Struct SessionSocket

pub struct SessionSocket<const C: usize> { /* private fields */ }

Represents a socket for a session between two nodes bound by the underlying network transport and the maximum transmission unit (MTU) of C.

It also implements [AsyncRead] and [AsyncWrite] so that it can be used on top of the usual transport stack.

Based on the configuration, the SessionSocket can support:

• frame segmentation and reassembly
• segment and frame retransmission and reliability

See the module docs for details on retransmission.

Retransmission driven by the Receiver

sequenceDiagram Note over Sender,Receiver: Frame 1 rect rgb(191, 223, 255) Note left of Sender: Frame 1 in buffer Sender->>Receiver: Segment 1/3 of Frame 1 Sender->>Receiver: Segment 2/3 of Frame 1 Sender--xReceiver: Segment 3/3 of Frame 1 Note right of Receiver: RTO_BASE_RECEIVER elapsed Receiver->>Sender: Request Segment 3 of Frame 1 Sender->>Receiver: Segment 3/3 of Frame 1 Receiver->>Sender: Acknowledge Frame 1 Note left of Sender: Frame 1 dropped from buffer end Note over Sender,Receiver: Frame 1 delivered

Retransmission driven by the Sender

sequenceDiagram Note over Sender,Receiver: Frame 1 rect rgb(191, 223, 255) Note left of Sender: Frame 1 in buffer Sender->>Receiver: Segment 1/3 of Frame 1 Sender->>Receiver: Segment 2/3 of Frame 1 Sender--xReceiver: Segment 3/3 of Frame 1 Note right of Receiver: RTO_BASE_RECEIVER elapsed Receiver--xSender: Request Segment 3 of Frame 1 Note left of Sender: RTO_BASE_SENDER elapsed Sender->>Receiver: Segment 1/3 of Frame 1 Sender->>Receiver: Segment 2/3 of Frame 1 Sender->>Receiver: Segment 3/3 of Frame 1 Receiver->>Sender: Acknowledge Frame 1 Note left of Sender: Frame 1 dropped from buffer end Note over Sender,Receiver: Frame 1 delivered

Sender-Receiver retransmission handover

sequenceDiagram Note over Sender,Receiver: Frame 1 rect rgb(191, 223, 255) Note left of Sender: Frame 1 in buffer Sender->>Receiver: Segment 1/3 of Frame 1 Sender--xReceiver: Segment 2/3 of Frame 1 Sender--xReceiver: Segment 3/3 of Frame 1 Note right of Receiver: RTO_BASE_RECEIVER elapsed Receiver->>Sender: Request Segments 2,3 of Frame 1 Note left of Sender: RTO_BASE_SENDER cancelled Sender->>Receiver: Segment 2/3 of Frame 1 Sender--xReceiver: Segment 3/3 of Frame 1 Note right of Receiver: RTO_BASE_RECEIVER elapsed Receiver--xSender: Request Segments 3 of Frame 1 Note right of Receiver: RTO_BASE_RECEIVER elapsed Receiver->>Sender: Request Segments 3 of Frame 1 Sender->>Receiver: Segment 3/3 of Frame 1 Receiver->>Sender: Acknowledge Frame 1 Note left of Sender: Frame 1 dropped from buffer end Note over Sender,Receiver: Frame 1 delivered

Retransmission failure

sequenceDiagram Note over Sender,Receiver: Frame 1 rect rgb(191, 223, 255) Note left of Sender: Frame 1 in buffer Sender->>Receiver: Segment 1/3 of Frame 1 Sender->>Receiver: Segment 2/3 of Frame 1 Sender--xReceiver: Segment 3/3 of Frame 1 Note right of Receiver: RTO_BASE_RECEIVER elapsed Receiver--xSender: Request Segment 3 of Frame 1 Note left of Sender: RTO_BASE_SENDER elapsed Sender--xReceiver: Segment 1/3 of Frame 1 Sender--xReceiver: Segment 2/3 of Frame 1 Sender--xReceiver: Segment 3/3 of Frame 1 Note left of Sender: FRAME_MAX_AGE elapsed
Frame 1 dropped from buffer Note right of Receiver: FRAME_MAX_AGE elapsed
Frame 1 dropped from buffer end Note over Sender,Receiver: Frame 1 never delivered

Implementations

impl<const C: usize> SessionSocket<C>

pub const PAYLOAD_CAPACITY: usize = SessionState<C>::PAYLOAD_CAPACITY

Payload capacity is MTU minus the sizes of the Session protocol headers.

pub const MAX_WRITE_SIZE: usize = SessionState<C>::MAX_WRITE_SIZE

Maximum number of bytes that can be written in a single poll_write to the Session.

pub fn new<T, I>(id: I, transport: T, cfg: SessionConfig) -> Self

where T: AsyncWrite + AsyncRead + Send + 'static, I: Display + Send + 'static,

Create a new socket over the given underlying transport that binds the communicating parties. A human-readable session id also must be supplied.

pub fn state(&self) -> &SessionState<C>

Gets the state of this socket.

pub fn state_mut(&mut self) -> &mut SessionState<C>

Gets the mutable state of this socket.

Trait Implementations

impl<const C: usize> AsyncRead for SessionSocket<C>

fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize>>

Attempt to read from the AsyncRead into buf.

fn poll_read_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &mut [IoSliceMut<'_>], ) -> Poll<Result<usize, Error>>

Attempt to read from the AsyncRead into bufs using vectored IO operations.

impl<const C: usize> AsyncWrite for SessionSocket<C>

fn poll_write( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize>>

Attempt to write bytes from buf into the object.

fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to flush the object, ensuring that any buffered data reach their destination.

fn poll_close(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to close the object.

fn poll_write_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from bufs into the object using vectored IO operations.