com.amazonaws.services.kinesis.leases.impl

Class LeaseRenewer<T extends Lease>

java.lang.Object

com.amazonaws.services.kinesis.leases.impl.LeaseRenewer<T>

All Implemented Interfaces:

ILeaseRenewer<T>

public class LeaseRenewer<T extends Lease>
extends Object
implements ILeaseRenewer<T>

An implementation of ILeaseRenewer that uses DynamoDB via LeaseManager.

Constructor Summary

Constructors

Constructor and Description
LeaseRenewer(ILeaseManager<T> leaseManager, String workerIdentifier, long leaseDurationMillis, ExecutorService executorService) Constructor.

Method Summary

Modifier and Type	Method and Description
void	addLeasesToRenew(Collection<T> newLeases) Adds leases to this LeaseRenewer's set of currently held leases.
void	clearCurrentlyHeldLeases() Clears this LeaseRenewer's set of currently held leases.
void	dropLease(T lease) Stops the lease renewer from continunig to maintain the given lease.
T	getCurrentlyHeldLease(String leaseKey)
Map<String,T>	getCurrentlyHeldLeases()
void	initialize() Bootstrap initial set of leases from the LeaseManager (e.g.
void	renewLeases() Attempt to renew all currently held leases.
boolean	updateLease(T lease, UUID concurrencyToken) Update application-specific fields in a currently held lease.

Methods inherited from class java.lang.Object

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

Constructor Detail

LeaseRenewer

public LeaseRenewer(ILeaseManager<T> leaseManager,
                    String workerIdentifier,
                    long leaseDurationMillis,
                    ExecutorService executorService)

Constructor.

Parameters:

leaseManager - LeaseManager to use

workerIdentifier - identifier of this worker

leaseDurationMillis - duration of a lease in milliseconds

executorService - ExecutorService to use for renewing leases in parallel

Method Detail

renewLeases

public void renewLeases()
                 throws DependencyException,
                        InvalidStateException

Attempt to renew all currently held leases.

Specified by:

renewLeases in interface ILeaseRenewer<T extends Lease>

Throws:

DependencyException - on unexpected DynamoDB failures

InvalidStateException - if lease table does not exist

getCurrentlyHeldLeases

public Map<String,T> getCurrentlyHeldLeases()

Specified by:

getCurrentlyHeldLeases in interface ILeaseRenewer<T extends Lease>

Returns:

currently held leases. Key is shardId, value is corresponding Lease object. A lease is currently held if we successfully renewed it on the last run of renewLeases(). Lease objects returned are deep copies - their lease counters will not tick.

getCurrentlyHeldLease

public T getCurrentlyHeldLease(String leaseKey)

Specified by:

getCurrentlyHeldLease in interface ILeaseRenewer<T extends Lease>

Parameters:

leaseKey - key of the lease to retrieve

Returns:

a deep copy of a currently held lease, or null if we don't hold the lease

updateLease

public boolean updateLease(T lease,
                           UUID concurrencyToken)
                    throws DependencyException,
                           InvalidStateException,
                           ProvisionedThroughputException

Update application-specific fields in a currently held lease. Cannot be used to update internal fields such as leaseCounter, leaseOwner, etc. Fails if we do not hold the lease, or if the concurrency token does not match the concurrency token on the internal authoritative copy of the lease (ie, if we lost and re-acquired the lease).

Specified by:

updateLease in interface ILeaseRenewer<T extends Lease>

Parameters:

lease - lease object containing updated data

concurrencyToken - obtained by calling Lease.getConcurrencyToken for a currently held lease

Returns:

true if update succeeds, false otherwise

Throws:

DependencyException - if DynamoDB update fails in an unexpected way

InvalidStateException - if lease table does not exist

ProvisionedThroughputException - if DynamoDB update fails due to lack of capacity

addLeasesToRenew

public void addLeasesToRenew(Collection<T> newLeases)

Adds leases to this LeaseRenewer's set of currently held leases. Leases must have lastRenewalNanos set to the last time the lease counter was incremented before being passed to this method.

Specified by:

addLeasesToRenew in interface ILeaseRenewer<T extends Lease>

Parameters:

newLeases - new leases.

clearCurrentlyHeldLeases

public void clearCurrentlyHeldLeases()

Clears this LeaseRenewer's set of currently held leases.

Specified by:

clearCurrentlyHeldLeases in interface ILeaseRenewer<T extends Lease>

dropLease

public void dropLease(T lease)

Stops the lease renewer from continunig to maintain the given lease.

Specified by:

dropLease in interface ILeaseRenewer<T extends Lease>

Parameters:

lease - the lease to drop.

initialize

public void initialize()
                throws DependencyException,
                       InvalidStateException,
                       ProvisionedThroughputException

Bootstrap initial set of leases from the LeaseManager (e.g. upon process restart, pick up leases we own)

Specified by:

initialize in interface ILeaseRenewer<T extends Lease>

Throws:

DependencyException - on unexpected DynamoDB failures

InvalidStateException - if lease table doesn't exist

ProvisionedThroughputException - if DynamoDB reads fail due to insufficient capacity