com.amazonaws.services.kinesis.leases.impl

Class LeaseCoordinator<T extends Lease>

java.lang.Object

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

Direct Known Subclasses:

KinesisClientLibLeaseCoordinator

public class LeaseCoordinator<T extends Lease>
extends Object

LeaseCoordinator abstracts away LeaseTaker and LeaseRenewer from the application code that's using leasing. It owns the scheduling of the two previously mentioned components as well as informing LeaseRenewer when LeaseTaker takes new leases.

Field Summary

Fields

Modifier and Type	Field and Description
protected IMetricsFactory	metricsFactory
static String	WORKER_IDENTIFIER_METRIC

Constructor Summary

Constructors

Constructor and Description
LeaseCoordinator(ILeaseManager<T> leaseManager, LeaseSelector<T> leaseSelector, String workerIdentifier, long leaseDurationMillis, long epsilonMillis) Constructor.
LeaseCoordinator(ILeaseManager<T> leaseManager, LeaseSelector<T> leaseSelector, String workerIdentifier, long leaseDurationMillis, long epsilonMillis, IMetricsFactory metricsFactory) Constructor.
LeaseCoordinator(ILeaseManager<T> leaseManager, LeaseSelector<T> leaseSelector, String workerIdentifier, long leaseDurationMillis, long epsilonMillis, int maxLeasesForWorker, int maxLeasesToStealAtOneTime, int maxLeaseRenewerThreadCount, IMetricsFactory metricsFactory)
LeaseCoordinator(ILeaseManager<T> leaseManager, String workerIdentifier, long leaseDurationMillis, long epsilonMillis) Constructor.
LeaseCoordinator(ILeaseManager<T> leaseManager, String workerIdentifier, long leaseDurationMillis, long epsilonMillis, IMetricsFactory metricsFactory) Constructor.
LeaseCoordinator(ILeaseManager<T> leaseManager, String workerIdentifier, long leaseDurationMillis, long epsilonMillis, int maxLeasesForWorker, int maxLeasesToStealAtOneTime, int maxLeaseRenewerThreadCount, IMetricsFactory metricsFactory) Constructor.
LeaseCoordinator(ILeaseTaker<T> leaseTaker, ILeaseRenewer<T> leaseRenewer, long leaseDurationMillis, long epsilonMillis, int maxLeasesForWorker, int maxLeasesToStealAtOneTime, IMetricsFactory metricsFactory)

Method Summary

Modifier and Type	Method and Description
void	dropLease(T lease) Requests that renewals for the given lease are stopped.
Collection<T>	getAssignments()
T	getCurrentlyHeldLease(String leaseKey)
static ExecutorService	getDefaultLeaseRenewalExecutorService(int maximumPoolSize) Returns executor service that should be used for lease renewal.
String	getWorkerIdentifier()
boolean	isRunning()
protected void	runRenewer() Runs a single iteration of the lease renewer - used by integration tests.
protected void	runTaker() Runs a single iteration of the lease taker - used by integration tests.
void	start() Start background LeaseHolder and LeaseTaker threads.
void	stop() Stops background threads and waits for STOP_WAIT_TIME_MILLIS for all background tasks to complete.
void	stopLeaseTaker() Requests the cancellation of the lease taker.
boolean	updateLease(T lease, UUID concurrencyToken) Updates application-specific lease values in DynamoDB.

Methods inherited from class java.lang.Object

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

Field Detail

WORKER_IDENTIFIER_METRIC

public static final String WORKER_IDENTIFIER_METRIC

See Also:

Constant Field Values

metricsFactory

protected final IMetricsFactory metricsFactory

Constructor Detail

LeaseCoordinator

public LeaseCoordinator(ILeaseManager<T> leaseManager,
                        String workerIdentifier,
                        long leaseDurationMillis,
                        long epsilonMillis)

Constructor.

Parameters:

leaseManager - LeaseManager instance to use

workerIdentifier - Identifies the worker (e.g. useful to track lease ownership)

leaseDurationMillis - Duration of a lease

epsilonMillis - Allow for some variance when calculating lease expirations

LeaseCoordinator

public LeaseCoordinator(ILeaseManager<T> leaseManager,
                        LeaseSelector<T> leaseSelector,
                        String workerIdentifier,
                        long leaseDurationMillis,
                        long epsilonMillis)

Constructor.

Parameters:

leaseManager - LeaseManager instance to use

leaseSelector - LeaseSelector instance to use

workerIdentifier - Identifies the worker (e.g. useful to track lease ownership)

leaseDurationMillis - Duration of a lease

epsilonMillis - Allow for some variance when calculating lease expirations

LeaseCoordinator

public LeaseCoordinator(ILeaseManager<T> leaseManager,
                        String workerIdentifier,
                        long leaseDurationMillis,
                        long epsilonMillis,
                        IMetricsFactory metricsFactory)

Constructor.

Parameters:

leaseManager - LeaseManager instance to use

workerIdentifier - Identifies the worker (e.g. useful to track lease ownership)

leaseDurationMillis - Duration of a lease

epsilonMillis - Allow for some variance when calculating lease expirations

metricsFactory - Used to publish metrics about lease operations

LeaseCoordinator

public LeaseCoordinator(ILeaseManager<T> leaseManager,
                        LeaseSelector<T> leaseSelector,
                        String workerIdentifier,
                        long leaseDurationMillis,
                        long epsilonMillis,
                        IMetricsFactory metricsFactory)

Constructor.

