Struct Metadata 

pub struct Metadata { /* private fields */ }

What the client knows about the cluster.

Implementations

impl Metadata

pub fn new() -> Self

pub fn update(&mut self, resp: &MetadataResponse)

Merge a MetadataResponse in.

Merge rather than replace: a response for one topic says nothing about the others, and replacing would silently drop leadership the client is actively using. Partitions carrying an error code are skipped, not recorded as leaderless — an error means “ask again”, and writing it down would cache the failure.

pub fn leader_for(&self, topic: &str, partition: i32) -> Option<&BrokerAddr>

Where to send a request for this partition, if known.

pub fn broker(&self, node_id: i32) -> Option<&BrokerAddr>

Look a broker up by node id — how a coordinator, which is named by id rather than address, is reached.

pub fn controller(&self) -> Option<&BrokerAddr>

The controller, if one has been named and its address is known.

pub fn invalidate_controller(&mut self)

Forget which broker is the controller, after it said it is not.

pub fn invalidate_partition(&mut self, topic: &str, partition: i32)

Forget one partition’s leader, leaving the rest of the map alone.

pub fn partition_count(&self, topic: &str) -> i32

How many partitions this topic has, or 0 if it has never been seen.

Taken from the last response that named the topic, so it is stable across elections: a partition without a leader still exists, and a count that dipped while one was being elected would silently move every key.

pub fn forget_topic(&mut self, topic: &str)

Forget a topic entirely — its count and every leader.

For a topic that was deleted. Deletion is the only way a partition count goes down, and it goes down by going away.

pub fn brokers(&self) -> impl Iterator<Item = &BrokerAddr>

Every broker the client has heard of, for connection cleanup.

pub fn is_empty(&self) -> bool

Trait Implementations

impl Debug for Metadata

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

Formats the value using the given formatter.

impl Default for Metadata

fn default() -> Metadata

Returns the “default value” for a type.