com.amazonaws.services.kinesis.leases.impl

Class Lease

java.lang.Object

com.amazonaws.services.kinesis.leases.impl.Lease

Direct Known Subclasses:

KinesisClientLease

public class Lease
extends Object

This class contains data pertaining to a Lease. Distributed systems may use leases to partition work across a fleet of workers. Each unit of work (identified by a leaseKey) has a corresponding Lease. Every worker will contend for all leases - only one worker will successfully take each one. The worker should hold the lease until it is ready to stop processing the corresponding unit of work, or until it fails. When the worker stops holding the lease, another worker will take and hold the lease.

Constructor Summary

Constructors

Modifier	Constructor and Description
	Lease() Constructor.
protected	Lease(Lease lease) Copy constructor, used by clone().
protected	Lease(String leaseKey, String leaseOwner, Long leaseCounter, UUID concurrencyToken, Long lastCounterIncrementNanos)

Method Summary

Modifier and Type	Method and Description
<T extends Lease> T	copy() Returns a deep copy of this object.
boolean	equals(Object obj)
UUID	getConcurrencyToken()
Long	getLastCounterIncrementNanos()
Long	getLeaseCounter()
String	getLeaseKey()
String	getLeaseOwner()
int	hashCode()
boolean	isExpired(long leaseDurationNanos, long asOfNanos)
void	setConcurrencyToken(UUID concurrencyToken) Sets concurrencyToken.
void	setLastCounterIncrementNanos(Long lastCounterIncrementNanos) Sets lastCounterIncrementNanos
void	setLeaseCounter(Long leaseCounter) Sets leaseCounter.
void	setLeaseKey(String leaseKey) Sets leaseKey.
void	setLeaseOwner(String leaseOwner) Sets leaseOwner.
String	toString()
<T extends Lease> void	update(T other) Updates this Lease's mutable, application-specific fields based on the passed-in lease object.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Lease

public Lease()

Constructor.

Lease

protected Lease(Lease lease)

Copy constructor, used by clone().

Parameters:

lease - lease to copy

Lease

protected Lease(String leaseKey,
                String leaseOwner,
                Long leaseCounter,
                UUID concurrencyToken,
                Long lastCounterIncrementNanos)

Method Detail

update

public <T extends Lease> void update(T other)

Updates this Lease's mutable, application-specific fields based on the passed-in lease object. Does not update fields that are internal to the leasing library (leaseKey, leaseOwner, leaseCounter).

Parameters:

other -

getLeaseKey

public String getLeaseKey()

Returns:

leaseKey - identifies the unit of work associated with this lease.

getLeaseCounter

public Long getLeaseCounter()

Returns:

leaseCounter is incremented periodically by the holder of the lease. Used for optimistic locking.

getLeaseOwner

public String getLeaseOwner()

Returns:

current owner of the lease, may be null.

getConcurrencyToken

public UUID getConcurrencyToken()

Returns:

concurrency token

getLastCounterIncrementNanos

public Long getLastCounterIncrementNanos()

Returns:

last update in nanoseconds since the epoch

isExpired

public boolean isExpired(long leaseDurationNanos,
                         long asOfNanos)

Parameters:

leaseDurationNanos - duration of lease in nanoseconds

asOfNanos - time in nanoseconds to check expiration as-of

Returns:

true if lease is expired as-of given time, false otherwise

setLastCounterIncrementNanos

public void setLastCounterIncrementNanos(Long lastCounterIncrementNanos)

Sets lastCounterIncrementNanos

Parameters:

lastCounterIncrementNanos - last renewal in nanoseconds since the epoch

setConcurrencyToken

public void setConcurrencyToken(UUID concurrencyToken)

Sets concurrencyToken.

Parameters:

concurrencyToken - may not be null

setLeaseKey

public void setLeaseKey(String leaseKey)

Sets leaseKey. LeaseKey is immutable once set.

Parameters:

leaseKey - may not be null.

setLeaseCounter

public void setLeaseCounter(Long leaseCounter)

Sets leaseCounter.

Parameters:

leaseCounter - may not be null

setLeaseOwner

public void setLeaseOwner(String leaseOwner)

Sets leaseOwner.

Parameters:

leaseOwner - may be null.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

copy

public <T extends Lease> T copy()

Returns a deep copy of this object. Type-unsafe - there aren't good mechanisms for copy-constructing generics.

Returns:

A deep copy of this object.