org.zalando.nakadi.service.subscription.zk

Interface ZkSubscriptionClient

All Known Implementing Classes:

CuratorZkSubscriptionClient

public interface ZkSubscriptionClient

Method Summary

Modifier and Type	Method and Description
boolean	createSubscription() Creates subscription node in zookeeper on path /nakadi/subscriptions/{subscriptionId}
void	fillEmptySubscription(java.util.Map<Partition.PartitionKey,java.lang.Long> partitions) Fills subscription object using partitions information provided (mapping from (topic, partition) to real offset (NOT "BEGIN").
long	getOffset(Partition.PartitionKey key) Returns current offset value for specified partition key.
void	incrementTopology() Increments value in /nakadi/subscriptions/{subscriptionId}/topology_version
boolean	isSubscriptionCreated() Checks if path /nakadi/subscriptions/{subscriptionId} exists in zookeeper
Partition[]	listPartitions() List partitions
Session[]	listSessions() Returns session list in zk related to this subscription.
void	registerSession(Session session) Registers client connection using session id in /nakadi/subscriptions/{subscriptionId}/sessions/{session.id} and value {{session.weight}}
void	runLocked(java.lang.Runnable function) Makes runLocked on subscription, using zk path /nakadi/locks/subscription_{subscriptionId} Lock is created as an ephemeral node, so it will be deleted if nakadi go down.
ZKSubscription	subscribeForOffsetChanges(Partition.PartitionKey key, java.lang.Runnable commitListener)
ZKSubscription	subscribeForSessionListChanges(java.lang.Runnable listener) Subscribes to changes of session list in /nakadi/subscriptions/{subscriptionId}/sessions.
ZKSubscription	subscribeForTopologyChanges(java.lang.Runnable listener) Subscribe for topology changes.
void	transfer(java.lang.String sessionId, java.util.Collection<Partition.PartitionKey> partitions) Transfers partitions to next client using data in zk.
void	unregisterSession(Session session)
void	updatePartitionConfiguration(Partition partition) Updates specified partition in zk.

Method Detail

runLocked

void runLocked(java.lang.Runnable function)

Makes runLocked on subscription, using zk path /nakadi/locks/subscription_{subscriptionId} Lock is created as an ephemeral node, so it will be deleted if nakadi go down. After obtaining runLocked, provided function will be called under subscription runLocked

Parameters:

function - Function to call in context of runLocked.

isSubscriptionCreated

boolean isSubscriptionCreated()
                       throws java.lang.Exception

Checks if path /nakadi/subscriptions/{subscriptionId} exists in zookeeper

Returns:

true if exists, false otherwise

Throws:

java.lang.Exception - if zk is in incorrect state

createSubscription

boolean createSubscription()

Creates subscription node in zookeeper on path /nakadi/subscriptions/{subscriptionId}

Returns:

true if subscription was created. False if subscription already present. To operate on this value additional field 'state' is used /nakadi/subscriptions/{subscriptionId}/state. Just after creation it has value CREATED. After {fillEmptySubscription(Map)} call it will have value INITIALIZED. So true will be returned in case of state is equal to CREATED.

fillEmptySubscription

void fillEmptySubscription(java.util.Map<Partition.PartitionKey,java.lang.Long> partitions)

Fills subscription object using partitions information provided (mapping from (topic, partition) to real offset (NOT "BEGIN"). Generated object in zk will look like this nakadi - {subscription_id} |- state: INITIALIZED |- event-types: ||- et1: |||- partitions: || |- 0: {session: null, next_session: null, state: UNASSIGNED} || ||- offset: {OFFSET} || |- 1: {session: null, next_session: null, state: UNASSIGNED} || |- offset: {OFFSET} ||- et2: | |-partitions: | |- 0: {session: null, next_session: null, state: UNASSIGNED} | ||- offset: {OFFSET} | |- 1: {session: null, next_session: null, state: UNASSIGNED} | |- offset: {OFFSET}

Parameters:

partitions - Data to use for subscription filling.

updatePartitionConfiguration

void updatePartitionConfiguration(Partition partition)

Updates specified partition in zk.

Parameters:

partition - Partition to update

incrementTopology

void incrementTopology()

Increments value in /nakadi/subscriptions/{subscriptionId}/topology_version

listSessions

Session[] listSessions()

Returns session list in zk related to this subscription.

Returns:

List of existing sessions.

listPartitions

Partition[] listPartitions()

List partitions

Returns:

list of partitions related to this subscription.

subscribeForSessionListChanges

ZKSubscription subscribeForSessionListChanges(java.lang.Runnable listener)

Subscribes to changes of session list in /nakadi/subscriptions/{subscriptionId}/sessions. Each time list is changed calls {listener} subscription.

Parameters:

listener - method to call on any change of client list.

Returns:

subscription

subscribeForTopologyChanges

ZKSubscription subscribeForTopologyChanges(java.lang.Runnable listener)

Subscribe for topology changes.

Parameters:

listener - called whenever /nakadi/subscriptions/{subscriptionId}/topology node is changed.

Returns:

Subscription instance

subscribeForOffsetChanges

ZKSubscription subscribeForOffsetChanges(Partition.PartitionKey key,
                                         java.lang.Runnable commitListener)

getOffset

long getOffset(Partition.PartitionKey key)

Returns current offset value for specified partition key.

Parameters:

key - Key to get offset for

Returns:

commit offset

registerSession

void registerSession(Session session)

Registers client connection using session id in /nakadi/subscriptions/{subscriptionId}/sessions/{session.id} and value {{session.weight}}

Parameters:

session - Session to register.

unregisterSession

void unregisterSession(Session session)

transfer

void transfer(java.lang.String sessionId,
              java.util.Collection<Partition.PartitionKey> partitions)

Transfers partitions to next client using data in zk. Updates topology_version if needed.

Parameters:

sessionId - Someone who actually tries to transfer data.

partitions - topic ids and partition ids of transferred data.