org.apache.kafka.clients.producer.internals
Class Metadata

java.lang.Object
  org.apache.kafka.clients.producer.internals.Metadata

public final class Metadata
extends java.lang.Object

A class encapsulating some of the logic around metadata.

This class is shared by the client thread (for partitioning) and the background sender thread. Metadata is maintained for only a subset of topics, which can be added to over time. When we request metdata for a topic we don't have any metadata for it will trigger a metadata update.

Constructor Summary

Metadata()
Create a metadata instance with reasonable defaults

Metadata(long refreshBackoffMs, long metadataExpireMs)
Create a new Metadata instance

Method Summary

void	add(java.lang.String topic) Add the topic to maintain in the metadata
void	awaitUpdate(int lastVerison, long maxWaitMs) Wait for metadata update until the current version is larger than the last version we know of
Cluster	fetch() Get the current cluster info without blocking
long	lastUpdate() The last time metadata was updated.
long	refreshBackoff() The metadata refresh backoff in ms
int	requestUpdate() Request an update of the current cluster metadata info, return the current version before the update
long	timeToNextUpdate(long nowMs) The next time to update the cluster info is the maximum of the time the current info will expire and the time the current info can be updated (i.e.
java.util.Set<java.lang.String>	topics() Get the list of topics we are currently maintaining metadata for
void	update(Cluster cluster, long now) Update the cluster metadata

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Metadata

public Metadata()

Create a metadata instance with reasonable defaults

Metadata

public Metadata(long refreshBackoffMs,
                long metadataExpireMs)

Create a new Metadata instance

Parameters:

refreshBackoffMs - The minimum amount of time that must expire between metadata refreshes to avoid busy polling

metadataExpireMs - The maximum amount of time that metadata can be retained without refresh

Method Detail

fetch

public Cluster fetch()

Get the current cluster info without blocking

add

public void add(java.lang.String topic)

Add the topic to maintain in the metadata

timeToNextUpdate

public long timeToNextUpdate(long nowMs)

The next time to update the cluster info is the maximum of the time the current info will expire and the time the current info can be updated (i.e. backoff time has elapsed); If an update has been request then the expiry time is now

requestUpdate

public int requestUpdate()

Request an update of the current cluster metadata info, return the current version before the update

awaitUpdate

public void awaitUpdate(int lastVerison,
                        long maxWaitMs)

Wait for metadata update until the current version is larger than the last version we know of

topics

public java.util.Set<java.lang.String> topics()

Get the list of topics we are currently maintaining metadata for

update

public void update(Cluster cluster,
                   long now)

Update the cluster metadata

lastUpdate

public long lastUpdate()

The last time metadata was updated.

refreshBackoff

public long refreshBackoff()

The metadata refresh backoff in ms