wraps a raw NET_StreamSocket and handles splitting the byte stream into discrete messages. Each message is sent/received with a 4-byte (host-endian) length header followed by the payload bytes.

Note

Receive draining: poll() loops NET_ReadFromStreamSocket until the kernel buffer is empty (returns 0). This is essential because each call to poll() must drain whatever the OS has queued, otherwise a snapshot stream that produces faster than the consumer reads will accumulate indefinitely in the kernel buffer (head-of-line blocking). See docs/networking.md.

recvBuf uses a head-offset compaction strategy instead of front-erase so draining N queued messages is O(N) total rather than O(N^2). The buffer is compacted (offset reset to 0) only when a threshold is crossed.

Constructor & Destructor Documentation

MessageStream() [1/2]

MessageStream::MessageStream ( )

default

PR-5b: default-construct so server Connection (which embeds a MessageStream) can be try_emplace'd into the clients map.

The actual socket is assigned right after via the MessageStream(NET_StreamSocket*) form.

MessageStream() [2/2]

MessageStream::MessageStream ( NET_StreamSocket * sock )

inline

Member Function Documentation

drainComplete()

void MessageStream::drainComplete

(

const std::function< void(const void *data, Uint32 size)> &

callback

)

Decode-only half of poll(): invoke the callback for each complete message currently buffered.

Stage 3c uses this from the game thread after pumpReads has run on the network thread. Together with pumpReads it does what poll() does in the single-threaded code path, just split across two threads.

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poll()

bool MessageStream::poll

(

const std::function< void(const void *data, Uint32 size)> &

callback

)

Read all available bytes from the socket and invoke the callback once per complete message frame.

Parameters

callback

Called with a pointer and length for each complete message.

Returns

False if the socket reports an error.

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pumpReads()

bool MessageStream::pumpReads

(

)

Read-only half of poll(): drain the kernel into recvBuf.

Stage 3c uses this from a dedicated network thread that owns kernel I/O. The corresponding drainComplete runs on the game thread to dispatch fully-received messages — both halves take a mutex around recvBuf so they don't race.

Returns

False on socket error (caller should disconnect).

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recvAvailable()

Uint32 MessageStream::recvAvailable ( ) const

inlinenodiscardprivatenoexcept

Bytes available for parsing in recvBuf, starting at recvHead.

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recvCompact()

void MessageStream::recvCompact ( )

private

Compact recvBuf: shift unconsumed bytes to the front, reset head.

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recvFront()

const Uint8 * MessageStream::recvFront ( ) const

inlinenodiscardprivatenoexcept

Pointer to the first unconsumed byte.

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send()

bool MessageStream::send	(	const void *	data,
		Uint32	size )

Send a framed message over the socket.

Parameters

data	Pointer to the payload bytes.
size	Payload length in bytes.

Returns

False if the send fails.

Member Data Documentation

recvBuf

std::vector<Uint8> MessageStream::recvBuf

private

Accumulates partial data between poll() calls.

recvHead

Uint32 MessageStream::recvHead = 0

private

Offset of next unconsumed byte in recvBuf (avoids O(N) erase).

socket

NET_StreamSocket* MessageStream::socket = nullptr

Underlying SDL_net stream socket.

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The documentation for this class was generated from the following files:

• src/network/MessageStream.hpp
• src/network/MessageStream.cpp