Trait SessionState 

pub trait SessionState {
    // Required methods
    fn store_outgoing_qos1(
        &mut self,
        packet_id: PacketId,
        topic: &Topic,
        payload: &[u8],
        retain: bool,
        properties: &PublishProperties,
    );
    fn remove_outgoing_qos1(&mut self, packet_id: PacketId);
    fn store_outgoing_qos2(
        &mut self,
        packet_id: PacketId,
        phase: Qos2Phase,
        topic: &Topic,
        payload: &[u8],
        retain: bool,
        properties: &PublishProperties,
    );
    fn advance_outgoing_qos2(&mut self, packet_id: PacketId);
    fn remove_outgoing_qos2(&mut self, packet_id: PacketId);
    fn store_incoming_qos2(&mut self, packet_id: PacketId);
    fn remove_incoming_qos2(&mut self, packet_id: PacketId);
    fn has_outgoing_qos1(&self, packet_id: PacketId) -> bool;
    fn has_outgoing_qos2(&self, packet_id: PacketId) -> bool;
    fn has_incoming_qos2(&self, packet_id: PacketId) -> bool;
    fn try_for_each_outgoing_qos1<B>(
        &self,
        f: Qos1Callback<'_, B>,
    ) -> ControlFlow<B>;
    fn try_for_each_outgoing_qos2<B>(
        &self,
        f: &mut dyn FnMut(OutgoingQos2<'_>) -> ControlFlow<B>,
    ) -> ControlFlow<B>;
    fn try_for_each_incoming_qos2<B>(
        &self,
        f: &mut dyn FnMut(PacketId) -> ControlFlow<B>,
    ) -> ControlFlow<B>;
    fn clear(&mut self);
}

Persistent session state that must survive across network connections.

Contract

Implementors must persist state durably when Session Expiry Interval > 0 (§3.1.2.11.2). When the interval is 0 (or absent), state only needs to live for the duration of the network connection.

No-alloc note

This trait uses an iterator-based try_for_each_* pattern instead of returning collections, keeping the crate no_alloc-compatible.

Callback type alias

Qos1Callback is provided to keep the QoS 1 visitor signature readable.

Required Methods

fn store_outgoing_qos1( &mut self, packet_id: PacketId, topic: &Topic, payload: &[u8], retain: bool, properties: &PublishProperties, )

Store a QoS 1 outbound publish (PUBLISH sent, awaiting PUBACK).

packet_id is the identifier assigned to the PUBLISH. topic and payload are the message content that must be stored so the message can be retransmitted with DUP=1 on reconnect.

fn remove_outgoing_qos1(&mut self, packet_id: PacketId)

Remove a QoS 1 outbound publish after PUBACK is received.

fn store_outgoing_qos2( &mut self, packet_id: PacketId, phase: Qos2Phase, topic: &Topic, payload: &[u8], retain: bool, properties: &PublishProperties, )

Store a QoS 2 outbound publish.

When phase is Qos2Phase::AwaitingPubrec, topic and payload contain the message content. When phase is Qos2Phase::AwaitingPubcomp, they may be empty (the implementation should discard the message payload per §4.3.3).

fn advance_outgoing_qos2(&mut self, packet_id: PacketId)

Advance a QoS 2 outbound publish to the PUBREL-sent phase.

Called when PUBREC is received with rc < 0x80. Implementations should update the phase and may discard the message payload.

fn remove_outgoing_qos2(&mut self, packet_id: PacketId)

Remove a QoS 2 outbound publish after PUBCOMP is received (or PUBREC with rc ≥ 0x80).

fn store_incoming_qos2(&mut self, packet_id: PacketId)

Store a QoS 2 inbound packet identifier (PUBREC sent, awaiting PUBREL from the server).

fn remove_incoming_qos2(&mut self, packet_id: PacketId)

Remove a QoS 2 inbound packet identifier after PUBREL is received and PUBCOMP has been sent.

fn has_outgoing_qos1(&self, packet_id: PacketId) -> bool

Check whether a QoS 1 outbound publish is stored for this packet ID.

fn has_outgoing_qos2(&self, packet_id: PacketId) -> bool

Check whether a QoS 2 outbound publish is stored for this packet ID.

fn has_incoming_qos2(&self, packet_id: PacketId) -> bool

Check whether a QoS 2 inbound packet identifier is stored (i.e., PUBREC was already sent for this packet ID).

fn try_for_each_outgoing_qos1<B>( &self, f: Qos1Callback<'_, B>, ) -> ControlFlow<B>

Iterate over all stored outgoing QoS 1 messages for retransmission on reconnect.

The callback receives (packet_id, topic, payload) for each stored message. Return ControlFlow::Break to stop early.

fn try_for_each_outgoing_qos2<B>( &self, f: &mut dyn FnMut(OutgoingQos2<'_>) -> ControlFlow<B>, ) -> ControlFlow<B>

Iterate over all stored outgoing QoS 2 messages for retransmission on reconnect.

For messages in Qos2Phase::AwaitingPubcomp, topic and payload may be empty. Return ControlFlow::Break to stop early.

fn try_for_each_incoming_qos2<B>( &self, f: &mut dyn FnMut(PacketId) -> ControlFlow<B>, ) -> ControlFlow<B>

Iterate over all stored incoming QoS 2 packet identifiers for re-acknowledging on reconnect.

Return ControlFlow::Break to stop early.

fn clear(&mut self)

Clear all session state. Called when connecting with Clean Start = 1.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl SessionState for InMemorySession

Available on crate feature alloc only.

impl SessionState for JournaledSession

Available on crate feature alloc only.