Parameters:

leaseManager - LeaseManager instance to use

leaseSelector - LeaseSelector instance to use

workerIdentifier - Identifies the worker (e.g. useful to track lease ownership)

leaseDurationMillis - Duration of a lease

epsilonMillis - Allow for some variance when calculating lease expirations

metricsFactory - Used to publish metrics about lease operations

LeaseCoordinator

public LeaseCoordinator(ILeaseManager<T> leaseManager,
                        String workerIdentifier,
                        long leaseDurationMillis,
                        long epsilonMillis,
                        int maxLeasesForWorker,
                        int maxLeasesToStealAtOneTime,
                        int maxLeaseRenewerThreadCount,
                        IMetricsFactory metricsFactory)

Constructor.

Parameters:

leaseManager - LeaseManager instance to use

workerIdentifier - Identifies the worker (e.g. useful to track lease ownership)

leaseDurationMillis - Duration of a lease

epsilonMillis - Allow for some variance when calculating lease expirations

maxLeasesForWorker - Max leases this Worker can handle at a time

maxLeasesToStealAtOneTime - Steal up to these many leases at a time (for load balancing)

metricsFactory - Used to publish metrics about lease operations

LeaseCoordinator

public LeaseCoordinator(ILeaseManager<T> leaseManager,
                        LeaseSelector<T> leaseSelector,
                        String workerIdentifier,
                        long leaseDurationMillis,
                        long epsilonMillis,
                        int maxLeasesForWorker,
                        int maxLeasesToStealAtOneTime,
                        int maxLeaseRenewerThreadCount,
                        IMetricsFactory metricsFactory)

Parameters:

leaseManager - LeaseManager instance to use

leaseSelector - LeaseSelector instance to be used for filtering leases during LeaseTaker execution.

workerIdentifier - Identifies the worker (e.g. useful to track lease ownership)

leaseDurationMillis - Duration of a lease

epsilonMillis - Allow for some variance when calculating lease expirations

maxLeasesForWorker - Max leases this Worker can handle at a time

maxLeasesToStealAtOneTime - Steal up to these many leases at a time (for load balancing)

maxLeaseRenewerThreadCount - Number of threads to use for lease renewal calls

metricsFactory - Used to publish metrics about lease operations

LeaseCoordinator

public LeaseCoordinator(ILeaseTaker<T> leaseTaker,
                        ILeaseRenewer<T> leaseRenewer,
                        long leaseDurationMillis,
                        long epsilonMillis,
                        int maxLeasesForWorker,
                        int maxLeasesToStealAtOneTime,
                        IMetricsFactory metricsFactory)

Parameters:

leaseTaker - LeaseTaker instance to be used.

leaseRenewer - LeaseRenewer instance to be used.

leaseDurationMillis - Duration of a lease

epsilonMillis - Allow for some variance when calculating lease expirations

maxLeasesForWorker - Max leases this Worker can handle at a time

maxLeasesToStealAtOneTime - Steal up to these many leases at a time (for load balancing)

metricsFactory - Used to publish metrics about lease operations

Method Detail

start

public void start()
           throws DependencyException,
                  InvalidStateException,
                  ProvisionedThroughputException

Start background LeaseHolder and LeaseTaker threads.

Throws:

ProvisionedThroughputException - If we can't talk to DynamoDB due to insufficient capacity.

InvalidStateException - If the lease table doesn't exist

DependencyException - If we encountered exception taking to DynamoDB

runTaker

protected void runTaker()
                 throws DependencyException,
                        InvalidStateException

Runs a single iteration of the lease taker - used by integration tests.

Throws:

InvalidStateException

DependencyException

runRenewer

protected void runRenewer()
                   throws DependencyException,
                          InvalidStateException

Runs a single iteration of the lease renewer - used by integration tests.

Throws:

InvalidStateException

DependencyException

getAssignments

public Collection<T> getAssignments()

Returns:

currently held leases

getCurrentlyHeldLease

public T getCurrentlyHeldLease(String leaseKey)

Parameters:

leaseKey - lease key to fetch currently held lease for

Returns:

deep copy of currently held Lease for given key, or null if we don't hold the lease for that key

getWorkerIdentifier

public String getWorkerIdentifier()

Returns:

workerIdentifier

stop

public void stop()

Stops background threads and waits for STOP_WAIT_TIME_MILLIS for all background tasks to complete. If tasks are not completed after this time, method will shutdown thread pool forcefully and return.

stopLeaseTaker

public void stopLeaseTaker()

Requests the cancellation of the lease taker.

dropLease

public void dropLease(T lease)

Requests that renewals for the given lease are stopped.

Parameters:

lease - the lease to stop renewing.

isRunning

public boolean isRunning()

Returns:

true if this LeaseCoordinator is running

updateLease

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

Updates application-specific lease values in DynamoDB.

Parameters:

lease - lease object containing updated values

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

Returns:

true if update succeeded, false otherwise

Throws:

InvalidStateException - if lease table does not exist

ProvisionedThroughputException - if DynamoDB update fails due to lack of capacity

DependencyException - if DynamoDB update fails in an unexpected way

getDefaultLeaseRenewalExecutorService

public static ExecutorService getDefaultLeaseRenewalExecutorService(int maximumPoolSize)

Returns executor service that should be used for lease renewal.

Parameters:

maximumPoolSize - Maximum allowed thread pool size

Returns:

Executor service that should be used for lease renewal.