Struct Pending 

pub(super) struct Pending {
    pub(super) publishes: HashMap<PacketId, PendingPublish>,
    pub(super) acks: HashMap<PacketId, PendingAck>,
    deadlines: BTreeSet<(Instant, PacketId)>,
    ack_timeout: Option<Duration>,
}

Fields

publishes: HashMap<PacketId, PendingPublish>

User-visible publish completions, keyed by the wire packet identifier. Per §4.4 the packet identifier is preserved across reconnects when the session is resumed, so it doubles as the stable handle for correlating PUBACK/PUBCOMP with the originating publish future.

acks: HashMap<PacketId, PendingAck>

SUBSCRIBE and UNSUBSCRIBE completions, keyed by packet id. Packet ids are unique across operations, so a single map serves both (a SUBACK and an UNSUBACK can never collide on the same id).

deadlines: BTreeSet<(Instant, PacketId)>

Ack-timeout schedule: one (deadline, packet_id) per in-flight operation that has been written to the wire, ordered so the earliest deadline is first. Empty when ack_timeout is disabled. Entries are removed exactly (keyed by the deadline stored on the operation) as operations are acknowledged, so no stale entry ever survives to fire.

ack_timeout: Option<Duration>

Per-operation acknowledgement deadline. None disables the schedule.

Implementations

impl Pending

pub(super) fn new(ack_timeout: Option<Duration>) -> Self

pub(super) fn earliest_deadline(&self) -> Option<Instant>

Earliest outstanding ack deadline, if any. The event loop arms its ack timer to this instant.

pub(super) fn mark_publish_sent(&mut self, packet_id: PacketId)

Arms (or re-arms, on retransmit) the ack deadline for a just-sent publish, including a QoS 2 PUBREL retransmit (same packet id as the publish it completes). No-op when the timeout is disabled or the publish is no longer tracked.

pub(super) fn mark_ack_sent(&mut self, packet_id: PacketId)

Arms the ack deadline for a just-sent SUBSCRIBE/UNSUBSCRIBE. No-op when the timeout is disabled or the operation is no longer tracked.

pub(super) fn remove_publish( &mut self, packet_id: PacketId, ) -> Option<PendingPublish>

Removes a publish, dropping its ack-deadline schedule entry.

pub(super) fn remove_ack(&mut self, packet_id: PacketId) -> Option<PendingAck>

Removes a SUBSCRIBE/UNSUBSCRIBE, dropping its ack-deadline schedule entry.

pub(super) fn fail_all(&mut self)

Fails every outstanding operation; used on user-requested disconnect when the client is being torn down. In-flight publishes are also failed (their futures resolve with Error::ConnectionClosed); the messages themselves remain in the session for retransmission on the next connection.

pub(super) fn fail_superseded_acks(&mut self, client: &Client<JournaledSession>)

Fails parked SUBSCRIBE/UNSUBSCRIBE completions superseded by a later request for the same filter, dropping their ack-deadline entries. See fail_superseded_acks.