Struct GroupMember 

pub struct GroupMember { /* private fields */ }

One member of one group.

Implementations

impl GroupMember

pub fn new(group_id: impl Into<String>, topics: Vec<String>) -> Self

pub fn with_protocol(self, protocol: RebalanceProtocol) -> Self

Use the cooperative protocol (KIP-429) rather than the eager one.

pub fn protocol(&self) -> RebalanceProtocol

pub fn lost(&self) -> &[TopicPartition]

What the last sync took away, for the caller to stop reading before it rejoins. Cooperative only; empty under the eager protocol, which revokes everything instead.

pub fn group_id(&self) -> &str

pub fn topics(&self) -> &[String]

What this member is subscribed to.

pub fn state(&self) -> MemberState

pub fn generation(&self) -> i32

pub fn member_id(&self) -> &str

pub fn is_leader(&self) -> bool

pub fn assignment(&self) -> &[TopicPartition]

What this member currently owns. Empty unless MemberState::Stable.

pub fn can_commit(&self) -> bool

Whether offsets may be committed right now.

Only in MemberState::Stable. Committing mid-rebalance is how a member writes an offset for a partition another member already owns — the coordinator would reject it as a stale generation, but only if the generation had already moved, and between revocation and rejoin it has not. The rule is cheaper than reasoning about the race.

pub fn step(&self) -> Step

What to do next, given where we are.

pub fn subscription(&self) -> Subscription

The subscription this member sends in JoinGroup.

pub fn set_topics(&mut self, topics: Vec<String>)

Change what this member wants to read. Forces a rejoin, because the group has to agree on the subscription before it can be assigned.

pub fn request_rejoin(&mut self)

Rejoin at the next step, keeping the subscription as it is.

For a change the group must agree on that is not a change of topics: a subscribed topic growing partitions is the case that exists. Only the leader computes an assignment, and it does so from metadata at join time — so the group learns about new partitions by rejoining, and nothing else makes it rejoin. Without this, a stable group keeps its old assignment until some unrelated rebalance happens to come along, and the new partitions go unread until then.

pub fn on_join( &mut self, error: i16, generation: i32, member_id: &str, leader_id: &str, members: Vec<Subscription>, ) -> Step

JoinGroup answered.

members is non-empty only for the leader. Returns the next step.

pub fn on_sync(&mut self, error: i16, assigned: Vec<TopicPartition>) -> Step

SyncGroup answered, carrying this member’s assignment.

pub fn on_heartbeat(&mut self, error: i16) -> Step

A Heartbeat answered.

pub fn on_leave(&mut self)

Leaving deliberately, so the group rebalances now rather than at the session timeout.

pub fn my_share(&self, assignment: &Assignment) -> Vec<TopicPartition>

The assignment the leader computed, for the leader’s own SyncGroup.

Trait Implementations

impl Clone for GroupMember

fn clone(&self) -> GroupMember

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for GroupMember

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.